Recharge Coefficient Research Articles

PERHITUNGAN AWAL IMBUHAN AIRTANAH ALAMI DAERAH ALIRAN SUNGAI CIKAPUNDUNG-GANDOK (KAJIAN PERBANDINGAN)

Groundwater recharge is a crucial factor in determining the permissible groundwater extraction within a watershed. In the Cikapundung watershed, the contribution of groundwater to raw water supply has been continuously declining, prompting a shift from groundwater to surface water usage. This study aims to quantify the groundwater recharge volume and recharge coefficient for each geological formation within the Cikapundung-Gandok watershed, covering an area of 90.4 km², and to compare the results with previous studies. The analysis estimates recharge volumes based on rainfall data from 8 stations around the Cikapundung-Gandok watershed from 2010 to 2019, geological formation data, and alternative recharge coefficients. The difference in recharge volume from previous studies is 393,348 m³/year or 1%. Two formations, Qvu and Qyu, which were not identified in earlier studies, supplement the existing geological dataset. The selected recharge volume for the Cikapundung-Gandok watershed is 33,232,004 m³/year or 1.05 m³/s, with the lowest contribution from the Lava formation (Qyl) at 1,364,504 m³/year or 0.04 m³/s and the highest from the Old Volcanic Product (Qvu) at 14,072,243 m³/year or 0.45 m³/s. The tentative recharge coefficients for each rock formation are as follows: Colluvium (Qc) 30%; Unweathered Old Volcanic Product (Qvu) 20%; Sand Tuff (Qyd) 10%; Lava (Qyl) 25%; Pumiceous Tuff (Qyt) 20%; and Young Volcanic Product (Qyu) 20%. The groundwater recharge data obtained can be used to set groundwater extraction limits and to plan for groundwater management using a conservative approach to ensure long-term sustainability.Keywords: groundwater recharge, recharge coefficient, geological formation, groundwater exploitation, Cikapundung-Gandok Watershed

Moisture Migration and Recharge Pattern of Low-Permeability Thick Cohesive Soil in Northern Margin of the Jianghan Plain

An extremely low hydraulic conductivity of cohesive soil causes a low transport rate of water and solute, with a time-consuming result, as we all know. Stable isotopes (δD and δ18O) and in situ monitoring systems of the data about soil water, rainfall, and groundwater were used to analyze the soil moisture migration pattern, using a conceptual model in the field test site, simulated by Hydrus 1D. The results show that multiple rainfalls’ accumulations can cause the water to recharge from soil moisture to micro-confined groundwater, gradually. The soil moisture dynamic change is composed of a dehydration period and absorption period; the cohesive soil water content below 5.0 m was affected by the micro-confined groundwater level and dehydrated in advance due to the level decline. The thick cohesive soil profile can be divided into a shallow mixing zone (0–2 m), steady zone (2–5 m), and deep mixing zone (5–15 m). The effective precipitation recharge was 234 mm and the average infiltration recharge coefficient (Rc) was 0.1389, but the water exchange between the cohesive soil moisture and groundwater was 349 mm in two hydrological years. This paper reveals the moisture migration and recharge pattern of low-permeability thick cohesive soil in a humid area with a micro-confined groundwater aquifer; this is of great significance for groundwater resources evaluation and environmental protection in humid climate plain areas.

Groundwater Recharge Assessment for Small Karstic Catchment Basins with Different Extents of Anthropogenic Development

