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Groundwater in arid areas is critical for drinking water supplies, irrigated agriculture, and the preservation of terrestrial ecosystems. In the semi-arid region of Guenfouda, shallow aquifers are vital for human habitation and agriculture. Many settlements acquire their water from wells and springs. However, these wells are particularly susceptible to seasonal fluctuations and may be depleted during dry periods. Therefore, a deeper understanding of the hydrogeology of deep aquifers is required. Using analysis of geologic and hydrogeologic data in a GIS environment, this study examined the efficiency of the gravity model in investigating the structure of deep aquifers. A combination of filtering techniques was applied on the gravity map. The developed model shows the general configuration of the Jurassic aquifer, which gradually dips to the north and northeast to a depth of about 2280 m. Statistical analysis revealed considerable spatial coherence between fractures and compartments of the aquifer. Consequently, the structural model obtained from gravity data can greatly improve our understanding of the aquifer structure in the survey area.

Playa wetlands are widely distributed across the High Plains of the central United States, providing a range of ecosystem services, such as groundwater recharge, surface water storage, and wetland habitat. Although playas are essential resources, few studies have examined the variability and controls on playa water storage. The purpose of this project is to determine how playa and watershed morphology, watershed land cover, and precipitation patterns affect timing and duration of water storage in playas. This project focuses on 92 playas distributed throughout a 10-county region in western Kansas. Playa and watershed morphology were calculated in a GIS environment and classified into quartiles based on playa and watershed surface area. Watershed tilled index (i.e., percent cropland versus grassland) was determined using 2016, 2017, 2018, and 2019 Cropland Data Layers available from the National Agricultural Statistics Service and classified as either cropland (more than 75% cropland), grassland (more than 75% grassland), or mixed. Monthly precipitation data for 2016–2019 were compiled from the Oakley 22S High Plains Regional Climate Center weather station. Playa water status for 2016–2019 was classified monthly as either standing water or dry (i.e., no visible standing water) by visually examining four-band satellite imagery with 3.7 m resolution available from Planet Explorer (www.planet.com). Playa water status is influenced by a combination of factors, including playa and watershed morphology, watershed land cover, and precipitation patterns. Larger playas have larger watersheds and standing water more frequently and for longer periods than smaller playas. Playas in cropland watersheds store water more frequently and for longer periods than playas in grassland watersheds, though differences are not statistically significant. Standing water within playas is positively correlated with monthly precipitation and reflects a short-term response to precipitation patterns, regardless of playa size or watershed land cover. The strongest controls on playa water status are playa area, monthly precipitation, and watershed area. Playas are critical resources for the High Plains, providing a range of ecosystem services that are dependent upon the playa’s ability to store water. Playa functions are under continued threat from cropland expansion, climate change, and playa and watershed modifications. To sustain playa functions in Kansas, efforts should focus on conserving larger grassland playas and reducing sediment inputs to playas in cropland watersheds.

In the present study, the groundwater potential zone was demarcated and suitable site selection for the water storage structures was identified in the Deoria watershed of Jharkhand by using analytical hierarchy process. Thematic layers of lithology, geomorphology, soil, lineament, lineament density, slope, relief, aspects, drainage, drainage density, land use and land cover, and groundwater depth maps were created. The watershed falls under fourth-order river basin. A major portion of the basin is mainly dominated by lower order streams. Groundwater potential zones were categorized as very good, good, moderate, bad, and very bad. Only 9.37% of the total watershed area falls under a very good category. Twenty-eight suitable sites were recognized for constructing water harvesting structure in the Deoria watershed. The vast majority of the Deoria watersheds were observed to be appropriate for check dam. The watershed is characterized as having a reasonable land-use class (forest, river bed), slope (under 15%) and soil type (sandy loamy topsoil) which fills the need for soil and water conservation and groundwater expansion. The appropriateness of other water storage structures like nala bandh, farm pond and bore well were apportioned on the grounds. Remote sensing, satellite data, and GIS techniques provide a convenient approach for delineating the potential of groundwater zones which ultimately support the better planning and management of groundwater resources.

Geographical information system and remote sensing are proven to be an efficient tool for locating water harvesting and recharge structures, groundwater potential, runoff, watershed prioritization through morphometric analysis. The management and conservation of watershed require scientific evaluation so that appropriate strategies can be implemented by the policymakers and stakeholders. This study evaluates the Parvati River Basin for prioritization of sub-watershed. We use analytical hierarchical approach with pairwise comparison matrix for ranking the parameters which has been derived through morphometric analysis of the watersheds. The linear (stream order, stream length, mean, stream length, stream length ratio, bifurcation ratio, rho coefficient), relief (basin relief, relief ratio, ruggedness number) and areal morphometric parameters (drainage density, stream frequency, texture ratio, form factor, circulatory ratio, elongation ratio, length of overland flow, constant channel maintenance) have been used for prioritization of watershed in the Basin. The results revealed that the basin comprises of complex topography with mountainous and hilly relief structures which results into high run-off. The prioritization of sub-watershed suggests that the largest watershed comprising of 36.09% total watershed area falls into medium category for water potential. The total area under very high to high category is 5.36% and 8.44% respectively. The relationship between morphometric parameter and watershed prioritization shows that the sub-watersheds SW1 and SW8 falls under very high to high category having high water holding capacity.

Water is an important resource of the earth’s surface and it is integral for all on this planet. The availability or the scarcity of water depends on the watershed characterizes that consider the basic, linear, and shape parameters of any waterbody. The objective of the study was to delineate 14 morphometric parameters in the Barind region (Dinajpur district, Bangladesh) for sustainable hydrological modeling. An ASTER-DEM of 30-meter resolution data, geographical information system (GIS), and Remote sensing technique were used for extracting drainage components of interest region. The whole study region was covered by the flow of the Purnovoba river, Jamuna river, Atrai river (part-1 and part-2). Research results found that the Purnovoba river had a high bifurcation ratio (0.9982) that defined hydrologically more disturbed than the other three watershed areas and it had a high stream frequency (0.8332) that denoted rocky having low infiltration capacity. Jamuna river had a low drainage density (0.7322) that defined more vegetation having higher permeability. Besides, the Jamuna river had the lowest no. of stream order that was insignificant in the steady runoff process and less prone to cause a flash flood. The research predicted that the availability of groundwater might decrease to Jamuna river in the future as it had the lowest basin area (217.42 sqr. km ) and perimeter (114.90 km) and the basin surface slope would become gentle to Atrai river part-1 for the lowest length of overland flow (0.6072). Purnovoba river experienced the lowest form factor (0.2351) which indicated the most possibility for erosion. The elongated ratio of all basins was greater than 0.5 which considered all the shapes were more elongated. These findings will help for further modeling of an integrated watershed for sustainable hydrological models in the Barind region.

