Soil Conservation Service Research Articles

Energy potential assessment and techno–economic analysis of micro hydro–photovoltaic hybrid system in Goda Warke village, Ethiopia

Abstract Rural Ethiopia has significant untapped potential for hydro and solar energy generation systems. However, challenges arise from seasonal variations and unfavourable topographic positions of flowing rivers, hindering the efficient exploitation of these resources. Despite the country’s abundance in hydro and solar energy resources, >75% of the population still lack access to electricity from the national grid. This work deals with energy resource potential assessment and techno–economic analysis of micro hydro–photovoltaic (PV) hybrid systems, considered in the case study of Goda Warke village, located in the Yaya Gulele district. A novel framework is proposed that utilizes the Natural Resource Soil Conservation Service curve number method to assess the energy potential of micro-hydro energy in ungauged basins, specifically at the exit point of the Girar River basin catchment. The average monthly flow rate in the basin is 0.975 m3/s, while the area exhibits a solar radiation potential of 5.39 kWh/m2/day. Energy policy promotes expanding access to modern energy sources and utilization of indigenous energy resources. Simulation results indicate that the hydro/PV/diesel generator (DG)/battery and hydro/PV/battery systems are the most optimal choices based on net present cost, with the inclusion of a DG for economic comparison. Micro-hydro energy covers most of the electric load in the area, achieving a capacity factor of 47.5%. The cost of energy and net present cost were found to be sensitive to variables such as the price of diesel fuel, pipe head loss, and the growth of the village load. The optimized system demonstrated a hydro energy potential of 1405.37 MWh/year and a PV energy output of 274.04 MWh/year, resulting in a levelized cost of energy of 0.0057 and 0.049 $/kWh for the hydro and PV components, respectively.

Integrated Hydrological Modeling for Watershed Analysis, Flood Prediction, and Mitigation Using Meteorological and Morphometric Data, SCS-CN, HEC-HMS/RAS, and QGIS

Flooding is a natural disaster with extensive impacts. Desert regions face altered flooding patterns owing to climate change, water scarcity, regulations, and rising water demands. This study assessed and predicted flash flood hazards by calculating discharge volume, peak flow, flood depth, and velocity using the Hydrologic Engineering Centre-River Analysis System and Hydrologic Modelling System (HEC-HMS and HEC-RAS) software. We employed meteorological and morphological data analyses, incorporating the soil conservation service (SCS) curve number method for precipitation losses and the SCS-Hydrograph for runoff transformation. The model was applied to two drainage basins (An-Nawayah and Al-Rashrash) in southeastern Cairo, Egypt, which recently encountered several destructive floods. The applied model revealed that 25-, 50-, and 100-year storms produced runoff volumes of 2461.8 × 103, 4299.6 × 103, and 5204.5 × 103 m3 for An-Nawayah and 6212 × 103, 8129.4 × 103, and 10,330.6 × 103 m3 for Al-Rashrash, respectively. Flood risk levels, categorised as high (35.6%), extreme (21.9%), and medium (21.12%) were assessed in low- and very-low-hazard areas. The study highlighted that the areas closer to the Nile River mouth faced greater flood impacts from torrential rain. Our findings demonstrate the effectiveness of these methods in assessing and predicting flood risk. As a mitigation measure, this study recommends the construction of five 10 m high dams to create storage lakes. This integrated approach can be applied to flood risk assessment and mitigation in comparable regions.

Predicting the peak flow and assessing the hydrologic hazard of the Kessem Dam, Ethiopia using machine learning and risk management centre-reservoir frequency analysis software

Abstract Flooding due to overtopping during peak flow in embankment dams primarily causes dam failure. The Kessem River watershed of the Awash basin in the Rift Valley of the Afar region in Ethiopia was studied intricately to predict the causes of the Kessem Dam safety using machine learning predictive models and risk management centre-reservoir frequency analysis. Recently developed recurrent neural network predictive models with hybrid Soil Conservation Service Curve Number (SCS-CN) were used for simulation of river flow. Peak daily inflow to the reservoir is predicted to be 467.72, 435.88, and 513.55 m3/s in 2035, 2061, and 2090, respectively. The hydrologic hazard analysis results show 2,823.57 m3/s and 935.21 m; 2,126.3 m3/s and 934.18 m; and 11,491.1 m3/s and 942.11 m peak discharge and maximum reservoir water level during the periods of 2022–2050, 2051–2075, and 2076–2100, respectively, for 0.0001 annual exceedance probability. The Kessem Dam may potentially be overtopped by a flood with a return period of about 10,000 years during the period of 2076–2100. Quantitative hydrologic risk assessment of the dam is used for dam safety evaluation to decide whether the existing structure provides an adequate level of safety, and if not, what modifications are necessary to improve the dam's safety.

