Watershed Management Strategies Research Articles

Vegetation pattern and topography determine erosion characteristics in a semi‐arid sandstone hillslope‐gully system

AbstractThe hillslope‐gully system serves as the primary contributor to both runoff and sediment yield. The WEPP (Water Erosion Prediction Project) model is often applied to investigate erosion characteristics at hillslope scale, demonstrating a high level of accuracy in simulating water erosion. In this study, according to in situ field monitoring (2014–2020) at a Pisha sandstone hillslope on the Loess Plateau, China, a total of 50 rainfall events’ data were used as climatic data to calibrate the soil parameters, and 11 different vegetation patterns and four slope gradients of hillslope‐gully systems were installed as inputs for the management and slope data, respectively. In systems A, B, C and D, the hillslope gradients were defined as 5°, 8°, 10° and 12° and the gully gradients as 15°, 20°, 25° and 30°, respectively. The results showed that the steeper the slope, the more severe the erosion. However, there was a critical value for the effect of slope on runoff. When the slope exceeded 8° and the gully exceeded 20°, the runoff no longer increased further and even decreased. The reduction in runoff in hillslope‐gully systems was in the following order (in mm): system D (3.4 ± 0.14) > system C (3.4 ± 0.14) > system B (3.39 ± 0.14) > system A (3.12 ± 0.13). Increasing vegetation cover could reduce erosion. Differences in runoff between vegetation patterns were not significant (p > 0.05) and ranged from 8% to 26%. However, there were significant differences in the sediment yield reduction benefits of different vegetation patterns (p < 0.05), ranging from 17% to 66%. It was observed that vegetation located in the lower slope produced a more pronounced effect in mitigating sediment when the degree of cover was the same. We conclude that implementing watershed management strategies based on the vegetation and topographic attributes of hillslope‐gully systems within the Loess Plateau, especially on Pisha sandstone hillslopes, serves as the fundamental approach to achieving sustainable watershed management.

MORPHOLOGY AND MORPHOMETRY CHARACTERISTIC OF RAYA WATERSHED

The study of watershed morphology and land use patterns significantly affects hydrological processes and runoff coefficients, highlighting the quantitative nature of watershed characteristics. The Raya Watershed in West Kalimantan influences local communities and aims to enhance understanding of its physical attributes and hydrological dynamics through detailed analysis of topography, soil composition, land use, and river networks. Findings inform watershed management and conservation strategies. The analysis of the Raya Watershed, spanning 29,982.96 hectares (87.34% of total area) with elevations below 100 meters, reveals flat terrain vulnerable to flooding, particularly in low-lying or sea-level regions, exacerbated by limited natural drainage. Lower elevations support crucial wetland and floodplain ecosystems. Hydrological disruptions from land use changes and climate fluctuations can harm biodiversity and water quality. Effective land use planning is vital to address flood risk and environmental concerns, mitigating impacts like property damage and population displacement. Soil-type mapping informs conservation efforts, ensuring ecosystem resilience. Sustainable land management practices, guided by watershed characteristics like drain density and stream frequency, are essential to mitigate biodiversity loss and ecological imbalances.

Modeling the sediment yield and estimating the best management practices in the Seybouse basin, Northeastern Algeria.

Identifying vulnerable areas to erosion within the watershed and implementing best management practices (BMPs) are crucial steps in mitigating watershed degradation by minimizing sediment yields. The present study evaluates and identifies the BMPs in the Seybouse basin, northeastern Algeria, using the Soil and Water Assessment Tool (SWAT) model. After successful calibration and validation, the model demonstrated a satisfactory ability to simulate monthly discharge and sediment. Then, the calibrated model was employed to evaluate the efficacy of diverse management practices in sediment control. In the SWAT, three soil and conservation practices, as well as vegetated filter strips (VFSs), grade stabilization structures (GSSs), and terracing were evaluated. The average annual sediment yield in the Seybouse watershed is determined to be 14.43 t/ha year, constituting 71% of the total soil loss. VFS demonstrated a sediment reduction of 37.30%, GSS 20.40%, and terracing 42.30%. Among these strategies, terracing results in the greatest reduction, followed by VFS. The results of this study area can be useful for informed decision-making regarding optimal watershed management strategies.