Climate change and anthropogenic development considerably influence groundwater resource distribution and conditions. Catchment basin groundwater recharge—discharge computation reliability is needed for effective groundwater management policy formulation and implementation and also for resolving environmental challenges in such a watershed. This paper compares groundwater recharge patterns between urbanized and nearly natural small catchment basins of Israel’s Western Mountain Aquifer (WMA). The correlation between precipitation volumes and surface runoff shows that surface runoff volume constitutes 3–4% of the precipitation volume in the Natuf catchment and 1–2% in the Te’enim catchment. These assessments reflect the differences in the land use, outcrop lithology, topography and hydrodynamic properties of the WMA within the model basins. A groundwater recharge assessment based on water balance and water table fluctuation methods was performed for the mountainous karstic Te’enim and Natuf catchment basins for all the available data from 2000 to 2020. The water balance method provided reliable estimates. The groundwater recharge assessment considered land use classification and climate changes during this period. The average multiannual groundwater recharge values for the 2000–2021 period varied from 17.6 × 106–24.8 × 106 m3 to 24.5–29.2 × 106 m3 for the Te’enim and Natuf catchment basins, respectively. For the relatively dry period of the 2013/2014–2017/2018 hydrological years when detailed measurements of the surface runoff were available, the corresponding groundwater recharge volumes were 17.6 × 106 m3 and 24.5 × 106 m3. The corresponding local groundwater recharge coefficients constitute 0.46–0.57 for the mostly agricultural Te’enim basin and 0.29–0.32 for the urbanized Natuf basin. A significant difference in the groundwater recharge coefficients between the studied catchments is caused mostly by the differences in land use. It is suggested that applying such a groundwater recharge estimation for small hydrological sub-basins can improve one’s understanding of the groundwater recharge distribution within a major basin, enabling the application of an accurate regional hydrogeological model that may be extrapolated to other similar regions.

Estimation of the groundwater recharge coefficient by minimizing the sum total error of a regional water balance

Estimation of the groundwater recharge coefficient by minimizing the sum total error of a regional water balance

Hydrodynamic Characterization of the Water Table of the Upper Dallol Maouri Basin (Niger)

The Dallol Maouri is a valley of an ancient tributary of the Niger River. The groundwater in this area of the upper Dallol Maouri is little known because of the weakness of the data. The purpose of this study is to make a hydrodynamic characterization of the water table of the upper dallol Maouri by piezometric approach. A piezometric monitoring network made up of 65 points (54 wells and 11 piezometers) was set up. Six (6) piezometric measurement campaigns were carried out from June 2018 to June 2021. The piezometric survey is carried out once every six months: in January and June corresponding respectively to the high and low water period. The results show that the water table is multi-layered in places with a combination of alluvial and Continental Terminal 3 (CT3) aquifers, or perched aquifers and inferoflux aquifers around permanent ponds. The flow direction of the Continental Terminal 3 (CT3) aquifer is mainly North-East/South-West. The piezometric levels are around 219 m (in the South-West part) and 281 m (in the North-East part). The hydraulic gradient varies from 0.018‰ to 1.83‰. The recharge zones are located in the outcrop zone of the aquifer and in the valleys. A lack of recharge is observed on the plateaus despite the presence of numerous permanent ponds. The recharge coefficient in 2020 is estimated at 25% of the total rainfall recorded.

Use of GIS to Estimate Recharge and Identification of Potential Groundwater Recharge Zones in the Karstic Aquifers, West of Iran

Estimating and studying groundwater recharge is necessary and important for the management of water resources. The main aim of this work is to estimate the value of the annual recharge in some parts of the Kermanshah and Kurdistan province located in the west of Iran. There are many approaches available for estimation of the recharge, but RS (remote sensing) and GIS (geographic information system) have provided and combined a lot of effective spatial and temporal data of large areas within a short time. For this purpose, nine information layers including the slope, aspect of slope, lithology, lineament density, drainage density, precipitation, vegetation density, soil cover, and karst features were prepared and imported to the ArcMap software. After preparing the information layers, they have to weigh based on their effects on the value of the recharge. In order to be weighted the different parameters, methods of judgment expert, reciprocal influences of parameters, and AHP were used. Using GIS, the results obtained from the final map indicated the average value for the recharge based on the average calculated coefficient of recharge. The annual recharge coefficient in the study area was estimated to be between 30% and 80%.