Seasonal variations in ecosystem service supply and demand based on the SWAT model: A case study in the Guanting Reservoir Basin, China

The match and mismatch between the supply and demand of ecosystem services (ESs) are closely related to watershed sustainable development. Previous studies have mainly focused on annual or interdecadal matching relationships, and little is known about the seasonal variations of the ES supply–demand relationship. Based on the SWAT (Soil and Water Assessment Tool) model and statistical data, we took the Guanting Reservoir Basin, a transitional ecosystem from semi-arid areas to arid areas, as the study area to analyze the supply and demand of water provisioning services and soil conservation services and identified their matching relationship on the seasonal scale. The results showed that the water provisioning services was in short supply, with a supply–demand ratio of 0.81, whereas the supply of soil conservation services was in excess of demand. In terms of seasonal variation, the mismatch of water provisioning services was particularly severe in winter, followed by that in spring. The mismatch of soil conservation services was relatively severe in winter, followed by that in summer. Such mismatches imply that we must pay attention to the misallocation of resources caused by seasonal variations. It is crucial that policy-makers consider the role of reservoirs and water transfer in providing seasonal water sources for sustaining water resources in transitional areas, and optimize land management to prevent the aggravation of soil erosion in winter.

Application of Dynamic Model for Designing Zero Runoff System to Control Erosion in Cocoa Fields

Land degradation in cocoa plantations is mainly caused by surface runoff erosion. Surface runoff can be reduced by applying a Zero Runoff (ZRO) system. This system effectively reduces runoff when its size sufficiently infiltrates all surface runoff. This study aims to determine the size, dimensions, and location of a ZRO system that effectively increases infiltration and prevents surface runoff. The size and dimensions of the system were designed using a water balance approach, where all surface runoff is collected in the ZRO system and then infiltrated. Surface runoff was calculated using the Soil Conservation Services (SCS) method. The potential infiltration rate is a function of the soil's saturated hydraulic conductivity and the system's surface area. The saturated hydraulic conductivity of the soil was determined using the falling head method. The size and dimensions of the system were determined through model simulation based on field physical condition data using a dynamic model. The research results showed that the size and dimensions of the system depend on the amount of rainfall, the area of the catchment area, and the saturated hydraulic conductivity of the soil. From the dynamic model simulation, all surface runoff will be infiltrated if the dimensions of the zero runoff system are 1 x 1 x 0.5 m. This size can accommodate a water volume between 0 – 0,006 m3, so with a system depth of 1,000 mm, there is no surface runoff.

Soil conservation ecosystem service supply-demand and multi scenario simulation in the Loess Plateau, China

Ecosystem services are an essential foundation for sustainable human development. In view of the severe soil erosion on the Loess Plateau (LP), it is important to explore the spatial and temporal characteristics of the supply-demand balance of soil conservation services (SCSs). In this study, the soil conservation ecosystem service supply-demand ratio was innovatively proposed to quantitatively assess the supply and demand balance of soil conservation. First, the InVEST model was used to spatially quantify the supply (soil retention) and demand (soil erosion) of soil conservation services (SCS) in the LP from 2005 to 2020. Meanwhile, the spatial variation characteristics of supply-demand matching were analyzed. Second, to predict the soil conservation ecosystem service supply-demand in the future, the InVEST-PLUS model was used to simulate the supply-demand balance under multiple scenarios in 2030. The natural development (NDS), ecological protection (EPS) and economic development scenarios (EDS) were coupled with shared socioeconomic pathways (SSPs) and representative concentration pathways (RCPs). The results showed that: (1) from 2005 to 2020, the annual average soil erosion modulus of LP increased by 60.58 (t/(hm²·a)); soil retention per unit area increased by 12.89 t/hm2; both increased from northwest to southeast, and the spatial matching pattern of supply-demand was mainly low-low and shifted to low-high each year; and (2) based on the LULC of LP simulated by the PLUS model, the kappa coefficient and overall accuracy were 86.29% and 91.14%, respectively. A total of 19.8% and 22.97% of the built-up land was expanded under the NDS and EDS scenarios, respectively, and a total of 17,515.65 km2 of forestland and grassland was expanded under the EPS scenario; (3) 2030. NDS-SSP245, 2030. EPS-SSP126 and 2030. EDS-SSP585 scenarios, moderate and high surpluses accounted for 11.40%, 14.34% and 10.80% of the total surplus area, respectively; compared to 2020, the high deficit increased by 49.67%, 43.29% and 56.65% respectively. The study provided innovations for the coupling degree of future ecosystem services simulated by the InVEST-PLUS model.

