Watershed Management Research Articles

Geospatial AI solution to monitor and mitigate increasing adverse ecological and hydrological impacts of climate change in Uttarakhand Himalaya (India).

Though climate change and its adverse ecological and geohydrological impacts are being experienced across the world in all types of ecosystems but as far as the Himalaya mountain ecosystem is concerned, the rate of climate change and subsequent impacts have reached an alarming stage due to anthropogenic and technogenic intervention on natural process and now need most effective and less time taking management strategy. Addressing this burning environmental problem, a geospatial artificial intelligence (GeoAI) technique-based case study is presented here from one of the most densely populated and urbanized regions of Himalaya mountain, viz Uttarakhand Himalaya, which is also called central Himalaya. The results of the study suggest that due to quite a high rate of climate change, the climatic zones shifting towards higher altitudes at the average rate of 5.6 2m/year, causing several adverse ecological impacts in terms of decreasing quality dense temperate forest cover (0.05%/year), snow cover (0.02%/year), water bodies (0.01%/year), agricultural land (0.31%/year), and horticultural land (0.01%/year). Conversion of these eco-friendly land use land cover into barren land, fallow land, and built-up land causes geohydrological consequences of climate change in terms of decreasing rainy days (1%/year), drying perennial springs (0.20%/year), perennial streams (0.11%/year), decreasing spring and stream discharge during non-monsoon season, increased extreme rainfall events (6-8%/year), and subsequent surface runoff during monsoon season. Further, the study advocates that the degraded geohydrological process has resulted in an increased frequency of disaster events (floods, cloudbursts, landslides. etc.) with a 3% (12 events) annual rate, causing great loss of environment, infrastructure, lives, and economy each year. Therefore, it has been very urgent to mitigate climate change and increase geohydrological disaster events through an integrated approach. Keep in view this, the present study proposed an integrated watershed management plan which is equally useful to be implemented across the Himalaya region and other similar ecosystems across the world.

Impact of Land use dynamics on the water yields in the Gorgan river basin

This research investigates the future dynamics of water yield services in the Gorgan River Basin in the North of Iran by analyzing land cover changes from 1990 to 2020, using Landsat images and predicting up to 2040 with the Land Change Modeler and InVEST model under three scenarios: continuation, conservation, and mitigation. The results indicate significant shifts in agricultural land impacted water yields, which fluctuated from 324.7 million cubic meters (MCM) in 1990 to 279.7 MCM in 2010, before rising to 320.1 MCM by 2020. The study uniquely assesses the effects of land use changes on water yields, projecting a 13.6 % increase in water yield by 2040 under the continuation scenario, a 3.9 % increase under conservation, and a 1.6 % decrease under mitigation, which limits changes on steep slopes to prevent soil erosion and floods. This underscores the interplay between land use, vegetation cover, and water yield, emphasizing strategic land management for water resource preservation and effective watershed management in the GRB.

Assessment of macrozoobenthic community dynamics in the Ijuk River: Implications for freshwater ecosystem health and conservation management

Background: Nestled within the Isau-Isau Wildlife Reserve, the Ijuk River stretches approximately 3 kilometers, serving as a vital conservation area. Its upstream region plays multiple ecological roles, including watershed management, hydrological regulation, microclimate control, soil fertility maintenance, microbial habitat provision, air quality regulation, and carbon sequestration. However, escalating human activities, particularly changes in land use, pose significant threats to its ecological balance. The particular concern is the conversion of forested areas into agricultural lands, primarily for coffee cultivation and mixed gardens, encroaching dangerously close to the riverbanks. This encroachment necessitates a critical reevaluation of the river's water quality, given its crucial role in supporting biodiversity and ecological equilibrium. Benthic insects dwelling in the riverbed serve as invaluable bioindicators, offering insights into the overall health of aquatic ecosystems. Methods: Conducted between January and July 2022 in the Isau-Isau Wildlife Refuge, Lawang Agung Village, Mulak Ulu District, Lahat Regency, the study aimed to assess the macrozoobenthic community structure across three river segments: upstream, midstream, and downstream. Employing field sampling, observational surveys, taxonomic identification, and data analysis, the research aimed to unravel the river's ecological dynamics. Findings: Through meticulous examination of benthic insect communities, the study revealed relatively favorable water quality in the Ijuk River. However, discernible declines in various ecological parameters, as evidenced by evaluation results, highlight the urgency of conservation efforts and proactive management strategies to mitigate further degradation and preserve the river's ecological integrity. Conclusion: Such endeavors are crucial for safeguarding the biodiversity and sustainability of this vital freshwater ecosystem. Novelty/Originality of this Study: The study uniquely assesses the macrozoobenthic community dynamics in the Ijuk River, revealing significant changes over two decades that highlight the river's ecological health and underscore the urgent need for conservation efforts. It offers a comprehensive, updated evaluation of the macrozoobenthic community structure, providing critical insights into the impacts of land use changes and human activities on freshwater ecosystems.