Spatial distribution of groundwater recharge, based on regionalised soil moisture models in Wadi Natuf karst aquifers, Palestine

Abstract. While groundwater recharge is considered fundamental to hydrogeological insights and basin management and studies on its temporal variability are in great number, much less attention has been paid to its spatial distribution, by comparison. And in ungauged catchments it has rarely been quantified, especially on the catchment scale. For the first time, this study attempts such analysis, in a previously ungauged basin. Our work is based on the results of field data (as published in Messerschmid et al., 2020) of several soil moisture stations, which represent five geological formations of karst rock in Wadi Natuf, a semi-arid to sub-humid Mediterranean catchment in the occupied Palestinian West Bank. For that purpose, recharge was conceptualised as deep percolation from soil moisture under saturation excess conditions, which had been modelled parsimoniously and separately with different formation-specific recharge rates. For the regionalisation, inductive methods of empirical field measurements and observations were combined with deductive approaches of extrapolation, based on a new basin classification framework (BCF) for Wadi Natuf, thus following the recommendations for hydrological Prediction in Ungauged Basins (PUB), by the International Association of Hydrological Sciences (IAHS). Our results show an average annual recharge estimation in Wadi Natuf catchment (103 km2), ranging from 235 to 274 mm (24 to 28×106 m3) per year, equivalent to recharge coefficients (RCs) of 39 %–46 % of average annual precipitation (over a 7-year observation period but representative of long-term conditions as well). Formation-specific RC values, derived from empirical parsimonious soil moisture models, were regionalised and their spatial distribution was assessed and quantified on the catchment scale. Thus, for the first time, a fully distributed recharge model in a hitherto entirely ungauged (and karstic) aquifer basin was created that drew on empirical methods and direct approaches. This was done by a novel combination of existing methods and by creating a unified conceptual basin classification framework for different sets of physical basin features. This new regionalisation method is also applicable in many comparable sedimentary basins in the Mediterranean and worldwide.

Developing a pan-European high-resolution groundwater recharge map – Combining satellite data and national survey data using machine learning

Groundwater recharge quantification is essential for sustainable groundwater resources management, but typically limited to local and regional scale estimates. A high-resolution (1 km × 1 km) dataset consisting of long-term average actual evapotranspiration, effective precipitation, a groundwater recharge coefficient, and the resulting groundwater recharge map has been created for all of Europe using a variety of pan-European and seven national gridded datasets. As an initial step, the approach developed for continental scale mapping consists of a merged estimate of actual evapotranspiration originating from satellite data and the vegetation controlled Budyko approach to subsequently estimate effective precipitation. Secondly, a machine learning model based on the Random Forest regressor was developed for mapping groundwater recharge coefficients, using a range of covariates related to geology, soil, topography and climate. A common feature of the approach is the validation and training against effective precipitation, recharge coefficients and groundwater recharge from seven national gridded datasets covering the UK, Ireland, Finland, Denmark, the Netherlands, France and Spain, representing a wide range of climatic and hydrogeological conditions across Europe. The groundwater recharge map provides harmonised high-resolution estimates across Europe and locally relevant estimates for areas where this information is otherwise not available, while being consistent with the existing national gridded datasets. The Pan-European groundwater recharge pattern compares well with results from the global hydrological model PCR-GLOBWB 2. At country scale, the results were compared to a German recharge map showing great similarity. The full dataset of long-term average actual evapotranspiration, effective precipitation, recharge coefficients and groundwater recharge is available through the EuroGeoSurveys' open access European Geological Data Infrastructure (EGDI).