Simulation of Long-Term Water Erosion in Rainfed Croplands of Eastern Washington

Highlights Water erosion in the inland Pacific Northwest was modeled with WEPP for the past (1940–1982) and present (1983–2020). Water erosion decreased from past to present in the study watersheds. Major factors are increased adoption of conservation practices and decrease in large precipitation events. Abstract. Water erosion is an ongoing problem in eastern Washington due to its hilly terrain, highly erodible silt loam soils, rain on thawing soil, and the prevalence of conventional tillage. The region is characterized by a Mediterranean-type climate with warm, dry summers and cool, wet winters. Three distinct precipitation zones, with annual totals low (<380 mm), intermediate (380–460 mm), and high (>460 mm), dictate the area’s crop rotations. A unique 43-year (1940–1982) dataset of winter erosion measured on multiple agricultural fields in Whitman County, eastern Washington, by Verle Kaiser, a USDA Soil Conservation Service agronomist, showed annual erosion rates averaging 53.8 Mg ha-1, far exceeding the current Natural Resources Conservation Service tolerable limit of 11 Mg ha-1 yr–1 for the soils in the area. Kaiser’s field data allowed us to compare the historical field-measured erosion rates with those simulated by the WEPP (Water Erosion Prediction Project) model. Anthropogenic factors, such as tillage and crop rotation, change with time. Conservation tillage, including reduced- and no-till, has been increasingly adopted in eastern Washington since the mid-1980s. The specific objectives of this study were to (1) apply the WEPP model to simulate soil erosion in eastern Washington and evaluate the interactive effects of climate and management, in addition to topography and soil, on water erosion in the study area, and (2) compare the simulation results with Kaiser’s historical field dataset and elucidate the long-term soil erosion trend. The WEPPcloud interface was used to delineate a watershed within each precipitation zone of the study area. Climate inputs were divided into two periods: the past (1939–1982) and the present (1983–2020). Erosion has noticeably decreased from the past to the present, with WEPP simulated annual erosion averaging 13.5, 34.5, and 52.6 Mg ha-1 for the past, and 9.5, 14.1, and 15.5 Mg ha-1 for the present, in the selected watersheds in the low-, intermediate-, and high-precipitation zones, respectively. The decreasing trend was primarily due to the increased adoption of conservation tillage and crop rotation, as well as a decrease in the number of high-intensity precipitation events in the present climate. Keywords: Inland Pacific Northwest, Soil erosion by water, Temporal trend, WEPP.

Assessment of LULC change and its impact on Surface Runoff using SCS-CN method for Noakhali Region, Bangladesh

Land use and land cover (LULC) change detection and its subsequent impact on hydrology are of significant importance in the field of urban planning and the sustainable management of water and land resources. The primary objective of this research work is to illustrate LULC map in a specific study area, which encompasses approximately 316.7 km² in the Noakhali region. Additionally, this study tries to examine the enduring impacts of LULC changes on surface runoff within the specified area. In order to achieve this goal, the analysis of LULC change trends in the region was conducted using Landsat OLI/TM data from 2000 to 2020. The analysis focused on five distinct classes: built-up land, vacant land, farmland, vegetation, and waterbodies. The research employs the Soil Conservation Service Curve Number (SCS-CN) model to evaluate the influence of LULC changes on surface runoff. Notably, the findings indicate a substantial increase in built-up areas from 1.05% in 2000 to 11.21% in 2020. This urban expansion is strongly correlated with a notable rise in surface runoff, as evidenced by a high correlation coefficient (R2 = 0.98) between urban expansion and modelled runoff depth. The observed increase in impervious urban areas contributes to a 2.65% rise in average runoff from 2000 to 2020, equivalent to an 8.96 mm increment in average runoff. The study underscores the profound implications for managing urban storm floods and designing urban areas, especially in rapidly expanding cities globally, with a focus on developing nations. The insights gained offer valuable information for informed decision-making in sustainable urban development and water resource management, not only in the Noakhali region but also beyond.