The Benanain Watershed is located in East Nusa Tenggara with an area of 3,181 km2 and is divided into 29 sub-watersheds. The East Nusa Tenggara itself is an eastern region of Indonesia with a unique climate condition called semi-arid. The high rainfall intensity occurring in short duration results in large surface runoff and erosion. Floods and erosion in semi-arid areas due to sensitive soils to drought and heavy rainfall extremely. This paper presents the application of the Soil Conservation Services-Curve Number (SCS-CN) real-flood flows through a digital map of soil type, land use, topography, and the heterogeneity of physical condition, especially for ungauged watersheds. The method used is an approach empirical to estimate runoff from the relationship between rainfall, land use, and soil hydrology groups. This watershed has a large area that must analyze every sub-watershed. The land-use of the Benanain watershed is secondary dryland forest by 44.26% and the hydrological soil group on the B group classification with medium to high absorption potential by 46.502% from the total area. The curve number value of the Benanain Watershed ranges from 56.54 to 73.90, where the mean CN value of 65.32. The rainfall (mm) for the 29 sub-watersheds in the Benanain Watershed has decreased by about 74.65% when being surface runoff or only 25.35% of water becomes surface runoff. The relationship between rainfall depth and CN is classified as standard response and trend line (flat slope) equilibrium occurs when rainfall depth value of 56.71 mm and CN is close to 66.30. The high variability of intense rainfall between the rainy season and the dry season had a significant influence on the curve number value in a large watershed area. Further analysis will be more accurate if it is supported by long rainfall data and observation runoff data as a control. Doi: 10.28991/cej-2021-03091711 Full Text: PDF

Recently, land-use change, as well as climate change through seasonal floods, have caused increasing damage to the Hajji Qushan watershed. Therefore, to reduce the peak discharge of floods, the construction of earth dams is necessary and inevitable. This study aimed to evaluate the effect of embankment structures on the reduction of peak discharge and their effects on the downstream flow regime. For this purpose, to present a favorite rainfall-runoff model and to route the mainstream channel, the HEC–HMS model was utilized. The required data included data from three rain gauge stations and two hydrometric stations. To delineate the boundaries of the watershed, ArcGIS 10.3 (HEC–GeoHMS extension) was implemented. To extract the digital elevation model (DEM), 10-m contour lines were used. The results showed the lack of satisfactory effects of dam construction on the reduction of peak flood discharge. The location of dam construction, reservoir capacity, and watershed area were of the factors that determined the possible reduction of flood risk.

Tambakbayan is one of the watersheds in Yogyakarta, Indonesia that is experiencing changes in land use. The research aims to analyze the distribution of intrinsic and specific groundwater vulnerability in the watershed that was influenced by land-use changes from 2006 to 2017. The data used are the RBI maps (containinh topographic and land-use information, 2006 and 2017), SRTM imagery, rainfall recorded at the Kambil, Prumpung, Bronggang, Santan, Gemawang, and Karang Ploso stations (2006-2017), soil map, and aquifer map. Land-use change was analyzed by comparing the RBI maps of 2006 and 2017; while the groundwater vulnerability was assessed with the Susceptibility Index a development of the DRASTIC method. The intrinsic groundwater vulnerability was generated based on physical conditions, including depth to the water table, aquifer media, groundwater recharge, and topography, while the specific groundwater vulnerability was a function of these attributes added with one anthropogenic parameter : land-use. Then, all of these parameters were analyzed with map ovelay. The results showed two levels of intrinsic vulnerability : low (2.18% of the watershed area) and medium (97.8%); and three classes of specific vulnerability : low (0.02%), medium (5.06%), and high (94.92%)in 2006. From 2006 through 2017, the areal percentage of the medium vulnerability increased, while that of the high vulnerability decreased due to the conversion of agricultural land to a reservoir in 2009.

The analysis of the watershed gives the surface area of land that rain streamed arrived in the river. The modern method to analyze the catchment is the ArcGIS program based on the Digital Elevation Model (DEM). The study area is An Najaf province, which area equaled about 27675 square kilometers. The HECGeoHMS (Hydrologic Engineering Center's Hydrologic Modeling System) is the link program on the ArcMap software that abled by serious steps to analyze the specific watershed. The auto analysis of the watershed area gives four basins for each outlet points located on the distributary Euphrates river. These four basins consisted of multi sub-basins and streams of rain flow. Basin 4 has the most significant volume, about 11.4% of the total case area of the basin, and the average slope is 3.2%. According to the amount of accumulative rainwater, basin 4 is essential when any obstruction is constructed at the end of the outlet point in the stream. This location of the construct is used to prevent the sediment in the Euphrates river and to avoid surface soil degradation. The arrangement of importance basin based on the advantage of water using to give maximum discharge and low evaporation is basin four at the first, basin two at the second.

Daihai Lake (DL), the third largest inland lake in Inner Mongolia, has shrunk severely given the conditions of no significant decrease in annual precipitation. On the basis of field surveys and Landsat remote sensing images, this study analyzed land use and land cover (LULC) changes in six periods of the DL watershed area during 1986–2019. Then, with the combination of the LULC results and the Soil Conservation Service–Curve Number method, we discussed the change characteristics and influence factors of the surface runoff in the watershed and the reason for DL shrinkage. From 1986 to 2019, the water area of DL decreased rapidly at a rate of −2.22 km2/year, and the area of farmland and grassland in the watershed changed strongly along the opposite trend. The surface runoff in the DL watershed was reduced by approximately 513.6 million m3 during the last 34 years. In addition to local rainfall, groundwater is also an important water supply to the lake and accounts for a greater proportion. The average recharge rate of groundwater to the lake is approximately 64.55 million m3 per year in the past 34 years. The area change of the DL is related to the runoff reduction, huge evaporation, and lake water use in thermoelectric power generation. The local precipitation cannot enter the groundwater in DLW. Large-scale exploitation of external groundwater for agricultural irrigation and industrial production is another important cause of lake degradation.

Rainfall and run-off prediction capabilities for flash flood need improvement in the high porn regions of mountain hazard, those caused massive distraction. At some point, these events result in a massive loss of life and property. This research demonstrates the application of soil conservation service (SCS), a hydrological model used to simulate the relationship between rainfall and run-off. The data cover a 62-year observation period of torrential rains and debris flows, which number up to thirty flow events, all occurring in the mountainous regions close to the Tieli watershed area. Rainfall hydrographs were generated for each of the said torrential rain cases and can be used as markers for flood warnings for critical rainfalls lasting from 1 to 24 h. The results show that the SCS model can successfully define the rainfall–run-off-water level relationship of small-medium-size catchments wherein the calculated run-off values show good agreement with measured discharges. Moreover, from the relationship of the water level and SCS calculated run-off is similar to the relationship obtained using measured run-offs. From this relationship, critical water levels that would correspond to the occurrence of a possibly devastating flood can be determined to provide for an early warning measure for the nearby regions.