Estimation of the Groundwater Recharge Coefficient Using the Minimization of the Sum Total Error of System Water and Groundwater Balance Equations

Estimation of the Groundwater Recharge Coefficient Using the Minimization of the Sum Total Error of System Water and Groundwater Balance Equations

Groundwater recharge estimation using empirical methods from rainfall and streamflow records

Study regionGumara and Ribb watersheds, Abbay Basin, Ethiopia. Study focusIn this paper, an attempt was made to estimate groundwater recharge from streamflow and rainfall records. The groundwater recharge was estimated by different empirical methods, including the water balance method. The Ribb and Gumara rivers streamflow data were collected from the Ministry of Water, Irrigation, and Electricity of Ethiopia for estimating groundwater recharge by using baseflow separation techniques. The climate data was obtained from the Amhara National Meteorology Agency for estimating rainfall recharge and water balance components. New hydrological insights for the regionGroundwater resource development needs the determination of groundwater recharge volume. The annual areal rainfall, reference evapotranspiration, and recharge from rainfall of the study area were estimated as 1399.8 mm, 1300.21 mm, and 253.70 mm, respectively. The evapotranspiration was determined using the Penman-Monteith method. The baseflow separation techniques of RORA, PART, WHAT, and RECESS were employed during this study. The recharge coefficient estimated from rainfall and streamflow data were found at 0.18 and 0.20 respectively, which indicated that the study area has high groundwater recharge volume which could be used for different groundwater development projects. This study provides evidence for the groundwater potential areas identified by using geospatial methods and groundwater development projects that can be practiced in the area.

Quantifying natural recharge characteristics of shallow aquifers in groundwater overexploitation zone of North China

To improve the accuracy of hydrological simulations in the groundwater overexploitation zone of North China, it is necessary to study the characteristics of shallow aquifer recharge on daily scale. Three shallow aquifer recharge indices were used to quantify shallow aquifer recharge in two ways. The recharge coefficient was used to quantify the amount of shallow aquifer recharge. The recharge duration and water table rise coefficient were used to quantify the recharge temporal process. The Spearman rank correlation coefficient and regression analysis were used to determine the relationships between aquifer water table depth (WTD), rainfall, and shallow aquifer recharge. The Jiangjiang River Basin, a tributary of the Haihe River, was selected as the study area. The results showed that the recharge coefficient first increased, then decreased, and finally leveled off as WTD increased. When WTD was between 5 and 6 m, the recharge coefficient reached its maximum (approximately 0.3). When WTD was greater than 10 m, the recharge coefficient remained stable (around 0.12). With regard to the sources and forms of recharge, preferential flow was dominant in the areas near the extraction wells. In contrast, plug flow became dominant in the areas distant from the wells. With the reduction of rainfall duration, the proportion of preferential flow contributing to aquifer recharge increased. With the increase of rainfall amount, the duration of aquifer recharge lengthened.

Responses of Spring Discharge to Different Rainfall Events for Single-Conduit Karst Aquifers in Western Hunan Province, China.

It is a challenge to describe the hydrogeological characteristics of karst aquifers due to the complex structure with extremely high heterogeneity. As the response of karst aquifers to rainfall events, spring discharge variations after precipitation can be used to identify the internal structure of karst systems. In this study, responses of spring discharge to different kinds of precipitations are investigated by continuously monitoring precipitation and karst spring flow at a single-conduit karst aquifer in western Hunan province, China. Recession curves were used to analyze hydrodynamic behaviors and separate recession stages. The results show that the shape of the recession curve was changed under different rainfall conditions. Recession processes can be divided in to three recession stages under heavy rain conditions due to water drainage mainly from conduits, fracture, and matrix at each stage, but only one recession stage representing drainage mainly from matrix in the case of light rain. With the change in amount and intensity of precipitation, the calculated recession coefficient at each stage changes in an order of magnitude. The influence of precipitation on the recharge coefficient and the discharge composition at each recession are discussed, and then the conceptual model diagram of water filling and releasing in the single-conduit karst aquifers is concluded. The findings provide more insight understand on hydraulic behaviors of karst spring under different types of rainfall events and provide support for water resource management in karst regions.