Effects of terrestrial dissolved organic matter on the growth, photosynthesis and colonial morphology of Microcystis aeruginosa at different levels of iron

Terrestrial dissolved organic matter (tDOM) holds great promise for controlling cyanobacteria blooms through watershed management. To identify tDOM that could inhibit the growth, photosynthesis and colony formation, unicellular Microcystis aeruginosa Kützing (FACHB-469) was cultivated and treated with varying concentrations of gallic acid, proline and tea polyphenols at different levels of iron. The results indicated that gallic acid and tea polyphenols could inhibit Microcystis growth by suppressing photosynthesis and colony formation by reducing extracellular polysaccharides (EPS) secretion. However, proline had no significant effect on the growth, photosynthesis, colony size and EPS content of Microcystis. Transcriptome analysis showed Microcystis may optimize the internal energy transfer mode of photosynthesis through the change of phycobilisome at different levels of iron. In addition, Microcystis adapted to different iron concentration environments by regulating the expression of genes associated with iron uptake and transport. These findings suggest that the effects of plant species on algal blooms should be considered in reforestation of watershed. This consideration necessitates finding a balance between the costs and benefits of controlling cyanobacteria blooms using tDOM.

Influence of anthropogenic activities on the trace organic contamination of lakes

Anthropogenic activities and urbanization can lead to the discharge of organic compounds into surface waters. It is important to investigate these relationships further to mitigate contamination better and prioritize protection efforts. This study aimed to verify the effect of specific anthropogenic factors on lake water contamination caused by trace organic contaminants (TrOCs) such as pharmaceuticals, pesticides and consumer product additives. Data on the detection and concentration levels of 54 TrOCs, major anthropogenic land use, and human activities from a large-scale study on Canadian lakes were used to reach this goal. The association of population and livestock densities, the presence of wastewater treatment plants (WWTPs) and hospitals as well as the agricultural and urban land use in the lakes' watersheds on lake water contamination was investigated by applying negative binomial and ordinal logistic regression models. These models were also controlled for lake/watershed area ratio, lake depth, water, residence time, watershed slope, precipitation, and sampling date. The statistical analysis confirmed that agricultural land use, urban land use, and WWTPs plants in lake watersheds are significantly associated with the number of TrOCs detected (incidence rate ratio > 1, p < 0.001) and the summed concentration of targeted TrOCs (odds ratio > 1, p < 0.001). Agricultural land use (odds ratio = 1.58, p < 0.001) and urban land use (odds ratio = 1.19, p < 0.02) were also significantly associated with the summed concentration of the targeted pesticides. This latter outcome thus suggests that urban centers are also important contributors to the concentration levels of pesticides in lakes. Overall, these results demonstrate that even in complex ecosystems such as lakes, it is possible to use a limited number of factors to explain anthropogenic contamination. This can help policymakers make informed decisions on contamination mitigation and provide insights into watershed management.

Leveraging innovization and transfer learning to optimize best management practices in large-scale watershed management

Recent research in evolutionary multi-objective optimization (EMO) highlights the concept of “Innovization”, which identifies essential patterns in high-quality, non-dominated solutions. This study introduces a novel method to pinpoint influential Best Management Practices (BMPs) in the Chesapeake Bay Watershed, optimizing the trade-off solution process. This approach, though innovative, demands considerable expertise and involves generating multiple solutions for expert analysis to detect commonly used BMPs. We devised three re-optimization strategies from these findings using an innovized BMP list, efficiently producing high-quality solutions. We also implemented transfer learning to adapt these strategies for new counties, demonstrating effectiveness in four West Virginia counties by reducing decision variables by 3% to 33% and achieving similar reductions in four additional counties. This showcases the potential of combining innovization with transfer learning to simplify complex optimization challenges, emphasizing its significant applicability in real-world settings.

