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Atolls islands are biogenic landforms that are intrinsically capable of adjusting their size, position, and elevation to changing sea levels. The vulnerability of atoll islands to sea level rise is not intrinsically due to their low elevation but primarily due to the loss of their island building capacity. The geophysical processes that control atoll island accretion are being impacted on global and local scales. Protecting and restoring the natural geophysical processes of atoll island accretion through local conservation actions is key to unlocking nature-based opportunities for enhancing atoll resilience to global change. Atoll islands are often perceived as inevitably lost due to rising sea levels. However, unlike other islands, atoll islands are dynamic landforms that have evolved, at least historically, to vertically accrete at a pace commensurate with changing sea levels. Rather than atoll islands' low elevation per se , the impairment of natural accretion processes is jeopardising their persistence. While global marine impacts are deteriorating coral reefs, local impacts also significantly affect accretion, together potentially tipping the scales toward atoll island erosion. Maintaining atoll island accretion requires intact sediment generation on coral reefs, unobstructed sediment transport from reef to island, and available vegetated deposition sites on the island. Ensuring the persistence of atoll islands must include global greenhouse gas emission reduction and local restoration of accretion processes. [ABSTRACT FROM AUTHOR]

• The overall impact of all the large dam-reservoir systems on the sediment fluxes at the delta scale was quantified. • Long-term datasets of daily water discharges and suspended sediment concentrations were analyzed. • The Red River system experienced two notable declines in sediment load in 1988 and 2009. • The annual sediment load has dramatically decreased by about 91% from the 1950s to 2021. • The decrease in sediment load is mainly attributable to a series of dam-reservoirs operating upstream. The sediment regime of the Red River system, the second largest in Vietnam, has undergone changes since the implementation of dams and reservoirs, with implications for downstream river processes. We analyzed long-term datasets of daily discharge and suspended sediment concentrations collected at key gauging stations downstream of the three main tributaries: HB on the Da River, YB on the Red River (main channel), VQ on the Lo River, and ST, the outlet of the Red River system. The results indicated a sharp reduction in the annual sediment load transported by the Red River system, as observed at the four stations. For example, at the ST station, there was a dramatic decline of 91% in sediment load, dropping from 117.9 × 106 ton/yr in the period 2009–2021 to 10.5 × 106 ton/yr in the period 1958–1987. The Red River system experienced two notable declines in sediment load. The first decline occurred from 1988 to 2008, which can be attributed to the commencement of Hoa Binh dam's operation in 1988. The second decline has taken place since 2009, coinciding with the utilization of new dam-reservoirs. Meanwhile, an abrupt change in water discharge was observed clearly since the end of 2008 at all four stations. However, the reductions in water discharges were found to be less pronounced when compared to the sediment budget. Based on our analysis, we concluded that the impacts of dam-reservoirs have had a more substantial influence on the system compared to variations in climate, such as air temperature and precipitation. [ABSTRACT FROM AUTHOR]

This study reveals the morphological transformations of a deep-water channel system within the Rakhine Basin in the northeastern Bay of Bengal through a comprehensive analysis of high-resolution 3D seismic data integrated with drilling logs. Employing the "source-channel-sink" paradigm, this investigation examined the impact of various factors, including tectonic transformations, sediment influx, slope dynamics, climatic changes, and relative sea-level fluctuations, on the evolutionary trajectory of these channel systems. Applying precise time-slicing techniques integrating root-mean-square amplitude attributes, coherent amplitude attributes, and horizontal amplitudes on seismic profiles, this investigation recognized three distinct stages in the evolution of channel-levee complexes (CLCs): the Middle Miocene erosional deep-water channel-levee complex (CLC-1), the Pliocene erosional-depositional deep-water channel-levee complex (CLC-2), and the Pleistocene depositional deep-water channel-levee complex (CLC-3). Comparative analysis revealed that the CLC-3 exhibits unique characteristics, including shallower channel depth (D), wider channel width (W C), extensive U-shaped cross-sectional area (S), broader natural levee width (W L) and height (H), and the highest tortuosity coefficient (L C /L S) when contrasted with the other two CLCs. Furthermore, this study substantiated how tectonic processes, primarily the collision between the Indo-Eurasian plates, resulting in the Himalayan and Indo-Burma Range orogenies, have shaped the region's geological and climatic framework, thereby influencing monsoon circulation and precipitation patterns, which in turn augmented detrital material influx into the basin. Moreover, this tectonic collision has led to gradual changes in the slope gradient of the Rakhine Basin and its deep-water areas, impacting internal flow velocities and channel curvature, thus governing deep-water channel systems' development and spatial distribution. Also, episodic sea level fluctuations were identified as significant contributors to sediment transport from shelves to deep-water regions and sediment deposit reworking. Overall, this study underscores the role of tectonic changes after the Eocene in driving the evolutionary dynamics of the deep-water channel system within the Rakhine Basin, Myanmar. [Display omitted] • Indo-Eurasian plate collision shaped the deep-water channel systems in the Rakhine Basin. • 3D seismic data reveals three evolutionary stages in these deep-water channel systems. • Pleistocene depositional channel-levee complex exhibits unique physical characteristics. • Tectonically affected slope dynamics have directed the channels' evolutionary dynamics. • Episodic sea level fluctuations have also supported these morphological transformations. [ABSTRACT FROM AUTHOR]

The Holocene sedimentary history of the Turbio River valley in semi-arid north-central Chile and its relationship to climate variability is presented in this study. Fluvial landforms and sedimentary deposits serve as essential records for studying the long-term dynamics of fluvial systems in response to external factors such as tectonic and climatic influences. The study area, located in the Andean Mountain range, is highly sensitive to hydrodynamic changes and sediment transport processes, making it suitable for studying fluvial dynamics and their relationship to climate fluctuations over millennia. In particular, the transitional semi-arid conditions of this region provide an opportunity to link Holocene fluvial sediments to climatic shifts. This study presents the analysis of well-preserved sedimentary deposits that outcrop along the valley walls, including grain-size distribution, stratigraphy, geochemical composition and radiocarbon dating to establish the chronological context. Facies association analysis, along with geochemical data, allowed the interpretation of depositional sub-environments and their evolution through time. We interpret the Holocene sedimentary evolution for the Turbio River valley as six time periods that reflect shifts in sediment source, energy regime, flow types, and sedimentary processes linked to fluctuations between wet and dry climatic conditions. The sedimentary sequence is interpreted as reflecting an initial high-energy period with continuous surface runoff followed by two periods of formation of extensive lakes, likely separated by periods of runoff intensification. The later part of the sequence reflects a more stable fluvial landscape that led to the excavation of the sedimentary fill. This sedimentary record provides valuable insights into past climate variations and their impact on the hydrodynamic conditions of the fluvial system in the region. Comparisons with other regional records support a broader understanding of climate change in the semi-arid Andes of Chile. • Rio Turbio sedimentary record is studied to reconstruct Holocene river dynamics. • Fluctuations in fluvial processes are related to alternating wet and dry periods. • A new model explains how the river evolved in response to Holocene climate variations. • Fluvial record provide valuable insights into past climates. [ABSTRACT FROM AUTHOR]

Some of the most disruptive effects of climate change are projected to be felt along the coastlines. The combined effects of future changes in water levels and wave climate along coastal areas constitute one of the most serious threats to their sustainable evolution, compromising critical infrastructures, resources, ecosystems, and communities. Understanding long-term changes in coastal areas remains challenging, however, due to their multivariate and multi-time-and-space-scale nature. In this study, we propose an innovative methodology for a complete vulnerability assessment of sandy low-lying coastal areas, based on dynamic, ensemble-based projections from the Coupled Model Intercomparison Project phase 5 (CMIP5). In the current Part I study, the effects of sea level rise (SLR) and nearshore wave climate changes on future shoreline evolution are assessed at five key-locations along the Portuguese coastline. Longshore sediment transport (LST) projections are computed, and sedimentary imbalances are quantified. Overall, robust shoreline retreat of up to 300 m is projected, especially along the Portuguese northern and central coastal areas, with continued erosion driven mainly by sediment imbalance and SLR. The projected decrease in future nearshore wave energy is responsible for a slight alleviation in erosion trends, up to 6.33%, whereas the increase of northerly incoming waves is expected to lead to northward beach rotations along western Mainland Portugal. The resulting shoreline evolution, responsible for the loss of up to 0.786 km2 of dry land by 2100 along the 14 km of analysed coastline, is projected to threaten several Portuguese urban areas, calling for the implementation of adequate coastal management and adaptation plans, to reduce the impacts of climate change on population, infrastructures, livelihood, and ecosystems. • An innovative methodology for a coastal vulnerability assessment is proposed. • Impact of SLR and wave climate changes on future shoreline evolution are assessed. • Robust shoreline retreat up to 300 m is projected along the Portuguese coastlines. • Shoreline evolution is responsible for loss of up to 0.786 km2 of dry land by 2100. [ABSTRACT FROM AUTHOR]

