GIS based groundwater modeling study to assess the effect of artificial recharge: A case study from Kodaganar river basin,Dindigul district,Tamil Nadu

Groundwater is a dynamic and replenishable natural resource. The numerical modeling techniques serve as a tool to assess the effect of artificial recharge from the water conservation structures and its response with the aquifers under different recharge conditions. The objective of the present study is to identify the suitable sites for artificial recharge structures to augment groundwater resources and assess its performance through the integrated approach of Geographic Information System (GIS) and numerical groundwater modeling techniques using MODFLOW software for the watershed located in the Kodaganar river basin, Dindigul district, Tamil Nadu. Thematic layers such as geology, geomorphology, soil, runoff, land use and slope were integrated to prepare the groundwater prospect and recharge site map. These potential zones were categorized as good (23%), moderate (54%), and poor (23%) zones with respect to the assigned weightage of different thematic layers. The major artificial recharge structures like percolation ponds and check dams were recommended based on the drainage morphology in the watershed. Finally, a threelayer groundwater flow model was developed. The model was calibrated in two stages, which involved steady and transient state condition. The transient calibration was carried out for the time period from January 1989 to December 2008. The groundwater model was validated after model calibration. The prediction scenario was carried out after the transient calibration for the time period of year up to 2013. The results show that there is 15 to 38% increase in groundwater quantity due to artificial recharge. The present study is useful to assess the effect of artificial recharge from the proposed artificial structures by integrating GIS and groundwater model together to arrive at reasonable results.     

Mapping of hard rock aquifer system and artificial recharge zonation through remote sensing and GIS approach in parts of Perambalur District of Tamil Nadu,India

Mapping of hard rock aquifer system and artificial recharge zonation were carried out in an area of 325 km^2 in parts of the Perambalur District,Tamil Nadu,India.This district has been declared as one of the over-exploited regions in Tamil Nadu by the Central Groundwater Board.To raise the groundwater level,suitable recharge zones were identified and artificial recharge structures are suggested using geomatics technology in the present study.To this end,various thematic maps concerning lithology,soil,geomorphology,land use,land cover,slope,lineament,lineament density,drainage,drainage density and groundwater depth level were prepared.Fissile hornblende gneiss(244 km^2)covered most of the study area followed by charnockites(68 km^2).Structural hills and rocky pediments characterize the major geomorphological features in the targeted area,and are followed by deep moderated pediments.The area is mostly used as crop and fallow land,followed by scrub land and deciduous forest.In the study area,the slopes are predominantly very gentle(142 km^2)and nearly level(66 km^2)ones.Besides,Groundwater level data of 58 wells have been generated,in which the minimum and maximum depth were 3 and 28 m respectively.Integration under the GIS environment has been carried out using all the thematic layers to identify the groundwater prospect zone through the introduction of weight and rank methods.Integrated output performances were classified into very poor,poor,moderate,good and excellent categories.All these classes were further divided into two groups as suitable and non-suitable area for the selection of recharge sites.Hard rock fractures were mapped as lineaments from satellite images,and besides that,rose diagram was also generated to find out the trend of the fracture.Furthermore,fracture data of 146 numbers have been collected using Brunton compass to generate rose diagram and were correlated with the rose diagram derived from lineaments.The present study significantly brought up a few areas such as Ammapalayam,Melapuliyur,Senjeri and around Siruvachur for artificial recharge.     

Mapping of hard rock aquifer system and artificial recharge zonation through remote sensing and GIS approach in parts of Perambalur District of Tamil Nadu,India

Mapping of hard rock aquifer system and artificial recharge zonation were carried out in an area of 325 km2 in parts of the Perambalur District, Tamil Nadu, India. This district has been declared as one of the over-exploited regions in Tamil Nadu by the Central Groundwater Board. To raise the groundwater level, suitable recharge zones were identified and artificial recharge structures are suggested using geomatics technology in the present study. To this end, various thematic maps concerning lithology, soil, geomorphology, land use, land cover, slope, lineament, lineament density, drainage, drainage density and groundwater depth level were prepared. Fissile hornblende gneiss (244 km2) covered most of the study area followed by charnockites (68 km2). Structural hills and rocky pediments characterize the major geomorphological features in the targeted area, and are followed by deep moderated pediments. The area is mostly used as crop and fallow land, followed by scrub land and deciduous forest. In the study area, the slopes are predominantly very gentle (142 km2) and nearly level (66 km2) ones. Besides, Groundwater level data of 58 wells have been generated, in which the minimum and maximum depth were 3 and 28 m respectively. Integration under the GIS environment has been carried out using all the thematic layers to identify the groundwater prospect zone through the introduction of weight and rank methods. Integrated output performances were classified into very poor, poor, moderate, good and excellent categories. All these classes were further divided into two groups as suitable and non-suitable area for the selection of recharge sites. Hard rock fractures were mapped as lineaments from satellite images, and besides that, rose diagram was also generated to find out the trend of the fracture. Furthermore, fracture data of 146 numbers have been collected using Brunton compass to generate rose diagram and were correlated with the rose diagram derived from lineaments. The present study significantly brought up a few areas such as Ammapalayam, Melapuliyur, Senjeri and around Siruvachur for artificial recharge.     

