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Land use and cover change are closely linked to catchment hydrology characteristics. Land uses and cover determine the ability of the catchment to collect, store, and release water. The catchment water storage and flow ability affect the quantity and timing of runoff, soil erosion, and sediment transport downstream. Agriculture on of the major drivers for the changes in water flow pathways, which also causes a catastrophic shift of aquatic ecosystems. We assessed the impact of land-use changes on the water flow characteristics in the Upper Pangani Sub catchment using the hydrologic model Soil and Water Assessment Tool (SWAT). Land use and cover changes within the Upper Pangani Sub catchment were analyzed between 1987 and 2017 using QGIS. The result shows that agriculture has expanded from 96,737 ha to 314,871 ha between 1987 and 2017. Bare land and built-up land have gained 14690 ha and 7083 ha respectively during this period. Land-use changes have affected the basin's land cover. Forest has decreased from 196558 ha to 106839 ha between 1987 and 2017. Bush land cover has lost 83445 ha during this period. Bushland cover fall victim to agricultural activities, whereas forest is cleared for logging and fire incidences. Consequently, surface runoff has increased from 60.84 to 73.02 (20.6% increase) between 1987 and 2017. Sediment yield has increase from 6.9 to 12.74 ton/ha (46% increase), and groundwater recharge has decreased from 106.53 to 99.56 (6.5% decrease). It concluded that land cover transformation alters hydrology characteristics of the catchment, resulting to fast surface flow, high rate of soil erosion and low infiltration rate. It is recommended that agro-forestry should be emphasized in the catchment. [ABSTRACT FROM AUTHOR]

• Hillslope erosion dynamic model integrating vegetation effect was established. • Unified baseline parameters were obtained across different land uses. • Effect of vegetation on soil detachment and sediment transport was revealed. • Contribution rates of vegetation to sediment reduction along slopes were quantified. Developing a process-based soil erosion model that comprehensively considers the effects of vegetation is complex but crucial for evaluating sediment reduction during vegetation restoration. Current understanding of the effect of vegetation on sediment reduction along hillslopes across different land uses is limited. In this paper, we developed a dynamic model of hillslope erosion that integrates the effects of vegetation on soil detachability and hydrodynamics (VED) based on the feedback mechanism between soil detachment and sediment transport. The VED was calibrated and validated with runoff plot data for woodland, grassland, and farmland in the Wuding, Yan, Jing and Wei Rivers of the Loess Plateau in China. Unified baseline parameters and decay coefficients of vegetation were obtained. The model validation results indicated that the coefficient of determination, Nash–Sutcliffe simulation efficiency and relative error ranged from 0.59 to 0.99, 0.56 to 0.90, and −45.99 % to 46.36 %, respectively. The decay coefficients for soil detachment capacity (Φ), sediment transport capacity (T c), and the sediment reduction effect of vegetation exhibited the following order: woodland > grassland > farmland. Compared with VED, existing process-based soil erosion models failed to effectively characterize the influence of vegetation on Φ and T c on the Loess Plateau, with differences of several orders of magnitude. The individual contributions of runoff, soil detachability, and hydrodynamics with vegetation impact on sediment yield were quantified by VED. The contribution rates of vegetation to sediment reduction decreased gradually with increasing slope length because the soil detachment capacity of bare slopes exceeded that of vegetated slopes, resulting in a faster increase in sediment yield. The contribution rates of vegetation to sediment reduction for woodland, grassland, and farmland with 20 %–60 % vegetation covers were 66.75 %–99.95 %, 57.43 %–99.63 %, and 27.91 %–88.63 % in the boundary conditions of this study, respectively. The results reveal the potential for integrating VED into other distributed watershed hydrological and sediment models to assess the effects of vegetation restoration on sediment reduction at a watershed scale. [ABSTRACT FROM AUTHOR]

• The runoff, sediment load and runoff erosion power decreased significantly. • Compared with runoff, runoff erosion power-sediment relationship is better. • The power function of runoff erosion power and sediment is better than linear. • Erosion in particular geographic locations responds strongly to runoff erosion power. In recent years, the acceleration of urbanization in the Yangtze River Economic Belt (YREB) has brought about problems such as soil erosion, ecosystem degradation and decline in ecological service functions. Therefore, this paper selects the Fujiang River Basin (FRB) in Upper Yangtze River (UYR), and analyzes the relationship between runoff erosion power (REP) and sediment transport (ST) on the basis of analyzing the variation characteristics of hydrological elements. Based on SWAT model, a variety of scenarios are set up to quantitatively analyze the impact of different land use changes on runoff and ST and REP in the basin. The results indicated that: (1) The annual precipitation in FRB from 1960 to 2018 did not change significantly, while the annual runoff, annual ST and annual REP decreased significantly. Compared with runoff and runoff depth, the relationship between sediment transport modulus (STM) and REP is the best, especially the power function between them is better than the linear function. (2) The results of the evaluation indexes of the simulation results of the SWAT model based on the measured runoff and sediment data from 2008 to 2018 are pass and above, that is, the simulation results are considered reliable. (3) Under the five scenarios of conversion of sloping farmland to forest, conversion of dry land to paddy field and conversion of grassland to bushland and forest land, the runoff and ST in the basin decreased but the overall range was small. The simulation results of SWAT model show that the erosion of specific areas in the basin shows the greatest degree of weakening with the decrease of REP. [ABSTRACT FROM AUTHOR]

• A new sediment connectivity index (IC ZQ) is proposed. • The correlation between IC ZQ and sediment yield modulus was improved. • Land use/cover change (LUCC) can significantly change sediment connectivity. • The on-site and off-site impacts caused by LUCC on IC were quantified. Soil erosion is an important cause of global land degradation and other ecological and environmental problems. Revealing the influence mechanism of land use/cover change (LUCC) on sediment yield can provide a scientific basis for efficient comprehensive and decision-making management of watersheds. As an important indicator of sediment yield and transport capacity, sediment connectivity has been widely studied in recent years. However, the existing index of sediment connectivity (IC) ignores the influence of upslope land use/cover on confluence and the corresponding changes in downslope sediment transport. Moreover, a formula describing the upslope and downslope components does not establish an effective correlation with existing soil erosion formulas. Therefore, the index is not closely related to the erosion process and does not reflect the physical process of sediment transport and sediment deposition. In addition, there have been few reports concerning the effect of LUCC on sediment connectivity inside (on-site impact) and outside (off-site impact) the changed patches. Consequently, by based on addition of the revised parameters of the effective confluence area (A r) and the runoff velocity factor (v) of the sediment delivery distributed (SEDD) model, an improved sediment connectivity index (IC ZQ) is proposed. The results indicate that IC ZQ has a significant linear relationship with annual runoff depth or sediment yield modulus in small watersheds within 100 km2 in the Loess Plateau, except for feature years containing rainstorm events (daily rainfall exceeding 50 mm). Therefore, the runoff and sediment transport capacity of small watersheds can be characterized by IC ZQ under the influence of LUCC and rainfall change. In 1982–2020, driven by LUCC with an enhancement in vegetation (forest and grass), the IC ZQ decreased in 90% of the area and decreased by a significant or extremely significant level over 48% of the area. To better understand the effects of LUCC on sediment connectivity, we analyzed on-site and off-site impacts with rainfall remaining unchanged to control the variables. The contribution rates of the on-site and off-site impacts caused by LUCC on sediment connectivity in Lvergou were 61% and 39%, 48% and 52%, respectively, over two typical periods (1985–1990 and 2015–2020). Due to the large proportion that off-site impacts occupied in the sediment connectivity change, the impact of LUCC on sediment connectivity cannot be ignored, especially when the associated scale is relatively small. The present study provides a quantitative method for the optimization of land use/cover patterns, such as vegetation restoration in watersheds along with a reference for further revealing the impact mechanism of erosion and sediment yield in watersheds. [ABSTRACT FROM AUTHOR]

