Run‐off transmission loss into karstified consolidated aquifer bedrock below ephemeral streams (wadis) has rarely been described nor quantified. This study presents unique data of long‐term high‐resolution field measurements and field observations in a semiarid to subhumid Mediterranean carbonatic mountainshed. The catchment with a 103 km2 surface area is subdivided into 5 subcatchments. Coupled run‐off measurements were made in the different stream sections (reaches), and transmission loss calculated from differences in discharge. Rainfall and run‐off observations from 9 automated precipitation gauging stations and 5 pressure transducers for automatic water level recording are complemented by manual measurements during 34 run‐off events covering a total measurement period of 8 consecutive years. Run‐off generation is strongly event based depending on rainfall intensities and depths. Both, run‐off generation and transmission losses are related to spatial patterns of bedrock lithologies (and hydrostratigraphy). Transmission losses range between 62% and 80% of generated run‐off, with most of the smaller events showing 100% transmission loss. Therefore, although event run‐off coefficients in the mountains can reach up to 22%, only 0.11% of total annual precipitation leaves the catchment as run‐off. Most run‐off infiltrates directly into the regional karst aquifers (Upper Cretaceous carbonate series), with transmission loss intensities of up to 40 mm/h below the stream channels. The factors determining run‐off—such as geology, pedology, vegetation cover and land use, relief and morphology, the semiarid to subhumid Mediterranean climate with a strong elevation gradient, and the patchiness of individual storm events distributed over the winter seasons—as well as the lithology and epikarst features of the bedrock are all characteristic for larger areas in the Mediterranean region. Therefore, we expect that our findings can be generalized to a large extent.

The increased attention given to international transboundary aquifers may be nowhere more pressing than on the western bank of the Jordan River. Hydropolitical analysis of six decades of Israeli and Palestinian pumping records reveals how ground water abstraction rates are as asymmetrical as are water allocations. The particular hydrogeology of the region, notably the variability in depth to ground water, variations in ground water quality, and the vulnerability of the aquifer, also affect the outcome. The records confirm previously drawn conclusions of the influence of the agricultural lobby in maintaining a supply-side water management paradigm. Comparison of water consumption rates divulges that water consumed by all sectors of the farming-based Palestinian economy is less than half of Israeli domestic consumption. The overwhelming majority of "reserve" flows from wet years are sold at subsidized rates to the Israeli agricultural sector, while very minor amounts are sold at normal rates to the Palestinian side for drinking water. An apparent coevolution of water resource variability and politics serves to explain increased Israeli pumping prior to negotiations in the early 1990s. The abstraction record from the Western Aquifer Basin discloses that the effective limit set by the terms of the 1995 Oslo II Agreement is regularly violated by the Israeli side, thereby putting the aquifer at risk. The picture that emerges is one of a transboundary water regime that is much more exploitative than cooperative and that risks spoiling the resource as it poisons international relations.

Abstract. Runoff observations with high spatial and temporal resolution before, during and since the Intifada in the occupied Palestinian West Bank, allow for new insights into the feedback between changing social systems and hydrological response under changing land forms. The lack of land control and infrastructure, movement restrictions and tight closure regimes, intensive settlement expansion and mushrooming unregulated solid waste dump-sites impact on runoff generation, groundwater recharge, flow patterns and rising water quality concerns. Long-term monitoring results from a 105 km2 Mediterranean climate catchment are presented. More research will strengthen these linkages. Changing socio-hydrological context of land sovereignty and equitable water rights remain paramount for addressing the chronic water crisis, establishing more symmetrical access and sustainable management of the shared water resources.

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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.