Analyzing the impacts of watershed management interventions and scenarios on soil erosion reduction using InVEST model in Yezat watershed, North West Ethiopia

ABSTRACT Land degradation is a serious problem for Ethiopia's productive capacity for land resources. To reverse these environmental dynamics, slow down soil degradation, and raise smallholder farmers’ agricultural yields, watershed management interventions have been implemented in Ethiopia since the 1980s. Thus, this study was aimed at assessing the effects of watershed management interventions on soil erosion reduction by using the InVEST model in the Yezat watershed, north-west Ethiopia. The modified ecosystem services valuation model (InVEST) was employed to evaluate soil loss reduction in response to watershed management interventions. Different watershed management intervention scenarios (baseline scenarios, afforestation scenarios, soil/stone bund scenarios, and integrated scenarios) were also applied to evaluate the effectiveness of watershed management interventions on soil loss reduction. The result of the study indicated that a high amount of mean annual soil loss (111 tons ha− 1 year−1) was observed in 2000 in the study area due to the expansion of cultivated land and built-up area at the expense of forest, shrubland, and grassland. However, the mean annual soil loss decreased from 111 tons per year in 2000 to 79 tons per year in 2021 in the study area due to different watershed management interventions. Additionally, at the baseline scenario, the estimated mean annual soil loss of the watershed was 111 tons ha-1 yr-1. Conversely, it was reduced to 49.3 ton ha-1 yr-1 in the reforestation scenario, 16.49 ton ha-1 yr-1 in the soil bund scenario, and 8.26 ton ha-1 yr-1 in the integrated scenario. The watershed covered by the very severe soil erosion severity class was reduced in all watershed management intervention scenarios. Among others, the highest soil erosion reduction was observed in the integrated (bio-physical) scenarios of watershed management interventions. Therefore, watershed management interventions and scenarios were the best mechanisms for soil loss reduction.

Evolution Characteristics of Meteorological and Hydrological Drought in an Arid Oasis of Northwest China

In the context of global warming, the acceleration of the water cycle increases the risk of meteorological drought (MD) and hydrological drought (HD) in the arid region of Northwest China. The Manas River Basin is a typical agricultural oasis and the largest oasis farming area in Xinjiang, Northwest China. Droughts in this basin have significant implications for both agricultural production and the livelihoods of inhabitants. To evaluate the MD and HD and provide information for drought relief in the MRB, the standardized precipitation evapotranspiration index (SPEI) and standardized runoff index (SRI) were calculated using long-term rainfall and runoff data. Subsequently, combined with ArcGIS 10.3 software and the trend analysis method, the SPEI and SRI characteristics were evaluated at different time scales (1-, 3-, 6-, and 12-month). There were three main findings. First, both MD and HD were alleviated, with significantly more HD alleviation. MDs in spring and autumn exhibited a trend of aggravation. The SRIs in summer, autumn, and winter increased significantly at a confidence level of p &lt; 0.01, with an insignificant decline in spring. In the 2010s, the frequency of light drought of MD was stable at 10% to 20%, while severe and extreme droughts increased. The frequency of HDs has decreased since the 1990s. Second, on annual and seasonal scales, MDs occurred mainly as light and moderate droughts. The highest frequency of MD was 24% of moderate droughts in winter. Spatially, the northern region of the MRB was characterized by more frequent light and extreme droughts. Third, runoff in the Manas River Basin increased significantly during the 1990s, which may have been related to the acceleration of glacial retreat in the Tianshan Mountains. This study can effectively reveal the changes in meteorological and hydrological drought in NWC and provide the basis for risk decision-making and management for watershed managers.

Comparative analysis of RUSLE and SWPT for sub-watershed conservation prioritization in the Ayu watershed, Abay basin, Ethiopia