Marine eutrophication in the North-East Atlantic (NEA) strongly relies on nutrient enrichment at the river outlets, which is linked to human activities and land use in the watersheds. The question is whether human society can reduce its nutrient emissions by changing land use without compromising food security. A new version of Riverstrahler model (pyNuts-Riverstrahler) was designed to estimate the point and diffuse nutrient emissions (N, P, Si) to the rivers depending on land use in the watersheds across a large domain (Western Europe agro-food systems, waste water treatment). The loads from the river model have been used as inputs to three marine ecological models (PCOMS, ECO-MARS3D, MIRO&CO) covering together a large part of the NEA from the Iberian shelf to the Southern North Sea. The modelling of the land-ocean continuum allowed quantifying the impact of changes in land use on marine eutrophication. Pristine conditions were tested to scale the current eutrophication with respect to a “natural background” (sensu WFD), i.e. forested watersheds without any anthropogenic impact. Three scenarios representing potential management options were also tested to propose future perspectives in mitigating eutrophication. This study shows that a significant decrease in nitrogen fluxes from land to sea is possible by adapting human activities in the watersheds, preventing part of the eutrophication symptoms in the NEA rivers and adjacent coastal zones. It is also shown that any significant achievement in that direction would very likely require paradigmatic changes at social, economic and agricultural levels. This requires reshaping the connections between crop production and livestock farming, and between agriculture and local human food consumption. It also involves cultural changes such as less waste production and a shift towards lower-impact and healthier diets where half of the animal products consumption is replaced by vegetal proteins consumption, known as a demitarian diet ( http://www.nine-esf.org/node/281/index.html ). [ABSTRACT FROM AUTHOR]

Variations in bed friction due to land cover type have the potential to influence morphologic change during storm events; the importance of these variations can be studied through numerical simulation and experimentation at locations with sufficient observational data to initialize realistic scenarios, evaluate model accuracy and guide interpretations. Two-dimensional in the horizontal plane (2DH) morphodynamic (XBeach) simulations were conducted to assess morphodynamic sensitivity to spatially varying bed friction at Dauphin Island, AL using hurricanes Ivan (2004) and Katrina (2005) as experimental test cases. For each storm, three bed friction scenarios were simulated: (1) a constant Chezy coefficient across land and water, (2) a constant Chezy coefficient across land and depth-dependent Chezy coefficients across water, and (3) spatially varying Chezy coefficients across land based on land use/land cover (LULC) data and depth-dependent Chezy coefficients across water. Modeled post-storm bed elevations were compared qualitatively and quantitatively with post-storm lidar data. Results showed that implementing spatially varying bed friction influenced the ability of XBeach to accurately simulate morphologic change during both storms. Accounting for frictional effects due to large-scale variations in vegetation and development reduced cross-barrier sediment transport and captured overwash and breaching more accurately. Model output from the spatially varying friction scenarios was used to examine the need for an existing sediment transport limiter, the influence of pre-storm topography and the effects of water level gradients on storm-driven morphodynamics. [ABSTRACT FROM AUTHOR]

Eroded soil from cropland watersheds is deposited as sediment into depressional wetlands such as playas degrading their ability to provide ecosystem services. Sediment removal from these degraded playa wetlands restores water storage volume. However, the effects of this restoration practice on carbon (C) and nitrogen (N) concentrations and C sequestration potential in playas has not been determined. One of the most important wetland systems and intensively cultivated regions in North America, the Rainwater Basin (RWB) of Nebraska, contained over 4000 playas but has lost 90% of them due to agricultural activities. Our objective was to examine the effects of sediment removal on wetland C and N concentrations and determine subsequent C sequestration potential. We also were interested in determining the importance of the presence of wetlands on the landscape to C sequestration given the loss of wetlands that has occurred. We hypothesized that sediment removal might decrease C sequestration potential and that the presence of wetlands on the landscape provides important C sequestration sites. To accomplish these objectives we sampled 60 playas and their immediate watersheds (20 each from reference condition, cropland, and restored through sediment removal) in 2013 and 2014 by coring soil/sediments (mollisols) to a depth of 50 cm. Restored playas contained 29% lower C and N in the top 5 cm than in reference and cropland land uses. The C in the top 5 cm was also 36% higher in the wetland than in the watershed. There were no differences in C and N among land uses/landscape positions at depths >5 cm. However, because restored playas had sediment removed, in some cases down to the clay pan of the historic playa soil surface, on an areal basis, restored playas stored 21% more soil organic carbon (SOC) in deeper horizons (25–50 cm) than reference or cropland conditions. Overall, SOC was similar among restored, cropland and reference wetlands to a 50 cm depth, indicating that sediment removal does not have a negative effect on C sequestration potential. On average, SOC was 15% higher in playas than in adjacent uplands, demonstrating the importance of playa wetlands on the landscape to C sequestration. Results of this study have widespread applicability because depressional wetlands are the dominant wetland type in temperate agroecosystems. [ABSTRACT FROM AUTHOR]

Changes in land use can affect local geomorphology and sediment dynamics. However, these impacts could conceivably lead to changes in geomorphological processes beyond the area of land use change, thereby evidencing a geomorphic connectivity in the landscape. We conduct a numerical modelling experiment, using the CAESAR landscape evolution model, to investigate the extent and nature of such connectivity in the River Swale basin. Six simulations are run and analysed. Two of these are reference simulations, where the basin has a hypothetical total grassland cover or total forest cover. In the other four simulations, half of the basin is subjected to either deforestation or reforestation during the simulation. Simulations are analysed for temporal trends in sediment yield and for spatial trends in erosion and deposition across the basin. Results show that deforestation or reforestation in one half of the basin can indeed affect the geomorphology of the other half, thus implying a geomorphological connectivity across the basin. This connectivity is locally very high, with significant morphological impacts close to where de- or re-forestation occurs. Changes are observed both downstream and upstream of the areas where the land use changes occurred. The impacts are more pronounced in the downstream direction and are still apparent in the basin scale sediment yields, as deforestation of half the basin can increase decadal sediment yields by over 100%, whilst reforestation of half the basin can lead to 40% decreases. However, our results also indicate a reverse connectivity whereby erosion and deposition in upstream headwaters and tributaries can, for the first time, be conclusively attributed to land use changes several kilometres downstream, due to alterations in the valley floor base level resulting from incision and alluviation. [ABSTRACT FROM AUTHOR]