• Decrease of suspended sediment transport in the Mediterranean over the last century. • Time series reconstruction using artificial intelligence. • Crucial role of climate change in the regulation of suspended sediment transport. • Secondary influences of the anthropic impact. The analysis of suspended sediment transport and of its variations over time is crucial for understanding environmental evolution and it is the key to future challenges caused by current global warming. The Mediterranean area is a hot spot for global changes, and the variation of precipitation amount and intensity will modify the environment of this region. In this work, we analyse the time series of suspended sediment transport of two rivers located in central Italy by using statistical and artificial intelligence techniques. Our study aims to re-analyze time series of suspended sediment transport, in order to demonstrate that climate change is responsible for the substantial decrease in the amount of sediment over the past century, in relation to the atmospheric teleconnections of the North Atlantic. Anthropic pressures like reforestation, land use change, and dam building have influenced the sediment transport capacity of rivers, causing a reduction of sediment concentration in water. These results are key factors to determine the future management of the Mediterranean areas, where the future scenarios predict a greater drop in yearly precipitation, and therefore a possible further decrease in the sediment transport capacity of the rivers, with major consequences for coastal and fluvial environments. [ABSTRACT FROM AUTHOR]

The study evaluated climate change impact on water flows and nutrient loads to surface water bodies in Lithuania by applying the SWAT model. Seven RCM and GCM combinations were selected and RCP4.5 and RCP8.5 climate change representative concentration pathways were selected for the study. The study concluded that an annual and winter increase in most river water flows are expected. The change will be driven by rising precipitation, mainly in the regions where it is already high. Less snow would result in less surface runoff, substituted by increased lateral and groundwater flows because of more water percolating through the soils. As a result, water flows could be expected to increase by 9.7% for RCP4.5 and by 35.4% for the RCP8.5 climate scenario by the end-century. Whereas sediment transport and phosphorus loads would tend to decline a little bit (median results are -11.4% and -5.6% respectively for the RCP4.5 scenario, -13.3% and -7.4% for the RCP8.5 by the end of century). Conversely, temperature driven nutrient mineralization and increased leaching are expected to cause a significant increase in nitrogen loads (by 23.1% for the RCP4.5 scenario and by 64.4% for the RCP8.5 by the end of century). Overall, it could be concluded that climate change related hydrometeorological and water quality changes were found to be the most profound for the end-century RCP8.5 climate change scenario. [ABSTRACT FROM AUTHOR]

• A strong signal of reduced winter conditions i.e. duration, snow accumulation and frost days. • Hydroclimatic regime shift alters the sediment flux seasonality in near future. • Thaw-seasons have important role controlling the annual sediment flux. Climate change alters high latitude hydrological cycle by diminishing the snow accumulation and spring flood magnitude, and by altering temperature and rainfall finally leading to hydroclimatic regime shift from snow-dominated to rain-dominated. These changes in temperature, precipitation patterns, and discharge strongly influence geomorphological processes in fluvial environments, leading to alterations in sediment transport, erosion, accumulation, and landscape changes. We conducted comprehensive analysis of hydroclimatic trends and shifts on boreal Oulanka River system, spanning over the past five decades. A strong signal of warming temperatures (+0.61 Celsius/decade), reduced winter conditions and warmer summers (+0.41 Celsius/decade) was detected. The spring flood magnitude diminished 7 %, but high discharge peaks (Q > annual p90m3/s) during other seasons increased 22 % together with 28 % increase of annual minimum discharge. Simultaneously, precipitation intensity increased during summer. The meander migration rate (mean 0.89 or 2.55 m/year) and bank erosion volume were interconnected to ground frost, high snow sum, high discharge, and high-water level during spring flood, but no significant long-term trends were observed. Our findings underscore that climate is the first-order control on fluvial geomorphology and emphasizes the complex interplay between various hydrological and climatic factors that shape the dynamics of river systems. Based on the results, we expect to see changes in the spatial–temporal distribution of high latitude rivers sediment flux in future. In addition, more attention should be addressed to the thaw seasons controlling the sediment transport, as majority of the observed shifts took place in these months. [ABSTRACT FROM AUTHOR]

Water erosion, a notorious major threat to food security and ecosystem sustainability, is strongly conditioned by spatial and temporal scale effects. This paper systematically reviews the scale issues in runoff and sediment delivery (SIRSD) as a research field by integrating the traditional review approach and bibliometric analysis. This review summarises SIRSD's roots and the scale effect on runoff and sediment delivery. Then, we provide quantitative insights into the SIRSD domain's development history, thematic structure, geographic distribution, international cooperation, and methodologies. Findings show that: i) SIRSD arises from the gap between the non-linearity of runoff and sediment delivery across scales and our ability to measure it. Point-based and short-term measurements cannot capture the non-linearities from the spatio-temporal heterogeneities and cross-scale interactions of factors or processes. ii) Previous literature provides evidence that the spatial scaling of specific runoff (r), soil erosion (SE), sediment yield (SSY), or sediment delivery ratio (SDR) with drainage area (A) or slope length (L) exhibits contrasting patterns due to distinct mechanisms. Infiltration-excess and saturation-excess processes account for inverse and positive r - A relations, respectively. Interrill-erosion and rill-erosion cause inverse and positive SE-L relations. Hillslope-erosion and channel/bank-erosion explain inverse and positive SSY-A relations. Downstream increasing deposition and additional sediment inputs drive inverse and positive SDR-A relations. These scaling relationships can be nonlinear or complex due to spatial heterogeneities in land use, vegetation, topography, climate, lithology, and soil characteristics. Hence, applying an empirical scaling equation developed from the region with distinct environmental contexts is not recommended. Furthermore, the existing scaling patterns or equations may require updating given global climate and land use change. iii) SIRSD is a complex and multidisciplinary issue investigated by scientists from 93 countries since 1928. International research has substantially facilitated the understanding of SIRSD; still, more collaboration should focus on less-developed countries with high soil and water loss risks and urgent conservation needs, such as those in Africa and South America under cropland expansion. iv) Scale mismatch and scale break have discredited large-scale erosion and sediment assessments. Incorporating gully and bank erosion into modelling, extending the scale range of the L factor, and expanding the sediment scaling scope from watershed to slope may make a difference. Therefore, more research with nested design incorporating multiple scales is necessary for cross-scale analysis and scalable modelling. Addressing global climate change requires improving real-time urban flood forecasting and integrating downscaled climate models with hydrology, erosion, and sediment transport models. • A bibliometric review of the global SIRSD research for the first time. • SIRSD is rooted in the gap between natural nonlinearity and our measuring ability. • Scaling of specific runoff, erosion, sediment yield, and SDR has diverse patterns. • Scale mismatch and scale break discredit large-scale modelling and assessments. [ABSTRACT FROM AUTHOR]

Late Cenozoic changes in the intensity of the East Asian Summer Monsoon (EASM) are reconstructed using both terrestrial and marine proxy records; however, proxies from terrestrial (e.g., loess, pollen, and pedogenic isotopes) and marine environments (e.g., foraminifer assemblages and geochemistry) commonly display large discrepancies both in the direction and timing of changes in the EASM. In part, these discrepancies reflect long-term changes in paleogeography that are independent of climate variations. We assess the influence of a rapidly uplifting orogen on EASM records by comparing temporally constrained gamma-ray, δ13C org , hematite/goethite, and magnetic susceptibility records from Late Miocene–Early Pleistocene strata of the Taiwan Western Foreland Basin to time-equivalent EASM proxy records in the South China Sea (SCS). Prior to the emergence of modern Taiwan (∼6.3–5.4 Ma), sediment in the SCS was largely derived from Eurasia and transported into the Pacific Ocean. Following its emergence and southwest migration of the collision zone ∼5.4 Ma, proto-Taiwan became a major sediment source to the SCS. The uplift and southwest migration of Taiwan and northwest migration of the Luzon volcanic arc resulted in the formation of southwest-flowing deep- (1500–2500 m water depth) and bottom-water (>2500 m water depth) currents and the SCS Branch of the Kuroshio Current. Together these currents transported sediment from Taiwan towards the SCS. Increased sediment input from Taiwan is recorded as a decline in hematite/goethite values in sediment records from the northern and central SCS. By ∼3.2 Ma, continued southwest migration and growth of the Taiwan orogen resulted in the formation of the Taiwan Warm Current, which remobilized some sediment from Taiwan towards the East China Sea. Despite strengthening of deep-water currents during the Late Pliocene–Early Pleistocene, relative sediment input from Taiwan to the wider SCS decreased. Consequently, relative contributions from Eurasia and Luzon increased. In the southern SCS, where the Mekong River has dominated sedimentation since the Late Miocene, proxy records show no influence from the Taiwan orogen and instead reflect environmental changes in Mainland Southeast Asia driven mainly by monsoon variability. Our results show that a rapidly uplifting orogen has the potential to significantly impact paleoclimate records >1000 km away from the collision zone. This highlights the influence of shifting sediment sources on paleoclimate proxy records, which must be considered in interpreting past climate change from the sedimentary record. • Taiwan orogenesis is linked to South China Sea climate proxies. • Rapid orogenesis can drive shifts in sediment source and ocean currents. • Tectonic activity is the dominant control on proxies prior to ∼3 Ma. • After ∼3 Ma, proxies reflect enhanced monsoon strength related to glaciation. [ABSTRACT FROM AUTHOR]