Integrated watershed management strategies for sustainable resource utilization using the SWAT model: case study of the Kalte River watershed, Rift Valley Basin, Ethiopia

ABSTRACT Most people who live in rural areas are highly dependent on shared access to natural resources including land, water, and forests for their food requirements and livelihoods. However, land degradation remains one of the biggest environmental problems worldwide. Therefore, this study proposed to develop integrated watershed management strategies for sustainable resource utilization in the Kalte River watershed. To achieve this, the SWAT model was simulated for 31 years (1992–2022), calibrated and validated at Wajifo and Humbo hydrological stations to determine the sediment and runoff from the watershed, highly sediment erosion-vulnerable part of the watershed was identified from the result of the model and the best watershed management practice was suggested for the study watershed. In total, 87,920 tons/year of sediment are yielded to Lake Abaya from the Kalte River watershed. The sediment yield was reduced by terracing at 64%, strip cropping at 59.32%, grassed waterway at 54.06%, and contour planting at 47.93%. Therefore, the highest efficiency management method in the Kalte River watershed is terracing. The watershed managers and scientific community are beneficiaries of the output of this study. Watershed managers and decision-makers can make use of the information to help them choose appropriate watershed management strategies and ensure sustainable watershed management.

Improving Flash Flood Hydrodynamic Simulations by Integrating Leaf Litter and Interception Processes in Steep-Sloped Natural Watersheds

More frequent high-intensity, short-duration rainfall events increase the risk of flash floods on steeply sloped watersheds. Where measured data are unavailable, numerical models emerge as valuable tools for predicting flash floods. Recent applications of various hydrological and hydrodynamic models to predict overland flow have highlighted the need for improved representations of the complex flow processes that are inherent in flash floods. This study aimed to identify an optimal modeling approach for characterizing leaf litter losses during flash floods. At a gauged watershed in the Hidegvíz Valley in Hungary, a physical-based model was calibrated using two distinct rainfall–runoff events. Two modeling methodologies were implemented, integrating canopy interception and leaf litter storage, to understand their contributions during flash flood events. The results from the model’s calibration demonstrated this approach’s effectiveness in determining the impact of leaf litter on steep-sloped watersheds. Soil parameters can estimate the behavior of leaf litter during flash flood events. In this study, hydraulic conductivity and initial water content emerged as critical factors for effective parametrization. The findings underscore the potential of a hydrodynamic model to explore the relationship between leaf litter and flash flood events, providing a framework for future studies in watershed management and risk-mitigation strategies.

Estimation of Water Yield and Soil Erosion in Samanalawewa Watershed in Sri Lanka using GIS-based InVEST Model

Ecosystem services (ES) are a group of tasks performed by the earth's ecosystems that are required to support life and offer benefits to humanity. Thus, this study explores two of the water-related ecosystem services, water yield, and soil retention that were distributed in the Samanalawewa Watershed (SW) and its eight sub-watersheds in Sri Lanka, over 20 years (2000-2020) with five- year time intervals. Soil and water conservation and water yield play an important role in ecosystem management. Hydrological balance is a crucial component of the hydrological ecosystem services. Assessing water yield and soil erosion are pivotal for watershed management. Thus, this study estimated and mapped the water yield and soil erosion, using the Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST 3.9.2) Annual Water Yield (AWY) and Sediment Delivery Ratio (SDR) model respectively. According to the obtained results, in 2000, 2005, 2010, 2015 and 2020, the estimated mean annual water yield was 2.62x105, 2.6x105, 3.5x105, 3.58x105 and 2.75x105 m3 ha-1year-1, respectively. Furthermore, the estimated mean annual soil erosion rates for the above- mentioned years were 53.2, 52.9, 69.7, 87.7 and 70.2 t ha-1 year-1. The estimated soil loss values of the SW are 10 to 18 times greater than the soil erosion tolerance (5 t ha-1 year-1) in Sri Lanka. The results show that the years 2015 and 2005 have the highest and the lowest water yield and total soil loss values, respectively. The upper part of the watershed has relatively moderate water yield and soil loss values than the lower part. These findings would be beneficial in developing watershed management strategies and in the implementation of suitable soil and water conservation techniques within the watershed. 
 Keywords: Ecosystem services, InVEST, Samanalawewa watershed, Soil erosion, Water yield