The effects of climate change and variability on river flows have been widely studied. However the impacts of such changes on sediment transport have received comparatively little attention. In part this is because modelling sediment production and transport processes introduces additional uncertainty, but it also results from the fact that, alongside the climate change signal, there have been and are projected to be significant changes in land cover which strongly affect sediment-related processes. Here we assess the impact of a range of climatic variations and land covers on the River Thames catchment (UK). We first calculate a response of the system to climatic stressors (average precipitation, average temperature and increase in extreme precipitation) and land-cover stressors (change in the extent of arable land). To do this we use an ensemble of INCA hydrological and sediment behavioural models. The resulting system response, which reveals the nature of interactions between the driving factors, is then compared with climate projections originating from the UKCP09 assessment (UK Climate Projections 2009) to evaluate the likelihood of the range of projected outcomes. The results show that climate and land cover each exert an individual control on sediment transport. Their effects vary depending on the land use and on the level of projected climate change. The suspended sediment yield of the River Thames in its lowermost reach is expected to change by −4% (−16% to +13%, confidence interval, p = 0.95) under the A1FI emission scenario for the 2030s, although these figures could be substantially altered by an increase in extreme precipitation, which could raise the suspended sediment yield up to an additional +10%. A 70% increase in the extension of the arable land is projected to increase sediment yield by around 12% in the lowland reaches. A 50% reduction is projected to decrease sediment yield by around 13%. [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]

The relation between rainfall, runoff, erosion and sediment transport is highly variable in Mediterranean catchments. Their relation can be modified by land use changes and climate oscillations that, ultimately, will control water and sediment yields. This paper analyses rainfall, runoff and sediment transport relations in a meso-scale Mediterranean mountain catchment, the Ribera Salada (NE Iberian Peninsula). A total of 73 floods recorded between November 2005 and November 2008 at the Inglabaga Sediment Transport Station (114.5 km 2 ) have been analysed. Suspended sediment transport and flow discharge were measured continuously. Rainfall data was obtained by means of direct rain gauges and daily rainfall reconstructions from radar information. Results indicate that the annual sediment yield (2.3 t km − 1 y − 1 on average) and the flood-based runoff coefficients (4.1% on average) are low. The Ribera Salada presents a low geomorphological and hydrological activity compared with other Mediterranean mountain catchments. Pearson correlations between rainfall, runoff and sediment transport variables were obtained. The hydrological response of the catchment is controlled by the base flows. The magnitude of suspended sediment concentrations is largely correlated with flood magnitude, while sediment load is correlated with the amount of direct runoff. Multivariate analysis shows that total suspended load can be predicted by integrating rainfall and runoff variables. The total direct runoff is the variable with more weight in the equation. Finally, three main hydro-sedimentary phases within the hydrological year are defined in this catchment: (a) Winter, where the catchment produces only water and very little sediment; (b) Spring, where the majority of water and sediment is produced; and (c) Summer–Autumn, when little runoff is produced but significant amount of sediments is exported out of the catchment. Results show as land use and climate change may have an important role in modifying the cycles of water and sediment yields in Mediterranean mountain catchments. [ABSTRACT FROM AUTHOR]

Abstract: The general progression of human land use is an initial disturbance (e.g., deforestation, mining, agricultural expansion, overgrazing, and urbanization) that creates a sediment pulse to an estuary followed by dams that reduce sediment supply. We present a conceptual model of the effects of increasing followed by decreasing sediment supply that includes four sequential regimes, which propagate downstream: a stationary natural regime, transient increasing sediment supply, transient decreasing sediment supply, and a stationary altered regime. The model features characteristic lines that separate the four regimes. Previous studies of the San Francisco Estuary and watershed are synthesized in the context of this conceptual model. Hydraulic mining for gold in the watershed increased sediment supply to the estuary in the late 1800s. Adjustment to decreasing sediment supply began in the watershed and upper estuary around 1900 and in the lower estuary in the 1950s. Large freshwater flow in the late 1990s caused a step adjustment throughout the estuary and watershed. It is likely that the estuary and watershed are still capable of adjusting but further adjustment will be as steps that occur only during greater floods than previously experienced during the adjustment period. Humans are actively managing the system to try to prevent greater floods. If this hypothesis of step changes occurring for larger flows is true, then the return interval of step changes will increase or, if humans successfully control floods in perpetuity, there will be no more step changes. [Copyright &y& Elsevier]

• Vegetation was the main landuse change type, with an increase of 46.65% in 1964–2018. • Connectivity index (IC) was spatially variable and lower in the main gully. • IC was impacted by re-vegetation, terrace, and dam land in descending order. • Connectivity variations were quantitatively related to sediment yield reduction. The spatial distribution of landscape pattern in catchments has a great impact on the potential sediment detachment and transport capacity. In this study, a sediment connectivity model was applied to evaluate the effect of the spatial distribution of landscape pattern on the sediment transfer in a typical catchment on the Loess Plateau in China based on land use and topography data in 1964, 2004, and 2018. Thereupon, the impacts of changes in different land use types on sediment connectivity and those of sediment connectivity changes on sediment yield reduction in the catchment were quantified. The results showed that (i) grassland and slope farmland were the main land use types in the catchment, and a decrease of the slope farmland area and an increase of the vegetation coverage occurred from 1964 to 2018; (ii) compared with 1964, most parts of the catchment in 2004 and 2018 had an overall lower connectivity index (IC); (iii) the distribution of sediment connectivity presented obvious spatial variability. The hill slopes and tributary gullies tended to be relatively well connected, and the main gully was highly disconnected. Scenario simulations showed that the potential sediment reduction effect was 20%−45% for vegetation, and <10% for terraces or dam lands in 1964, 2004, and 2018. The effect of impounding sediment by check dams was not included in IC calculation in this study, and it was found that the sediment impounded by these dams accounted for about 16% of sediment discharge reduction during 1995–2004 and 1% during 2005–2018. The IC reduction was responsible for 84% of the decrease of sediment discharge during 1995–2004 and 99% during 2005–2018, reflecting that vegetation restoration and terrace construction on slopes has become the main drivers for reducing IC value and sediment yield. [ABSTRACT FROM AUTHOR]