The Thar Desert is a major sediment depocenter located in southwestern Asia and bordering the Indus drainage system to its east. It is unclear where the sediment that built the desert is coming from, and when the desert experienced phases of construction. In particular, we seek to establish the role of the South Asian monsoon in the initial formation and subsequent expansion of the desert. Here we integrate bulk-petrography and heavy-mineral data with U-Pb ages of detrital zircon grains to understand how the Thar Desert relates to the major potential sediment sources in the Himalayan orogen and to the large rivers that adjoin it to the west and north. Bulk petrography and heavy-mineral data from eolian sand in Cholistan (NE Pakistan) show closer similarity with that of Himalayan tributaries than eolian sand in Sindh (S Pakistan), which contains heavy-mineral suites close to those of mainstream Indus sand largely supplied by erosion of the Karakorum and Kohistan ranges. Kohistan is a particularly rich source of heavy minerals and is thus over-represented in provenance budgets based on that proxy alone. U Pb ages of detrital-zircon fail to show a sharp difference between dune sands in Sindh and Cholistan but confirms a somewhat greater supply from the Himalaya in Cholistan and from the Karakorum, Kohistan, and Nanga Parbat in Sindh. Zircon ages are similar in Sindh desert sand and in the Indus Delta, and are most similar to deltaic sand dated as 7 ka or older in the deglacial period. In parallel, the age signature of Cholistan sand resembles more that of older river channels found along the northwestern edge of the desert (e.g., paleo-Ghaggar-Hakra) than that of modern Himalayan tributaries (e.g., Sutlej). Both Cholistan and Sindh sands suggest that sediment supply to the desert was greater during the early Holocene when the summer monsoon was stronger. The southwesterly summer monsoon was the most effective agent of eolian transport and recycling of Indus delta sediments entrained towards the central and northern parts of the Thar Desert. [ABSTRACT FROM AUTHOR]

• (234U/238U) were analyzed for the Changjiang estuary sediments. • Catchment erosion was revealed by sediment comminution age. • Climate changes play a leading role in catchment erosion. • Human activities changed the natural erosion processes since the late Holocene. Catchment erosion not only plays an important role on landscape evolution, but also determines the exposure of rock debris in the regolith profile, and therefore impacts the chemical weathering and associated CO 2 absorption and ultimately global climate. But climate also modulates erosion and complex interaction loops, especially at large scale can hamper a clear understanding of these processes. Here we mainly use Uranium-series Comminution Age (t com) of core sediments from Changjiang estuary to reconstruct the catchment erosion, and the relationship with climate changes and human activities during the last 14 kyrs. Since 14 ka, the sea level has been rising continuously until current highstand system tract in the East China Sea where the Changjiang estuary is located. The sediments in the Changjiang estuary mainly come from the upper reaches erosion zone during this period, but the sediment supply from the middle and lower reaches has gradually increased since the Late Holocene. The period can be divided into two modes. The first mode happens from the Bølling-Allerød period to the Mid-Holocene when the sea level rose rapidly, and the t com of sediment recorded the residence time in the upper reaches erosion zone, with a periodic pattern of t com in a good agreement with climate changes. During the cold and dry periods, the longer t com (average 460 kyrs) is consistent with less precipitation resulting in shallower erosion with transported material mainly coming from the soil with longer residence time. In contrast, during the warm and wet periods, the t com is shorter (average 290 kyrs), with the more abundant precipitations that contribute to deeper erosion in the upper catchment, and more fresh material transported to the estuary through stronger hydrodynamic forces. The second mode is more chaotic and corresponds to 0 to 4 ka, when climate was warm and humid and stable sea level, but t com fluctuated from 200 kyrs to 650 kyrs. The increasing river flooding caused by abundant precipitation leads to lateral migration of the river channel in the middle and lower reaches, and the sediments deposited in the floodplain were eroded and mobilized again. In addition, the rapid development of human activities since 2 ka has accelerated deforestation and agricultural cultivation, leading to localized erosion of the floodplain. These remobilized sediments were transported to the estuary and deposited, resulting in a larger t com value. This study overall indicates that, in the millennial scale, the t com of fine detrital fraction shows a sensitive and quick response to catchment erosion, and provides new insights into quantifying the time scale of sediment source to sink processes and inferring the paleoenvironment accurately climate changes. [ABSTRACT FROM AUTHOR]

[Display omitted] • Continued erosion is expected to occur in the sandy shores. • Equilibrium relationship between sediment supply and hydrodynamic forces has been severely disrupted. • Global climate change-induced sea level rise has a small effect on erosion in the short term. • Human activities are the critical effect on the erosion. • Reduced seaward sediment transport by coastal surface runoffs is a new factor. Most sandy shores (SSs) are currently experiencing erosion to various degrees due to the combined impact of increasing climate change and human activities. In order to reveal the evolution of the SSs in the Shandong Peninsula (SP), shoreline and elevation changing data are obtained from 29 SSs and results show that most (27 of 29) of the SSs exhibited erosion. The length of the SSs has decreased by 241.4 km from 2010 to 2020, and the average shoreline recession rate was found to be 1.0 m/a and the downward erosion rate was in the range of 0.05 to 0.10 m/a. Climate change-induced sea level rise has a smaller effect on the erosion in the short term and the construction of massive coastal engineering structures has become a major cause of local coastal erosion. The coastal erosion rate caused by river damming and sand mining in the early years has abated and reduced seaward sediment transport induced by the expansion of the built-up area has become a new factor of coastal erosion. In the past decade, the 672 km2 net increase in land area mainly originated from human activities, has occupied the original space for hydrodynamic energy dissipation, which has severely disrupted the balance between sediment supply and the hydrodynamic environment and the system then rebalance itself by eroding unprotected SSs. Therefore, with the increase in hydrodynamic forces caused by climate change and the scarcity of sediment supply caused by human activities, continued erosion is expected to occur in the SSs. [ABSTRACT FROM AUTHOR]

• The streamflow, sediment and heat flux input to the delta substantially increased. • The changes in the sediment and carbon pathways across delta is the result of thermal erosional processes. • Lena Delta is the World's hot spot in hydrological consequences of climate change. Water and sediment supply are essential to the health of deltaic ecosystems. Diverse datasets were integrated to better understand how climate change is shifting the supply of water and sediment to the largest polar distributary channel pattern – the Lena River Delta. Here the increase in warming rate from an average air temperature is from 4.1 °C for the period 1950–99 to 6.1 °C during 2000–21, which is higher than in the adjacent polar regions. Streamflow and sediment yield entering the Lena Delta have increased since 1988 by 56.3 km3 and 6.1×106 t, respectively; meanwhile, the Lena River's increases in water temperature in June, July–August and September were found to be as much as 1.1, 0.6 and 0.05 °C. These changes have a pronounced effect on sediment regimes in particular parts of the delta. Based on analyses of correlations between various hydroclimatic drivers and sediment concentration changes across particular distributaries of the Lena Delta extracted from Landsat datasets, bank degradation driven by thermal erosional processes (which are in turn related to air and soil temperature increases) is proved to be the primary factor of the sediment regime in the delta. The study also highlights that sediment load changes are sensitive to wind speed due to remobilization of bottom sediment. Sums of daily air temperature and wind speed over 3 days are correlated with sediment concentration changes in the delta. The results also indicate that carbon transport across the delta (both POC and DOC) depends on sediment transport conditions and water discharge and might increase by up to 10 %. We conclude that the Lena Delta can be recognized as the global hot spot in terms of the hydrological consequences of climate change, which is altering sediment regimes, stream hydromorphology and carbon transport. [ABSTRACT FROM AUTHOR]

[Display omitted] • Climate and human contributions to NPP were 62% and 38% in Loess Plateau. • Precipitation contributed to NPP much than temperature in 2000–2020. • The feedback of GTGP to NPP and climate was higher in second decade. • GTGP brings environmental benefits (river sediment, PM 2.5 , dust weather). Net primary productivity (NPP) has been the subject of numerous studies, but the qualitative and comparative study on NPP that considers human activities, climate change, and their interactions is still insufficient. The Grain for Green Program (GTGP) was established in the Loess Plateau since 1999, could be used as a reference study. The temporal and spatial patterns, change trend, and driving factors of vegetation NPP were analysed in Loess Plateau using data derived from GLASS NPP (the Global Land Surface Satellite Product), meteorology, atmospheric quality, hydrology and land use by correlation and improved residual trend analysis from 2000 to 2020. After GTGP implementation, the climate and human contributions to vegetation NPP were 62 % and 38 %. NPP increased at a rate of 6.3 g C m−2 a−1 from 2000 to 2020, which was higher in 2010–2020 (6.9 g C m−2 a−1) than it was in 2000–2010 (5.7 g C m−2 a−1). The same trend was followed by the contribution of climate change to NPP between 2010 and 2020 (70.6 %) and 2000–2010 (65 %). The GTGP core area was mostly where the vegetation NPP rising zone was located. From the original bare land in the desert area, 4442 km2 of vegetation grew and increased the NPP (68.7 g C m−2). Under the warm–humid climatic trend, the climate factors contributed to NPP more in grasslands (40 %) compared to woodlands (29 %) and precipitation (33 %) was more sensitive than temperature (12.7 %). Consequently, sediment transport, PM 2.5 and dusty weather decreased significantly. In conclusion, although climate change has a greater impact on vegetation, human activities have enhanced the impact faster in the first decade, which benefit and profit from the environment finally. [ABSTRACT FROM AUTHOR]