Assessment of surface water potential and groundwater recharge in ungauged watersheds: a case study in Tamil Nadu,India

Many of the states in India have been facing water scarcity for more than 2 decades due to increased demand, because of the increase in population and higher living standards. Consequently, many states have almost fully utilized the available surface water resources and are exploiting groundwater to augment water supplies. Investigations were carried out in the upper Thurinjalar watershed of Ponnaiyar basin in Tamil Nadu to determine the availability of surface water and to investigate the potential for enhancing groundwater recharge to support the water demand in the watershed. Increasing the water availability would also enable the community to convert the 46% of the land area in the watershed that is currently underutilised into productive uses. The surface water potential for the upper Thurinjalar watershed was assessed by applying the USDA–NRCS model with daily time steps. This modelling exercise indicated that the annual runoff from the 323 km² area of the watershed is 61 million m³. Groundwater recharge in the watershed was assessed by carrying out daily water balance method and indicated that about 43 million m³ of water from recharge is available on an annual basis or about 14% of annual rainfall. A simple regression model was developed to compute groundwater recharge from rainfall based on water balance computations and this was statistically verified. The modelling indicated that there is sufficient water available in the watershed to support current land uses and to increase the productivity of underutilised land in the area. The study also demonstrates that simple regression models can be used as an effective tool to compute groundwater recharge for ungauged basins with proper calibration.     

Identification of potential groundwater recharge zones in Vaigai upper basin,Tamil Nadu,using GIS-based analytical hierarchical process (AHP) technique

Groundwater recharge is an important process for the management of both surface and subsurface water resources. The present study utilizes the application of analytical hierarchical process (AHP) on geospatial analysis for the exploration of potential zones for artificial groundwater recharge along Vaigai upper basin in the Theni district, Tamil Nadu, India. The morphology of earth surface features such as geology, geomorphology, soil types, land use and land cover, drainage, lineament, and aquifers influence the groundwater recharge in either direct or indirect way. These thematic layers are extracted from Landsat ETM+ image, topographical map, and other collateral data sources. In this study, the multilayers were weighed accordingly to the magnitude of groundwater recharge potential. The AHP technique is a pair-wise matrix analytical method was used to calculate the geometric mean and normalized weight of individual parameters. Further, the normalized weighted layers are mathematically overlaid for preparation of groundwater recharge potential zone map. The results revealed that 21.8 km² of the total area are identified as high potential for groundwater recharge. The gentle slope areas in middle-east and central part have been moderately potential for groundwater recharge. Hilly terrains in south are considered as unsuitable zone for groundwater recharge processes.     

Artificial groundwater recharge to a semi-arid basin: case study of Mujib aquifer,Jordan

Mujib watershed is an important groundwater basin which is considered a major source for drinking and irrigation water in Jordan. Increased dependence on groundwater needs improved aquifer management with respect to understanding deeply recharge and discharge issues, planning rates withdrawal, and facing water quality problems arising from industrial and agricultural contamination. The efficient management of this source depends on reliable estimates of the recharge to groundwater and is needed in order to protect Mujib basin from depletion. Artificial groundwater recharge was investigated in this study as one of the important options to face water scarcity and to improve groundwater storage in the aquifer. A groundwater model based on the MODFLOW program, calibrated under both steady- and unsteady-state conditions, was used to investigate different groundwater management scenarios that aim at protecting the Mujib basin. The scenarios include variations of abstraction levels combined with different artificial groundwater recharge quantities. The possibilities of artificial groundwater recharge from existing and proposed dams as well as reclaimed municipal wastewater were investigated. Artificial recharge options considered in this study are mainly through injecting water directly to the aquifer and through infiltration from reservoir. Three scenarios were performed to predict the aquifer system response under different artificial recharge options (low, moderate, and high) which then compared with no action (recharge) scenario. The best scenario that provides a good recovery for the groundwater table and that can be feasible is founded to be by reducing current abstraction rates by 20% and implementing the moderate artificial recharge rates of 26 million(M)m³/year. The model constructed in this study helps decision makers and planners in selecting optimum management schemes suitable for such arid and semi-arid regions.     