Abstract: The purpose of this paper is to provide background information and sample locations for research on agricultural water management issues of the lake Laguna de Bay, Philippines, addressed in this special issue. We introduce the key features of the lake, the rationale for catchment selection, agricultural land uses of the selected catchment, and describe the instrumentation installed for water quality measurements. Laguna de Bay is the largest freshwater lake in the Philippines and the second largest in Southeast Asia. It has a surface area of 900km2 in the form of three bays. The eastern bay of the lake is important for aquaculture and leisure activities. It is also planned as a future source of drinking water for Metro Manila as it is the least impacted by human activity of the three bays. In contrast to the central and western bays, the eastern bay has little urbanisation or industrial activities in its catchments. The main risk of water quality degradation is from diffuse non-point source pollution from its predominantly agricultural catchments. There are 24 catchments surrounding the lake of which the Pagsanjan-Lumban catchment is the second biggest. However, the Pagsanjan-Lumban catchment provides the largest flow of water into the lake. The predominant land uses in this catchment are coconut plantations (33%), and cropland mixed with coconut plantation (26%). Rice production is also an important land use in the catchment. For this study the Pagsanjan-Lumban catchment was instrumented with automatic water samplers and water level loggers at 4 sites that are representative of the major sources of agricultural contaminants in the catchments surrounding the eastern bay of the lake. This allowed the quantification over 2 years of concentrations and loads of sediment, nutrients and selected pesticides being transported off-site at the sampling sites. Background information and details of the instrumentation of this catchment are given in this manuscript and details of the findings from the water analyses and modelling are given in subsequent manuscripts. [Copyright &y& Elsevier]

Abstract: This paper reports on the edge-of-field loads of sediment, nitrogen, phosphorus and organic carbon transported from three main land uses, namely an apple and a cherry orchard and a vineyard, in the Mt Lofty Ranges (MLR), South Australia over a three year period. There is a plethora of data in Australia on nutrient losses from dairy but prior to this study there was limited data from horticultural activities which are predominant in the MLR. Generally the highest total suspended solids (TSS) were found in surface drainage from the vineyard. At all three sites the highest TSS load was found in the first runoff event of the year but large flow events were accompanied by spikes in TSS concentration. Generally, within an event, the highest TSS concentration was found at the peak of flow and decreased on the receding limb of the hydrograph. The total nitrogen (TN) concentration exceeded the Australian environmental trigger value of 1mg/L in >50% of the samples from the apple orchard and >90% of the samples from the cherry orchard and vineyard. The total phosphorus (TP) concentrations exceeded the Australian environmental trigger value of 0.1mg/L in <10% of the samples from the apple and the cherry orchard but in >90% of the samples from the vineyard. Trends in the timing of the transport of TN, TP and TOC were only clearly observed when flow was large. After the initial seasonal flush of contaminants, generally only a very large runoff volume was sufficient to generate large loads of TN, TP and TOC during the season. Generally, the concentration of TP and TOC but not TN during a flow event was high at the start and declined with flow rate. In low flow situations, these trends were not clear. The transport of TN during an event was variable and unpredictable. [Copyright &y& Elsevier]

Abstract: Suspended sediment transport into Laguna Lake (Philippines) due to soil erosion from agricultural activities in the Pagsanjan–Lumban catchment is of great concern because of its impacts on water quality. The Pagsanjan–Lumban catchment contributes about 18–20% of the total freshwater inflows to the lake but represents only 10% of the catchment area. In this study the suspended sediment transport model, SedNet, was used to assess the relative impacts of changes in land use within the catchment on the quantities of suspended sediment discharged to the lake. The SedNet model predicted the total suspended sediment supply from the Pagsanjan–Lumban catchment (280km2) to be 231.2kt/y of which almost 70% was predicted to come from Balanac River, 23% from Bombongan River and the remaining 7% from the catchment downstream of these two river systems. Overall, the suspended sediment supply was predicted to decrease by 8% for every 20% of intercropped coconut plantations converted to forest. A greater reduction in the total suspended sediment yield discharging to the lake was predicted when reforestation was targeted at the steep slopes (<6.6°) than when reforestation was untargeted (20% reduction compared with approximately 7%). The major limitation with the application of the SedNet model for this work was the limited availability of input data such as more detailed land use classifications (i.e. differentiating plantation into various kinds of crops, as well as different types of grass covers) and information about gullies throughout the catchment. This improved data input would provide greater accuracy and confidence in the modelling. However, the model was very useful for giving a preliminary assessment of the sources of suspended sediment transported from the catchment, and for targeting reforestation for reducing suspended sediment accessions to the lake. [Copyright &y& Elsevier]

Summary: In this study, groundwater spring potential maps produced by three different methods, frequency ratio, weights of evidence, and logistic regression, were evaluated using validation data sets and compared to each other. Groundwater spring occurrence potential maps in the Sultan Mountains (Konya, Turkey) were constructed using the relationship between groundwater spring locations and their causative factors. Groundwater spring locations were identified in the study area from a topographic map. Different thematic maps of the study area, such as geology, topography, geomorphology, hydrology, and land use/cover, have been used to identify groundwater potential zones. Seventeen spring-related parameter layers of the entire study area were used to generate groundwater spring potential maps. These are geology (lithology), fault density, distance to fault, relative permeability of lithologies, elevation, slope aspect, slope steepness, curvature, plan curvature, profile curvature, topographic wetness index, stream power index, sediment transport capacity index, drainage density, distance to drainage, land use/cover, and precipitation. The predictive capability of each model was determined by the area under the relative operating characteristic curve. The areas under the curve for frequency ratio, weights of evidence and logistic regression methods were calculated as 0.903, 0.880, and 0.840, respectively. These results indicate that frequency ratio and weights of evidence models are relatively good estimators, whereas logistic regression is a relatively poor estimator of groundwater spring potential mapping in the study area. The frequency ratio model is simple; the process of input, calculation and output can be readily understood. The produced groundwater spring potential maps can serve planners and engineers in groundwater development plans and land-use planning. [ABSTRACT FROM AUTHOR]

Abstract: The fringing reef of southern Moloka’i is perceived to be in decline because of land-based pollution. In the absence of historical records of sediment pollution, ratios of coral Ba/Ca were used to test the hypothesis that sedimentation has increased over time. Baseline Ba/Ca ratios co-vary with the abundance of red, terrigenous sediment visible in recent imagery. The highest values at One Ali’i are near one of the muddiest parts of the reef. This co-varies with the lowest growth rate of all the sites, perhaps because the upstream Kawela watershed was historically leveed all the way to the nearshore, providing a fast-path for sediment delivery. Sites adjacent to small, steep watersheds have ∼decadal periodicities whereas sites adjacent to mangrove forests have shorter-period fluctuations that correspond to the periodicity of sediment transport in the nearshore, rather than the watershed. All four sites show a statistically significant upward trend in Ba/Ca. [ABSTRACT FROM AUTHOR]