• Compared dynamics of discharge and sediment loads in four large basins. • Explored the impact of climate, and human activities on water and sediment. • Sediment transport showed significant decreasing trends with abrupt changes. • Human activities played a predominant role in reducing sediment transport (>80%). • Impacts of land cover change on sediment loads were basin-independent. Human activities and climate are two key factors affecting hydrological and soil erosion processes. Understanding their impacts on water discharge and sediment transport is very important for sustainable development of watersheds, particularly in subtropical regions with high precipitation and high sediment loads. We here compared the long-term dynamics of water discharge and sediment transport in four large contiguous watersheds in subtropical China and explored the importance of the main influencing factors including climate, nature endowment such as geology, and human activities. Significant differences have been observed between watersheds in terms of sediment and water discharge (p < 0.001). Pairwise comparison among the four basins demonstrated significant differences in sediment modulus among 5 of the 6 pairs (p < 0.05). The sediment modulus in the Lishui Basin was significantly higher than those in other basins, mainly due to the substantial presence of steep slopes in the mountainous region, which is prone to soil erosion. Temporally, sediment transport in the four basins was well synchronized showing significant decreasing trends with abrupt change points (p < 0.001). In contrast, no trends and abrupt change points were detected in water discharge, mainly influenced by precipitation. Human activities played a predominant role to the reduction of sediment transport (80% to 102%) compared with those of climate (-2% to 19%) across the four basins. Additionally, our study also showed land cover had various basin-independent impacts on the change of sediment transport. Through cross-basin comparisons of the long-term changes in water discharge and sediment transport, our study revealed the similarities and differences in their driving mechanisms, providing valuable information for land use planning and water resource management in large subtropical basins. [ABSTRACT FROM AUTHOR]

• Ridge slope erosion included inter-rill erosion, headward erosion, and rill erosion process. • Erosion rate reached the maximum during headward erosion process. • The dominated erosion process was detachment-limited after headward erosion occurring. • Re-detachment, transport, and deposition simultaneously occurred with the appearance of headward erosion. Extreme rainfall is becoming more frequent and intense, which no doubt increases the risks and uncertainty of water erosion in widely-used contour ridge systems. Ridge slope erosion can increase the probability of contour failure occurrence and then induce contour ridge losing anti-erosion properties. However, there is little understanding of ridge slope erosive process controlled by contour ridge system responding to extreme rainfall. In this study, five rare earth elements were applied in different ridge segments and soil layers to monitor the successive development of ridge slope erosion process under extreme rainfall in contour ridge system. Simulated rainfall experiments at high rainfall intensity (100 mm h−1) lasting for 60 min were conducted in runoff plots with ridge tillage practices characterized by microtopography indices and ridge geometry indices. Results showed that three sub-processes were observed for ridge slope erosion, including inter-rill erosion, headward erosion, and rill erosion. Headward erosion mainly resulted from the break-point at ridge surface and sidewall collapse at ridge toe, and the pouring of ponding water in furrow greatly promoted rill development. Erosion rate was the largest during headward erosion process, and rill erosion contributed the most to eroded source. The dominated erosion process was transport-limited during inter-rill erosion process, and detachment-limited during headward and rill erosion processes. Sediment transport and deposition processes as well as their transformation occurred simultaneously after the development of headward erosion. Eroded sediment was mainly from the low part of ridge, which was transported by raindrop-impacted sheet flow or overflow. These findings provide better responding of agricultural tillage to global climate change and references for the development of physically-based erosion models. [ABSTRACT FROM AUTHOR]

• Climate change effects on ice regime and water and sediment processes examined. • The ice flood reaches of the Yellow River in Inner Mongolia are taken as the case study. • Mann–Kendall test applied to define the years of temperature mutations and trends. • Meteorological condition and breakup type affect sediment transport in the channel. • Complex relationship exists among channel, hydrodynamic, sediment, and ice factors. The presence of winter ice in cold regions changes the water level, flow rate, velocity distribution, and other parameters of the river, which in turn affects the sediment concentration and channel evolution. Based on data obtained from Toudaoguai Hydrological Station from 1959 to 2021, this study examines the characteristics of the ice regime during cold and warm winters and the water and sediment transport processes along the Yellow River in Inner Mongolia in the context of climate change. The Mann–Kendall test and trend analysis were applied to define the years of temperature mutations and their trends, and the temperature mutation point was determined to be the 1987/1988 season. The study considers the effect of climate change on the combination of hydrological and hydraulic conditions. Therefore, trends in suspended sediment transport, ice type formation, water discharge, and storage in different ice flood seasons (November 1 to March 31, from 1998 to 2021) were attained. Based on the cumulative negative air temperature, winters were categorized into three types, warm, normal, and cold (52.2%, 17.4%, and 30.4%, respectively). Strong and weak grades further divide cold and warm winters, and statistical analyses were used to examine the characteristics of ice, water discharge, channel storage, and sediment transport. The duration of open water, freeze-up, ice cover, and breakup periods were calculated, and the relationship between the suspended sediment transport rate and discharge rate in these various ice periods was defined. The obtained relations show that the suspended sediment rate during the ice cover and first drift was smaller than that during the open water and post-breakup conditions. For the ice cover period, the sediment transport rate was on average approximately four times smaller than the freeze-up condition and six times smaller than the open water condition. The reduced sediment transport rate in the freeze-up period can be attributed to the weakened vertical turbulent mixing and increased flow resistance. [ABSTRACT FROM AUTHOR]

The late Paleozoic glacial-to-postglacial turnover evolved complexly across Gondwana. Successions bearing volcaniclastic material that can be radiometrically dated provide crucial information about the timing of those climate events. The southernmost part of the Paraná Basin, for instance, has a high-precision geochronological framework. The eastern sector of this basin (Paraná State and north of Santa Catarina State), however, lacks radiometric ages, but conversely, has a more complete stratigraphic record, and paleontological information still poorly explored for the purpose of biostratigraphic correlation. This work examines the glacial-to-postglacial interval in the Paraná State, represented by the upper Itararé Group (Taciba Formation; glacial) and lower–middle Rio Bonito Formation (postglacial). Sedimentological, paleontological and geochemical data from outcrops, cores and well logs were used to decipher the timing, paleoclimatic and paleogeographic scenarios of this transition. The examined succession comprises four stacked units (U1 to U4, from older to younger). Diamictite-dominated units (U1 and U3), here interpreted as consecutive glaciation–deglaciation events, are separated by non-glacial, continental to shallow marine deposits, commonly bearing fossil plants and coal seams (U2). An important transgression followed the first deglaciation, which is equivalent to the " Eurydesma transgression", based on the presence of marine invertebrates of the homonymous fauna in the Passinho Shale. U2 holds elements of two different floras, i.e., Phyllotheca – Gangamopteris (P–G), predating the " Eurydesma transgression", and Glossopteris – Brasilodendron (G–B), above the transgression. Therefore, U2 is interpreted as an interglacial interval, once it records a climate improving before the last glacial episode of U3, which is further supported by relatively high values of the Chemical Index of Alteration (CIA). Deposits of U3, associated with a decrease in the value of the CIA, are unconformably overlain by U4. The occurrence of coal-bearing postglacial facies (U4) associated with the G–B Flora, coincides with an increase in the CIA values. Sediment transport was toward the SW in all units and in the same direction it is observed an overall thinning of U1 and U3 and thickening of U2. The interglacial P–G Flora of the study area correlates with postglacial southernmost floras, based on U–Pb CA-TIMS Asselian ages of tonsteins. Correlation of the Eurydesma fauna-containing Passinho Shale with equivalent successions with high-precision age control in southern Africa, allowed us to position both deglaciations of the Taciba Formation (U1 and U3) in the Asselian. These findings suggest that U1 and U3 record two early Permian glacial episodes, with the younger one (U3) disappearing southward. Accordingly, our results indicate that the glacial-to-postglacial turnover was diachronous along the eastern belt of the Paraná Basin, being progressively older southward, considering that interglacial fossil plant assemblages in the eastern margin correspond in time to postglacial assemblages farther south. • The examined succession includes two glaciation-deglaciation stages insterspersed by interglacial deposits and an uppermost postglacial interval. • The interglacial stage is time equivalent to postglacial deposits farther south, suggesting that the last glaciation was limited to NE Paraná Basin • Biostratigraphy based on floral and faunal assemblages indicates an early Permian age. • The glacial–postglacial transition is diachronous along the eastern margin of the basin. [ABSTRACT FROM AUTHOR]