Ecosystem dynamics and hypoxia control in the East China Sea: A bottom-up and top-down perspective

Decades of overfishing have greatly altered the community structure in the East China Sea (ECS). The decrease of top predators in the food web has weakened the control exerted from higher trophic levels. As a result, the biomass of benthic crustaceans, representing the third trophic level, has increased. This has probably led to a restriction of the second trophic level, diminishing its ability to control primary producer biomass. Consequently, the ecological pyramid of trophic levels in the ECS has been altered, reducing the top-down control on the first trophic level. This has made algal blooms more susceptible to occur under nutrient loads, temperate temperatures, and light availability. The reduced abundance of the fourth trophic levels has caused a larger portion of primary productivity to sink directly to the benthic community, bypassing the food web. This influx of sinking organic matter has resulted in organic enrichment in the bottom waters, impacting the biomass and diversity of benthic organisms. Furthermore, it has intensified anthropogenic carbon storage in the sediment. Subsequently, intense decomposition processes occur, leading to the development of anoxia and even hypoxia. The seasonal hypoxia off the Changjiang Estuary can be attributed to the combined influence of top-down control and bottom-up control related to nutrient loading, and terrestrial inputs. In order to mitigate extreme hypoxia events, it is necessary to implement comprehensive fisheries policies that prioritize the maintenance of a healthy and functional ecosystem. This approach should go beyond relying solely on watershed management strategies to regulate riverine inputs. Plain language summaryDecades of overfishing changed the food web in the East China Sea and weaken the resistance of ecosystem to hypoxia. Commercial fishing on top predators decreases the fourth trophic level while relatively increases the third trophic represented by crab and shrimp, which enhances grazing on the zooplankton. The decrease of the second trophic level fails to control the biomass of phytoplankton, thus more primary productivities directly sink to the benthic community and cause organic enrichment. The elevated flux of organic matters to the bottom waters causes the thrive of the carbs and shrimps, as well as more remineralization processes and eventually low oxygen level. Unlike the bottom-up perspective of hypoxia mechanism off the Changjiang Estuary, which is from the nutrient load, phytoplankton bloom, quick sink, effective decomposition and eventually hypoxia, the top-down control focuses on the changes of ecosystem structure and thus derived hindered energy transfer, changed community structure, enhanced carbon sink, elevated remineralization and ultimately hypoxia. These two mechanisms combine with each other and control the seasonal hypoxia off the Changjiang Estuary and even other coastal regions around the world.

Catchment land use effect on mercury concentrations in lake sediments: A high-resolution study of Qinghai Lake

Mercury (Hg) contamination in aquatic environments presents a significant ecological and human health concern. This study explored the relationship between catchment land use and Hg concentrations within Qinghai Lake sediment, the largest lake in China, situated on the Qinghai-Tibet plateau. The study entailed detailed mapping of Hg sediment concentrations and a subsequent environmental risk assessment. Considering the complex nature of the plateau landform and surface vegetation, the study area was delineated at a 100 km radius centered on Qinghai Lake, which was divided into 30 sectors to quantify relationships between land use and the sediment Hg concentration. The results revealed a mean sediment Hg concentration of 29.91 μg/kg, which was elevated above the background level. Kendall's correlation analysis revealed significant but weak associations between sediment Hg concentrations and three land use types: grassland (rangeland and trees) (rs = 0.27, p < 0.05), crops (rs = −0.37, p < 0.05), and bare ground (rs = −0.25, p < 0.1), suggesting that growing areas of grassland correlated with higher Hg levels in the lake sediment, in contrast to bare ground or crops area, which correlated with lower Hg concentrations. Multiple linear regression models also observed weak negative relationships between bare ground and crops with sediment Hg concentration. This research methodology enhances our understanding of the impact of land use on Hg accumulation in lake sediments and underscores the need for integrated watershed management strategies to mitigate Hg pollution in Qinghai Lake.