Ethiopia is currently facing a major environmental problem caused by soil erosion. In order to tackle this problem, it is essential to implement a comprehensive watershed management approach and give priority to conservation efforts depending on the level of severity. Therefore, the objective of this research is to evaluate the mean annual soil erosion and rank the sub-watersheds for conservations in the Ayu watershed, utilizing the Revised Universal Soil Loss Equation (RUSLE) model and the Sub-Watershed Prioritization Tool (SWPT). RUSLE was utilized to predict the annual average soil erosion rate, while SWPT was applied to conduct Weighted Sum Analysis (WSA) for ranking sub-watersheds. Support Vector Machine (SVM) was employed for classifying land use and land cover. The Relative importance of morphometric and topo-hydrologic features in the SWPT was analyzed using a Random Forest model. The Bland-Altman plot and Wilcoxon Signed Rank Test were employed to assess the agreement in prioritizing watersheds between RUSLE results and the SWPT. Furthermore, field observations were conducted to validate the land use classification by collecting ground data. In addition, the study was enhanced with local viewpoints by conducting focus group discussions with agricultural experts and farmers to obtain qualitative insights and validation of resuts. The findings showed that soil loss varied from 0 to 110 t/ha/yr, with an average of 8.95 t/ha/yr, resulting in a total loss of 384365.3 tons annually. The comparison of RUSLE and SWPT showed a moderate positive relationship (r = 0.59). The results of the Bland-Altman plot indicate a consistent agreement between the two methods. However, there is inconsistency among the five sub watersheds. This study enhances the knowledge of soil erosion patterns and offers useful guidance for watershed conservation techniques. It can be also used as a beneficial framework for managing watersheds, with possible uses outside of the Ayu watershed.

Effects of Surface Area and Water Level Variability on Fisheries Production in Lake Naivasha, Kenya

Lake Naivasha is a freshwater, a Ramsar site and an Important Bird Area. It provides multiple services to the surrounding communities such as Fishing, Tourism and Agriculture. Lake Naivasha has been experiencing a water level variation cycle over the years as a result of it being shallow and experiencing high evaporation. Variation in water levels leads to flooding, and receding which disrupts the Lake ecosystem thus causing direct and indirect effects on fishing. The study was conducted to establish the relationship between Surface area and water level variability and fish yield and revenue in Lake Naivasha. Primary data was collected using a semi-structured questionnaire, and Key informant interviews. Secondary data was collected using Landsat images that provided the temporal and spatial water level variability and documentary analysis between 1989 to 2022. Both descriptive statistics and inferential statistics were used for data analysis. The results show a positive correlation between Surface area Variability and fish yield (r= 0.6261, R2= 0.3920) and fish revenue (r= 0.5219, R2= 0.2724). Surface area variability accounts for 39% of the variation in total fish yield, and 27% of the fish revenue. The study recommends continuous monitoring and surveillance of the lake level, and water quality by the relevant government agencies, as well as watershed management and conservation measures for the sustainability of the Lake’s fishery.

Exploring the nexus between water quality and land use/land cover change in an urban watershed in Uruguay: a machine learning approach.

The expansion of urban areas contributes to the growth of impervious surfaces, leading to increased pollution and altering the configuration, composition, and context of land covers. This study employed machine learning methods (partial least square regressor and the Shapley Additive exPlanations) to explore the intricate relationships between urban expansion, land cover changes, and water quality in a watershed with a park and lake. To address this, we first evaluated the spatio-temporal variation of some physicochemical and microbiological water quality variables, generated yearly land cover maps of the basin adopting several machine learning classifiers, and computed the most suitable landscape metrics that better represent the land cover. The main results highlighted the importance of spatial arrangement and the size of the contributing watershed on water quality. Compact urban forms appeared to mitigate the impact on pollutants. This research provides valuable insights into the intricate relationship between landscape characteristics and water quality dynamics, informing targeted watershed management strategies aimed at mitigating pollution and ensuring the health and resilience of aquatic ecosystems.

Morphometric analysis in the sub basins of the Kali River using Geographic Information System, Karnataka, India

Morphometric analysis serves as a crucial tool for quantitatively characterizing drainage basins and exploring the intricate relationships between hydraulic parameters and geomorphological characteristics. This study presents a comprehensive morphometric analysis of the Kali Subbasin in Karnataka, covering an area of 1175.45 km². Utilizing remote sensing data and GIS tools, we quantified various morphometric parameters, including stream order, stream length, bifurcation ratio, drainage density, stream frequency, form factor, and circularity ratio, to understand the basin's geomorphological and hydrological characteristics. The study area is classified as a seventh-order basin displaying a dendritic drainage pattern with a drainage density of 2.853 km/km². Notably, the bifurcation ratio ranges from 4.396 to 3, indicating low to moderate structural control within the basin. The subbasin's elongated shape, with an elongation ratio of 0.604 and a circularity ratio of 0.298, indicates moderate peak flow and high susceptibility to erosion. Relief parameters showed significant elevation variations, contributing to intense erosion and heightened flood risks in lower-lying areas. The study identifies the basin's transition to a mature geomorphic stage, evidenced by an escalating stream length ratio from lower to higher orders. These findings underscore the importance of tailored watershed management strategies, including floodplain zoning, retention basins, afforestation, and terracing, to mitigate flooding and soil erosion. The study's insights are crucial for developing effective, localized water resource management plans and enhancing the resilience of the Kali Subbasin to future hydrological challenges.