Beach accretion is the natural mechanism that allows dry beaches to recover. Human response to climate change produces hardening of the coasts and the incident marine climate, which increases beach erosion produced during winter and prevents a full recovery during summer. Beach nourishments are performed all around the world to fight coastal erosion with a nature-friendly philosophy. Softer techniques as beach scraping are also widely applied. A kind of beach scraping is proposed here as an innovative nature-assisted beach enhancement technique, that aims to accelerate naturally produced sand accretion on the beach profile. It consists of mechanically ploughing the intertidal area of a beach to create ridges and furrows. Prototype-scale laboratory experiments were performed to analyse its effectiveness under controlled conditions. Seven 1 h tests having different water levels and the same initial bottom geometry and sea state conditions (H s = 0.3 m, T p = 7 s) were performed. Sea state, sand, and initial slope characteristics assured accretive conditions. Ploughed and flatbed initial slope geometries were simultaneously tested into two sub-channels of the wave flume. The results indicate that the bottom roughness is 3.57 times larger for the ploughed geometry. Consequently, wave energy dissipation is larger for the ploughed geometry, and therefore, the significant wave height at the shoreward end of the study area is 11% smaller for the ploughed geometry. This smaller wave height under the ploughed morphology leads to more accretive conditions, as observed from the measured onshore sediment transport, which is 2.9 times larger than the natural transport, and the larger accreted sediment volume in all seven test cases. These results demonstrate the effectiveness of ploughing to enhance natural beach accretion under highly probable accretion conditions. Further research is required to define the thresholds of marine conditions in which the potential of beach ploughing can be exploded. • Working with nature. • Ploughing the intertidal area of a beach enhances natural accretion. • Real scale laboratory experiments measuring sediment transport. • Mechanically ploughing increases bed roughness. • Extra wave energy dissipation is produced by ploughing. [ABSTRACT FROM AUTHOR]

• Proglacial areas show complex dynamics of sediment transport. • Today proglacial areas act as both sediment storage and sediment source areas. • Positive temperature anomalies lead to changes in sediment connectivity. • Extreme precipitation and snow-melt events enhance functional connectivity. Proglacial areas in high-mountain environments are among the most dynamic landscape zones in terms of morphological, sedimentological, and hydrological changes. In fact, in such areas both glacial and paraglacial dynamics exert a strong control on water fluxes (and thus on bedload transport capacity) and on sediment supply. Because of the rapid changes undergoing in these environments, the understanding of the dynamics of sediment transfer and the prediction of how this will change in future still remain a challenge. In this study, we used four different high-resolution topographic surveys to quantitatively analyse the spatio-temporal patterns of sediment transport that occurred in the proglacial area of the Sulden glacier (South Tirol, Italy). The topographic surveys covered the period 2013–2019 and – by building DEMs of difference (DoDs) – we calculated the volumes of erosion and deposition occurring at the glacier terminus and along its outflow channels. Our results indicate that, within the analysed time-period and for different areas, erosion and deposition generally show similar values, suggesting that the analysed proglacial areas has been acting both as a sediment trap and as a sediment source for the downstream river reaches. In addition, the results indicate a complex morphological dynamics, which have strongly impacted coarse sediment connectivity in the upper catchment. In particular, high temperatures and the recent and rapid glacier melt, have promoted a direct control on the structural connectivity within the proglacial area. Morphological changes have increased or decreased sediment connectivity depending on pre-existing morphological features. In contrast, extreme precipitation events, both in term of rainfall and snowfall, have locally and temporally increased the functional connectivity, sometimes leading to long-term modifications in the proglacial area. Overall, in the analysed time-period sediment transfer has been extremely dynamic, suggesting that sediment in the downstream river channel may have been supplied with irregular pulses associated with the morphological changes taking place in the proglacial area. [ABSTRACT FROM AUTHOR]

This study investigated the spatiotemporal variation of arsenic (As) distribution, species and its behaviour in the aquatic environment changed by extended dry and heavy rainfall periods in the area adjacent an abandoned gold mine, South Korea. As appears to be transported from the mine wastes to Guryong stream through groundwater baseflow and leachate. The oxidation-reduction potential (ORP) conditions changed spatially and temporally following dry and heavy rainfall periods, and rainfalls caused decrease in the stream pH. As mainly existed as arsenates (AsO 4 3-) bound with H, Ca, and Fe in water. In groundwater, the lower the pH and the ORP, the higher the proportions of acid species of arsenate (HAsO 4 2-, H 2 AsO 4 -) and arsenite (H 3 AsO 3), resulting in increased As mobility and toxicity, respectively. In stream, the primary influencing factor of As variation is the ORP. Under oxidizing conditions, As in stream could precipitate as amorphous FeAsO 4 ·2H 2 O and FeOOH in the streambed. Then, the ORP decrease could remobilize As by redissolution and desorption of As bound to bed sediments. Thus, streambed sediments acted as a temporary sink-and-source for As, and extension of source areas accompanied with physical transport after heavy rainfalls. [Display omitted] • Total As concentration and pH-Eh conditions controlled As behavior in water. • Dryness and rainfalls change the pH and ORP conditions in the aquatic environment. • Streambed sediments acted as a sink-and-source in groundwater-stream interface. • Physical transport of bed sediments could extend the areas of As-pollution potential. [ABSTRACT FROM AUTHOR]

The present and paleo-drainage networks, depositional surfaces, fault throw, slope of the downthrown fault blocks, soil properties, sediment characteristics and published optically stimulated luminescence (OSL) ages are used to define the role of tectonics and climate in the growth of forty-five terminal fans (TFs) in the Indo-Gangetic foreland basin. Twenty-three TFs show a single exposed surface throughout, suggesting no or imperceptible breaks in sedimentation during their formation. In contrast, twenty-two TFs show multiple growth surfaces, separated by soil profiles and erosional surfaces. The available optically stimulated luminescence (OSL) dates of these depositional surfaces suggest different phases of TF growth. Tectonically triggered surface faulting altered accommodation space, slope of the substrate, and sediment supply and initiated new TF depositional cycles. The tectonically stable periods, in contrast, did not form TFs, despite the favourable humid climate conditions. Instead, the dry and humid climatic regimes, when combined with frequent surface faulting, produced and remobilized sediments more quickly, promoting TF growth. The humid climate TFs are spatially extensive (average area = 2000 km2), with clay horizons interspersed between sand facies. The dry climates TFs are smaller (average area = 1370 km2), with intervening calcrete horizons and surface salt-efflorescence. Low precipitation and inadequate sediment supply hampered the growth of these dry climate TFs. Despite a considerable period of surface exposure, the surfaces of dry climate TFs lack a well-developed soil profile. The upper Ganga Plain provides more accommodation space across the faults than the middle Ganga Plain. Accommodation space and substrate slope have little effect on TF area unless climatically triggered sediment remobilization occurs. For a given accommodation space and substrate slope, steeper sloping TFs occupy less area than lower sloping ones. Faults with throws of <5 m and substrate slopes of <2° do not form TFs; instead sediment wedges are formed across fault slope breaks. The TFs in the upper Ganga Plain show more growth surfaces than the middle Ganga Plain. The older growth surfaces are either progressively arranged across the direction of channel shift or occur as inliers in between the younger alluvium. Well-developed distributaries on the older TFs disperse sediment more readily, rather than accumulating it in proximal fan regions. However, the younger TFs, with relatively less-developed distributary channel networks, vertically stack sediments in their proximal part and occasionally transport sediment as sheet floods to their distal end regions. The combined geomorphic response of TFs to tectonic events and climatic fluctuations is, therefore, simultaneous for TF growth and stabilization. • Ganga Plain terminal fans (TF) form at topographic slope breaks away from mountains. • TF growth mechanism investigated using remote sensing and field investigations. • Ganga Plain TFs develop as a result of tectonic-climatic interactions. • Tectonics provides overall accommodation space for TF building. • Climate then controls TF growth (humid periods) and inactivity (drier periods). [ABSTRACT FROM AUTHOR]

• Review of hydro-morphological responses to LULC and climate changes. • The first review paper of this type focused on tropical regions. • A comprehensive review of 60 case studies. • Meta-analysis of the findings of all case studies. • Significant correlations are revealed between LULCC and hydrological processes. Tropical regions have experienced the fastest Land Use Land Cover Change (LULCC) in the last decades, coupled with climate change (CC) this has affected the hydrological and geomorphological processes of river systems. With the increased demand for land, the general trend has been the loss of forest land to agriculture and settlements. These changes have altered the water balance components through enhanced or reduced evaporation, peak flow, flooding, and river morphology. The aim of this review paper is to provide a meta -analysis on the effects of spatiotemporal changes in climate and LULC on river hydro-morphology in the tropics. Following a systematic search, 60 case studies were identified, of which the majority (68%) experienced forest loss due to agricultural and urban expansion, resulting in increased streamflow, surface flow, and total water yield and decreased ET and groundwater recharge. 12% of the case studies showed the impacts of LULCC on channel morphology features through sediment transport and riverbank erosion. Results from this study show limited correlation between LULCC and hydrological variables, indicating that there are likely other factors controlling hydrological processes. Catchment heterogeneity including soil and topography play an important role. Based on studies that project these changes into the future, similar trends are expected over the next decades, with differences based on LU and climate scenarios. There are still limited studies on river hydro-morphology responses to LULCC and CC in the tropics despite the major changes taking place there. In light of future changes, more studies are needed to improve our understanding. [ABSTRACT FROM AUTHOR]