Watershed Management for Sustainable Livelihoods: Integrating Local Pond Ecosystems in Malda, West Bengal

This research article explores the intricate relationship between watershed management, local pond ecosystems, and sustainable livelihoods in the Malda district of West Bengal. The study investigates the potential of integrating local pond ecosystems into watershed management strategies as a means to enhance economic prosperity, ecological resilience, and community well-being. Through a multidisciplinary approach, combining ecological assessments, socioeconomic surveys, and participatory engagement, the research aims to provide insights into the synergies that exist between watershed management practices and the sustainable livelihoods of the local villagers. The research methodology involves field studies encompassing hydrological analysis, biodiversity assessments, and community consultations, aimed at understanding the dynamics of local pond ecosystems and their interconnectedness with the broader watershed. Special attention is given to the diverse ecosystem services provided by these ponds, such as water provisioning, nutrient cycling, and supporting aquatic biodiversity, and how they contribute to the overall resilience of the watershed. The findings of this study are expected to contribute valuable information for policymakers, environmental practitioners, and local communities in Malda district, offering a comprehensive understanding of how the integration of local pond ecosystems into watershed management plans can foster sustainable livelihoods. The article discusses potential strategies for optimizing the co-management of these resources, balancing the ecological health of the ponds with the socioeconomic needs of the local population. Ultimately, this research aims to provide a blueprint for sustainable watershed management practices that prioritize the conservation and utilization of local pond ecosystems, fostering a harmonious balance between ecological integrity and the livelihood aspirations of the communities in Malda, West Bengal.

Accelerated export and transportation of heavy metals in watersheds under high geological backgrounds

The geological background level of metals plays a major role in mineral distribution and watershed diffuse heavy metal (HM) pollution. In this study, field research and a distributed hydrological model were used to analyze the distribution, sources, and pollution risk of watershed HMs in sediments with high geological HM backgrounds. Study showed that the mineral distribution and landcover promoted the transport differences of watershed HMs from upstream to the estuary. And the main sources of Co, Ni, and V in the estuarine sediments were natural sources. Sources of Pb and Zn were dominated by anthropogenic sources, accounting for 76% and 64% of their respective totals. The overall ecological risk of anthropogenically sourced HMs was dominated by Pb (46.6%), while the contributions of Co and Ni were also relatively high, accounting for 35.70% and 33.40%. Moreover, redundancy analysis showed that HM variations in the sediments were most sensitive to soil erosion and mineralizing rock distribution. The spatial patterns of watershed HMs from natural sources were significantly influenced by P loading, precipitation, and forest distribution. This combination of experiments and model improves the understanding of watershed HM variation and provides a new perspective for formulating effective watershed HM management strategies.

Watershed management in Ethiopia and its effects on soil quality and productivity

Indigenous peoples have utilized watershed management techniques for ages. It has substantial ramifications for improved productivity and improved soil management. This essay examined Ethiopia’s soil quality and production improvements as they relate to watershed management strategies. In particular, the roles of the government and other partners who started soil and water conservation initiatives are described. These initiatives had unsatisfactory or unsuccessful results because the community was not involved, the land was held insecurely, there were disincentives, and the planning units were too large. Ethiopia’s Federal Democratic Republic has copied community-based participatory watershed management. It has had a great impact on the restoration of highly damaged areas and provided local populations with a source of income. For instance, Amhara, the Oromia, and Tigray Regional States’ well-managed watersheds of the Abraha Atsbaha, Gerebshelela, Bechyti, Goho Cheri, Kereba, and Bedesa Kela rivers have boosted agricultural incomes and food security. Additionally, the environmental soundness, commercial feasibility, and social acceptability of watershed management must be assessed.

Evolving environmental awareness and shifts in management priorities: a socioeconomic lens on the min river basin, China