Abstract: The threat imposed by increased sediment loading rates ranks among the most important stressors affecting coral reef ecosystems worldwide. This study represents an effort to quantify the effects of unpaved roads on erosion rates in a dry sub-tropical area of Puerto Rico and is intended to aid in developing scientifically-based erosion mitigation strategies. Hence, the specific objectives of this study were to: (1) measure sediment production rates from unpaved roads; (2) evaluate the effect of precipitation, rainfall erosivity, slope, plot length, and vegetation cover on sediment production rates; and (3) compare measured sediment production rates to published surface erosion data from roaded and natural sites in the Eastern Caribbean. Sediment production from nine abandoned road segments with varying slopes and plot lengths were measured with sediment traps in southwestern Puerto Rico from August 2003 to September 2005. The overall average sediment production rate was 0.84Mg ha− 1 yr− 1, and the range of observed values was 15–50 times higher than locally-measured natural erosion rates. Only four of the nine study sites had a statistically significant correlation between sediment production and total rainfall and this is attributed to progressive changes in some of the conditions controlling erosion rates. Sediment production rates were dependent on slope raised to the 1.6th power, as well as to the product of plot length times slope1.6. Average erosion rates were inversely but poorly related to vegetation cover. An observed decline in sediment production rates was observed for all nine study segments, and this amounted to a statistically significant difference between observations made during the early stages of monitoring (Period 1: August 2003–April 2004) relative to those during the latter parts of the study (Period 2: May 2004–September 2005). Annual erosion rates during Period 1 amounted to 0.18 to 4.0Mg ha− 1 yr− 1 for road segments with 1% and 22% slopes, respectively; rates during Period 2 were between 0.024 and 0.52Mg ha− 1 yr− 1, or only 13% of those during Period 1. Differences in sediment production rates between the two periods are attributed to more intense rainfall during Period 1 and to a notably higher vegetation cover during Period 2. Rainfall appears to play a paradoxical role in controlling surface erosion rates on abandoned road surfaces in a sub-tropical dry region. While ample rainfall is needed to generate erosion by rainsplash and overland flow, once rainfall satisfies soil moisture requirements for sustaining vegetation colonization it may also contribute to declining sediment production rates. Therefore, any model that attempts to properly address the temporal variation in erosion rates occurring on abandoned roads in a climatic setting where moisture availability is a limiting factor must not only follow the more traditional surface armoring-based approach but must also integrate the effects of re-vegetation. Such types of models will eventually become useful tools to properly assess the effects of past, current, and future land use practices on erosion rates, and to improve mitigation and land development strategies to lessen the impact on vital marine habitats. [Copyright &y& Elsevier]

Abstract: The Daly River occupies a mainly undisturbed large catchment in the Australian wet–dry tropics. Concerns about possible increased sediment input to the River from clearing and cropping have motivated this study of fine sediment sources. Using geochemical tracers for both modern sediments and alluvial bench deposits, it is shown that, for the last ~30 years, 89–97% of the fine sediment originates from erosion by gullying and channel change. There is no discernible input of top soil from the cleared land adjacent to the Daly River in the study area. The analysis and OSL dating of the alluvial benches have also provided data on the age of (and inferences about the causes of) bench formation, flood frequency change, sedimentation rate change, and episodes of sand transport. The benches are being destroyed as the channel widens (contributing sediment to the river) and the bed of the Daly appears to be shallowing, both responses to increased overbank flows. The sediment source created by channel widening is almost all the result of hydrologic change, with no discernible role for land use. [Copyright &y& Elsevier]

Abstract: Bedload sediment is not only a major pollutant, but can also act as a transporter of pollutants. Sediment flow behavior often reflects the characteristics of a watershed, such as land use and management. To clarify the behavior of sediment flow under different spatial scales and storm types in the Chinese purple soil area, the sediment flow behavior in three small agro-watersheds with different catchment areas, physical characteristics and land use types was investigated during natural rainfall events from 1999 to 2000. The results showed that there were three types of sediment hydrographs, waveform or linear with a low sediment concentration (1.13±0.58gl−1), logarithmic decrease (3.41±4.13gl−1), and compound linear and logarithmic decrease (9.58±10.90gl−1). During PP-type rainfall events (high-intensity rainfall occurred during the prophase of the rainfall process) and ML-type rainfall events (high intensity rainfall occurred during the middle of the rainfall event), the waveform or linear type sediment hydrographs or the logarithmic decrease type hydrographs were generated in each of the three agro-watersheds. However, sediment hydrographs produced by IM-type rainfall events (discontinuous rainfall with obvious segments) depended on the spatial scale of the watershed. As the spatial scale decreased, the hydrographs were transformed from the logarithmic decrease type to the compound type. In addition, it was found that the S = aQ b model could effectively simulate the sediment hydrologic process of a single rainfall event. The information provided in this study will help evaluate and prevent soil and water loss and non-point source pollution in the purple soil region. [Copyright &y& Elsevier]

Abstract: Variations in the coupling of sediment transfer between different parts of a fluvial catchment, e.g., hillslope to axial stream, can hamper understanding but are an integral part of the geomorphological record. Depositional environments respond to a combination of land use, climate, storms (floods), and autogenic conditioning. The distribution of sediment in the upland landscapes of NW England is out of equilibrium with contemporary climate and geomorphological processes; more a function of peri- and paraglacial mobilisation of glacigenic deposits. Soil and vegetation development after deglaciation have interrupted any progression toward sediment exhaustion with sediment release controlled largely by extrinsic perturbation, with late Holocene anthropogenic activity, climate and extreme hydrological events the likely candidates. This paper presents a new radiocarbon-dated Holocene geomorphological succession for the River Hodder (NW England), alongside evaluating new palaeoecological and geoarchaeological data to discern the impacts of human activity. These data show a late Holocene expansion in human occupation and use of the landscape since the Iron Age (700–0 cal. B.C.), with more substantial changes in the character and intensity of upland land use in the last 1300 years. The geomorphological responses in the uplands were the onset of considerable and widespread hillslope erosion (gullying) and associated alluvial fan development. Interpretation of the regional radiocarbon chronology limits gullying to four, more extensive and aggressive phases after 500 cal. B.C. The downstream alluvial system has responded with considerable valley floor deposition and lateral channel migration that augmented sediment supply by remobilising the existing floodplain terraces and led to the aggradation of a series of inset alluvial terraces. The timing of these changes between states of aggradation and incision in alluvial reaches reflects the increased connectivity between the hillslope and alluvial systems. Aspects of both the regional climate and land use histories are conducive to increasing discharge and sediment flux, but the region wide lowering of erosion thresholds appears a key driver conditioning these sediment-rich conditions and producing a landscape that was more susceptible to erosion under lower magnitude flows. [Copyright &y& Elsevier]