[Display omitted] • The Brazilian semiarid is the most densely populated dry region in the world. • Sediment source apportionment was quantified in a semiarid ephemeral catchment. • The combination of conventional and alternative tracers improved source discrimination. • Our results may gain high visibility given the climate change projections for the semiarid regions. The Brazilian semiarid is the most densely populated dry region in the world. Although climate change projections underline the need for the creation of integrated strategies to protect water resources in the semiarid, sediment source apportionment data remain scant for this environment. Accordingly, we evaluated sediment source contributions in one of the most relevant Brazilian semiarid catchments by combining geochemical and colour tracer properties. In doing so, we explored the applicability of colour tracers as a low-cost alternative to the use of time-consuming and costly properties, such as geochemical tracers. Two source classification schemes were used based on environmentally contrasting regions within the catchment (upper, middle and lower catchment parts) and land use (Caatinga biome - natural vegetation, unpaved roads, and channel banks). Suspended sediments (SS) and bed sediments (BS) were used as target sediment. A total of 660 individual source material samples were collected and composited. Geochemical and colour tracers were measured on the source and target sediment samples and used as potential fingerprints to discriminate and quantify the sediment source contributions. The geochemical tracers provided weak source discrimination based on land use. However, combining geochemical and colour tracers improved the final outputs. Using the MixSIAR model, the lower catchment contributed more sediment than the other regional sources. The Caatinga (SS = 49 %; BS = 47 %) contributed more sediment than channel banks (SS = 35 %; BS = 39 %). Overall, our results suggest that the recovery and conservation of the Caatinga vegetation and the stabilization of channel banks, especially in the lower catchment part, are critical for improving sediment supply control in the semiarid study basin. More studies are needed to evaluate the conservative behaviour of colour tracers in ephemeral rivers. [ABSTRACT FROM AUTHOR]

The Himalayan foreland basin, manifested as the Indo-Gangetic Plain (IGP) on the surface, has been filling up with sediment, carried by the Himalayan river network. Since 1960, several sediment budget records have been established for this region, estimated by different approaches, and averaged over different time scales. Here, we have compiled 196 records of sediment load, sediment yield, and erosion rate published between 1960 and 2022 for different catchments across the IGP. We categorised the data as long-term (multi-centennial to multi-millennial) and short-term (annual to multi-decadal) records, based on the timescale they are averaged upon. We find that there is a clear gradient of sediment yield across the IGP where long-term sediment yield decreases from ∼5800 t/yr/km2 (Sutlej basin) in the west to ∼1200 t/yr/km2 (Ganges basin) in the east and the short-term yield decreases from ∼1800 t/yr/km2 (Sutlej basin) in the west to ∼100 t/yr/km2 (Ganges basin) in the east. Our analysis shows that the driving factors of sediment generation and dispersion vary throughout the region and among the integration timescales. The region south of the Main Frontal Thrust, specifically the IGP, is highly populated and the short-term records suggest an anthropogenic bias. However, we show that only a low but measurable percentage of the annual sediment load is trapped by anthropogenic interventions, such as dams and barrages, when we compare the short- and long-term sediment loads. Among 172 sampled catchments, both short (n = 87) and long-term (n = 60) loads from basins with area >100 km2, show nearly log-linear correlation with their respective basin sizes. However, in case of the Ganga-Brahmaputra basin, the slope of the best fit line for the short-term loads is 30% lower compared to long-term loads. The short-term load estimations for the same basin size are consistently lower than the long-term loads. We attribute this discrepancy on the lag in response time of the vast IGP dispersal system. We note that the variability of long-term erosion rates from west to east correspond well (R2 = 0.77, n = 6) with the variability of mean normalized channel steepness indices for all major catchments to the south of the Main Frontal Thrust region. To the north of the Main Frontal Thrust, the variation of long-term erosion rates correlates well with channel steepness within a single catchment, but not in a similar fashion across different catchments from west to east. We observe that the linear relationship between long-term erosion rate and channel steepness index for individual basins to the north of the MFT is influenced by the presence of high vegetation density; however, any correlation between long-term erosion rates with mean annual rainfall and vegetation cover is absent. Our analyses suggest that short-term records are more susceptible to vegetation cover changes in steep terrains, but landscape erosion rates at these timescales are also driven by various degrees of landscape steepness. We show that short-term records are influenced by transient sediment storages on the IGP that respond to past tectonic and climatic forcing. This underlines the importance of understanding transient sediment storages when interpreting short-term records in the context of recent climatic changes and anthropogenic impacts. [ABSTRACT FROM AUTHOR]

• Landslide contribution to basin sediment budget was determined. • Individual landslide tracing and routing was conducted. • Coupling between landslide and climate change impact was analysed. Mass movements such as landslides are prominent sources of sediment in post-seismic mountain belts. Earthquake triggered landslides can generate substantial volumes of fresh sediment and this may have significant long-term (decade to millennium) geomorphic effects on landscape evolution. Downslope and downstream transport of sediment into the channel network is sensitive to meteorological perturbations especially for extreme rainfall events. However, no established techniques can explicitly fingerprint/track landslide-derived sediment under climate change. In this study, we use a new tracing function incorporated into CAESAR-Lisflood (CL) to track the landslide-derived sediment dynamics in response to climate change. The hourly future rainfall sequences under two climate scenarios (RCP4.5, RCP8.5) were firstly generated using 'NASA Earth Exchange Global Daily Downscaled Projections (NEX-GDDP)' dataset and then used as hydrological input to drive CL simulations. The landscape evolution at the Hongxi basin, which suffered great damage from the Wenchuan earthquake (Ms 8.0), was then simulated for 93 years (2008–2100) using CL under two climate scenarios. The results show that the landslides can greatly increase the sediment yield and climatic perturbations can lead to variation of sediment dynamics, the coupling of these two factors perform a combined impact on sediment budget, while the interplay and relevant importance between landslides and climate impact is dependent on the landslide density of specific basin. The landslide-channel connectivity (location of landslides with respect to river channels) plays an important role in post-earthquake sediment evacuation. The yearly sediment yield generated by the landslides can be stable after 20 years under both RCP 4.5 and RCP 8.5 scenarios in the study basin. These findings are of great importance to understand the interplay between landslide and climatic perturbations and support the risk management and mitigation after the 2008 Wenchuan earthquake. [ABSTRACT FROM AUTHOR]

The Eocene was a critical period of global plate reorganization and it also saw the Earth's climate transition from the warmhouse state to the coolhouse state. Reconstructing the Eocene sedimentary history in the climate-sensitive Southern Ocean is important for understanding paleoenvironmental changes in response to the accelerated Australia/Antarctica separation and global cooling throughout the middle and late Eocene. Here, we present the first detailed multiproxy record of a continuous sequence from International Ocean Discovery Program (IODP) Site U1514 in the Mentelle Basin off southwestern Australia. Our aim is to reconstruct the sediment provenances and paleoenvironmental evolution in response to the abovementioned climatic and tectonic changes in the mid-high southern latitudes during the Eocene. Provenance analyses based on Sr-Nd isotopes, trace elements, and clay mineral assemblages suggest that Eocene sediments at Site U1514 predominantly originated from the southwestern Australian continent and the Naturaliste Plateau. Sediment provenance variations during the middle Eocene indicate that the onset of fast separation between Australia and Antarctica at 43 Ma caused an increased supply of volcanic materials from the Naturaliste Plateau between 43 and 38 Ma. Terrigenous inputs to the Mentelle Basin during the middle Eocene were primarily controlled by paleoclimate changes rather than tectonic processes because coeval clay mineralogical changes (higher kaolinite/smectite ratio and MAR kaolinite) indicate a period of stronger physical erosion and chemical weathering on the western Australian continent that resulted in increased terrigenous materials delivered to the Mentelle Basin. Our results reveal a 5 Myr-long (43–38 Ma) warming reversal in the southern mid-high latitudes, providing an exception to the generally short-lived (10–100 kyr-long) hyperthermals that interrupted the long-term global cooling throughout the middle to late Eocene. As for the late Eocene (38–37 Ma), tectonic processes related to the sudden acceleration in seafloor spreading in the Tasman Sea led to the exposure of shallower areas, resulting in rapid detritus accumulation at the study site. During the late Eocene (37–34 Ma), major sediment provenance shifted from distal source areas (e.g., the Yilgarn Craton) to relatively proximal sources (e.g., the Leeuwin Block and Perth Basin). We interpret that the regional uplift in southwestern Australia and coeval climate cooling resulted in the diversion and inactivation of large drainage systems, thus blocking the transportation of sediment from distant regions. • First detailed record of the Eocene source-to-sink process in the Mentelle Basin. • The onset of fast Australia/Antarctica separation caused increased volcanic input. • Regional warming led to enhanced chemical weathering in Australia during 43–38 Ma. • Regional uplift and global cooling induced sediment source change during 37–34 Ma. [ABSTRACT FROM AUTHOR]