An Assessment of Groundwater Recharge at a Regional Scale for Sustainable Resource Management: Province of Alicante (SE Spain)

For decades, the Province of Alicante, located in the Southeast of Spain, has experienced important economic development associated with groundwater exploitation. The scarcity of superficial resources and irregular distribution in the time and space of rainfall, typical of the Mediterranean environment, together with the extensive limestone outcrops, have made groundwater a key resource for the area. However, insufficient knowledge about aquifers, especially the lack of precise recharge estimates, hinders regional water management. This study establishes updated recharge estimates and water budgets for the 200 aquifers found in Alicante, using readily usable methodologies and available data. These are soil water budget models, groundwater flow models, water table fluctuation methods, and spring flow analyses. The results show low mean annual values of recharge from precipitation (69 mm/year and a coefficient of 12%) and two main differentiated domains. The first one, in the northeast of the province, under more humid climatic conditions with larger carbonate aquifer systems, has higher recharge coefficients, ranging from 14% to 24%, and greater resources. For the rest of the province, where aquifers are smaller and annual averages of rainfall range between 250 and 400 mm, average recharge rates are low (9–12%).

Modelación preliminar del flujo subterráneo en un sector de la cuenca inferior del arroyo del Azul (Buenos Aires, Argentina)

Se contruyó un modelo de flujo subterráneo, de carácter distribuido, con entradas y parámetros uniformes para todo el dominio de modelación. Este abordaje simplificado se realizó con el fin de caracterizar procesos generales y ajustar el modelo conceptual preliminar en el área de llanura del arroyo del Azul. Se propusieron metodologías a fin de completar las series discontinuas de niveles freáticos que fueron utilizados como condición de borde aguas arriba seleccionando una regresión lineal entre anomalías diarias de diferencias entre precipitación y evapotranspiración potencial con un retardo semanal con resultados de ajuste satisfactorios. Se consideraron como parámetros globales de calibración la transmisividad del acuífero, el coeficiente de almacenamiento, un coeficiente de recarga, una profundidad crítica para la evapotranspiración y un coeficiente de forma para la curva evapotranspiración vs. profundidad freática. Los coeficientes de eficiencia de Nash-Sutcliffe entre niveles modelados y observados en 6 pozos de control oscilaron entre 0.58 y 0.72. Tras la calibración, se concluyó que los parámetros obtenidos permiten una representación satisfactoria de la evolución de los niveles freáticos en los pozos de observación y de los patrones espaciales de las isofreáticas. Se pone en evidencia el rol prominente del proceso de evapotranspiración, el cual impacta directamente en el acuífero, representando una salida relevante del sistema. En el período de simulación de 43 meses, de características levemente secas, la recarga constituyó el 17 % de la precipitación, el 87 % de la misma retornó a la atmósfera como evapotranspiración, y el acuífero abastecería el 12.7 % de la evapotranspiración potencial del período. Se considera que la modelación simplificada permitió una aceptable representación del comportamiento del acuífero freático.

Estimation of Ground Water Recharge for Irrigation Water Budget Planning in Kanzenze Swamp

Groundwater is the dynamic local water source for agriculture, industry, wildlife and human development activity. Hence, in order to sustain long-term groundwater use, make intelligent groundwater allocation decisions and water budget planning, develop on-farm water management strategies, the estimation of the net groundwater recharge from agricultural areas like Kanzenze swamp is paramount important. The study findings therefore showed that Ground Water Recharge estimation for the study area ranges from 33.85mm to 52.96mm while the average mean of ground water recharge is about 45.06mm per year. The coefficient of ground water recharge is ranging from 3.41% to 5.27% while average mean recharge coefficient is 4.06% recharged to ground water level yearly. However, monthly basis planning have advantages for farmers’ water budgeting. It revealed that highest recharge coefficient is recorded in months of March, April and November representing 17.22% and 17% of the mean monthly rainfall while the lowest recharge coefficient is recorded during the period of June, July and February representing 16.17%, 15.73% and 16.71% of the average monthly rainfall. Thus, it is recommended that utmost farmers around the Kanzenze swamp should plan the irrigation activities and minimizes unnecessary water use consumption in such way that in June and July there is water enough water even taught there is shortage of rainfall. It meant that priori irrigation systems should be applied to obtain optimum moisture content and water table levels for effective crop production mainly horticultural crops in season C rather than season A and season B of cultivation in Rwanda.