Hydrogeological component assessment for water resources management of semi-arid region: a case study of Gwalior,M.P., India

Groundwater management is of fundamental importance to meet the rapidly expanding urban, industrial and agricultural water requirements in semi-arid areas. To assess the current rate of groundwater withdrawal and possibility of recharge of potential aquifer in the semi-arid regions is essential for water management. The present study aimed to identify potential area for groundwater recharge structure in the Gwalior area based on land use, rainfall variation, hydrological component and statistical analysis. In this work, a stream survival approach was used for the assessment of water channel by using triangulated network and regression analysis to find out the correlation of individual component with reference to water management. Land use/land cover (LULC) map prepared from multispectral satellite images of the study area and used to validate the hydrological component and the results observed through the regression model shows good correlation. Therefore, immediate and effective water management schemes are required for sustainable water resource development and management in the area.     

泸西喀斯特断陷盆地地表水与地下水流域边界与水动力性质

在详细调查基础上,采用系统科学及水文地质分析方法,依据地形地貌、地层岩性、地质构造、示踪试验、地下水排泄基准面、喀斯特发育条件及发育规律等剖析论证流域边界,并通过钻探及示踪试验进行验证。研究结果:（1）对泸西喀斯特断陷盆地南东部的水系统边界向北移进行了修正,证实了三塘一带深部不发育的喀斯特是地下水分水岭边界,使得泸西喀斯特断陷盆地流域的径流系统和边界圈化更加准确;（2）泸西喀斯特断陷盆地流域地表水、地下水转化频繁,地表水径流特征主要以小江河在水库、河流、伏流间的径流转化过程为体现,地下水在侵溶山区接受大气降水补给后,上层径流以泉、暗河的形式在泸西盆地底面排泄后转化成地表水,最终汇集于盆地南部、通过工农隧洞及落水洞排向小江,而下层径流则以小江水面为基准,通过深层径流排泄。      

Identifying potential sites for artificial groundwater recharge in sub-watershed of River Kanhan,India

Groundwater is an important decentralized source of drinking water. Being underground, it is relatively less susceptible to contamination. In addition to domestic needs, it is extensively used for irrigation and industrial purposes. It is therefore necessary to implement groundwater recharge systems by capturing the rainwater runoff. In the present study, GIS-based hydrological assessment of watershed has been used to identify the potential sites for locating the groundwater recharge structures. Based on land use, soil and topography, rainfall runoff modelling was carried out in GIS for a sub-watershed of River Kanhan, in Nagpur District, Maharashtra State, India. Five potential sites with maximum flow accumulation were delineated using the rational method for peak runoff estimation. As the groundwater recharge potential also depends on the geological and geomorphological characteristics of land, analytic hierarchy process (AHP) with expert’s judgement was used for ranking the sites. The criteria considered in AHP were geological features, i.e. lineament density, depth to bedrock and soil cover; geomorphological features, i.e. drainage density, slope, landforms and land use/land cover; and water table level fluctuation. The site P5 with maximum flow accumulation and sandstone rock formation was ranked first. The site P1, where catchment has well-developed drainage and geological formation shows rock with secondary porosity, was ranked second.     

Groundwater sustainability indicators in parts of Tiruppur and Coimbatore districts,Tamil Nadu

The present study emphasizes the use of groundwater sustainability indicators, developed to assess the sustainability of the aquifer in Uppar Odai sub-basin located in part of Tiruppur and Coimbatore districts, Tamil Nadu. There are seven indicators discussed based on their relevance in groundwater sustainability. In most parts of the subbasin, groundwater development already exceeds 80% of the groundwater recharge. The results have shown that the sub-basin area has been contaminated with low hazard pollutant such as nitrate and fluoride. In addition, about 28% and 32% of the sub-basin area respectively is not suitable for irrigation. The analysis of water level data for the last 42 years has shown decline in water table. However, the water level condition has improved in the recent years due to water conservation measures. The basin requires necessary groundwater planning and management to maintain sustainable aquifer condition.     