An optimization model for the impervious surface spatial layout considering differences in hydrological unit conditions for urban waterlogging prevention in urban renewal

The expansion of impervious surfaces during urbanization, as well as the irrationality of their spatial layout, is one of the main causes of urban waterlogging. Optimizing the spatial layout of impervious surfaces through urban renewal is important for urban waterlogging prevention. The differences in hydrological conditions among different hydrological units affect the optimization efficiency of the spatial layout of impervious surfaces in different hydrological units. Therefore, this study proposes an effective optimization model for impervious surface spatial layout, employing a hybrid approach that couples the Soil Conservation Service Curve Number (SCS-CN) model, nondominated sorting genetic algorithm 2 (NSGA2), and multiple linear programming (MLP) algorithm. This approach is applied in a case study of Guangzhou, China. The results show that (1) compared to the MLP-SCS model, the enhanced model not only provides reduced runoff coefficients but also achieves a better spatial balance of the retention water volume. (2) Compared to the conditions before optimization, medium- and high-density impervious surfaces significantly change after optimization, and the connectivity between patches is reduced. The optimized layout alters the original gradient connection method, preventing the aggregation of runoff from high-density impervious surfaces and thereby reducing the risk of urban waterlogging during heavy rain. This study can provide a reference for optimizing the spatial layout of impervious surfaces aimed at urban waterlogging prevention in urban renewal planning.

An Evaluation of the Impact of Urban Growth on Runoff in Abeokuta, Southwestern Nigeria

Abeokuta is one of the urban areas in Nigeria with high cases of runoff fatalities in recent times, indicating the need for a proper understanding of prominent runoff-generating mechanisms, as well as the causative factors. Consequently, this paper, which is focused on flood-prone settlements, is aimed at providing information on the impact of change in urban land use on runoff in the study area. The specific objectives were to determine the change in average runoff in terms of the Soil Conservation Service Curve Number (SCN-CN), and to assess the impact of urban growth on runoff in the area. The SCN-CN was derived from the 30m spatial Shuttle Radar Topography Mission Digital Elevation Model (SRTM DEM). At the same time, land cover change was estimated using Landsat TM+ from 2000 and Landsat 8 OLI from 2018. Data were analysed using the Hydrologic Engineering Centre’s Hydrologic Modelling System (HEC-HMS) and ArcGIS (version 10.1). The results showed a 14% increase (from 39% in 2000 to 53% in 2018) in urban areas of selected catchments; and a relative increase in average CN from 76.9 units in 2000 to 79.9 units in 2018, suggesting an increase in runoff potential relative to the increase in urban/impermeable space in the catchment. Annual discharge depth increased from 891.84mm to 956.9mm, while peak discharge increased from 161.9m3 /s to 196.2m3 /s. Runoff in the study area tends to exhibit spatial variability that is similar to the pattern exhibited by built-up areas across the study area, suggesting that the development of built-up areas can explain runoff exacerbation in part of the area. The use of SCN-CN and satellite images makes the approach reproducible, and the mixed methods of geographic information system and hydrological model revealed the spatial variability typically hidden in stand-alone hydrological models. The paper recommends further studies with the use of less coarse datasets, as well as the implementation of policies that focus on sustainable urban growth in the region, and other cities.

Estimation of Natural Groundwater Recharge in Altun Kopri Basin NE Iraq

The main objectives of the current study are to classify and assess the climate, estimate the actual evapotranspiration and runoff, determine the soil water budget, and estimate groundwater recharge. The climate of the study area is classified as Humid to Moist and Moist to Subarid. Evapotranspiration was determined by using the Thornthwaite method, with its annual value equal to 1342.68 mm. The Runoff was estimated by using the simple and widely used method of Soil Conservation Service Curve Number, the total runoff was 127.6 mm, which represents 36.44% of total rainfall precipitation. The groundwater recharge was estimated according to the modified Thornthwaite-Mather soil water budget, which equals 58.6 mm and represents 16.74 % of the total annual precipitation. The quantity of renewal groundwater is about 47.88 MCM.