Sources and selective preservation of organic matter in the karst watershed: evidence from sediment records in a plateau deep lake, Southwestern China.

Human activities have greatly altered terrestrial carbon (C) dynamics associated with vegetation cover and land use changes, thereby influencing the C sink in downstream ecosystems. However, the transport and preservation of organic C from soils that experience serious erosion in the karst area are scarce, particularly at catchment scales. In this study, chemical characteristics of organic matter (OM) isolated from the topsoil, overlying water, and lake sediments, as well as subsequent source identification, were inferred from the molecular, spectroscopic, and carbon isotopic (δ13C) signatures in a typical karst catchment, Southwestern China. The results indicated that the elemental compositions of the calcareous soil and paddy soil significantly differed from the yellow soil. High similarities existed in the fluorescence spectra of humic substances (HS) extracted from the front two soil types with those of lake sediments, indicating the homogeneous nature of OM molecular structure. The C/N ratios of six dissolved OM fractions and sedimentary HS along with δ13C values consistently reflected the primary terrestrial source. It was estimated to account for 60% of total organic C in sedimentary OM by end-member mixing modeling in accordance with soil erosion intensity and large recharge coefficient of this catchment. The evolution of soil loss and lake productivity can be well deduced from sediment records of organic C content, C/N ratio, and the specific information of HS. This research highlighted that the composition, source, and fate of OM in the karst lake was mainly dominated by the terrestrial C flux, rather than in-lake production. Furthermore, soil type and erosion intensity have significant effects on the nature of eroded OM and ultimate preservation.

Development of an Apparent Recharge Coefficient (ARC) for Estimating Groundwater Storage Changes due to Precipitation Events Using Time Series Monitoring Data

Significant variation in the precipitation events caused by global climate change has made it difficult to manage water resources due to the increased frequency of unexpected droughts and floods. Under these conditions, groundwater is needed to ensure a sustainable water supply; thus, estimates of precipitation recharge are essential. In this study, we derived an apparent recharge coefficient (ARC) from a modified water table fluctuation equation to predict groundwater storage changes due to precipitation events. The ARC is calculated as the ratio of the recharge rate over the specific yield (R/Sy); therefore, it implicitly expresses variation in Sy. The ARC varies spatially and temporally, corresponding to the precipitation events and hydrogeological characteristics of unsaturated materials. ARCs for five monitoring wells from two basins in Korea in different seasons were calculated using a 10-year groundwater level and weather dataset for 2005–2014. Then, the reliability of the ARCs was tested by the comparison of the predicted groundwater level changes for 2015 and 2016 with observed data. The root mean square error ranged from 0.03 to 0.09 m, indicating that the predictions were acceptable, except for one well, which had thick clay layers atop the soil layer; the low permeability of the clay slowed the precipitation recharge, interfering with groundwater level responses. We performed a back-calculation of R from the Sy values of the study areas; the results were similar to those obtained via other methods, confirming the practical applicability of the ARC. In conclusion, the ARC is a viable method for predicting groundwater storage changes for regions where long-term monitoring data are available, and subsequently will facilitate advanced decision making for allocating and developing water resources for residents, industry, and groundwater-dependent ecosystems.

Introducing the recharge–discharge relationship to evaluate the recharge coefficient of karstic aquifers: thematic and indexing approaches

ABSTRACT Karst aquifers and springs are important with respect to their potential for supplying drinking water in regions suffering from water scarcity in Iran. Accordingly, it is essential to determine the recharge potential of the catchment and the regions with higher obtainability potential. This study provides a road map for the Sheshpeer catchment in southern Iran. A recharge potential (RP) map was produced from which a recharge index (RI) was computed for several selected springs in the catchment. Furthermore, the unit discharge (q) – defined as the average annual discharge for a given catchment area and unit rainfall depth for each spring – was calculated. The plot of q versus RI for the springs showed a linear positive relationship between the two variables (R 2 = 0.9). Applying the trend equation of this plot to the whole Sheshpeer karstic catchment reveals that its long-term recharge coefficient is 0.74.