Assessment of artificial aquifer recharge potential in the Kucuk Menderes River Basin, Turkey

The Kucuk Menderes River Basin in western Turkey has been facing continuous groundwater-level decline for decades. Previous studies have suggested that, to avoid aquifer depletion in the basin, artificial recharge structures should be constructed. To assess artificial aquifer recharge potential in one of the subbasins, a two-dimensional (2-D) groundwater model was set up using SEEP/W software. The material functions and parameters used in the model for both saturated and unsaturated conditions were taken from previous studies. The model has been calibrated under transient conditions. The excess runoff volume that could be collected in the recharge basins was estimated from flood frequency analysis. Various scenarios were simulated to observe the change in groundwater level and storage with respect to different exceedance probabilities. Simulation results suggest that a significant increase in groundwater storage is achieved by applying surface artificial-recharge methods. In addition to the recharge basins, to reinforce the effect of artificial recharge, simulations are repeated with underground dam construction at the downstream side of the basin. Although groundwater storage is increased with the addition of the dam, the increase in groundwater storage was not sufficient to warrant the construction.     

Spatial and temporal variation in the trends of hydrological response of forested watersheds in Thailand

Thailand has undergone significant forest cover changes in recent decades, and this is likely to have altered the hydrological functioning of many watersheds; however, such potential impacts are not fully understood. To contribute towards a better understanding of the potential hydrological impacts of forest cover changes, this study examines the temporal trends of several hydrological indices in eight watersheds of Thailand over the period from 1982 to 2013. A number of hydrological indices (runoff coefficient, baseflow index, flow duration indices, streamflow elasticity, dryness index) were analysed using a combined Thiel–Sen/Mann–Kendall trend-testing approach, to assess the magnitude and significance of patterns in the observed data. These trend tests indicated that the change in the hydrological response of watersheds varied with the change in structure and composition of forest species. A significant increase in runoff (viz. average flow) was observed in those watersheds covered with natural forests, whereas a significant reduction in runoff (viz. baseflow and low runoff) was observed in those watersheds where the land cover was changed to Para rubber plantations and reforested areas. It is also noteworthy that the watersheds covered by natural forest showed more streamflow elasticity than plantations or reforested areas. These results highlight the importance of considering both forest types/dynamics and watershed characteristics when assessing hydrological impacts.     

Groundwater recharge study based on hydrological data and hydrological modelling in a South American volcanic aquifer

In humid subtropical regions, baseflow is mainly governed by aquifer discharges and this dynamic is fed by groundwater recharge. To better comprehend the watershed groundwater recharge using a large-scale approach, two watersheds located over the Serra Geral Aquifer System (Southern South America) were studied. Three different groundwater recharge methods were utilized to study the baseflow: a simplified water budget, a hydrograph separation using the Eckhardt filter with different ways of obtaining the BFI_max parameter, and the MGB–IPH hydrological model, which is unprecedented in being used for this purpose. These methods showed a general mutual convergence, where recharge magnitude remained similar in most methods. The MGB–IPH model proved to be a useful tool for understanding the occurrence of groundwater recharge. Uncertainties associated with the representativity of interflow demonstrated by hydrograph separation and shown in the model may indicate that the groundwater recharge estimate could be lower than those obtained considering hydrograph numerical filters.     

基于遥感技术估算藏东南山区地下水径流模数方法

如何科学评估野外场地条件下的地下水径流模数对于满足工程水文地质需求具有重要应用价值.结合现场调查、遥感解译和气象水文观测等技术手段,通过建立线性回归模型,开展了帕隆藏布流域场地条件下的地下水径流模数估算研究.结果表明:研究区具有典型的季节性积雪融雪规律.冬季积雪在夏季大量融化产流,作为地下水的一个额外补给源.去除融雪产流对径流模数影响后,研究区岩浆岩裂隙型、变质岩裂隙型、碎屑岩裂隙型、碳酸盐岩-碎屑岩裂隙溶隙型含水介质地下水径流模数分别在1.081~2.792 L/s·km2、1.833~3.225 L/s·km2、1.128~2.889 L/s·km2、3.455~3.879 L/s·km2之间.估算结果显示本文所建立的地下水径流估算模型可作为藏东南地区及类似条件区域地下水径流模数估算新方法,为雅鲁藏布江下游梯级开发等大型基础工程提供重要的水文地质参数支撑.      