Land uses have long modified aeolian sedimentary dynamics as has occurred in the Jandía isthmus (Fuerteventura, Canary Islands, Spain), where changes in vegetation cover, the reduction of sediment available for transport and the building of barriers to sediment transport have induced beach erosion. In the last 62 years the beach area has experienced a reduction of 800,000 m2. The aim of this paper is to analyse the current situation (in terms of sediment availability, longshore drift and the distribution of protected plant species) in order to make soft management proposals to respond to the current erosive situation. Based on a methodology that combines field work, coastline digitalization and longshore drift calculations, it is found that each year the system loses about 96,000 m3 of sediment which needs to be replaced in order to stop erosion. Four possible ways to manage the system are discussed: passive non-intervention management to allow the ecosystem to evolve and adapt to the new conditions; remobilization of the sedimentary deposits of the isthmus that feed the beaches; beach nourishment from other areas of the system or from outside the system, and; mechanical recirculation of the sands. The viability of each management system is analyzed, particularly with regard to long-term sustainability, as well as its compliance or otherwise with the protection measures that are in place. Paradoxically, the only measures that can alleviate the problem in the long term are incompatible with the current protective measures. In other words, the isthmus and the Sotavento beaches in Jandía are an example of an ecosystem in which the restrictions imposed as a result of its protected status, that do not take into account the tendences of the ecosystem, in fact constitute an obstacle to its conservation and do not allow the adoption of measures that could slow down the degradation process and, ultimately, impede its disappearance. [Display omitted] • Beach evolution is analyzed for a period of 62 years. • Protected species, marine dynamic, sediment availability and land uses are analyzed. • Four management ways are proposed from the current status of the ecosystem. • Erosion problems cannot be solved with the current legislation. [ABSTRACT FROM AUTHOR]

Abstract: An un-mixing model is formulated within a Bayesian Markov Chain Monte Carlo framework for use within land-use fingerprinting to study watershed erosion processes. The model has two new components: (1) An equation and erosion process parameter are used to weight tracer signatures from each erosion process within a land-use. (2) An extra tracer distribution and episodic erosion parameter are used to represent soil eroded throughout the sampling duration and thus include the episodic nature of erosion. To test specification of these new parameters, the un-mixing model is applied in the 15km2 Jerome Creek Watershed in the Palouse Region of Northwestern Idaho. Erosion processes include surface erosion upon mountain slopes due to logging in the forest land-use and rill/interrill erosion on cultivated slopes and headcut erosion in riparian floodplains of the agricultural land-use (winter wheat/peas rotation and hay pasture). Episodic erosion occurs for the event where the model is applied. A sensitivity analysis shows that the smallest Bayesian credible set results when the new parameters are specified using hydrologic data and process-based models. The un-mixing model predicts that 90% of the eroded-soil originated from the agricultural land-use and 10% originated from the forest land-use. A comparative study is performed that estimates 90.5% and 9.5% of eroded-soil originated from the agricultural and forest land-uses. Successful performance of the un-mixing model highlights future application as a standalone probabilistic tool to monitor watershed erosion processes that exhibit non-equilibrium conditions and provide calibration data for process-based watershed models. [Copyright &y& Elsevier]

Abstract: At present large collective fields in the Czech Republic are being split up into smaller spatial units. Moreover, a large number of former state farms are abandoned, resulting in an increase of the area of set-aside land. Between 1990 and 2000 the area of pasture land in the Czech Republic increased 150%. The ongoing landscape dynamics has a significant impact on soil erosion and sediment delivery to rivers and reservoirs. In some cases sedimentation records in retention ponds at the outlet of rural drainage basins show a 75% decrease of the mean annual sediment export since 1990. It may be expected that the EU enlargement will be a significant driver for future land cover change in Central and Eastern Europe. In this paper some possible land cover change scenarios for rural areas in the Czech Republic were considered. Next, these scenarios were used as an input for a spatially distributed sediment delivery model in order to evaluate their impact on soil erosion and sediment delivery. The results show that the spatial pattern of land cover change seems to be more important than the percentage of land cover change, which encourages the development and application of spatially explicit land cover change models. [Copyright &y& Elsevier]

Abstract: Sedimentary material from coastal and nearshore areas in the Mississippi Delta region are comprised of different organic carbon sources with diverse ages that require isotopic and elemental records for resolving the various sources of plant residues. Carbon isotopic (13C, 14C) values were used to differentiate contributions from plants using the C3, C4, and/or CAM (crassulacean acid metabolism) carbon fixation pathways. , and iodine concentrations indicated that wetland plant residues are a significant source of organic carbon in a sediment core from the Mississippi River delta region collected at a 60m water depth. This sediment core had been extensively described in Oktay et al. [Oktay, S. D. , Santschi, P. H. , Moran, J. E. , Sharma, P. , 2000. The 129Iodine Bomb Pulse Recorded in Mississippi River delta Sediments: Results from Isotopes of I, Pu, Cs, Pb, and C. Geochim. Cosmochim. Acta 64 (6), 989–996. ] and significantly, includes unique features that had not previously been seen in the marine environment. These special features include a plutonium isotopic close-in fallout record that indicates a purely terrestrial source for these sediment particles and the elements associated with it, and a distinct iodine isotopic peak (as well as peaks for plutonium and cesium isotopes) that indicate little bioturbation in this core. Our carbon isotopic and iodine data can thus be compared to published records of changes in drainage basin land use, river hydrology, and hydrodynamic sorting of suspended particles to elucidate if these changes are reflected in nearshore sediments. This comparison suggests a significant contribution for organic carbon (OC) from C4 plants to these sediments during the 1950’s to early 1960’s. Relative older carbon isotopes, and episodically high iodine concentrations (up to 34ppm) were observed during this time period that (1) indicate sediment deposition that is coincident with the times of major hydrological changes induced from dam and levee building in both the upper and lower reaches of the Mississippi River drainage basin, and (2) suggest episodic organic carbon deposition from wetland plant residues. [Copyright &y& Elsevier]

Abstract: Agricultural land use changes can influence soil erosion process. The objective of this study was to investigate impact of historical land use changes on soil erosion and sediment transport in the Kali Basin study area, a small catchment located in a national park at Lake Balaton, Hungary. The Kali Basin is of high landscape value where vine (Vitis spp.) growing has been ongoing since the Roman times. Lake Balaton is a recreational area of international significance, thus research on sediment and nutrient fluxes is of paramount importance for lake protection. The SEDEM/WATEM distributed erosion and sediment transport model was used to calculate sediment fluxes from the Kali Basin catchment into the lake. The model was calibrated against long-term measured suspended sediments at the catchment outlet and it was validated against independent soil survey data. Application of GIS methods for model development and interpretation was emphasised. Results showed that, despite the low overall sediment export from the catchment, land use changes introduced by property ownership and agricultural changes have decreased average sediment production in the catchment but increased relative sediment export to Lake Balaton. This is due to changes in the land cover pattern that allow more sediment transported to the river system. Erosion impact of dramatic land use changes such as change to centrally directed economy after the WWII and transition to market economy a decade ago in the study area are discussed. Similar land use changes due to socio-economic changes are typical in most of Central and Eastern European New Member States and Candidate Countries, thus the investigation of similar sites is an important contribution to the understanding of erosion impact of land use changes and to efficient agricultural and landscape management in the enlarged European Union. [Copyright &y& Elsevier]

