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[en] The accurate assessment of groundwater and its management requires obtaining reliable estimates of hydraulic conductivity (K) and specific storage (Ss). A large number of empirical, laboratory and field techniques have been developed over the last several decades. However, research suggests that Hydraulic Tomography (HT) yields the most accurate hydraulic parameter estimates that can then be used to build robust groundwater flow models. The majority of algorithms used for HT analysis has relied on geostatistics, however, a number of studies have shown that smooth K and Ss estimates are obtained when the inversion begins with homogeneous hydraulic parameter estimates and when data densities are not high. These smooth estimates are not visually appealing from a geological standpoint. One could overcome this by integrating geological data that are typically available through outcrops and borehole logs. Here, we examine the usefulness of geological data for HT analysis in unconsolidated deposits by: (1) comparing “traditionally” calibrated geological models to highly parameterized geostatistical inverse models and (2) using geological models as prior information for the geostatistical inversion approach. The investigation has been conducted with laboratory sandbox experiments, at a small-scale field site on the University of Waterloo campus consisting of highly heterogeneous glaciofluvial deposits and using data obtained from a municipal well field. Results reveal that the calibration of groundwater models built primarily with geological data, yields mixed results in terms of model performance, perhaps reflecting the uncertainties in geological structures along the vertical direction and between boreholes. The geostatistical inversion approach without the explicit reliance of geological data yields improved model performance over traditional geological models when data densities are high, although the resulting K and Ss distributions may not be geologically appealing. On the other hand, when geological data are fused with the geostatistical inversion approach, the resulting K and Ss estimates are more visually appealing from a geological standpoint, and that model performance is most robust. Overall, our results suggest the joint use of both geological and pumping test data for HT analysis when accurate geological data are available
[en] Changes in the intensity of precipitation as a result of global warming are expected to be especially pronounced in the tropics. The impact of changing rainfall intensities on groundwater recharge remains, however, unclear. Analysis of a recently compiled data set of coincidental, daily observations of rainfall and groundwater levels remote from abstraction for four stations in the Upper Nile Basin over the period 1999-2008 shows that the magnitude of observed recharge events is better related to the sum of heavy rainfalls, exceeding a threshold of 10 mm day-1, than to that of all daily rainfall events. Consequently, projected increases in rainfall intensities as a result of global warming may promote rather than restrict groundwater recharge in similar environments of the tropics. Further monitoring and research are required to test the robustness of these findings, but the evidence presented is consistent with recent modelling highlighting the importance of explicitly considering changing rainfall intensities in the assessment of climate change impacts on groundwater recharge.
[en] Understanding groundwater resources and their informed management ask for regular monitoring of groundwater state variables, both quantity and quality. Collected observations need to be stored, processed and shared among stakeholders. The Global Groundwater Monitoring Network (GGMN) assists (already since 2007) in improving the quality and accessibility of groundwater information and eventually the understanding of the state of groundwater resources (www.un-igrac.org/ggmn). This abstract summarises some advances in data collection, processing and sharing, accounted within GGMN activities. Although automatic groundwater monitoring and even telemetric transmission of data are becoming widely used, manual collection of data is still present or even predominant, the choice depending on parameters and purpose of the monitoring, groundwater regime, available resources, and others. In order to facilitate data collection in the field and data transmission to the GGMN Portal, a mobile (smartphone) application is recently developed. This GGMN App enables users to geo-reference and register groundwater monitoring wells, store groundwater monitoring data in the field and (immediately or later if WIFI is not available) transfer data to GGMN and store it there. In GGMN, data can be processed and optionally shared with other data providers and stakeholders One of the most effective ways to share time series data among online data portals is through an automated Sensor Observation Service (SOS). This service has been recently implemented in GGMN and tested by connecting GGMN and the Groundwater Information Network (GIN) of the Geological Survey of Canada. Since GGMN aims to serve as a global monitoring focal point, the ultimate goal is establishing the same or comparable data sharing services with as many as possible national groundwater services around the world. IGRAC is preparing a global overview of national groundwater services with a focus on temporal and spatial processing of groundwater observations. It is a general impression that collected observations are not processed sufficiently. On the other hand, some services exhibited creative approaches in the processing of (in particular) spatial variability of groundwater variables. These approaches will be promoted through the IGRAC global overview and some of them are considered to be implemented in GGMN soon.
[en] This work is about the study of new under water zones for the Andresito town location in Flores district. This searching is carried out by preliminary photo interpretation Esc. 1.20.000. for the prospect ion.
[en] The study area is part of the Western High Atlas. The plain of Ouled Bou Sbaâ is located hundred kilometers west of Marrakesh, it is part of the Atlantic trays area. It is a complex basin, with a succession of synclines and anticlines oriented NE-SW between the mountain chain of the High Atlas and the Tensift river.The compilation of geological data, drilling data, geological sections and the analysis of the reconnaissance boreholes logs show that this area is constituted by thick sedimentary series dated from Paleozoic to Quaternary. Hydrogeologically, these series show the superposition of two aquifers; the first one is an unconfined groundwater flow system housed in the Quaternary, Eocene and Turonian; the second one is a deep confined groundwater flow system and located at the heart of the Cenomano-Turonian aged synclines. The feeding of these two reservoirs is ensured by the infiltration of surface waters of the high Atlas’s mountains as well as by stoma at the piedmont.By establishing piezometric maps, it has been noticed that on one hand the free groundwater layers have a hydraulic continuity. On the other hand the confined aquifer located at the Sidi Mokhtar’s syncline, in the north of the working area has a flow oriented from SSW towards NNE while the one in the syncline of Idouirane situated in the south has a groundwater flow oriented from SW to NE. As there is a separation materialized by the Marmouta anticline, the two aquifers do not have hydraulic continuity.