Percolation pond as a method of managed aquifer recharge in a coastal saline aquifer: A case study on the criteria for site selection and its impacts

Percolation ponds have become very popular methods of managed aquifer recharge due to their low cost, ease of construction and the participation and assistance of community. The objective of this study is to assess the feasibility of a percolation pond in a saline aquifer, north of Chennai, Tamil Nadu, India, to improve the storage and quality of groundwater. Electrical resistivity and ground penetrating radar methods were used to understand the subsurface conditions of the area. From these investigations, a suitable location was chosen and a percolation pond was constructed. The quality and quantity of groundwater of the nearby area has improved due to the recharge from the pond. This study indicated that a simple excavation without providing support for the slope and paving of the bunds helped to improve the groundwater quality. This method can be easily adoptable by farmers who can have a small pond within their farm to collect and store the rainwater. The cost of water recharged from this pond works out to be about 0.225 Re/l. Cleaning the pond by scrapping the accumulated sediments needs to be done once a year. Due to the small dimension and high saline groundwater, considerable improvement in quality at greater depths could not be achieved. However, ponds of larger size with recharge shafts can directly recharge the aquifer and help to improve the quality of water at greater depths.     

广西平南某矿区岩溶地下水连通试验研究

广西平南某矿区在人工疏水过程中地下水位持续下降,形成以采区为降落漏斗、周边地下水向采区径流排泄的地下水流场。位于矿区东侧的秦川河成为危及矿区施工安全的最大隐患。为了查明矿区岩溶地下水径流途径、径流特征,进而了解矿区采矿排水的主要来源及周边地表河的影响,在矿区周围进行了地下水连通试验。试验结果表明:矿区岩溶含水介质渗透性差异较大,含水层各向异性明显;矿区北部、东南部存在连通性较好的地下水径流带,北部流速为0.3 ~ 20 m/h,东南部流速为3.72 ~ 98 m/h;矿区南部、西南部与周边地下水连通性较差,与矿区以南的浔江存在地下分水岭;矿区东部一采区矿坑排水主要来自东侧秦川河渗漏补给及北部地下水侧向径流补给,矿区西部二采区矿坑排水补给来源为北部地下水侧向径流及大气降水。因此,采矿疏水过程中应及时掌握秦川河水位变化情况,采取帷幕等有效手段对水害进行治理,以确保生产安全。      

Drainage morphometry of upper Vaigai river sub-basin, Western Ghats, South India using remote sensing and GIS

The study area is a one of the sub-basin of Vaigai River basin in the Theni and Madurai districts, Western Ghats of Tamil Nadu. The Vaigai sub-basin extends approximately over 849 km² and it has been sub-divided into 48 watersheds. It lies between 09°30′00″ and 10°00′00″N latitudes and 77°15′10″ and 77°45′00″ E longitudes in the western part of Tamil Nadu, India. It originates at an altitude of 1661m in the Western Ghats of Tamil Nadu in Theni district. The drainage pattern of these watersheds are delineated using geo-coded Indian remote sensing satellite (IRS) ID, linear image self-scanning (LISS) III of geo-coded false colour composites (FCC), generated from the bands 2, 3 and 4 on 1:50,000 scale in the present study. The Survey of India (SOI) toposheets 58G/5, 58 G/6, 58G/9 and 58G/10 on a scale of 1:50,000 scale was used as a base for the delineation of watershed. In the present study, the satellite remote sensing data has been used for updation of drainages and the updated drainages have been used for morphometric analysis. The morphometric parameters were divided in three categories: basic parameters, derived parameters and shape parameters. The data in the first category includes area, perimeter, basin length, stream order, stream length, maximum and minimum heights and slope. Those of the second category are bifurcation ratio, stream length ratio, RHO coefficient, stream frequency, drainage density, and drainage texture, constant of channel maintenance, basin relief and relief ratio. The shape parameters are elongation ratio, circularity index and form factor. The morphometric parameters are computed using ESRI’s ArcGIS package. Drainage density ranges from 1.10 to 4.88 km/km² suggesting very coarse to fine drainage texture. Drainage frequency varies from 1.45 to 14.70 which is low to very high. The bifurcation ratio ranges from 0.55 to 4.37. The low values of bifurcation ratios and very low values of drainage densities indicate that the drainage has not been affected by structural disturbances and also that the area is covered under dense vegetation cover. Elongation ratio ranges from 0.11 to 0.57. Drainage texture has the minimum of 1.63 and maximum of 11.44 suggesting that the drainage texture is coarse to fine. It is concluded that remote sensing and GIS have been proved to be efficient tools in drainage delineation and updation. In the present study these updated drainages have been used for the morphometric analysis.     