Rapid socio-economic development has led to a significant deterioration in the water environment, which has limited sustainable regional development. The soil and water assessment tool (SWAT) and statistical regression method were used to model the ammonia nitrogen (NH4+-N) pollution and explore the impacts of land use and socio-economic factors on NH4+-N pollution within the Weihe River watershed in China from 2015 to 2018. The result of SWAT model revealed that the NH4+-N concentrations were usually relatively high under low runoff conditions and relatively low under high runoff conditions. The average NH4+-N concentration in the upper reaches was 0.77 mg/L, whereas it was 0.87 mg/L in the middle and lower reaches of the watershed. Serious NH4+-N pollution mainly occurred in 2015 and 2016, and the V (2.0 mg/L) and V+ (>2.0 mg/L) water quality classes were associated with approximately 6.67% and 28.94% of the total watershed area, respectively. The multiple linear regression indicated that the building land and secondary industry were the significant controlling factors (P < 0.01). According to the scenario analysis, modelled scenarios for interception measures reduced the NH4+-N load to a greater degree than scenarios for source control measures. To improve the surface water quality in the Weihe River, it is recommended to adjust industrial structure, increase sewage treatment, and strengthen the rural management of the watershed.

Observations and modeling are used to assess potential impacts of sediment releases due to dam removals on the Hudson River estuary. Watershed sediment loads are calculated based on sediment-discharge rating curves for gauges covering 80% of the watershed area. The annual average sediment load to the estuary is 1.2 Mt, of which about 0.6 Mt comes from side tributaries. Sediment yield varies inversely with watershed area, with regional trends that are consistent with substrate erodibility. Geophysical and sedimentological surveys in seven subwatersheds of the Lower Hudson were conducted to estimate the mass and composition of sediment trapped behind dams. Impoundments were classified as (1) active sediment traps, (2) run-of-river sites not actively trapping sediment, and (3) dammed natural lakes and spring-fed ponds. Based on this categorization and impoundment attributes from a dam inventory database, the total mass of impounded sediment in the Lower Hudson watershed is estimated as 4.9 ± 1.9 Mt. This represents about 4 years of annual watershed supply, which is small compared with some individual dam removals and is not practically available given current dam removal rates. More than half of dams impound drainage areas less than 1 km2, and play little role in downstream sediment supply. In modeling of a simulated dam removal, suspended sediment in the estuary increases modestly near the source during discharge events, but otherwise effects on suspended sediment are minimal. Fine-grained sediment deposits broadly along the estuary and coarser sediment deposits near the source, with transport distance inversely related to settling velocity.

River sedimentation is an important indicator for ecological and geomorphological assessments of soil erosion within any watershed region. Sediment transport in a river basin is therefore a multifaceted field yet being a dynamic task in nature. It is characterized by high stochasticity, non-linearity, non-stationarity, and feature redundancy. Various artificial intelligence (AI) modeling frameworks have been introduced to solve river sediment problems. The present survey is designed to provide an updated account of the latest and most relevant AI-based applications for modeling the sediment transport in river basin systems. The review is established to capture the subsequent developments in the advanced AI models applied for river sediment transport prediction. Also, several hydrological and environmental aspects are identified and analyzed according to the results produced in those studies. The merits and constraints of the well-established AI models are further discussed in much detail, particularly considering state-of-the art, modeling frameworks and their application-specific appraisal, and some of the key proposed future research directions. Together with the synthesis of such information to drive a new understanding of models and methodologies related to suspended river sediment prediction, this review provides a future research vision for hydrologists, water scientists, water resource engineers, oceanography and environmental planners.

Constructed agricultural treatment wetlands are key tools for removing nitrate (NO3–) from surface waters. Due to limited funds for NO3– removal practices, investments need to be in the most cost-effective practices. Furthermore, NO3– removal practices that take less land out of production may be more appealing for farmers. Therefore, three types of wetlands were compared to determine NO3– removal effectiveness and cost effectiveness across a watershed. The three wetland types included large wetlands with drainage areas greater than 60 ha; small, edge-of-field wetlands with drainage areas covering fewer than 60 ha; and small, edge-of-field wetlands with a dual treatment system of surface treatment and subsurface treatment following infiltration. The Agricultural Conservation Planning Framework (ACPF) toolbox model was used to determine best placements for each wetland type in the Elm Creek watershed in southern Minnesota, United States. The Soil and Water Assessment Tool (SWAT) model was used to estimate the volume of tile discharge and nitrate-nitrogen (NO3-N) concentration into each wetland over a 10-year period. A spreadsheet model was used to estimate the reductions of NO3– in each wetland over the same 10-year period. Small, edge-of-field wetlands with a saturated hydraulic conductivity (Ksat) of 0.17 m d–1 were more effective at removing NO3– for the area removed from crop production in order to create the wetland (kg ha–1 y–1) and as cost effective (US$ kg–1 NO3-N removed) as the large wetlands. When the small wetlands had a low Ksat (8.64 × 10–5 m d–1), they were more effective for each area removed from crop production (p = 0.06) but not as cost effective (p = 0.003). This study suggests that constructing many small, edge-of-field treatment wetlands with high conductivity, dual-treatment systems to reach nutrient reduction goals would cost the same as constructing large wetlands but would remove fewer hectares of cropland from production. If landowners are interested in removing only a few hectares from crop production at a time, the wetland restoration would possibly still be beneficial. Minimum hectares should not be a limitation for restoration program enrollment as long as the wetland to watershed area ratio is still viable.

Yarehalli micro-watershed lies between 750 51' 37.58'' to 750 53' 29.93'' East longitudes and 130 58' 59.95'' to 140 1' 3.72'' in Davanagere district of Karnataka. The drainage networks of micro-watershed were delineated from the Survey of India topographical map of 1:50,000 scale. ArcGIS software was used for evaluation of linear, areal and relief as pects of the micro- watershed. The present study reveals that, drainage pattern of the study area is dendritic with trunk order 4th. The watershed area, perimeter, maximum length and width of the watershed was 977 ha, 10.00 km, 4.40 km and 2.20 km respectively. The mean value of bifurcation ratio is 3.23, the micro-watershed have been suffered less structural disturbance and drainage pattern has not been distorted. The value of drainage density is 2.31 km km-2 which indicated that, the region is having permeable subsoil material and good vegetative cover. The value of form factor indicates micro-watershed is approaching towards elongated shape of watershed. The present study reveales that, GIS based approach in evaluation of geo-morphological characteristics is more appropriate than conventional techniques. Over all study suggests that the micro-watershed should be treated with soil and water conservation measures.