The catchments of Pine Creek, Idaho, USA (200 km2), and the Droˆme River in the Droˆme Department, France (1640 km2), illustrate contrasting changes in land use, bedload sediment production, and channel response. Hard-rock mining began in the catchment of Pine Creek near the end of the 19th century and, together with road construction, timber harvest, and historically heavy grazing of uplands, resulted in increased tributary bedload yield. Increased bedload migrating to the channel, combined with removal of large cedar trees on the floodplain, resulted in channel instability, which propagated downstream over a period of decades. On many reaches of Pine Creek, active channel width has increased by over 50% since 1933. Over roughly the same time period, the Droˆme River catchment was extensively reforested (after at least one century of denudation and heavy grazing) and numerous check dams were constructed on torrents to reduce erosion. As a result, the Droˆme River has experienced a reduction in bedload sediment supply since the late 19th century. In addition, gravel has been extracted from some reaches. Consequently, the channel has degraded and gravel bars have been colonized with woody riparian vegetation. Channel widths in wide, braided reaches decreased from 1947 to 1970 by 60%.On Pine Creek, channel instability has resulted in bank erosion (exposing contaminated mine tailings) and increased flood hazard. On the Droˆme River, degradation has undermined bridges and embankments, and lowered the water table in areas dependent on groundwater for irrigation, resulting in loss of 6 million m3 of groundwater storage since 1960. Though they differ in drainage area by nearly an order of magnitude, Pine Creek and the Droˆme River provide an excellent contrast in that they represent two sides of an epicycle of alluvial sedimentation set off in each case by land disturbance. In both cases, the most recent channel changes, though in opposite directions, were viewed as negative by river managers. On Pine Creek, managers have removed (or protected from erosion) mine tailings, and have attempted to train the stream into a more stable channel, and most rock waste piles (the principal sediment sources) have recently been controlled. On the Droˆme River, managers have prohibited gravel mining and adopted new policies to permit coarse sediment to migrate through the river system. [Copyright &y& Elsevier]

• Annual sediment yields using SEMEP are typically 50–300 ton/km2·yr. • RMSE of model with SEMEP is 53 ton/km2·yr less than that of existing models. • Sediment transport into alluvial rivers is affected by river wetlands and water. • Watershed morphometric characteristics can represent sediment transport. • Geospatial analysis shows urbanization's erosion features, yielding rich sediment. South Korea experiences numerous local sedimentation problems, such as landslides, upland erosion, aggradation and degradation, and flood plain sediment deposition. This has necessitated the development of a reliable and consistent approach for modeling sediment processes in the country. In this study, samples obtained from 35 gauging stations at five alluvial river basins in South Korea were used together with the modified Einstein procedure and series expansion of the modified Einstein procedure to determine the total sediment load at the sampling locations. Using two different methods, the total sediment load of majority of the 35 considered rivers were found to be typically 50–300 ton/km2·yr. A model tree data mining technique was used to develop a model for estimating the specific degradation based on certain meaningful parameters, namely, the 1) elevation at the middle relative area of the hypsometric curve [m], 2) percentage of wetland and water, 3) percentage of urban land, 4) mean annual precipitation [mm], 5) main stream length [km], and 6) watershed form factor [km2/km2]. The root mean square error of the predictions of the proposed model was found to be 55 ton/km2·yr less than those of existing statistical models. Erosion loss maps obtained by the revised universal soil loss equation (RUSLE), satellite images, and aerial photographs were also used to represent the geospatial features affecting erosion and sedimentation. The results of the geospatial analysis indicated that the transport of sediment into the alluvial rivers was affected by the wetlands located near the rivers, and also enabled clear delineation of the unique erosion features of construction sites in the urban areas. In addition, the watershed morphometric characteristics could be used to accurately represent the sediment transport. The proposed data mining methodology promises to facilitate the solution of various erosion and sedimentation problems in South Korea. The geospatial analysis procedure would also enable the understanding of spatially varied erosion and sedimentation processes under different conditions. [ABSTRACT FROM AUTHOR]

Sediment budget is a valuable tool for describing the sediment production, transfer and storage in a watershed and its components depend on different watershed physical properties. The present study aimed to evaluate the relationship between 22 geomorphological factors and sediment budget components in a small mountainous watershed in the west of Iran, using ordinary least square, geographically weighted regression and bivariate regression. The distribution map of erosion and deposition was prepared using 137Cs in 15 sub-watersheds and the internal area. According to the results, the maximum net erosion rates were related with the sub-watersheds with medium slope (<20%) which strongly reveals the role of landuse and its interaction with the slope steepness. In addition, the mean sediment delivery ratio for 15 sub-watersheds was 28.43%, which decreased to 12.63% by increasing the area to the whole watershed due to trapping and redepositing mainly because of low slope agricultural lands close to the outlet. This finding reflects the interaction effects of the area and slope on the reduction of sediment delivery ratio by increasing the probability of trapping and redistribution of sediment. The Gravelius's shape index, equivalent rectangular width, and order of the main river were the most related geomorphological factors with total erosion and deposition. It is possible to estimate net erosion and sediment delivery ratio using equivalent rectangular width and topographic wetness index, respectively. The most important factor on sediment budget in the study area was topographic wetness index, probably because it depends on the slope as well as hydrological properties of the sub-watersheds. Unlabelled Image • Geomorphological factors related to sediment budget components were examined using OLS and GWR. • Land use and its interaction with slope steepness determined net erosion rates. • Low slope agricultural lands close to the outlet affected sediment transport and Sediment Delivery Ratio. • TWI was the most important geomorphological factor influencing net erosion and Sediment Delivery Ratio. [ABSTRACT FROM AUTHOR]

Coastal dunes have received growing attention in recent years because of the ecosystem services they provide and the high anthropic pressure that they have historically been subjected to and continue to endure. Such pressure especially affects arid dune fields where any changes are more noticeable due to their natural dynamics. The aim of this paper is to analyze the relationship between the degradation of an arid aeolian sedimentary system (El Médano, Tenerife, Spain) due to historical long-term land uses and its subsequent biogeomorphological evolution. The methodology combines historical sources (historical documents, aerial and common photographs and oral sources) and current ones (orthophotos, LiDAR data and field work). In order to analyze the response of the system to these uses, 8 plots were chosen in which 3 different historical land uses had resulted in the total or partial elimination of the vegetation and landforms. Biogeomorphological variables were measured on 461 nebkhas in these plots. The main results show that the historical land uses studied in this paper (aerodrome , aggregate extraction and crop cultivation) modified the entire system, with changes observed in the topography, vegetation cover and sediment availability for transport. Changes in topography and distance from shore were important factors in its recovery capacity. This research contributes to our understanding of the different aeolian sedimentary dynamics that can be detected in the same dune field (especially with nebkha landforms) and is of particular importance for making appropriate environmental management decisions to facilitate the recovery of the ecosystem. • Aggregate extractions on the foredune have an irreversible impact. • Different environmental patterns in a dunefield are responses to historical land uses. • Distance to the coast acts as a main factor in system recovery. • Historical land uses modify the natural gradients of the system. • Biogeomorphological patterns in 461 nebkhas were analyzed. [ABSTRACT FROM AUTHOR]