Integrated multi-parameter approach for delineating groundwater potential zones in a crystalline aquifer of southern India

Groundwater resources in the semi-arid regions of southern India are under immense pressure due to large-scale groundwater abstraction vis-à-vis meager rainfall recharge. Therefore, understanding and evaluating the spatial distribution of groundwater is essential for viable utilization of the resource. Here, we assess groundwater potential at the watershed scale, in a semi-arid environment with crystalline aquifer system without a perennial surface water source using remote sensing, geophysical, and GIS-based integrated multi-parameter approach. GIS-based weighed overlay analysis is performed with input parameters, viz., geology, geomorphology, lineament density, land use, soil, drainage density, slope, and aquifer thickness. The watershed is categorized into four zones, namely, “very good” (GWP4), “good” (GWP3), “moderate” (GWP2), and “low” (GWP1) in terms of groundwater potential. Overall, ~?70% of the study area falls under moderate to low groundwater potential, indicating a serious threat to the future availability of the resource. Therefore, serious measures are required for maintaining aquifer resilience in this over-exploited aquifer (e.g., restricting groundwater withdrawal from GWP1 and GWP2 zones). Further, as the aquifer is under tremendous anthropogenic pressure, rainwater harvesting and artificial recharge during monsoon are advocated for sustainable aquifer management. Due to the direct dependence of crop production vis-à-vis farmer economy on groundwater, this study is an important step towards sustainable groundwater management and can be applied in diverse hydrological terrains.     

南方小型岩溶流域与非岩溶流域的释水过程及径流组分差异

我国南方岩溶流域和非岩溶流域下垫面条件和含水介质结构的差异造成了不同的产汇流过程及机制,进而导致不同释水时段径流组分的开发利用价值不同。为深入理解岩溶流域的产汇流机制并探索岩溶流域的水资源评价方法,文章对鄂西庙沟岩溶流域和高家坪非岩溶流域共31次洪水过程进行了流量衰减分析,对比分析了两个流域的标准衰减方程、典型次降雨的释水过程以及不同洪峰流量下的径流组分差异。结果表明:岩溶流域的释水过程快于非岩溶流域,其衰减系数比非岩溶流域大40％;两个流域的河流基流均来自裂隙介质释水,裂隙介质为流域的主要储水空间,但非岩溶流域的裂隙介质比例比岩溶流域高8.8％;随洪峰流量增加,两个流域的地表径流占比均呈对数形式增大,地下径流占比均呈对数形式减小;岩溶流域径流组分随洪峰流量变化比非岩溶流域更为敏感,其地表径流占比变幅为4％~40％,而非岩溶流域则始终小于10％。文章定量评价了管道和裂隙介质在流域中的导水及储水功能,在进一步刻画岩溶流域产汇流过程及机制方面进行了有益的探索,研究结果可为岩溶山区水资源评价和流域水文模型的改进提供科学依据。     

GIS and SBF for estimating groundwater recharge of a mountainous basin in the Wu River watershed,Taiwan

The temporal and spatial distributions of precipitation are extremely uneven; so, careful management of water resources in Taiwan is crucial. The long-term overexploitation of groundwater resources poses a challenge to water resource management in Taiwan. However, assessing groundwater resources in mountainous basins is challenging due to limited information. In this study, a geographic information system (GIS) and stable base-flow (SBF) techniques were used to assess the characteristics of groundwater recharge considering the Wu River watershed in central Taiwan as a study area. First, a GIS approach was used to integrate five contributing factors: lithology, land cover/land use, lineaments, drainage, and slope. The weights of factors contributing to the groundwater recharge were obtained from aerial photos, geological maps, a land use database, and field verification. Second, the SBF was used to estimate the groundwater recharge in a mountainous basin scale. The concept of the SBF technique was to separate the base-flow from the total streamflow discharge in order to obtain a measure of groundwater recharge. The SBF technique has the advantage of integrating groundwater recharge across an entire basin without complex hydro-geologic modelling and detailed knowledge of the soil characteristics. In this study, our approach for estimating recharge provides not only an estimate of how much water becomes groundwater, but also explains the characteristics of a potential groundwater recharge zone.