Rainfall-runoff relationship in arid regions is unique and challenging to study. Studies for bridging the hydro-meteorological knowledge gap for planning, designing and managing water resources is therefore vitally important. The objective of this study is to develop a method for estimating unit hydrograph at reasonably finer time resolutions (10-min and 1-h) which can be easily adaptable by practitioners at sub-catchment levels, especially when the focus area is ungauged. Observed wadi-flow at 5-min interval and tipping bucket rainfall measurements at 1-min interval were obtained to cover 10 major watersheds in Oman. The deconvolution method was applied to derive the unit hydrographs (UHs) from wadi-flow and excess rainfall. Key catchment characteristics such as the watershed area, length of the main wadi and the length to the centroid of the catchment area were derived from digital elevation model (DEM) data. The whole study area was then divided into 515 sub-catchments with various shapes and sizes. A strong relationship was found between the wadi length and the length to the centroid of the catchment area (R2>0.89). This relationship was then adopted to simplify the classical Snyder method to determine UHs. Moreover, several parameters of the Snyder method were calibrated to the arid environment by matching the peak-flow, lag-time and three time-widths (75%, 50% and 30% of the peak-flow) of 10-min and 1-h UHs with physical characteristics of the watersheds. All developed relationships were validated with independent rainfall and wadi-flow events. Results indicate that the calibrated parameters in these arid watersheds are quite distinct from those suggested for other regions of the world. A marked difference was found between the 10-min UHs estimated by the S-hydrograph method and the deconvolution method. Therefore, it is concluded that a method depends on natural hydro-meteorological conditions would be more practical in arid region. The proposed methodology can be used for water resources management in arid regions having similar climate and geographical settings.

Wildfires are landscape scale disturbances that can significantly affect hydrologic processes such as runoff generation and sediment and nutrient transport to streams. In Fall 2016, multiple large drought‐related wildfires burned forests across the southern Appalachian Mountains. Immediately after the fires, we identified and instrumented eight 28.4–344 ha watersheds (four burned and four unburned) to measure vegetation, soil, water quantity, and water quality responses over the following two years. Within burned watersheds, plots varied in burn severity with up to 100% tree mortality and soil O‐horizon loss. Watershed scale high burn severity extent ranged from 5% to 65% of total watershed area. Water quantity and quality responses among burned watersheds were closely related to the high burn severity extent. Total water yield (Q) was up to 39% greater in burned watersheds than unburned reference watersheds. Total suspended solids (TSS) concentration during storm events were up to 168 times greater in samples collected from the most severely burned watershed than from a corresponding unburned reference watershed, suggesting that there was elevated risk of localized erosion and sedimentation of streams. NO₃‐N concentration, export, and concentration dependence on streamflow were greater in burned watersheds and increased with increasing high burn severity extent. Mean NO₃‐N concentration in the most severely burned watershed increased from 0.087 mg L⁻¹ in the first year to 0.363 mg L⁻¹ (+317%) in the second year. These results suggest that the 2016 wildfires degraded forest condition, increased Q, and had negative effects on water quality particularly during storm events.

Flooding is one of the problems that often occurs in the DKI Jakarta area, which one of the causes is the change of land use in watersheds that were originally into development areas. Whereas, its often the cross section of the river will be disrupted due to the loss of the riverbanks and the narrower cross section of the river. In order to overcome this, the Jakarta Provincial Government in 2013 normalized several rivers that crossed the DKI Province and one of them was the Pesanggrahan River which will be further investigated. The purpose of this study is to analyze the effect of river normalization on erosion and sedimentation which will result in changes in the longitudinal and cross section of the river. To get an accurate map of the Watershed Area, Arc-GIS software is used while identification of river flow before and after normalization was carried out based on data from Central Office of River Region Ciliwung-Cisadane, Ministry of Public Works. Sediment samples were taken at 3 points on the river, upstream, middle and downstream, that were reviewed to determine the gradation of the sediment grains. The HEC-RAS application is used to simulate sediment transport on the river section before and after normalization. The simulation results are used to determine the cross section changes due to erosion and sedimentation and to determine the water level in the river. From the water level, the hydraulic radius can be calculated and then carried out sediment transport calculation using Ackers-White equation since the equation using grain distribution from range 0.02 – 4.94 mm. The results it was found that the sediment transport in the upstream point increased 155.11 tons / year, at the midpoint increased 89.64 tons / year and the downstream point decreased 0.28 tons / year.

Debris flow activity increased after the Wenchuan earthquake, and many debris flows continue to occur. Recently, a catastrophic debris flow event was triggered by strong rainfall on 20 August 2019 in Wenchuan County, China. The main purposes of this article are to analyse the activity characteristics of this disaster and further to analyse the long-term activity of debris flow in Wenchuan County based on the analysis results of this disaster. According to a field survey and remote sensing image interpretation, this strong rainfall triggered 15 debris flows that occurred simultaneously in the large watershed in northern Wenchuan County, and they were characterised by strong channel erosion and a disaster chain effect. The activity and sediment supply capacity of landslides have decreased significantly, and the landslides that provided materials for this debris flow event are mainly distributed on both banks of tributaries. The amounts of triggering rainfall and antecedent accumulated rainfall for this debris flow event were 13.7 mm and 47.1 mm, respectively. In addition, the channel runoff formed by strong short-duration rainfall eroded the channel deposits, and temporary check dams failed due to slope failures; these are the main causes for debris flows in the next period. Analyses of the debris flow volume versus watershed area and the maximum erosion modulus prove that the debris flow activity in Wenchuan County is decreasing with time, but more than 5~10 years will be required to recover to the pre-earthquake level.

The Jurua Watershed region, an important tributary of the Amazon River, lacks scientific information related to climate and environmental variables. In this sense, this study intends to analyze the environmental dynamics of the Jurua Watershed in the Amazon. We used monthly weather data derived from Reanalysis 2. The products fire foci, vegetation index and surface water index derived from the MODIS sensor for a monthly time series from 2001 to 2018. The ARIMA model was used to simulate future changes from NDFI. The lowest rainfall years of the series were 2005, 2010 and 2016 also observed for soil moisture in 2005 and 2016; the most rainfall years were 2009 and 2014, with the highest values of flooded areas in January, 23,772 km2. The highest concentration of fire foci occurred in August and September, coinciding with the lowest NDFI values found (1421 km2 and 890 km2), with the years 2005 and 2010 with highest fire foci. The EVI showed higher values from October to December with values close to 0.57, the lowest values in June and July (0.50). The years 2009 and 2015 showed largest flooded area records, 2005 and 2010 the lowest records. The PCA pointed out the rain as the variable of greatest influence in the basin with 0.98, followed by hot flashes with − 0.90. NDFI was highly correlated with rainfall and ARIMA modeling allowed the generation of a reliable future scenario and a significant downward trend in flooded areas by 2030.

