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[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] 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] 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] 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 range of the compositions of environmental isotopes has been used to distinguish the sources and processes of groundwater recharge and to estimate the age of the groundwater in the Basaltic aquifer in Yarmouk basin, SW of Syria Stable isotopic data from the groundwater in the basaltic aquifer show that the groundwater in the area is derived from meteoric water. The principal recharge areas are the Mts Al-Arab and Harmon, which is reflected the mean isotopic composition of the rainwater. The groundwater from the central zone is modified by the admixture of the influx of groundwater recharged in the Mts region and direct infiltration in lower part and Laja plateau. The groundwater has undergone a significant degree of evaporation during the mechanism of recharge. The ages of groundwater corrected by Netpath model are between 2000/y old to recent age.
[en] The aqueous speciation of U(VI) is extremely complex, and exerts a strong influence on the stability and migration of U in groundwater. The solubility of precipitated uranyl is determined by the activity of the free uranyl cation (UO22+), which, in turn is directly related to its concentration. Aqueous complexation can dramatically increase the solubility of precipitated U by the formation of U species at concentrations that are many orders of magnitude above that of the free cation. The speciation chemistry of uranium in aqueous systems is mainly controlled by the pH, redox potential and complexing agents such as carbonates, phosphates, vanadates, fluorides, sulfates and silicates. Therefore, it is essential to evaluate the hydrochemical characteristics of the groundwater in U contaminated region to predict the fate of U transport
[en] Groundwater systems in arid regions will be particularly sensitive to climate change owing to the strong dependence of rates of evapotranspiration on temperature, and shifts in the precipitation regimes. In agricultural areas, such changes in climate may require increased irrigation, putting stress on existing water supplies. In this study, a regional-scale numerical groundwater model was developed for the Oliver region of the south Okanagan, British Columbia, Canada, to simulate the impacts of future predicted climate change on groundwater. In future time periods (the 2050s and 2080s), the most noticeable change in the water budget is the increased contribution of recharge to the annual water budget, estimated at 1.2% (2050s) and 1.4% (2080s) of the total annual budget relative to the current conditions. This increase is related primarily to increases to irrigation return flow resulting from higher irrigation needs under warmer temperatures and a longer growing season. Increases in recharge and irrigation return flow will result in higher water tables with future climate conditions, particularly in the irrigation districts. Median value increases in groundwater level of up to 0.7 m by the 2080s are estimated.
[en] The National Institute of Nuclear Research of Mexico (ININ), has developed a technique that allows to study the association of recharge mechanisms, residence times of the water in the aquifers, as well as the local lithology and the geochemical parameters. The viability of this technique was proven on November 2004 in the aquifers (La Perita, El Tunel y El Pedregal) located in the Asuncion Tepexoyuca, Estado de Mexico. It was observed that so much the aquifer El Tunel like La Perita are used for the human consumption, the aquifer of El Pedregal is used for the fish cultivation. The studies were carried out during March 2003 to November 2004. In the aquifer La Perita the maximum values of the radon concentration (0.76 Bq L-1) they were observed in the summertime time (December). In the spring El Tunel the maximum values of the radon concentration (4.08 Bq L-1) they were observed in the rainy season (September) this increment can be due to the contributions of the recharge of aquifers that it allows the haulage of the radon of other alternating roads of infiltration of the rain water. Of the physicochemical and radiochemical analyses carried out in the water samples of the studied aquifers, it is deduced that they are waters of good quality since for the human consumption since that they are inside on the maximum permissible limits as for their potability according to national and international standards. Likewise it was observed that the water of the aquifers is a single aquifer, since that its differences they due to the time of permanency of the water inside the aquifer. The classification of the underground water deduced that it is calcic and/or magnesic bi carbonated water belonging to the type of meteoric waters of recent infiltration. (Author)
[en] In the semiarid central part of Tunisia the water resources are becoming increasingly rare because of the scarcity and irregularity of the precipitation and a steadily growing need for fresh water. This study addresses the use of geochemical and isotopic data to analyze the relationship between the El Haouareb dam and the Ain El Beidha and the Kairouan alluvial plain aquifers systems for durable groundwater management. In the Ain El Beidha basin the hydrogeological and geochemical investigations showed that: - The general direction of the groundwater flow is mainly from the SW to the NE, i.e. towards the hydraulic sill of El Haouareb which allows the connection between the Ain El Beidha basin and the Kairouan plain, - The salinity distribution displays a zonation in apparent relationship with the lithological variation of the aquifer formation, - Mineral exchange between groundwater and the aquifer matrix is the dominant process in determining groundwater salinity. The isotopic data confirm the flow directions of groundwater and shows that the recharge of Ain El Beidha aquifers takes place from the floods of the Khechem and Ben Zitoun wadies and also by preferential infiltration of runoff at the front of hill slopes area. Close to preferential recharge areas, groundwater 3H contents reflect a recent input of surface water, whereas the radiocarbon data indicate a longer residence time downstream. The isotopic characteristics of Ain El Beidha groundwater (small space and temporal changes) authorize the use of averaged values for the dam-aquifer water exchange. Under natural conditions, groundwater recharge of the alluvial aquifer of Kairouan plain occurs by infiltration of the Merguellil floods and from the Ain el Beidha groundwater flow close the karstic hydraulic sills. Since the construction of the El Haouareb dam, these natural mechanisms have been strongly modified: the dam waters infiltrate into the karst, mix with the Ain el Beidha groundwater, and feed the karst before reaching the Kairouan plain aquifer (springs). Groundwater under flow is estimated at 9 M m3 year-1 and the karstic spring flow is evaluated at 10 M m3 year-1. The spring waters show an intermediate isotope composition between dam reservoir water and the upper catchment of Ain el Beidha basin. The contribution of dam water in mixed water (spring) varies between 21 to 66% depending on time. Values from 18O and 2H ratio are well correlated with the karstic spring flow and with the water level in the reservoir. The hydrogeological study helped to understand the hydrodynamic functioning of the Kairouan plain aquifer system and identified a decline of the water table levels (1.5 m year-1). This decrease is explained mainly by over exploitation (4.8 M m3 year-1). The hydrochemical investigation indicated that the rock-water interaction is the main process contributing to the groundwater salinization. All the samples collected in the Merguellil basin are of the main hydrochemical type: Cl-SO4-Na. Stable isotope values measured in the upstream part of plain, closer the dam, differ from other parts of the aquifer, therefore suggesting a significant input from evaporated dam waters mixed with Ain el Beidha groundwater (spring water coming from the karst). This contamination can be observed as far as 7 km downstream. However, isotopic imprint of the previous recharge process (infiltration of wadi floods) are still noticeable. The residence time of the groundwater was estimated by carbon-14 dating that shows variable values of transit velocity of the groundwater ranging from 3.36 to 0.44 m year-1 depending on the groundwater flow and on the lithological variability of the aquifer. (Author).
[en] Bari Doab is depleting the most in groundwater and therefore needs to be recharged. This paper presents a possibility of recharging Bari Doab through the abandoned Sukh-Beas channel. For this purpose, 25 cross sections were taken and ten infiltration tests were performed. Three different HEC-RAS models were run to find its channel capacity at different reaches. The infiltration capacity of the Sukh-Beas Nallah was found to be a total of about 808 cfs, which can be used to recharge the groundwater, after some necessary steps have been taken to improve the infrastructure.