[en] The Mitidja Plain is situated in the north of Algeria, the Eastern part (575km2) lies by the sea in the north and is limited by the Atlas Monntains in the south. the region has two main aquifers separated in some places by the El-Harrach Formation (Calabrian), The Plaisancian marls (lower Pliocene) are the substratum of the whole area, the second and most important aquifer, Mitidja formation, is alluvial, coastal. The Eastern Mitidja plain constitutes a subterranean water reservoir essential for the agricultural, urban and industrial development of the capital Algiers. Recently, industrial activities, the spreading of exhaustive agricultural practices and the urbanization of the plain have lowered the quality of water. As many of the Mediterranean countries, Algeria has known a severe dryness during the last two decades. Unfavourable climatic conditions causing long period droughts have predictably led to a contamination of coastal groundwaters along the Mediterranean by ingressive seawater. Intensive pumping practices in use for the sake of securing water allocation for both populations and agriculture have drastically affected the groundwater reserves through overexploitation of the resource creating a consequent drawdown in the water table. During the dry season, the mobile fresh/sea water interface moves forward farther inland contaminating wells and boreholes. Two approaches making use of both hydrochemical and isotopic tools were applied to assess the extent of seawater intrusion. The Br vs. Cl plot showed that the points align in a parallel way to seawater dilution line confirming thus a marine origin for those elements. Na/Cl ratio vs. Cl plot brings to the fore two poles of points: one composed of shallow unaffected groundwater and a second one composed of deeper boreholes and wells in which seawater is present to different extents. This is further confirmed by isotopes which exhibited a wide range of values mirroring the affected and unaffected areas as well as those points submitted to intermingling between different endmembers
[en] This publication summarizes the result of the project on the use of isotope techniques for the study of recharge and discharge of the Sokoto-Rima hydrological basin in the semi-arid and northwestern part of Nigeria
[en] Hydrogeological modeling is an indispensable decision support tool for sustainable groundwater resources management. However, one of the major issues in Groundwater numerical modeling is related to the basic data preparation required for running this open sources or commercial packages models. The experienced user or a newcomer of various existing powerful models such as MODFLOW, FEFLOW, etc, is often lost during the data preparation phase. Hence, one of the main motivations for this work is to develop an expert system able to reproduce heuristics mechanisms of hydrogeologists/experts in order to assist engineers/researchers in the main stages (essentially prior) of hydrogeological modeling (to analyze and study in depth the aquifer system). rule based expert system, called ALAES (ALae Aquifer Expert System), dedicated to this purpose, was built adopting object oriented approach, and using an Expert System Shell. It includes: 114 class, 1136 instances, 179 functions, 192 rules and two types of interfaces. This work describes the main steps of ALAES development, its top level object hierarchy, and corresponding heuristics rules. Most of the advice given by ALAES working system was evaluated and validated in the Moroccan Rhis-Nekor aquifer case study. ALAES allows to: i) select the appropriate hydrogeological model depending on the aquifer problem studied and judge its modeling feasibility, ii) prepare the necessary inputs data for Hydrodynamic model, iii) guide the user during the modeling process, and determinate the optimal future water management scenario of groundwater resources.
[en] The scientific works of this scientist cover the vast area of mathematical sums of applied hydrodynamics, filtration theory and underground hydraulics and their enclosures in the problems of theory of channel processes; groundwater hydrology
[en] The North China Plain (NCP) is one of the biggest groundwater systems in the world, and the development and utilization of groundwater has led to severe land subsidence. The NCP has more than 80% of the total area of severe subsidence in China, so the situation of prevention and control of land subsidence is severe. Due to diverse sedimental environment, different geological conditions, and intensive groundwater abstraction, the mechanism of land subsidence is complex. With the help of earth observing technique and traditional monitoring tools, the disaster process of land subsidence was monitored, and the developing history and current situation were analyzed. Also, the difference features of land subsidence and the mechanism of hysteretic deformation were analyzed with the help of strain-stress diagrams and soil mechanics tests. The results show that the subsidence areas are mainly located in the areas of the Quaternary sedimentary depressions, having characteristics of west-east sub-zone and north-south subsection. The major contribution layers to the land subsidence have varied with the change of groundwater abstraction layers. The drought is an important and indirect factor enlarging the scale of land subsidence by reducing natural recharge and leading to the increase of groundwater abstraction for emergency water supply. The hysteresis of land subsidence is obvious, and the time of hysteresis can last for twenty-five years. Besides the consolidation, the creep is another important reason for the hysteresis which can reach 28.3% of the total deformation for the Late Pleistocene strata in the Cangxian uplift. The deformation characteristics of the soil layer bear strong relationship to the physical characteristics and variation pattern of groundwater levels. The strata at different depths have distinct deformation characteristics such as elastic, visco-elastic, and visco-elastic-plastic deformations, and shallow aquifer groups indicate typical elastic deformation.