Land use changes cause changes in the hydrological cycle components and increase or decrease the amount of runoff and erosion in the watershed. Some land use changes become one of the most important problems in some watersheds all over the globe as the case in Ziarat watershed in Golestan province, Iran. Therefore, investigated the impacts of optimal scenario for development of residential areas on soil loss caused by surface runoff and raindrops using the TOPSIS method and WetSpa spatial hydrological distributed model in this study. ArcGIS-based TOPSIS multi-criteria decision making model was used to forman optimal scenario of residential development. WetSpa model inputs consist of digital maps including digital elevation model, land cover and soil texture (with 30 m cell size) and continuous time series of precipitation, evaporation and air temperature over hourly step for 6 years (2007–2013). The accuracy of flow simulations for the calibration period, depending on the Nash-Sutcliffe model efficiency was 67.02% and the suspended sediment concentration and sediment yield were 63.08% and 72.22%, respectively. According to the evaluation criteria considered in this study and using TOPSIS method, 37 hectares of the total watershed area is proper for residential development, but now the residential area of this watershed is more than 141.3 hectares. The amount of soil loss due to raindrops in the whole reference period was 381.54 kg/s and the amount of soil loss due to surface runoff was 227.715 kg/s. After applying the optimal residential development scenario in the WetSpa calibrated model, the amount of soil loss due to surface runoff and raindrops was compared in the two scenarios of current residential status and optimal residential development scenario. The results showed that the amount of soil loss due to surface runoff decreased significantly, but the soil loss caused by raindrops increased. Finally, as the amount of soil loss caused by surface runoff is significantly reduced compared to the soil loss caused by raindrops, the amount of total soil loss decreased.

The Cimanuk River with a total watershed area of 4010.8 km2 flowing from the Garut Regency to Indramayu Delta is the longest in West Java Province. However, the cumulative effects of climate change, increased population, and fish farming in the coastal area have continuously pressured the availability of water resources in its watershed. This study was, therefore, aimed to analyze the impact of land use and climate change on surface runoff and groundwater using a SWAT model. This is a physically based semi-distributed hydrological model with various applications, particularly to simulate water balance and watershed management. Daily discharge record for 2005–2008, land use data for 2002–2017, and the simulated climate (1979–2003) and projected climate data (2075–2099) retrieved from MRI-AGCM3.2 20-km by the Meteorological Research Institute of Japan Meteorological Agency were used in this research. The result showed that the calibration and validation of SWAT model have exhibited satisfactory criteria for hydrological simulations. The modeled period showed land use changes caused a general increase in runoff and decline in base flow contribution to annual streamflow. The changes between the current and projected climate exhibited increase in Qmax/Qmin ratio in certain years.

Erosion is a series of sedimentation processes associated with weathering, releasing, transporting, and settling grains of earth or earth's crust. As a watershed, watersheds are very vulnerable to erosion and sedimentation problems. This research was aimed to predict the erosion danger level at Rambut Watershed Area based on the Universal Soil Loss Equation Formula, by applying a Geographical Information System analysis. Based on the formula, we used four types of maps, i.e. rainfall, soil, slope, and land cover map. On each map, classification was done to get four to five classes based on a specific factor standard. To get the final result from the erosion danger levels which is categorized into five classes, they are very light, light, moderate, heavy, and very heavy, it is necessary to overlay the four types of maps. The results showed that the erosion danger levels at Rambut watershed area ranged from very light to very heavy, with the percentages of the affected areas are 46.91%; 35.13%; 12.47%; 3.67%; and 1.82% respectively. The very heavy and heavy danger areas covered 356.02 ha. And 717.99 ha. respectively. The results are used as a database to make a good planning watershed area management. Keywords: Erosion, GIS, overlay, USLE, watershed management, weathering

The West Branch of the Little River in Stowe, Lamoille County, Vermont has been widely studied, and this area is regularly subject to flooding. The West Branch joins the Little River, which flows into the Winooski and drains into Lake Champlain. This area has undergone extensive development as an economic response to the ski resort industry over the past 50 years, and the recreational pathway is on the banks of the river. The Little River is adjusting to the loss of historic floodplain area, channel modifications (straightening and gravel mining), and runoff changes. In this project, a DEM with 10 and 30 meters resolution will be used to determine the watershed area for the outlet point at the south of Stowe for hydrological analysis. This project intends to describe the watershed flow direction with a unit hydrograph that shows when water discharge at the outlet is at its height during a rainfall event and produce the floods prediction map by predicting the nature of flood events to help in planning and responding to flood events effectively using ArcGIS Pro 2.0. The results show the time it takes water to flow to the outlet ranges from 0 seconds (rain that falls on the outlet itself) to over 8 hours and 46 minutes. The amount of water has accumulated, indicating that water will flow at its fastest when funneling toward the outlet point downstream of the town with no exception, indicating that water will flow at its fastest when funneling toward the outlet point downstream of the town.

Land-use change and lack of conservation in Bogowonto Watershed area have caused land degradation due to erosion and landslides. The rate of land degradation can be measured through the morphological characteristics of the soil and landscape. This study aimed to identify the relationship between the morphological characteristics of the soil and the rate of land degradation in Bogowonto Watershed area. The research framework initiated from the interpretation of thematic maps, surveys and field observations, and verification using land degradation assessment software. Sample points were determined using a stratified random sampling method. In general, land degradation is affected by slope, limited soil development, suboptimal conservation measures, and land-use change. Particularly, land degradation is affected by the type of landscape and the morphological characteristics of the soil. Volcanic hilly landscapes show a degradation rate of fine to very fine, characterized by thick soil depth (>60 cm), generous root distribution, loamy textured soil, fine soil particle size (Ø

Understanding spatial variability of water table depth (WTD) in larger peatland area is crucial for peat conservation. This study investigated spatial patterns of WTDs in a peatland watershed of about 0.151 km2, located in the Zoige basin of the Qinghai-Tibet Plateau, China. Using conventional dipwells, we measured WTDs on 5/17/2017, 5/20/2017, 5/23/2017, 7/17/2017, and 9/18/2017 at 114, 103, 105, 77, and 81 locations, as well as peat depths (H) and elevations at 119 and 831 locations over the watershed, respectively. Then, we performed hotspot analysis and Geographically Weighted Regression (GWR) modeling, showing (1) highly localized spatial patterns of WTDs, H, and S (slope gradient, calculated from elevations), and (2) the area that had statistically significant local coefficients for H ranged between 51 and 57% of the total watershed area, while that for S was only less than 11%. These complex spatial patterns of WTDs were further illustrated by our results of examining WTD changes in the lateral and longitudinal directions for two types of channels, deep gullies whose beds are deep and cut through the peat layer and shallow artificial ditches. The findings suggested that spatial and temporal changes of WTDs at the watershed scale may only be examined by collecting in situ samples, which may be achieved using an efficient sampling method provided in this study.

