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Andesitic volcanic hydrosystems in Indonesia are mostly hydrogeologically unknown despite their socio-economic importance. The development of robust and easy-to-implement methodologies to conceptualize and quantify the water cycle components becomes a prerequisite for their sustainable management.We developed a lumped hydrological model to mimic the structure and functioning of a previously unknown hydrosystem located on the flanks of the Salak volcano (West Java). The structure of the aquifers was revealed with electrical resistivity tomography. The distinction between springs fed by the extensive artesian aquifer and others fed by shallow perched aquifers was obtained mostly using hydrochemistry. The elevation of the recharge area was identified using isotopic analysis of spring water.After designing the hydrological model structure, we carried out a probabilistic parameters exploration using the multiple-try differential evolution adaptive Metropolis algorithm to calibrate aquifer discharge. Multiple Markov chains allow a better exploration of the parameter values. The Bayesian approach provides the best water cycle simulation with a parameter uncertainty analysis, improving the accuracy and representation of the water cycle appropriate for previously unknown hydrosystems.

This paper aims to propose a methodology to interpret electrical resistivity tomography (ERT) in an andesitic volcanic context and to feed hydrogeological conceptual model of the structure of the aquifers in volcanic context. The study takes place in Pandaan, in the northeastern part of Arjuno Welirang volcano, Indonesia. The district relies on the groundwater supply to sustain its needs (industries, agriculture, domestics). Therefore, characterizing the aquifers boundaries and functioning is important to apply sustainable groundwater management. The methodology is in two steps, first geological and hydrogeological mapping, leading to the ERT location identifications. And second, interpretation of electrical resistivity tomography profiles with the subsurface hydrogeological dataset. In this paper, the relationships between volcanic facies and aquifer properties are well described through 15 ERT profiles, calibrated with geological outcrops, borehole logs, and hydrogeological data. The geophysical signature shows that, in the proximal–medial zone of the Arjuno Welirang volcano, major springs are located where the lava flows end (lava tip) and are in contact with a clayey layer/lahars. In the medial zone, below and above the clayey/lahars layer, the volcanic sandstone and tuff breccia respectively support unconfined and confined aquifers, with the evidence of artesian boreholes for the latter and dug wells for the former. These results lead to an improved hydrogeological conceptual model for this research area. [ABSTRACT FROM AUTHOR]

Based on research work in the Truyere River catchment of the Massif Central (Lozere Department, France), a methodology has been developed for delineating favorable prospecting zones of a few square kilometers within basement areas of several hundred, if not thousand, square kilometers for the purpose of siting high-yield water wells. The methodology adopts a functional approach to hard-rock aquifers using a conceptual model of the aquifer structure and of the functioning of the main aquifer compartments: the alterites (weathered and decayed rock), the underlying weathered-fissured zone, and the fractured bedrock. It involves an economically feasible method of mapping the thickness and spatial distribution of the alterites and the weathered-fissured zone, on which the long-term exploitation of the water resource chiefly depends. This method is used for the first time in hydrogeology. The potential ground water resources were mapped by GIS multicriteria analysis using parameters characterizing the structure and functioning of the aquifer, i.e., lithology and hydrogeological properties of the substratum, nature and thickness of the alterites and weathered-fissured zone, depth of the water table, slope, fracture networks and present-day tectonic stresses, and forecasted ground water quality. The methodology involves a coherent process of downscaling that, through applying methods that are increasingly precise but also increasingly costly, enables the selection of sites with diminishing surface areas as the work advances. The resulting documents are used for ground water exploration, although they can also be applied to the broader domain of land-use management., Introduction The economic development of a region commonly depends on the availability of sufficient quantities of affordable high-quality water. Drilling programs carried out over the last few decades in basement [...]

The African continent is probably the one with the lowest density of hydrometric stations currently measuring river discharge, despite the fact that the number of operating stations was quite important until the 70s. This new African Database of Hydrometric Indices (ADHI) is compiling data from different sources carefully checked for quality control. It includes about 1500 stations with at least 10 years of daily discharge data over the period 1950-2018. The average record length is 19 years and for over 100 stations complete records are available over 50 years. With this dataset spanning most regions of the African continent, several hydrometric indices have been computed, representing mean flow characteristics and extremes (low flows and floods), and are made accessible to the scientific community. The database will be updated on a regular basis to include more hydrometric stations and longer time series of river discharge. The ADHI database is available for download at: https://doi.org/10.23708/LXGXQ9 (Tramblay and Rouché, 2020). [ABSTRACT FROM AUTHOR]