• Daily sampling of aquatic chemistry after megafires in a large catchment. • Significant increases in major parameters and highly distorted CQ relationships. • Extreme dynamism and transient behaviour with monotonic recovery in ∼3–12 months. • Greatest sensitivity to erosion during initial flow events following fire. • Initial dominance of NH 4 and rapid biogeochemical cycling of N species. Increased frequency and intensity of drought, wildfires and flooding due to climate change has major implications for river water quality, yet there are limited high-temporal resolution data capturing the combined transient impacts of these extreme events at large catchment scales. We present flow-stratified water quality data from a large coastal catchment (Macleay River, Australia) spanning severe drought and extensive fires followed by flooding. We examine concentrations (C), discharge (Q) and flux of suspended sediment, major ions, dissolved organic carbon (DOC) and key nutrients (NO 3 and PO 4), with a focus on the critical first-flush period after the fires. Highly elevated suspended sediment (∼5500 mg L−1; >100x median pre-fire levels) during the initial post-fire period reflected enhanced erosion from fire-impacted, high-relief landscapes, with peak monthly suspended sediment loads of ∼1.1–3.7 t ha−1. The greatest sensitivity to erosion was during initial flow events following fire, highlighting the compounding effect of sequential extreme events on sediment transport. Maximum solute concentrations typically occurred during the first hydrograph peak post-fire with significantly (P = 0.01) elevated major ions following the order of K>Ca>SO 4 >HCO 3 ≈Mg>Cl>Na, broadly reflecting the composition of ash materials. Distorted CQ relationships for major ions, DOC and nutrients indicated mobilisation behaviour and enhanced surface runoff during initial hydrograph peaks post-fire, with mean concentrations and CQ relationships progressively shifting to those approximating pre-fire within ∼3–12 months. Elevated DOC (∼7x; P = 0.01) displays distinct changes in fluorescence excitation-emission matrix spectral characteristics, attributable to both fire and drought. Both NO 3 N (160 μM) and PO 4 (7.5 μM) were significantly elevated after the fires (∼15–22x; P = 0.01), with maximum monthly loads of 0.82 and 0.14 kg ha−1 respectively. Fast biogeochemical cycling of dissolved inorganic nitrogen (DIN) species occurred during initial flow events following fire, with NH 4 N initially dominant (>80% of DIN) and exceeding ecosystem guideline threshold values (>100 μM NH 4 N), followed by rapid (∼1 week) nitrification. The extreme dynamism and transience of water quality parameters highlights the critical importance of high-frequency sampling to adequately capture the compound impacts drought, fires and floods on aquatic systems. [Display omitted] [ABSTRACT FROM AUTHOR]

The Jinsha River, the upper reaches of the Yangtze River, winds and incises through the eastern margin of the Tibetan Plateau, where Asian monsoon climate prevails. Along the Jinsha River, extensive and thick Quaternary valley fillings and multiple river terraces have been developed. However, their specific relations to climate change and tectonics remain elusive. In this study, we conducted field investigation, chronological studies and numerical modeling in its lower reaches. Our study indicates that the extensive valley fillings in the Wudongde-Menggu segment were formed in cold-arid climate with Optically Stimulated Luminescence (OSL) ages of ~23–19 ka B.P., coinciding with the timing of the Last Glacial Maximum (LGM). We suggest that the post-LGM warming and humidifying, by restrained sediment supply while enhanced discharge, switched the valley from prevailing aggradation into incision. Multiple subsequent fill-cut terraces, postdating the LGM, were formed and nested in the valley fillings. OSL data indicate that sediments of three terraces (T1–T3) were formed at ~10 ka B.P., ~11.5–12.5 ka B.P. and ~13.5 ka B.P., respectively. Our study suggests that these terraces are sensitive records of millennial and sub-millennial cold-arid climate perturbations superimposed over the post-LGM deglaciation. Our modeling highlights a high sensitivity of valley aggradation and incision to cold-arid and warm-wet climate change, as well as a fast valley landscape response in the Jinsha River characterized by high sediment transport influx. We propose that valley landscape and terraces serve as a timely record for climate change in certain rivers with short response time threshold characterized by high sediment transport influx. • Valley filling was driven by the cold-arid climate in the LGM. • Fill-cut terraces record sub-millennial cold-arid climate perturbations. • Modeling supports a sensitive and fast response of Jinsha River to climate change. • The present valley landscape remains in a transient adjustment since the LGM. [ABSTRACT FROM AUTHOR]

In the past decade, sediment connectivity has become a widely recognized characteristic of a geomorphic system. However, the quantification of functional connectivity (i.e. connectivity which arises due to the actual occurrence of sediment transport processes) and its variation over space and time is still a challenge. In this context, this study assesses the effects of expected future phenomena in the context of climate change (i.e. glacier retreat, permafrost degradation or meteorological extreme events) on sediment transport dynamics in a glacierised Alpine basin. The study area is the Sulden river basin (drainage area 130 km2) in the Italian Alps, which is composed of two geomorphologically diverse sub-basins. Based on graph theory, we evaluated the spatio-temporal variations in functional connectivity in these two sub-basins. The graph-object, obtained by manually mapping sediment transport processes between landforms, was adapted to 6 different hydro-meteorological scenarios, which derive from combining base, heatwave and rainstorm conditions with snowmelt and glacier-melt periods. For each scenario and each sub-basin, the sediment transport network and related catchment characteristics were analysed. To compare the effects of the scenarios on functional connectivity, we introduced a connectivity degree, calculated based on the area of the landforms involved in sediment cascades. Results indicate that the area of the basin connected to its outlet in terms of sediment transport might feature a six-fold increase in case of rainstorm conditions compared to "average" meteorological conditions assumed for the base scenario. Furthermore, markedly different effects of climate change on sediment connectivity are expected between the two sub-catchments due to their contrasting morphological and lithological characteristics, in terms of relative importance of rainfall-triggered colluvial processes vs temperature-driven proglacial fluvial dynamics. • Functional connectivity analysis based on 8 sediment transport processes • 6 scenarios are defined for average and extreme meteorological conditions. • Graph-theory based network analysis for each scenario • Consideration of future phenomena related to climate change [ABSTRACT FROM AUTHOR]

Cape Darnley Bottom Water (CDBW) is a major contributor to Antarctic Bottom Water (AABW) formation in the MacRobertson Land continental shelf area, East Antarctica. As the production of CDBW is dependent on intense sea ice formation in the Cape Darnley Polynya Region, it is sensitive to climatic changes, such as global warming. Studying paleo-conditions of CDBW during Antarctica's transition from coolhouse to icehouse during the middle to late Miocene allows to gain knowledge about the onset of bottom water production in the Cosmonaut/Prydz Bay region as well as changes in the strength and outflow path of the CDBW. In order to study the paleo-conditions of the CDBW, we have investigated the formation history of a 200 km long, 70 km wide sediment drift (Darnley Drift herein) at the western flank of Wild Canyon. In the early Miocene, the upper rise was dominated by turbiditic channel-levee growth and large continental sediment supply off the MacRobertson Land continental shelf. Therefore, no indications of CDBW formation were observed. During the middle Miocene, the dominant sediment transport regime transformed from turbiditic to contouritic mode, mirroring Antarctica's climatic transition into an icehouse world. This climatic transformation caused the initiation of CDBW, which is inferred from the onset of Darnley Drift formation as a levee-drift and its growth to a maximum areal extent of 60,000 km2, four times the size of today. Since the late Miocene/early Pliocene the sedimentation rate has been strongly reduced and bottom current controlled deposition dominated. The growth of mixed levee-drifts along the continental slope-rise transition parallel to Darnley Drift suggests an intensification of paleo CDBW generation and outflow to be comparable to observations of recent CDBW, in addition to an intensification of the Antarctic Slope Front and Circumpolar Deep Water. • Darnley Drift sedimentary formation history reveals outflow of paleo Cape Darnley Bottom Water since the middle Miocene. • Cooperation Sea sediments off MacRobertson Land Coast, East Antarctica, investigated by 13000 km of seismic reflection data. • Darnley Drift formed as a Miocene mixed-drift including a shift of predominant current regime. • Mixed-drift formation history mirrors Antarctica's climatic transition into an icehouse world during the middle Miocene. [ABSTRACT FROM AUTHOR]

[Display omitted] • We proposed a method for fine-tuning stochastic modeling of sediment yield. • Underlying characteristics of sediment transport are used to tune the model. • Various stream regimes are examined to estimate/predict sediment yield. • Various ecoregions are investigated across the conterminous United States. • The effect of watershed properties on the sediment yield process is studied. Sediment transport is a major contributor to a non-point source of pollution impacted by various factors that are modulated by climatic changes and anthropogenic influences. Quantifying and disentangling the contribution of these factors to sediment yield at large scales and across different flow regimes has not been fully explored. Here we present a framework to fine-tune a stochastic sediment yield model by classifying discharge and Suspended Sediment Load (SSL) observations based on the underlying governing processes in unregulated streams with various hydrological regimes. This stochastic model, rooted in copula theory, constructs a joint distribution between discharge and SSL storm events using historical time series of observations, classified based on seasonality, hysteresis patterns, and hydrograph components of the sediment transport processes. We include hydrological, land use, and geological properties of the watersheds to describe and discuss the effects of different factors on applying the underlying dynamics to enhance sediment yield estimation/prediction accuracy. We evaluated the proposed method on 67 streams across the United States. Our results show significant improvements in sediment yield modeling performance. [ABSTRACT FROM AUTHOR]