This study aims to (1) Determine land cover in the Karajae watershed area. (2) Identifying the Location of Water Sources through Soil Analysis of Water Assessment Tools (SWAT). (3) Make a map describing the unit of land available and the location of the water source in the Karajae watershed. This research was conduct in the Karajae Watershed from July to September 2017. Primary data is obtained directly through the interpretation of satellite imagery to make land cover maps. Retrieval of data on land cover in the field doing by adjusting the classification of land cover in the field with the results of the interpretation of satellite imagery purposively base on accessibility. Secondary data is data covering the general condition of the research location obtained from the study of literature and other data related to research. The secondary data includes the DAS Boundary Map, River Network Map, DEM 30m Aster, 2016 Land Closure Map, Soil Type Map, Climate Data. This study used the SWAT model. The results obtained from this study are the 2016 Landsat Image Interpretation Results 2016 and the Karajae watershed field check results. There are 11 types of land cover which are dominated by dryland agriculture with a percentage of land area of 35.1% followed by shrubland cover with an area of 17.0% and bush mixed dryland agriculture with a percentage of the area of 12.5% and low-density dryland forest with a percentage of the area by 12.2%. Land cover has the smallest percentage of area, namely ponds by 0.2%. The results of SWAT analysis identification obtained 17 sub-watersheds as water sources that have high water availability, spread in three districts, namely Sidenreng Rappang, Barru District and Pare-Pare City. The results of the classification of water availability values in 17 sub-watersheds that have high water availability values, namely the western Bacukiki sub-watershed, located in the City of Pare-pare where the sub-watershed covers 4 villages namely new Bojo, Bumi Harapan, Lumpue, Wattang Bacukiki with the availability value water of 133,952,197.80 m3.

The saturated riparian buffer (SRB) is a new and cost-effective conservation practice that diverts agricultural tile drainage toward subsurface discharge within riparian buffers to achieve nitrate (NO3-N) removal. Conservation planners want to understand the potential role of the SRB practice for reducing NO3-N loads from tile-drained agricultural watersheds. The Agricultural Conservation Planning Framework (ACPF) includes a tool for identifying riparian zones where the SRB practice can be installed with minimal risks of unintended consequences (i.e., crop inundation and streambank failure). Watershed assessment of the potential role for SRBs, however, must identify where SRB-suited sites can actually receive drainage from tile-drained fields. This study compared the extent of SRB-suited riparian sites among 32 Iowa watersheds, and estimated the proportion of each watershed that was tile drained and located above SRB-suited riparian zones. Results showed the extent of sites suited for SRBs did not significantly differ among three Major Land Resource Areas (MLRAs) in Iowa, from which the selected watersheds were randomly chosen. Most watersheds had suitable sites along 30% to 70% of streambank lengths, where tile drainage from 15% to 40% of the watershed areas could be diverted, based on estimated extents of tile drainage above suitable sites. Therefore, the SRB has an important potential role for water quality improvement in many tile-drained watersheds in Iowa. However, the SRB practice is not readily designed for treating drainage from headwater catchments, which frequently comprised more than 30% of watershed areas in headwater streams of north central Iowa (MLRA 103), where tile drainage is extensive.

There is an increasing need to quickly and accurately identify areas where agricultural conservation practices can provide the greatest reduction in nutrient and sediment runoff. Geographic information systems (GIS)-based tools and indices are promising for identifying critical areas that are significant contributors of nonpoint source pollution loads with limited data. One such tool, the Soil Vulnerability Index (SVI), is tested here in Beasley Lake and Goodwin Creek watersheds in Mississippi. The SVI runoff component results are compared against aerial images and long-term land use histories in the watershed to determine if a higher SVI score is related to visibly degraded land or land removed from cultivation. SVI results are also compared to sediment yield estimates generated with the Annualized Agricultural Non-Point Source pollution model (AnnAGNPS) to determine the degree of agreement. The SVI runoff score demonstrated agreement with imagery and land use histories in both watersheds. The SVI categories and corresponding AnnAGNPS-predicted sediment yield also had moderate agreement, with 45% and 68% of watershed area in agreement in Beasley Lake and Goodwin Creek watersheds, respectively. In general, the tool is a quick way to assess spatial areas potentially contributing to nonpoint source pollution, which can then be combined with field-based knowledge and/or imagery to provide valuable insight for placement of conservation practices.

Effect of climatic and physiographic factors on surface runoff is critical to study for soil conservation and water harvesting. In this study, the spatial variations of climatic and physiographic factors and their spatial correlation with surface runoff was investigated. The rainfall and temperature records were used for mapping climatic factors. Digital Elevation Model (DEM) was utilized in estimation and mapping of physiographic factors as well as watershed delineation and runoff estimation. The models were generated using runoff and influencing factors (rainfall, temperature, slope and elevation). The relationship between runoff and influencing factors was derived by developing statistically sound regression models. The spatial correlation indicated that the maximum surface runoff was generated in the areas receiving high rainfall (>1450 mm) whereas, runoff tend to decrease with rise in temperature above a certain value (18 ˚C). The runoff also showed significant variability with slope and elevation changes. Maximum change in runoff was predicted by one unit change in temperature followed by elevation, slope and then rainfall. The regression model was found to be adequately fit to the predicted runoff by using influencing factors. The study identified potential water harvesting sites for sustainable water supply in Rawalpindi district.

Non-point source pollution of phosphorus (P) is a primary cause of eutrophication of aquatic ecosystems, and poses a persistent management challenge due to the dynamic and poorly understood processes controlling the transport and transformation of P at the watershed scale. We examined phosphorus inputs, retention, and riverine losses in 62 diverse watersheds that included a wide range of land cover and use (minimally disturbed to human dominated) and human P inputs in Minnesota, USA. Fertilizer inputs from row crop cultivation were the dominant source of P to agricultural watersheds. A large majority of P inputs was retained in watershed soils or removed in agricultural products. However, fertilizer input was the most important factor associated with average annual river transport of total, dissolved, and particulate phosphorus (PP). Mean annual runoff increased total and dissolved P yields and decreased P retention. Dissolved P made up a significant portion of annual river loads at sites with high rates of P inputs and river TP export, with the ratio of dissolved to PP export increasing with crop cover and fertilizer inputs. PP export rose with larger extents of eroding bluffs near channels. Bluffs constitute only a small proportion of watershed area, but make a disproportionately high contribution to sediment loads due to their close proximity to river channels that are increasingly affected by human and climate-driven changes to river hydrology. Together, our results suggest that rising discharge and flow variability due to climate change and agricultural intensification coupled with high rates of P inputs will maintain elevated fluvial P export into the future. Without reductions in P inputs and reductions in both soluble P losses and stream bank erosion, reversal of water quality degradation will be difficult to achieve.

Specific degradation (SD) is defined as the ratio of the sediment yield divided by the watershed area to compare sediment yield at the basin scale. The SD from 35 watersheds was calculated from field measurements of discharge and sediment concentrations. The watershed characteristics for each watershed were analyzed using GIS tools. All sediment gauging stations are located in alluvial river reaches and the estimated specific degradation typically ranges between 100 and 1,000 tons/km2·yr. Six regression models based on the watershed characteristics are proposed to estimate the mean annual sediment yield. The most useful relationship is function of the drainage area and mean annual precipitation. The proposed models were tested and validated with 15 additional river stations. The root mean square errors (RMSE) of the predictions are approximately 100 tons/km2·yr which is found to be satisfactory. The proposed models should be useful to estimate the sediment yield from ungauged watershed in South Korea.