Surface Flux Patterns of Nutrient Concentrations and Total Suspended Solids in Western Carpathian Stream within Agricultural, Forest, and Grassland Landscapes

The intricate processes of surface water erosion are vital for ecological systems and river-scale management; yet, understanding them comprehensively remains a challenge. Forested agricultural catchments, especially in the Carpathian region, face significant degradation, potentially leading to inorganic nutrient leaching and total suspended solid (TSS) flux. Continuous rainwater inundation of soils in river valleys exacerbates this issue. Utilizing innovative tools like SWAT+, studies have revealed higher concentrations of inorganic nutrients in main watercourses from flysch catchments, with agricultural use linked to N-NO3− concentrations and pasture use linked to anion P-PO43−. Maintaining detailed records is crucial for researchers comparing data. SWAT+ proves valuable for studying TSS washing out and inorganic nutrient leaching, informing collaborative watershed management policies involving stakeholders from agriculture, conservation, and water management sectors. The insights on nutrient leaching, particularly phosphorus (P) and nitrogen (N), are instrumental for shaping policies targeting nutrient pollution within pasture land use for EU agriculture. These findings can guide policy frameworks focused on sustainable practices, especially for eco-schemes, and encourage collaborative watershed management efforts.

Statistical analysis of water quality change by total maximum daily load policy stage

This study aimed to derive major pollutants for standard watersheds with relatively high pollution levels and identify their trends. Hence, the water quality index (WQI) and multivariate statistical techniques were used to analyze the water quality evaluation of standard watershed during the total maximum daily load (TMDL) policy period implemented since 2004. The WQI was calculated for 41 standard watersheds, divided into 14 main streams and 27 tributaries. Consequently, in the main stream, WQI decreased as it moved downstream after the MS5 site. In the tributary, WQI values were found to be low at TS11, TS15, TS16, and TS17 sites. However, the Mann–Kendall test results indicated that the overall WQI value was increasing, suggesting that the water quality of the study basin was improving as the TMDL policy phase progressed. Principal component analysis of the group with relatively low WQI among the standard watersheds revealed that water temperature, dissolved oxygen, total phosphorus, chemical oxygen demand, biochemical oxygen demand, and electrical conductivity were the main variables in the main stream cluster. In the tributary stream cluster, total phosphorus, dissolved oxygen, total suspended solids, total nitrogen, and electrical conductivity showed high loading values. This study proposed a series of methods to provide the basic data required for watershed management through detailed water quality assessment methods, statistical techniques for deriving major pollutants, and trend analysis of water quality evaluation.

Biophysical Resource Characterization, Identification and Prioritization of Major Constraints and Potentials of Gara Ebanu Community Watershed in Sululta District, Ethiopia

Baseline characterization helps to understand the initial livelihood condition of the people in the watershed before and after the intervention of the project to measure the amount of change attained by the project. The objective of the study was to characterize baseline information on the existing biophysical resource used as benchmark for planning and impact monitoring and to identify and major constraints and potential in the watershed. The watershed was selected depending on agro-ecological representation, prevalence of resource management and land degradation problems and accessibility for intensive follow-up. Based on the preliminary outlet identified during the watershed selection process, the watershed boundary was delineated using GPS data and the map of watershed was geo-referenced and digitized for its contour, roads, rivers, and other features. Both primary and secondary data were used for the study and primary data was collected through field observation, household survey, focus group discussion and interview of the key informants. From the total 103 household heads living in the watershed, 62 household heads were selected as a respondent for the study. The collected data was managed and analyzed using Statistical Package for Social Sciences (SPSS) and Microsoft excel 2010. The results of the study showed that about 29.4% of the watershed slope was characterized by flat lands, 45.7% moderate slope and 24.9% steep lands. As well as soil fertility status of cultivated land in the watershed were 33.9% low, 55.9% moderate and 10.2% high. The results of the study showed that the major constraints identified by sampled household heads were decline of soil fertility, soil erosion, climate change, land shortage, and deforestation were significantly contributed to the low crop yield in the watershed. About 27.4% of the sampled households had encountered decline of soil fertility problems, 25.8% of sample farmers encountered soil erosion problem, and 22.6% of sample farmers encountered climate change problem in the watershed. From the identified major constraints, the highest priorities were given for decline of soil fertility, soil erosion problem, shortage of feed and fodder, and decline of crop productivity respectively. In the watershed, immediate short-term actions should be taken particularly participatory integrated watershed management were recommended.