As an important component in East Asia sediment source-to-sink systems, small mountainous rivers in Taiwan deliver disproportionately large amounts of sediments to oceans. Although the modern fluvial sediment transport processes, discharge fluxes and sediment compositions have been well investigated, the drainage evolution of these mountainous rivers remains understudied and sediment fluxes are expected to vary greatly in glacial-interglacial cycles due to the tremendous climatic fluctuations. To define how the drainage of Taiwan mountainous rivers has evolved since the last glaciation, we target a sediment core (98 m in length) from the Zhuoshui River delta, western Taiwan and conduct sediment petrography, heavy mineral analysis, detrital zircon U Pb geochronology and clay mineralogy to investigate provenance variations and river basin evolution since 60 ka. Sediments of the last glaciation show comparatively high illite crystallinity index values, low metasedimentary lithic fragment and stable heavy mineral contents and similar detrital zircon U Pb ages with downstream signatures, indicating prominent sediment contributions from the Coastal Plain and Western Foothills regions (elevation <1 km) during the glaciation. However, characteristics of the deglacial and Holocene sediments indicate high contributions from the higher Hsueshan Range and Central Range regions (elevation >1 km). We suggest that headward extension and drainage capture since the deglaciation, which was most likely due to the increasing monsoon rainfall, account for the provenance variations in the discharged sediments. This implies a climate-driven drainage reorganization of the small mountainous rivers in Taiwan since the last glaciation. Our findings highlight the previously-overlooked, variable provenance information from Taiwan in glacial-interglacial cycles, and the dynamic source signatures are important to East Asia sediment source-to-sink studies. [Display omitted] • The provenance of Zhuoshui River sediments has changed since the last glaciation. • The provenance variation was caused by climate-driven drainage reorganization. • The river system of Zhuoshui River was not developed during the last glaciation. • The Zhuoshui River headward extended and captured other basins in the Holocene. [ABSTRACT FROM AUTHOR]

• Fire-induced hydrological impacts were assessed using the OpenLISEM model. • Rainfall dominated the catchment hydro-sedimentary responses before and after fire. • Fire led to a mean increase of 57% in peak discharge and up to 31% in sediment yield. • Sediment sources partly changed from croplands to burnt areas. Wildfires can have strong negative effects on soil and water resources, especially in headwater areas. The spatially explicit OpenLISEM model was applied to a burned catchment in southern Portugal to quantify the individual and combined impacts of wildfire and rainfall on hydrological and erosion processes. The companion paper has calibrated and assessed model performance in this area before and after a fire. In this study, the model was applied with design storms of six different return periods (0.2, 0.5, 1, 2, 5, and 10 years) to simulate and evaluate pre- and post-wildfire hydrological and erosion responses at the catchment scale. Our results show that rainfall amount and intensity played a more important role than fire occurrence in the catchment discharge and sediment yields. Fire occurrence was found to be an important factor for peak discharge, indicating that high post-fire hydro-sedimentary responses are frequently related to extreme rainfall events. The results also suggest a partial shift from runoff to splash erosion after fire, especially for higher return periods. This can be explained by increased splash erosion in burned upstream areas saturating the sediment transport capacity of surface runoff, limiting runoff erosion in downstream areas. Therefore, the pre-fire erosion risk in the croplands of this catchment was partly shifted to a post-fire erosion risk in upper slope forest and natural areas, especially for storms with lower return periods, although erosion risks in croplands were important both before and after fires. These findings have significant implications to identify areas for post-wildfire stabilization and rehabilitation, which is particularly important given the predicted increase in the occurrence of fires and extreme rainfall events with climate change. [ABSTRACT FROM AUTHOR]

Previous research in southwest British Columbia (BC) suggested that projected climate change would result in in increases in the frequency of debris flows on the order of a 10% by the end of the century compared to the last approximately 30 years (Jakob and Lambert, 2009). Advances in climate modeling now allow higher resolution simulation of precipitation compared to the work completed in 2009. Regional climate models have become better able to resolve convective activity at a finer temporal scale. This paper quantifies and projects changes in the frequency and magnitude of shallow landslides and resulting debris flows because of the impacts of climate change for the North Shore Mountains of Vancouver, BC. Analysis of a landslide database curated by Metro Vancouver shows a doubling in the frequency of landslides since 1981, prior to which recording was sporadic. How much of the increase since 1981 is attributable to recording improvements cannot be quantified which implies that it is too early to attribute frequency changes unambiguously to climate change. Prior to 2004, the average volume of shallow landslides was 1800 m3, whereas after 2004, this volume increased 7-fold to 13,000 m3. In particular, landslides with volumes exceeding 10,000 m3 appear to have increased abruptly since in the early 2000s. Using a Poisson model, we project an increase of up to 300% in the frequency of shallow landslides until the end of this century. A multivariate regression analysis suggests that this increase in landslide frequency will be accompanied by a potential increase in the average landslide volume of up to 50% for Relative Concentration Path (RCP) 8.5. Such changes may challenge watershed management attributable to increases in sediment transport rates, widening channels and in some cases may transition from single thread to braiding or anastomosing. The likelihood of landslides impacting and impounding water courses is projected to increase as is the turbidity in reservoirs because of the influx of fine-grained sediment. Outside of the Vancouver watersheds, infrastructures will increasingly be tested by more frequent and sometimes higher magnitude landslides. • Detailed examination of the effects of climate change on shallow landslides in southern BC • Up to almost 400% increases in the frequency of shallow landslides under the RCP 8.5 scenario by the 2080s. • Up to 50% increase in average landslide volume under the under the RCP 8.5 scenario by the 2080s. [ABSTRACT FROM AUTHOR]

• Hydrologic model parameterization produces greatest uncertainty for sediment transport forecasts via GCMs. • Water and sediment forecasts are under-predicted 49% and 35% when only precipitation and temperature are included. • Streamflow and sediment yield forecasts increase by 19% and 14% for the shear-limited landscape and transport-limited stream. Forecasting change in sediment transport using global climate model ensembles is under-developed in the hydrology community due to a lack of knowledge regarding the variance structure of predictions. We investigate the uncertainty of forecast sediment transport from sources, including global climate model realizations, global climate model ensemble design, forecasted hydrologic inputs, and hydrologic modeling parameterizations. We then forecast sediment transport for the gently rolling watershed in Kentucky, USA. Contrary to past research forecasting hydrology with global climate models, hydrologic model parameterization was the most significant source of variance impacting forecasted sediment transport variables. Forecast of sediment transport responses shows the propagation of uncertainty from the hydrologic model parameterization was over two times greater than the uncertainty from the selected global climate model realizations. This result emphasizes researchers focused on forecasting sediment transport with global climate models may need to give as much, or more, consideration to their water–sediment linkages as climate-water–sediment linkages. Hydrologic inputs from climate change, including forecast precipitation, temperature, relative humidity, solar radiation, and wind speed, impacted sediment transport. Considering changes in precipitation and temperature alone under-predicts streamflow and sediment transport by 49% and 35%, respectively, compared to including all meteorological variables inputs. Variance introduced across the three different global climate model ensembles was a relatively small source of variance impacting forecasted streamflow or sediment yield. The results suggest a quantitative effort by the researcher to design the global climate model ensemble by considering representativeness, historical performance, and independency will lead to robust results. Ensemble average forecasts forecast streamflow and sediment yield to increase by 19% and 14%, respectively, for the lowland watershed. The sediment transport forecasts reflect the shear-limited landscape of the watershed and the transport-limited conditions in the stream channel. [ABSTRACT FROM AUTHOR]

Recent reductions of sediment transport are observed in Bouregreg River and estuary close to the city of Rabat in Morocco. The cause of this evolution in sediment transport which may be due to human activities (dam, pollution), climate variability and natural events has been investigated from a paleo-hydrological approach. Sedimentological and geochemical analyses of slackwater flood deposits are used to assess the impact of a dam installed in 1974 and the climate change on the evolution of sediment transport during about 60 years. Higher accumulation rate of about 3,64 cm/year is observed between 1950 and 1978, whereas it was much lower about 0,41 cm/year between 1990 and 2017. This strong decrease in sediment rate appears much more due to the impact of dam construction rather than to climate change, however climate change in an increasing concern for the future. • The paleo-hydrology is an excellent approach to estimate the impact of dam and climate change on fluvial sediment transport. • One potential climatic driver of river discharge in Morocco is the North Atlantic Oscillation (NAO). • Recent reduction of sediment transport is observed in Bouregreg River in Morocco, after the construction of dam since 1974. • Strong decrease in sediment rate appears much more due to dam effect than to climate change. [ABSTRACT FROM AUTHOR]

In the present study, we addressed the potential impact of climate change on coastal erosion along the 28 beaches of the Basque Coast (150 km). A shoreline evolution model including cross-shore and alongshore sediment transport formulations, short- and long-term processes and hard structure treatment is developed. The historical analysis of the shoreline evolution is performed by forcing the model with waves and storm surges from reanalysis data, and with tides from in situ water level measurements. The model is calibrated and validated by using morphological information derived from the KostaSystem coastal video monitoring system. The analysis of the future impact of climate change on the sandy beaches is carried out using two sea level projections (RCP 4.5 and RCP 8.5 scenarios) and their confidence intervals, combined with synthetic wave series that allowed a probabilistic fashion outcome. The results show that the shoreline mean erosion due to both short- and long-term processes is in the range of 10–45 m under the RCP 4.5 scenario and 14–66 m under RCP 8.5 by the year 2100, which indicate the great vulnerability of the beaches of the Basque Coast. Still, the response of the studied systems is highly variable, owing to the intrinsic characteristic of each site. This result points to the difficulty of taking general management measures and highlights the need for management strategies at the local level. • A shoreline evolution model suitable for urban beaches is set up along the sandy systems of the Basque Coast. • The model outcome is validated against the data obtained from a video monitoring system and handled in a probabilistic way. • A new climate change beach impact indicator (beach recovery potential loss) is analysed. • Shoreline mean erosion is in the range of 10–45 m under the RCP 4.5 scenario and 14–66 m under RCP 8.5 by the year 2100. • Results point to the need of local management strategies. [ABSTRACT FROM AUTHOR]