The Alteration of Flood Peak Discharge by Land Cover Change in Prek Thnot Watershed, Kampong Speu Provine, Cambodia

This study analyses the alterations of peak catchment runoff from Prek Thnot watershed using the Soil Conservation Service Curve Number (SCS-CN) methodology. Two major studies using different approaches have previously been conducted in the catchment, albeit producing inconsistent results. The Snowy Mountain Hydro-electric Authority published the first study in 1967 and found that the peak surface flow runoff over a 10-year return period was 710 m3/s. The second study was conducted by the Japanese International Cooperation Agency (JICA) between 1991 and 2006 and reported a peak catchment discharge of 1,380 m3/s. To date, there has been no discussion comparing the two studies to determine why the discharge during the later study was double that of the first. As the annual rainfall during the two study periods was similar, it is suggested that this discrepancy may be attributed to physical changes in the watershed, such as changes to forest cover. We deployed the Hydrologic Engineering Centre-Hydrologic Modeling System to simulate the peak runoff of the catchment. Our result was very similar to the JICA finding. Our data suggested that the increase in catchment discharge may be attributed to the conversion of 26% of forest cover in the catchment to agricultural land since the early 2000s. This information is useful for flood management practices, particularly with respect to managing catchment runoff in the context of rapid deforestation and the hydrological impacts of climate change within the watershed. The paper analyzes the impact of land-use changes on catchment runoff and provides valuable insights for flood management practices in the context of climate change and deforestation.

Development of Synthetic Unit Hydrographs Using Spatial Proximity Regionalization for the Makiling Forest Reserve, Philippines

There is a dearth of streamflow data in the Philippines to generate hydrographs needed for flood forecasting and water resources assessment. A method of generating and calibrating synthetic hydrographs using model simulations and spatial proximity regionalization is presented. Synthetic unit hydrographs of four storm events in the gauged watershed of Makiling Forest Reserve were generated using Soil Conservation Service Unit Hydrograph, Clark Unit Hydrograph, and Snyder’s Unit Hydrograph methods. The generated synthetic hydrographs for each runoff modeling technique were calibrated with the actual hydrographs of the watershed. Snyder’s Unit Hydrograph model results were the most acceptable based on the Nash-Sutcliffe Efficiency, Index of Volumetric Fit, and Relative Error of Peak Flow. The weighted values of the calibrated watershed parameters computed using spatial proximity regionalization technique and the hyetographs derived from the Rainfall Intensity Duration Frequency Curve of the University of the Philippines Los Baños-National Agrometeorological Station were used to generate the synthetic unit hydrographs for three neighboring ungauged watersheds at 2-, 5-, 10-, 15-, 20-, 25-, 50, 100-year return periods. Total runoff volume, the magnitude of peak flows, and time to peak derived from the generated hydrographs can be used in watershed planning, water resources management, flood forecasting and the design of various water control structures.

Strategi Pemetaan Genangan Banjir Sungai di Kota Pekalongan Menggunakan Model SCS-CN

Pekalongan City consistently experiences annual floods. In this research, we aimed to map the distribution of potential flood inundation in Pekalongan City under two scenarios: the existing land cover and urban planning (Rencana Tata Ruang Wilayah/RTRW). We utilized hydrological modeling to assess the suitability of the RTRW for future implementation. The Soil Conservation Service – Curve Number (SCS-CN) method was employed, incorporating Digital Elevation Model (DEM) data, soil data, precipitation data, and two sets of land cover data (existing and urban planning). The findings indicate that under the existing land cover, approximately 13.97% of the area is susceptible to flooding, while the remaining 86.03% is not at risk. Conversely, the model using the urban planning (RTRW) scenario suggests that 14.06% of the area has the potential to flood, while 85.94% is not susceptible to flooding. The increase in potential flooding in the urban planning scenario may be attributed to the expansion of residential areas and the reduction of plantation and dry land cover. Furthermore, in assessing monthly modeling results, we observed that the area with flood potential is highest in December 2022 and lowest in June 2022. Considering topographical conditions (DEM), we found that the potential for flood inundation is fairly and evenly distributed in flat areas, mostly with elevations of less than 11 meters. Areas at higher elevations are predominantly free from flood potential, but it is noteworthy that certain areas in the Pekalongan Selatan District, with elevations higher than 11 meters, still have the potential for flooding. Keywords: Flood, hydrology model, SCS-CN, existing land cover, urban planning

How does urbanization impact the supply–demand relationship of agroecosystem services? Insights from farmland loss in the Huaihe River Basin, China