Socio-Economic Characterization, Identification and Prioritization of Major Constraints and Potentials in Gara Ebanu Community Watershed in Sululta District, Ethiopia

Baseline characterization builds necessary foundation for the plan and obtains proper information for elective planning, implementation and monitoring of the research and development endeavors. The objective of the study was to document baseline information on socio-economic for planning and impact monitoring and to identify and document major socio-economic constraints and potential in the watershed. A total of 62 sample households were selected randomly from all farmers engaged in farming activities in the watershed. The average inorganic fertilizer (NPS and Urea) used in the watershed were 75 kg/ha and 75 kg/ha respectively. The response of the respondents showed that the average yield obtained in the watershed was about 10 qt/ha for barley, 12 qt/ha for wheat, 5 qt/ha for faba bean and field pea 6 qt/ha. The major livestock feed type in the watershed were crop residue (93.5%) followed by hay making (91.9%), grazing in the field (80.6%), local beverage by-products (72.6%), concentrates of different type (67.7%), green feed (50%), stubble grazing (41.9%) and improved forage (14.5%). The result of survey shows that the major income sources of the farmers living in the watershed were livestock production (77.4%) followed by crop production (45.2%) and off-farm activities (25.8%). About 71% of the households have encountered high cost and shortage of agricultural inputs followed by low crop productivity (19.4%), crop disease (8.1%) and existence storage pests (1.6%) were the common in the watershed. In the watershed, high cost of agricultural inputs, low crop productivity, crop disease, shortage of animal feed and fodder, inflation, lack of employment opportunity and other income source were addressed as the highest priority issues by the community that are contributing to the crop productivity reductions and low level of their livelihood in the watershed. By considering the addressed problem related to crop production, livestock production and socio-economic, the interventions on introduction and demonstration of improved and high yielding crop varieties that are resistant or tolerant to the already existing and emerging pests to increase production and productivity of crops should be done. In general, immediate short-term actions should be taken particularly participatory integrated watershed management were recommended.

Assessment of gully influencing factors and susceptibility using remote sensing-based frequency ratio method in Sunshui River Basin, Southwest China.

Gully erosion is a serious global environmental problem associated with land degradation and ecosystem security. Examining the influencing factors of gullies and determining susceptibility hold significance in environmental sustainability. The study evaluates the spatial distribution, influencing factors, and susceptibility of gullies in the Sunshui River Basin in Sichuan Province, Southwest China. The frequency ratio method supported by satellite images and the gully inventory dataset (1614 gully head points) with different influencing factors were applied to assess the distribution and susceptibility of gullies. Additionally, gully head points were grouped into a training set (70%, 1130 points) and a test set (30%, 484 points). Spatial distribution results indicated that most gullies are located in the middle and upper part of the basin, characterized by moderate elevation (2100-3300m), steep slopes (11.63-27.34°), abandoned farmland, and Cambisols soil, and fewer gullies are located in lower part characterized by lower elevation, gentle slopes, and low vegetation coverage. Land use and land cover influence on susceptibility is significantly greater than other factors with a prediction rate of 33.9, especially farmland abandonment, while the occurrence of gullies is also more often on southwest-orientated slopes. Gully susceptibility highlighted that the study area affected by the very low, low, moderate, high, and very high susceptibilities to these gullies covered an area of about 16%, 23%, 32%, 26%, and 3% of the total basin respectively, which indicates 61% of the study area is susceptible to gully erosion. Moderate to high susceptibility is situated in the upper and middle part, consistent with the spatial distribution of gullies in the basin, and very high susceptibility (3%) is distributed in both the lower and upper parts of the basin. These results have important implications for soil loss control, land planning, and integrated watershed management in the mountainous areas of Southwest China.