• Survey after the rainstorm provides rare data of soil erosion and sediment transport. • The hillslope erosion was dominated by slope failure and gully incision in rainstorm. • Stream power thresholds of gully incision in grassland and woodland were quite large. • Almost all the sediment of hillslope transported to downslope channel in this event. • Reasonable agricultural management reduced decuples of erosion risk A comprehensive investigation of rainstorms and its impact on soil erosion on hillslope are important, but field observed data are rare worldwide. We aimed to assess and quantify the magnitude of soil erosion and its subsequent influence on hillslope with different land use pattern under an extreme rainstorm. We studied an extreme rainstorm on July 26, 2017 in Zizhou county on the Loess Plateau, China. 218 mm rain fell within 15 h with a maximum intensity of 52 mm h−1 for 1 h. In rainstorm core, we investigated soil erosion characteristics on six hillslopes with different land use patterns which composed of sloping farmland (SF), grassland (GL), woodland (WL) and pasture (PA) on different slope positions. Three soil erosion types (rill, slope failure and gully incision) along the six hillslopes were measured in each land, respectively. The stream power was calculated to quantify the erosion effectiveness of rainstorm. The subsequent alteration of serious gully and slope failure were measured after two years. The soil erosion intensities of hillslopes were in range of 6.94 × 103-95.89 × 103 t km−2. Soil erosion intensities on hillslopes with sloping farmland were several decuples larger than that on the hillslopes with woodland and grassland. Gully incision and slope failure supplied the most sediment of hillslope while rill erosion cannot be ignored only in sloping farmland. The scarce vegetation cover, the concave surface, side slope with large height, unreasonable drainage ditch and weeding were the main reasons for the serious erosion under this storm event. The gully incision thresholds of stream power were about 175 W m−2, 370 W m−2, less than 35 W m−2 and more than 460 W m−2 for PA, GL, SF and WL, respectively. Almost all the sediment of gully transported from hillslope into downslope channel. The risk of gully incision increase 5 fold and decrease to 14 % in fallow farmland and farmland under cultivation after rainstorm. Woodland and grassland with high vegetation coverage stood the erosion test of this extreme rainstorm due to high anti-erosion ability instead of runoff reduction and sediment interception. Reasonable agricultural management, such as avoiding weeding before extreme rainstorm and filling gully after erosion reduced decuples of erosion risk. Natural recovery of slope surface is not expected in these fragmentized slopes during a short period. [ABSTRACT FROM AUTHOR]

• We used suspended sediment data during a period of consecutive explosive cyclogenesis. • Spatial land use plays an important role in the suspended sediment yield. • Sediment concentrations are largely dependent on sediment depletion during the previous events. During the winter of 2013/2014, a sequence of explosive cyclogeneses occurred in NW Spain, causing severe flooding and substantial economic damage. Peak discharges were extremely high in many areas, with return periods in excess of 2–5 years. The heavy flow registered during these episodes provides a unique opportunity to evaluate the sedimentological effects resulting from high-magnitude flow events. Such events are relatively rare and the technical difficulties in sampling with sufficiently high frequency means that few observations on sediment transport can be gathered during the same. In this study, we present detailed hydrological and sedimentological observations across a period of consecutive explosive cyclogeneses from two small-sized catchments (i.e., the Corbeira stream and headwater of the Mero river) located in Galicia (NW Spain), in order to examine the factors controlling suspended sediment (SS) dynamics during high-magnitude flow events. The study sites are representative of the biophysical conditions (e.g. rainfall pattern, land use, vegetation cover and management practice) in NW Spain. The catchments of the Corbeira stream and headwater of the Mero river are similar with respect to climate, land use and management practice. The main differences are the distribution of land use and catchment size (Corbeira: 16 km2 and Mero: 65 km2). Large amounts of sediment were transferred in both catchments in response to flow events. A high variability in SS load during these was also observed in the two catchments, which is attributed to variation in rainfall characteristics, magnitude peak discharge, antecedent conditions controlling sediment availability, and suggests that sediment supply and transport vary widely over time. Higher concentration and variability of SS was observed in the Corbeira catchment. Differences in SS dynamics were also noted between the catchments that may be attributed to differences in the spatial distribution of land use, which influence the location of the erosion source and SS availability, and directly and indirectly affects connectivity between the sediment source area and the stream. In the Corbeira catchment, the SS load was closely linked to the hydrological response and rainfall, whereas in the Mero basin, preceding conditions, i.e. the sediment depletion during the previous events, played an important role. The results demonstrated that peak SS concentrations may coincide with, or lag behind, peak discharge, and factors other than discharge (mainly the location of the sediment source and its connectivity with the drainage network) have a major influence on SS concentrations. [ABSTRACT FROM AUTHOR]

• We have developed modeling framework in a Loosely Coupled System. • The hydrologic cycle components are modelled using Soil and Water Assessment Tool. • Land use conversion due to human action is developed using Agent-based Modeling framework. • Climate change scenarios predict higher streamflow. • Combined climate and land use change scenarios project to reduce sediment load. Climate and land use change are the two primary factors that affect different components of hydrological cycle as well as sediment transport in the watershed. Quantifying potential impact of these two stressors enables decision makers to formulate better water resource management strategies to adapt to the changing environment. To that end, we have developed an integrated modeling framework employing an Agent-based approach to simulate land use conversion that then serves as input to the Soil and Water Assessment tool (SWAT) in a loosely coupled fashion. The modeling framework was tested on the Neshanic River Watershed (NRW), 142 km2 area in central New Jersey that contains mix of urban, agricultural and forested lands. An ensemble of 10 different global climate models (GCMs) for two different greenhouse gas emission scenarios including representative concentration pathways-4.5 and 8.5 (RCP-4.5 and 8.5) were employed to model future climate from 2020 to 2045. Land use conversion for 2040 was developed based on six driving factors including distance to residential lands, agricultural lands, roads, streams, train stations, and forest using three land use transition potential models and further, the best transition potential model accompanied with some local land use restrictions. The study evaluated various components of hydrological cycle and sediment transport for the three different scenarios one-at-a-time including climate change alone, land use change alone, and combined climate and land use change. Results indicate that the changing climate will have a larger effect on the hydrologic cycle than intensifying urban land uses in the study watershed. The climate change scenarios, either alone or in composite with land use change, predict higher streamflow (32% and 36% increase over baseline, respectively), overriding the effect of land use change which predicts a decline of 5% in streamflow. The increase in streamflow results in an increase in sediment loading, presumably due to an increase stream downcutting. Conversely, the effect of land use change (in this case the conversion of agricultural land to low density residential uses), is predicted to decrease sediment load. When modelled in composite, the effect of changing land use (in this case the conversion of erodible agricultural fields to suburban development) appears to override the adverse effect of climate change, enhancing watershed resiliency by reducing sediment load and thereby improving health of the downstream aquatic ecosystems. [ABSTRACT FROM AUTHOR]