The impact of human activities on sensitive watershed terrains is a critical consideration in the management of urban ecosystems. Degradation of sensitive ecosystem features such as watershed land areas is often irreversible due to the extent and intensity. The vulnerability of 150 m watershed management zone of Otamiri river Owerri Imo State, Nigeria was studied by topographic analysis using 1977 digital elevation model (DEM), 1977 aerial photos, Shuttle Radar Topographic Mission DEM of 2000, 2012 satellite imagery and the 2016 Master Plan of the study area. The impact of human activities in elevation change was observed in the parts of substantial human activities while topographical stability was recorded for areas of very low human activities.

The Fukushima Daiichi Nuclear Power Plant (FDNPP) accident released the most significant quantity of radiocesium into the environment since Chernobyl, and detailed measurements over the initial 5 years provide new insights into fluvial redistribution of radiocesium. We found that the high initial activity concentration of 137Cs-bearing suspended sediment in rivers was followed by a steep exponential decline (λ1) which extended to approximately 1 year after the accident, while the rate of initial decline in radiocesium activity concentration in water was an order of magnitude higher than rates measured after Chernobyl. Fluvial transport of 137Cs to the ocean from the Abukuma river totaled 12 TBq between June 2011 and August 2015 and almost all this radiocesium (96.5%) was transported in the particulate form. The primary sources of 137Cs were paddy fields, farmland, and urban areas [plaque-forming unit (PFU)], discharging 85% of the exported 137Cs from 38% of the watershed area. After 1 year, activity concentrations were lower and exhibited a more gradual secondary decline (λ2) which was associated with reduced radiocesium losses from PFU areas, while forest areas continue to represent more stable contaminant stores.

The increasing land use changes can alter the existence of vegetation cover on open land such as paddy fields and mooring into grass or shrubs, plantations, and tend to increase the proportion of land area built. Vegetative technology is often chosen because in addition to reduce erosion and sedimentation in rivers also have economic value (productive crops) and can restore the water system of a watershed. The researcherr used a model of soil vegetation engineering to maintain water distribution in Krueng Pase watershed in North Aceh District. To achieve these objectives, a model of grass vegetation was adopted as a water and land conservation strategy in the Krueng Pase Basin of North Aceh Regency. The model of grass vegetation can withstand runoff and increase infiltration. The average of plant retention to hold rain water in this research is for land (without vegetation) 33%, grass and herbs 77%, and shrub 81%. Meanwhile, to know the water denit used non-linear regression equation. The results show that vegetation grasses and other soil cover crops can withstand erosion and sediment. The relationship between water discharge and sediment was obtained by coefficient of determination (R2 = 0.98). This shows the water debit due to precipitation affecting the sedimentation volume.

The quality of water has deteriorated due to urbanization and the occurrence of urban stormwater runoff. To solve this problem, this study investigated the pollutant reduction effects from the geometric and hydrological factors of green infrastructures (GIs) to more accurately design GI models, and evaluated the factors that are required for such a design. Among several GIs, detention basins and retention ponds were evaluated. This study chose the inflow, outflow, total suspended solids (TSS), total phosphorus (TP), watershed area, GI area (bottom area in detention basins and permanent pool surface area in retention ponds), and GI volume (in both detention basins and retention ponds) for analysis and applied both ordinary least squares (OLS) regression and multiple linear regression (MLR). The geometric factors do not vary within each GI, but there may be a bias due to the number of stormwater events. To solve this problem, three methods that involved randomly extracting data with a certain range and excluding outliers were applied to the models. The accuracies of these OLS and MLR models were analyzed through the percentage bias (PBIAS), Nash-Sutcliffe efficiency (NSE), and RMSE-observations standard deviation ratio (RSR). The results of this study suggest that models which consider the influent concentration combined with the hydrological and GI geometric parameters have better correlations than models that consider only a single parameter.

In this study, SWAT hydrological model was used to differentiate the effects of drought and changes in land use on hydrological balance of the system in Eskandari Watershed area. To this end, The SWAT model was implemented separately using other user maps to investigate the impact of land use changes on the hydrological cycle of the watershed. Additionally, Van Loon model was used to investigate the effects of drought and water scarcity on discharge. The results showed that the watershed area could meet its environmental needs due to an 11% decrease in rainfall and droughts in 2008 and 2009. Additionally, the average monthly simulated flows were 2.4 m3/s and 2.9 m3/s in the natural and turbulent periods, respectively, indicating a decrease of nearly 18%, which is related to the 11% decrease in rainfall in this Watershed. Furthermore, the average observational flow in the turbulent period was 4 mm, which showed a growth of nearly 13% in comparison to the observational flow in the turbulent period. Decreased rainfall and increased discharge in this period indicated the effect of land use change and human activities on the catchment.

The Moroccan High Atlas is very sensitive to soil erosion due to its steep slopes, torrential rains, and degraded plant cover. The degradation of fertile soils in this mountainous watershed influences negatively upon agricultural productivity. The objective of this study is to quantify soil erosion in the Tifnout Askaoun watershed in southern Morocco. The Revised Universal Soil Loss Equation (RUSLE), the geographic information system (GIS) techniques, and the Tropical Rainfall Measuring Mission (TRMM) data were adopted for mapping the annual rate of soil loss in this watershed area of around 1488 km2. The spatial distribution of annual soil erosion rates was obtained by integrating the geo-environmental variables into a GIS. These variables are the rainfall erosivity (R) generated from the TRMM data, the soil erodibility factor (K), the length and slope inclination (LS), the vegetation and management factor (C), and the practice support factor (P). Results reveal an average annual soil erosion rate of 14.44 t/ha/year and a good correlation with the slope length and steepness factor (r = 0.72) and in a lesser extent with the rainfall erosivity factor (r = 0.63). The sub-catchments of the study area were mapped and grouped into five classes of vulnerability to soil erosion risk, with results indicating that the Toubkal sub-catchment is the most threatened by water erosion risk as reflected by an average erosion rate of 48.05 t/ha/year. Approaches and results from this study, which was conducted between 2017 and 2019, may benefit researchers and decision-makers concerned with soil management primarily in mountainous areas where soil degradation impacts the activities of the rural population.

Soil erosion is the most challenging and continuous environmental problems resulting in both on-site and off-site effects in the world particularly in Ethiopia. Karesa watershed is one of the most erosion-prone watersheds which received little soil conservation attention. This study was conducted to estimate average annual soil loss rate using Geographic Information System and Universal Soil Loss Equation Model adapted to Ethiopian condition. The following datasets were obtained from different sources for estimating annual soil loss such as 15 years mean annual rainfall data for estimating erosivity factor, digital soil map for estimating soil erodibility factor, 30 m × 30 m resolution Digital Elevation Model for estimating slope length and slope steepness (LS) factor, Landsat6ETM+ images with 30 m × 30 m resolution for detecting vegetation cover and conservation practice factor. The result reveals that 42,413.72 ton per year soil loss from 9939 ha entire watershed or 4.27 tons per hectare per year average annual soil loss rate was observed. The mean annual soil loss rate was classified into four erosion severity classes as very less, less, moderate and high. The result also implies that 94.4% (9383.07 ha) of the watershed areas contributes 81.13% of the total soil loss which were observed from two slope classes (0-15% and 15-30%) and categorized under very less to less soil loss (0-6.25 tons ha-1yr-1). On the other hand, moderate to high soil loss (6.25-25 tons ha-1yr-1) was obtained on slope classes of >30% which covers 555.93 ha (5.6%) of the watershed areas and contributes 18.82% of the total soil loss indicating the maximum share of slope mainly due to cultivation of marginal land,intensive cultivation, poor vegetation cover during critical rainfall period. Moreover, about 2,184.93 ha of the watershed area requires integrated soil and water conservation measures. Key words: Conservation priority, soil erosion, Universal Soil Loss Equation Model (USLE), geographic information system (GIS), Karesa watershed