Watersheds have experienced economic and demographic development for decades. In China, this development has been associated with environmental degradation, including water quality deterioration, abnormal stream flow, and biotic resource depletion. Effective watershed management incorporates sustainability and public involvement, enabling the long-term security of the human and natural world. Management strategies however need to take into account local conditions, as every watershed is unique. This paper adopts the analytic hierarchy process (AHP) combined with the random forest model to investigate the shift in participants’ environmental awareness across different socioeconomic groups over the past 15 years. Additionally, it scrutinizes the changing public perceptions on the management priorities and areas requiring enhancement. The AHP index highlighted the importance of environmental behavioral intentions (EBI) as a component of environmental awareness (EA). Between 2006 and 2021, significant changes occurred in public environmental awareness (perception, knowledge, behavioral intention) and perceived management priorities, stressing the need for timely adjustment of management policies. Notably, environmental concern (EC) appears to have decreased over time, reflecting effective management and increased governmental attention. Emphasis on the recreational ecosystem services offered by watershed forests has increased. Males, individuals aged over 40-years-old, and individuals located in the upper reaches possessed higher risk perceptions than other groups. These findings may help policymakers to adjust management priorities based on geographic region and may assist them in promoting more effective measures to communicate watershed sustainable management goals and strategies to the public.

Effect of Land Use on Stream Water Quality and Biological Conditions in Multi-Scale Watersheds

Understanding the relation between watershed land use and stream conditions is critical for watershed planning and management. This study investigated the effects of land use on stream water quality and biological conditions in sub-watersheds and micro-watersheds across the Han River watershed in South Korea. We developed random forest models for each water quality and biological indicator using the proportions of urban, agricultural, and forested areas. Our results indicate that water quality and biological indicators were significantly affected by forest area at both scales, and the sub-watershed models performed better than the micro-watershed models. Accumulated local effects were used to interpret the effect of each explanatory variable on the response variable. The plots for water quality and biological indicators with proportions of watershed land use demonstrated similar patterns at both scales, although the relation between land use and stream conditions was slightly more sensitive in micro-watersheds than in sub-watersheds. Urban and agricultural areas showed a lower proportion of water quality and biological condition variability in the micro-watersheds than in the sub-watersheds, while forests showed the opposite results. The findings of this study suggest that different spatial scales should be considered when developing effective watershed management strategies to maintain stream ecosystems.

Simulation of sediment yield and evaluation of best management practices in Azuari watershed, Upper Blue Nile Basin

Abstract This study was conducted to simulate the sediment yield and evaluate best management practices (BMPs) for sediment control in the Azuari watershed, Upper Blue Nile basin, Ethiopia using the Soil and Water Assessment Tool (SWAT) model. As inputs for the model, 30 years (1991–2020) of daily values of meteorological data were used. For model simulation, daily stream flow and sediment data were collected for the periods from 1988 to 2012. The study area was delineated into 19 subwatersheds and the sediment yield was estimated in each subwatershed using the modified universal soil loss equation. The average simulated sediment yield in the watershed was found to be 10.81 t/ha/yr. Six subwatersheds were identified to have high to severe sediment yields and are considered hotspot areas which require prior mitigation measures to control sediment. Four soil and conservation measures were evaluated in SWAT as BMPs namely filter strip, terracing, strip cropping, and contouring. Filter strip was found to reduce sediment by 35.61%, terracing by 20.44%, strip cropping by 44.12%, and contouring by 43.6%. Thus, the implementation of strip cropping resulted in maximum sediment yield reduction. The findings of the study would help to make informed decisions on best watershed management strategies.

The role of integrated watershed management in climate change adaptation for small-scale farmers in Southwest Ethiopia

Climate change severely affects smallholder farmers in developing countries such as Ethiopia. To overcome the impacts, the government of Ethiopia has been undertaking a massive adaptation programs including integrated watershed management practices. However, there is a limited understanding of climate change, adaptation strategies, and the effect and acceptance of the implemented techniques. The objective of this study was to assess climate variability, farmers’ climate change adaptation strategies, and the role of watershed management in climate change adaptation. A multi-stage sampling technique was used to select 255 household heads from three rural kebeles (lowest administrative unit of government) in high, mid, and low-elevation areas. The household survey, focus group discussion, and key informant interview record were used to collect data. In addition, long term meteorology record was used. Data were analyzed using descriptive statistics and a multinomial logit model. The results showed that more than 80% of the farmers, in each elevation, perceived climate variability such as increasing temperature and rainfall fluctuations. The perceived variability is more pronounced in the low-elevation areas. The meteorology record also showed fluctuation in rainfall. About 90% of respondents in each elevation area perceived population pressure, cultivation, and deforestation as the major causes of climate variability. About 90% of respondents perceived crop yield decline due to climate variability. In drought years, crop yield and livestock production decline by ∼50% compared to the average year. Adjustment of crop planting time, crop diversification, selling household assets, participating in off-farm activities, and using government aid were practiced as climate change adaptation measures. About 70% of farmers perceived the positive role of watershed management in climate change adaptation. On average, 36–43% of the farmers in the study area participated in watershed management activities such as the construction of bunds and tree planting, which assist in coping with climate variability impacts. Farm size, sex, education, and farming experience positively and significantly affect the adaptation practices of the farmers. Policymakers and practitioners need to consider the issues related to climate variability and watershed management as a strategy for climate change adaptation. Policy intervention by the Federal government on sustainable watershed management and rural livelihood strategies could assist in sustainable environmental management and climate change adaptation.