China’s urbanization has gradually become the dominant factor in farmland loss, but it remains unclear how urbanization impacts the supply–demand relationship of agroecosystem services at different rates of farmland loss, which in turn poses new challenges to the ecological security of farmland. Taking the Huaihe River Basin as a case, this paper analyzes farmland loss from 2000 to 2020, as well as changes in the supply–demand relationship of four types of agroecosystem services: food production, socio-economic security, carbon sequestration, and soil conservation, revealing the driving mechanisms of urbanization on the supply–demand relationship of agroecosystem services in sub-regions with different rates of farmland loss. The results show that: (1) A total of 13588.11 km2 of farmland was converted to construction land from 2000 to 2020, accounting for 75.62 % of the total amount of farmland converted to different land types, and 95.57 % of the total amount of farmland converted to construction land. (2) There was a surplus supply of grain production services and socio-economic security services, while there was a deficit in the supply of carbon sequestration services, and a balance in the supply–demand of soil conservation services. (3) The matching degree of supply–demand for agroecosystem services was lower in the Rapid Loss Area compared to the Medium Loss Area and Slow Loss Area. (4) Urbanization was divided into population, economic, and spatial urbanization. The supply–demand relationships of agroecosystem services were impacted greatly by spatial urbanization in the Rapid Loss Area and by economic urbanization in the Medium Loss Area and Slow Loss Area.

Identifying eco-functional zones on the Chinese Loess Plateau using ecosystem service bundles

Optimizing the function of ecosystem services (ESs) is vital for implementing regional ecological management strategies. In this study, we used multi-source data and integrated modelling methods to assess the spatiotemporal variations in eight typical ESs on the Chinese Loess Plateau from 2000 to 2015, including grain production, raw material provision, water conservation, carbon storage service, soil conservation, oxygen production, recreation, and net primary productivity (NPP) services. Then, we divided the ecosystem service bundles (ESBs) according to relationships among the eight ESs, obtaining four types of eco-functional areas at the county (city or banner or district) level based on the spatial clustering of similarities in different ES types. We also identified and assessed the contributions of influencing factors to these eco-functional areas using principal component analysis (PCA) across spatiotemporal scales. We found that the spatiotemporal variations in different ESs were noticeable, with an overall increase in grain production and soil conservation services, no significant change in carbon storage service, and overall decreases in raw material provision, water conservation, oxygen production, recreation, and NPP services. From 2000 to 2015, the number of significant synergistic ES pairs decreased, while that of significant trade-off pairs increased. To the changes of ESBs in the eco-functional areas, the results indicated that the indirect loss of these ESs from forest and grassland due to urban expansion should be reduced in ecological development area (ESB 2) and multi ecological functional area (ESB 3). Meanwhile, crop planting structures and planting densities should be adjusted to reduce ES trade-offs associated with water conservation service in grain-producing area (ESB 4). Lastly, ESB-based eco-functional zoning can be used to improve ecological restoration management strategies and optimize ecological compensation schemes in ecologically fragile area (ESB 1).

Matching and coupling coordination between the supply and demand for ecosystem services in Hunan Province, China

Understanding of the ecosystem services (ESs) supply–demand balance, coupling, and coordination are vital for sustainable development in society. To reveal the changing pattern and underlying mechanisms of the supply–demand matching, coupling, and coordination in ESs, in this study, we used the InVEST model to quantify the supply of the following three ESs in Hunan Province in central China from 2000 to 2018: soil conservation (SC), water yield (WY), and carbon retention (CR). Using socioeconomic data, the capacity and demand for food supply (FS) and the demand for the other three ESs were quantitatively evaluated. The Z-score standardized data were used to divide the quadrants to clarify the supply–demand matching situation. Additionally, the elasticity coefficient model and coupling coordination degree (CCD) model were used to evaluate the supply–demand coupling relationship and coordination level. Our results indicate the following: (1) The supply of CR and FS in Hunan Province increased by 12.67% and 19.48%, respectively, while that of SC and WY decreased by 2.57% and 22.83%, respectively; the demand for SC, WY, CR, and FS increased by 0.329%, 9.43%, 142.05%, and 6.23%, respectively. The supply of CR is less than the demand, showing a clear supply–demand contradiction; the supply of SC, WY, and FS exceeded the demand; both had notable spatial heterogeneity. (2) The area of high supply–high demand (HS–HD) and high supply–low demand (HS–LD) matching types decreased, whereas the low supply–low demand (LS–LD) and low supply–high demand (LS–HD) matching types increased. Additionally, the Changsha–Zhuzhou–Xiangtan urban agglomeration (CZX) and selected districts in northern and central Hunan face a shortage of ESs. (3) The supply–demand coupling relationship of the SC and FS services was primarily positive while that of the WY and CR services was negative. (4) The supply–demand CCD of the four ESs was in an unbalanced state and demonstrated different trends. This study provides novel insights for decision-making regarding the optimisation of the spatial pattern of the land use in Hunan Province.