Water reservoirs in most parts of the world face the problem of sedimentation. Environmental impacts and land-use changes/landslide have enormous potential to generate more sediment load in water reservoirs. Hence, the capacity of water reservoirs in Pakistan has been constantly reducing due to sedimentation. In this study, we have computed the environmental impacts on sedimentation load in Tarbela and Mangla water reservoirs using multi-satellite and ground-based data. The total drainage area of watershed is calculated using Shuttle Radar Topographic Mission data. Satellite data from NOAA-AVHRR are used to monitor urban development and changes in vegetation area, while MODIS data are used to estimate the snow area in the watershed region. Normalized Difference Vegetation Index is used to estimate the temporal changes in vegetation cover, whilst principle component analysis is applied to monitor urban changes in watershed region. Similarly, snow cover area in the study region is estimated using Normalized Difference Snow Index algorithm. Rainfall data obtained from Pakistan Meteorological Department are used to evaluate the relationship between sedimentation deposited in water reservoirs and annual rainfall amount. Results of the current study reveal that increase in urban development and high amount of precipitation has direct relationship with the load of sedimentation, while amount of vegetation has inverse relationship with the load of sedimentation in water reservoirs of the country.

Watershed management can be started by evaluation how the response of watershed hydraulic toward rainfall and become run off that will flow downstream. Transformation of rain into flow is a method used to find out effect of land use change and its parameter toward flow hydrograph. Watershed Kr. Pase is one of most rapid reduction of forest area. Land use change occurred in this watershed affecting discharge amount of run off which required further calculation. This calculation using the rational method by calculating rainfall intensity parameter (I),watershed area (A), and flow coefficient (C) in watershed. Data of land use provide in this study are on year 2007, 2013, and 2017 which will examine watershed Kr. Pase into subwatershed model, whereas from map analysis obtained three subwatersheds. After some calculation off run off discharge at watershed Kr. Pase, than it is use sub-watershed with longest concertration time (tc).

A new phenomenon has been investigated - an increase in the winter and early spring streamflow of northern rivers. Assuming that the increased discharge may be due to permafrost degradation in river basins, the thaw rate was estimated by modeling. A mathematical model that takes into account the typification of the four permafrost categories, reflecting the dependence of the runoff on the cryological conditions of the watershed areas, showed a rapid degradation of sporadic permafrost and expansion of discontinuous permafrost at the account of continuous one.

Soil-water storage (SWS) highly correlates with changes to land use and land restoration, and is an important variable for managing water resources and environmental restoration in water-limited terrestrial ecosystems. The Gully Land Consolidation project (GLC) was implemented in 2011 on the Chinese Loess Plateau and it may influence the spatial distribution and temporal variability of SWS at the watershed scale. However, there have been limited studies assessing the magnitude and pattern of such changes. We measured SWS to a depth of 5 m nine times over four seasons across two watersheds－one treated by the GLC project (GT-T, n = 89) and the other untreated (GT-U, n = 72). We then used correlation analysis, principle component analysis, multiple linear regression analysis, generalized linear model, and regression kriging to evaluate the seasonal variability, as well as spatial patterns, of SWS. Mean SWS in the spring, summer, autumn, and winter ranged from 830 to 934 mm in the GT-T watershed and from 681 to 771 mm in the GT-U watershed. Land use was the most important factor for predicting SWS in the two watersheds. After land management as a result of the GLC project, SWS exhibited different spatial patterns in the GT-T watershed compared with the GT-U watershed. Dynamics of SWS between adjacent seasons in the GT-U watershed displayed more variability than that in the GT-T watershed. In both watersheds, soil water volume (SWV, i.e., SWS per unit area × watershed area) declined from spring to summer (-3.9% in the GT-T and -13.4% in the GT-U), and increased from summer to autumn (11.7% in the GT-T and 20.7% in the GT-U). After the whole year, SWV displayed different degrees of increase in the two watersheds (10.6% in the GT-T, 2.7% in the GT-U) due to the effect of land restoration. The ratios of SWV in the gully land filled in the GT-T watershed to the SWV of the whole GT-T watershed for the four seasons ranged from 21.4–23.3%, with a mean value of 22%. Our results provide new insights regarding how human engineering of landscapes (as exemplified by GLC project) affect the spatial distribution of SWS and the dynamics of SWV storing capacity at the watershed scale. Understanding the dynamics of SWS/SWV between seasons is essential to evaluate, model and manage the soil water resources in human-affected watersheds.

The present research work accentuates the hydrogeological evaluation for Devdari watershed of Maharashtra, Central India, using remote sensing, GIS, and multi influencing factor (MIF). The thematic layers of land use/land cover, groundwater depth, slope, drainage, flow direction, flow accumulation and geomorphology were prepared using IRS-LISS-III satellite data coupled with Shuttle Radar Topography Mission data on 23.50 and 30 m spatial resolution, respectively. The raster layers of these themes were estimated by employing ArcGIS software 10.3 and multi-influencing factor method and subsequently assigned with the relative weights as per their groundwater potential characteristics. For acknowledgement of the groundwater potential map, all the thematic layers and their respective weightage values were subjected to weighted overlay analysis (WOA) method. The evolved map demonstrates six groundwater potential zones in the study area, i.e., poor to nil (0.27 km2), very poor (0.95 km2), poor (17.67 km2), moderate (0.33 km2), good (9.51 km2), very good (14.665 km2) and excellent (1.84 km2). A field check survey was carried out to ascertain the validity of groundwater potential maps. The results of study area disclose that the area of watershed with poor, moderate and good-to-excellent groundwater potential zones is evaluated to allow precipitated water to infiltrate into subsurface and finally contribute to groundwater recharge in the watershed area.

The relationship between peak specific discharge and watershed area is examined for large, rare and extreme floods in Malaysia using a distributed hydrological model. Envelope curves for specific discharge for these events and the uncertainty is quantified. The relationships between rainfall duration and intensity as a function of watershed size were also examined. As a result, three main regions were defined to estimate the peak discharge as a function of watershed size for large, extreme and rare floods. The average magnitudes for the PMP and the world’s extreme rainfall events were 5 and 12 times larger than the 100-year event, respectively. The envelope curves may assist engineers and other interested parties to estimate the peak discharge for watershed up to 100,000 km2, especially for ungauged watersheds.