Spatial and Temporal Variations of Land Use and Land Cover In Kadiri Watershed Using Rs &amp; Gis Techniques

The change detection and land use and land cover (LULC) maps are more important powerful forces behind numerous ecological systems and fallow land. It is widely known that land use/land cover (LULC) changes significantly alter watershed hydrology and sediment yields. The impact, especially on erosion and sedimentation, is likely to be exacerbated in regions dominated by high rainfall patterns such as monsoons. RS &amp; GIS technologies are very useful to determine the LULC changes. Present research area Kadiri Watershed of Anantapur district of Andhra Pradesh, India, drains an area about 240 km2 including 15 villages. The average annual rainfall in this area varies between 600mm to 700mm in which 60%, 35% and 5% of total rainfall occurs in South-West (S-W),North-East (N-E) and in Summer seasons respectively. The current research focuses on demarcating the spatiotemporal LULC changes. These effects directly affect the ecosystem, land resources, cropping pattern and agriculture. LULC assessment and surveillance are essential for long-term planning and sustainable use of natural resources. The LULC maps were prepared for the study area using Landsat-5, Senthinel 2 images pertaining to pre-monsoon and post-monsoon seasons of 2013, 2017 and 2021. Variations in the extents of agriculture, plantations, scrubs, water bodies, open lands, and built-up areas were noted during these years in the pre-monsoon season, and they ranged from 22 to 35 and 43%, 2 to 3 and 5%, 22 to 28%, 1 to 4%, 52 to 29 and 15%, as well as 1 to 5%, respectively. Similar fluctuations were seen in the post-monsoon season, where they ranged from 29 to 40 and 47%, 3 to 7%, 33 to 30%, 2 to 4%, 32 to 20 and 7%, as well as 1 to 5%. Kadiri watershed, an agriculturally dominant area, has seen an increase in cultivated land due to the conversion of fallow land and open scrub into cropland as a result of good rainfall received during the south-west monsoon during in assessment years and implementation of watershed development activities. These findings highlight the potential impacts of LULC changes in a monsoon-dominated watershed and may contribute to the development of successful LULC-based watershed management strategies for prevention of flooding and sediment loss.

Biomonitoring for Watershed Protection from a Multiscale Land-Use Perspective

The types and intensification of land use in the watershed affect the living organisms in aquatic ecosystems differently; this impact will also vary according to temporal and spatial scales. Understanding these interactions is crucial in the design of biomonitoring programs to detect the effect of different pollutants in freshwater ecosystems and improve watershed management and conservation strategies. Therefore, this paper qualitatively reviews biomonitoring studies in freshwater ecosystems to evaluate the impact of different land use types on multiple scales in watersheds. The paper is organized into four sections. The first section presents biomonitoring in different freshwater systems (streams, rivers, lakes, and reservoirs). In the second section, we describe the biomonitoring characteristics of the main land use types. In the third section, we explain how spatial and temporal scales affect biomonitoring. Finally, in the fourth section, we focus on biomonitoring planning and future prediction and discuss how to design biomonitoring programs and how to use models and eDNA in biomonitoring. Our review will assist in decision-making regarding biomonitoring programs in watersheds and will guide future studies on the different bioindicators for various land use types in diverse ecosystems worldwide.

