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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]

• 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]

• 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]

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]