Pollution characteristics and risk assessment of surface sediments in nine plateau lakes of Yunnan Province

Sediment is the indicator of nutrient and heavy metal pollution in water environment, which can obviously reflect the pollution state in lakes. This paper reviews the literature of surface sediment pollution assessment of nine plateau lakes (Dianchi Lake, Erhai Lake, Fuxian Lake, Qilu Lake, Lugu Lake, Yangzonghai Lake, Yilong Lake, Xingyun Lake and Chenghai Lake) in Yunnan Province in the past ten years. TN (TN), total phosphorus (TP), copper (Cu), zinc (Zn), lead (Pb), chromium (Cr), cadmium (Cd), nickel (Ni), arsenic (As), mercury (Hg) are selected. As an evaluation index, the average contents in surface sediments of nine plateau lakes were 3517.53 mg/kg, 1826.86 mg/kg, 72.52 mg/kg, 215.43 mg/kg, 39.51 mg/kg, 69.66 mg/kg, 1.31 mg/kg, 43.83 mg/kg, 12.77 mg/kg and 0.21 mg/kg, respectively. Nutrient and heavy metals in sediments were evaluated by single pollution index method, ground accumulation index method and potential ecological risk index method. The results showed that nutrient pollution was serious, and the average pollution level was heavy pollution. Eight kinds of heavy metals were in moderate or below the pollution level. Cd and Hg were the main contributing factors in the ecological risk assessment of heavy metals. The correlation analysis shows that the TN pollution in surface sediments of nine plateau lakes is related to the average water depth, recharge coefficient and population density of the lakes.

Field-based estimation and modelling of distributed groundwater recharge in a Mediterranean karst catchment, Wadi Natuf, West Bank

Abstract. While groundwater recharge is one of the most prominently covered subjects in hydrogeology, the spatial distribution of recharge has been given relatively little attention, especially in semi-arid, karstic aquifers. Under conditions of highly diverse geology, relief, vegetation and land use, the complexity and variability of spatially distributed hydrological processes remains a challenge in many regions around the world. This is particularly true for hitherto ungauged basins, such as Wadi Natuf, a 103 km2 large karstic Eastern Mediterranean watershed in the Palestinian upstream mountain and recharge area of the Western Aquifer Basin (WAB), which is shared with Israel in the coastal plain. In this first in a series of two papers, distributed recharge is estimated and represented, based on 7 years of extensive field observations and measurements and based conceptually on observable physical landscape features such as geology, land use and land cover (LU/LC) and especially soil conditions. For the first time in the WAB, a forward calculated soil moisture and percolation model (SMSP) was set up with parameters directly gained from field observations. The model was parameterised in a strictly parsimonious manner, as a one-dimensional model (a.k.a. “tank”, bucket or box model). This is based on dominant hydrological processes, in particular saturation excess in the soil column, and identifying patterns of linkage between different landscape features. Average soil thickness was encountered at the range of decimetres, rarely above one metre. Both soil thickness and LU/LC features, such as terraced olive groves or forests as well as grassland or barren rock outcrops, were found to be highly formation specific. This linkage allowed us to further simplify the model and its requirements in a realistic manner for eight soil moisture stations, chosen at six different geological formations with typical soil and LU/LC representations. The main result of the model was the determination of formation-specific recharge coefficients, spatially ranging between 0 % and almost 60 % of annual rainfall or up to 300 mm a−1 in Wadi Natuf's climate. The karstified main aquifers showed recharge coefficients (RC) above 40 % and even the less prominent slightly aquitardal local aquifers reached RC values above 30 %. The model was separately tested on two conceptual levels: on the level of basin form (soil moisture) and basin response (signatures of peak recharge and local spring discharge events) under well-controlled conditions in isolated sub-catchments. In principle, our approach is applicable in many of the scarcely gauged karstic groundwater basins around the world with a highly diverse landscape and geology.