Identification of Watershed Conditions and Formulation of Watershed Management Strategies

In Indonesia, 39 watersheds were deemed essential in 1994, and the importance of watersheds grew in 2000. The existence of a watershed has the role of being able to sustain water availability, maintain the balance of the ecosystem and as a container for flowing water. The Musi-Sugihan-Banyuasin-Lemau River Area (WS MSBL), which has an area of 86680 km2 and is made up of 23 primary watersheds, is one of the largest watersheds in the Sumatra region. Research was done to determine the state of the watershed so that a strategy for watershed conservation could be chosen. In-depth interviews with stakeholders in the form of focus group discussions (FGD) were utilized as the study method to collect both secondary and primary data about the circumstances of the watershed as well as to gain in-depth management outcomes. The study's findings demonstrate that managing the WS MSBL watershed involves more than only technical issues; it also necessitates involving associated institutions and stakeholders, necessitating the creation of operational watershed management strategies.

MODELLING THE IMPACTS OF SELECTED WATERSHED MANAGEMENT STRATEGIES ON SEDIMENT REDUCTION UPSTREAM OF SHIRORO DAM, NIGERIA

This research utilized a regulated hydrological model, Soil and Water Assessment Tool (SWAT) interfaced with Geographical Information System (GIS), in studying the effectiveness of the chosen watershed management strategies on sediment reduction upstream of Shiroro dam, Nigeria. Selected management approaches were modelled while calibration and validation of the model were achieved using observed streamflow data. Findings indicated a good correlation during calibration and validation period. Application of reforestation, vegetative filter strips and stone bunds in the watershed reduces sediment production by 27 %, 39 %, and 15 % respectively. Thus, the sediment management scenarios depicted within this research are considerably sustainable and effective.

Identification of groundwater potential zones in the Rabigh-Yanbu area on the western coast of Saudi Arabia using remote sensing (RS) and geographic information system (GIS)

The groundwater potential zones in the Rapigh-Yanbu area, on the west coast of Saudi Arabia, were evaluated using remote sensing and geographic information system data leading to the establishment of major watershed development and management strategies. Many factors, including slope, drainage density, land use, geology, lineament density, elevation, yearly precipitation, and soil type distribution, affect the hydrogeological characteristics of coastal aquifers. The Rabigh-Yanbu coastline groundwater potential zones were located and mapped using these characteristics. The annual precipitation rate is categorized into 2–28 mm, 29–52 mm, 53–76 mm,77–107 mm, and 108–164 mm within the study area. The highest elevation was ordered with the lowest rank of 1, while the lowest elevation was given the highest rank of 5. Slopes of 0°–9° were present in the majority of the study region, while slopes of 9°–63° were present in the northwest. Based on the slope, the research area was separated into five classes; 0-3o; 4-9o; 10–16o; 17–25o; 26–63o. Based on the drainage density map; 0–0.36 km2, 0.37–0.53 km2, 0.54–0.73 km2, 0.74–1.32 km2, 1.33–3.31 km2. The majority of the fractures trended NE–SW and NW–SE. A map of lineament density was made using the line density method. This map makes it obvious that the region was divided into five classes; 0–0.02 km2, 0.03–0.08 km2, 0.09–0.13 km2, 0.14–0.2 km2, and 0.21–0.34 km2. The classification of soil types in the study region into four classes such as clay loam, clay, sandy clay, and loam. Accordingly, the clay soil was ranked 1, while the loam soil was given the highest rank of 4. The Precambrian rocks had low groundwater potential because of their reduced porosity and were ranked 1, while Quaternary deposits had a high porosity and good groundwater potential and were given a high rank of 3. According to the likelihood of groundwater supply, the area is divided into four categories: very good, good, moderate, and poor. The area with very good groundwater potential covered 1,384 km2, while the area with good groundwater potential covered 30,498 km2, according to the findings. The study area had 34,412 km2 of somewhat appropriate land for groundwater development. In contrast, 1,734 km2 of the study area is scarce. The best zones featured the lowest slopes, the least number of lineaments, and the most drainage. The lineaments, which serve as the main conduits for groundwater flow and storage, have significant levels of groundwater recharge capacity in the study area. Managing groundwater according to these identified potential zones will maximize their benefits and increase the groundwater yield. This will help in creating new agricultural, urban, and industrial communities in this strategic area and contribute toward achieving the goals of Saudi Vision 2030.