Ecological Function Zoning Framework for Small Watershed Ecosystem Services Based on Multivariate Analysis from a Scale Perspective

A thorough comprehension of distribution features of ecosystem services (ESs) and the influencing mechanisms can offer scientific guidance for the ecosystem management of small watersheds. We analyzed the spatial distribution patterns, interrelationships, and service hotspots of ESs across pixel and administrative scales using a multi-level statistical analysis approach in the Ashi River Basin. Through the quantitative calculation of the InVEST model, the findings revealed a decrease in soil retention, water yield, total nitrogen and phosphorus export, carbon storage, and habitat quality, while an increase in food production was observed during the period from 1995 to 2015. Through the geographical detector, the spatial heterogeneity of most individual ESs was influenced by land use patterns. Through redundancy analysis, terrain factors had the highest contribution rate to the integral ESs. Socio-economic factors and climate factors also drove the ESs’ amount and spatial distribution. At the pixel scale and administrative scale, there were distinctions in the correlations between all ESs, reflected by the fact that the relationships between ESs at the administrative scale were generally weaker and no more significant than at the pixel scale. Based on the number and distribution of hotspots in ESs and the clustering results of influencing factors, the framework of ecosystem zoning was constructed. This basin was divided into three ecological zones, and the management policies were formulated according to the ecological environment. This study clarifies the internal and mutual connection between ESs and influencing factors across two scales, thus contributing to the advancement of management strategies for ecological conservation and socio-economic development within the context of small watersheds.

Quantifying the impacts of climate change and human activities on runoff and suspended sediment load in the Lhasa River Basin, Tibetan Plateau

AbstractQuantifying the attribution of climate change and human activities on runoff and suspended sediment load is crucial for formulating future watershed management measures, especially in the ecologically fragile alpine region, which is more susceptible to climate change and human activities. In this study, the temporal changes in runoff‐suspended sediment load and the potential impact factors (i.e., precipitation, potential evapotranspiration (PET), land use/land cover change (LULC) and reservoir operation) were investigated in the Lhasa River Basin (LRB) from 1956 to 2020. In addition, the contributions of those factors to the changes in runoff and suspended sediment load were quantitatively evaluated based on physically‐based Soil and Water Assessment Tools (SWAT). The results indicated that annual runoff and suspended sediment load showed an increasing but insignificant trend during 1956–2020, while annual precipitation and PET showed a significant increasing trend at a rate of 0.94 and 1.07 mm/yr, respectively. LULC mainly presented an increase in forestland area followed by a decrease in grassland and bare land area due to the implementation of ecological projects. Runoff and suspended sediment load changed abruptly at approximately 1995 and 2005 based on three abrupt change identification methods, thus, the study period was further divided into three substages: baseline period (P0, 1956–1994), dramatically increased period (P1, 1995–2004) and slightly decreased period (P2, 2005–2020). The attribution analysis showed that climate change was the dominant contributor to runoff and suspended sediment load increments during P1. LULC caused the decline in runoff and suspended sediment load in both P1 and P2, with their contribution increasing significantly from 0.40% and 4.73% in P1 to 50.24% and 51.79% in P2, respectively. Reservoir operation was the second key factor in runoff and suspended sediment load reduction in P2, contributing 42.07% and 43.72%, respectively. These findings provide the scientific foundation for reasonably allocating water resources and statistical support for the benefit evaluation of implementing ecological projects in the basin.

Analyzing the impacts of watershed management interventions and scenarios on sediment export reduction in yezat watershed, north west Ethiopia using InVEST model

ABSTRACT This study aimed at assessing the long term impacts of watershed management interventions and scenarios on sediment export reduction in the data-scarce region of the Yezat watershed in north-west Ethiopia. The modified ecosystem services valuation model (InVEST) was employed to evaluate the amount of sediment export in the watershed. Different watershed management intervention scenarios were applied to evaluate the effectiveness of watershed management interventions on sediment export reduction. The results of the study showed that the mean annual sediment yield was 35 tons ha yr in 20000, due to the expansion of cultivated land and built-up area. Conversely, it decreased from 35 ton ha yr in 2000 -18.4 ton ha yr in 2021 due to watershed management interventions. On the contrary, moderate, severe, and very severe categories of sediment export intensity were high in 2000. But it decreased in 2021 due to watershed management interventions. The mean annual sediment export in the baseline scenario (BS) was 35 tons per year, which was reduced to 13.39 tons per year, 3.46 tons per year, and 1.17 tons per year in the reforestation scenario, soil/stone bund, and integrated scenarios, respectively. The result revealed that areas covered by high sediment severity classes were reduced.