PREDICTION OF RUNOFF BY SYNTHETIC UNIT HYDROGRAPH METHODS FOR THE DESIGN STORMS IN WARANA RIVER BASIN, MAHARASHTRA, INDIA

The authors' goal was to calculate average representative unit hydrographs (UHs) from a few isolated storms for the upper Warana River basin in Maharashtra, India. Based on the approaches used by Snyder, the Soil Conservation Service (SCS), the Central Water Commission (CWC), and Common, synthetic unit hydrographs were created. This study was utilised to choose appropriate correlation coefficients for Synthetic Unit Hydrograph (SUH) evaluation for the ungauged basins with identical hydrological conditions. The outcomes were then analyzed with those attained using other techniques and with the actual UH. In order to calibrate and validate the effectiveness of Snyder's model, the authors employed it on the sub-basins of the Warana river basin. The hydrograph's shape resembled the observed UH produced by the other methods, according to the results, and the peak discharge calculated using Snyder's technique had the lowest percentage error (0.26%)

A comparative assessment and geospatial simulation of three hydrological models in urban basins

Abstract The risk of flooding is a destructive natural hazard, and it is increasing due to heavy rainfall and anthropogenic factors. Hydrologic–hydraulic models serve as valuable tools for flood forecasting and predicting future flow patterns. These models evaluate and simplify processes in ungauged basins. In this study, three hydrologic models (soil conservation service [SCS], Snyder, and Temez) were used to calculate synthetic unit hydrographs for the Humaya and Tamazula River (H-T-R) basin. Additionally, the flows derived from the three models were simulated in Hydrological Engineering Center River Analysis System for various return periods (2, 5, 10, 25, 50, and 100 years). The accuracy of the models SCS, Snyder, and Temez was evaluated using the root-mean-square error (1162.44, 144.76, and 2890.6); Nash–Sutcliffe efficiency (−51.12, 0.19, and −312.28); R 2 (0.97, 0.94, and 0.94), and kappa index (0.8534, 0.9895, and 0.7155), respectively. The data used in this study were obtained from a hydrometric station located on the Culiacan River. The main findings indicate that the Snyder model demonstrated a better predictive capability compared to the Temez and SCS models, albeit with a tendency to overestimate. Simulated flood depths are deeper in the upstream areas, particularly upstream from the Musala Island bifurcation on the Tamazula River, with values of 11.82 m for SCS, 9.76 m for Snyder, and 13.5 m for Temez. The simulation revealed potential overflow zones along the Tamazula River, particularly at the channel bifurcation and near the confluence with the Humaya River, during the 100 year return period simulation.

Water Balance Calculation and Climate Type for Proposed Dam in Bastora Basin Erbil, North Iraq

Bastora basin is located 20 kilometers north-east of Erbil city. This study's objective was to determine the water equilibrium based on the climate in Erbil, northern Iraq's Bastora basin, a catchment that was of interest for potential dam building. The meteorological conditions were taken into account by the water balance method based on meteorological data collected between 1995 and 2020 at the Permam metrological site. The average annual rainfall was 597.9 millimeters, and the relative humidity was 52.56 percent. The average amount of water that evaporated each year was 1835 mm, and the average temperature was18.1 Co, wind speed was2.09 m/sec, and amount of sunshine each day were 8.2 hours. The Kharrufa method was used to find out if evapotranspiration was happening and to find out when it was deficit and surplus. The results show that there is a total potential evaporation of 1836.4 mm/year, a surplus of 301.26 mm, and a shortage of 1539.41 mm. Soil Conservation Service (SCS) is used to calculated runoff, which is 174 mm per year. The yearly recharge rate for the Bastora Basin was determined to be 3.08 x 105 m3/year, while the water surplus is 50.39 percent of the annual rainfall. Unep, Mather, and Al-Kubaisi classifications were among those utilized to determine the basin's climatic kind. According to the results of these approaches, the sequences of climatic classification in the region are found to be semi-arid, dry, and humid to moist