30 juil. Mots clefs: Hydrochimie, isotope, recharge, minéralisation, Yaoundé. Journal of l’utilisation des cours d’eau comme dépotoir des ordures ou. Les caractéristiques chimiques témoignent cependant d’une influence humaine relativement modérée sur l’ensemble du cours. Abstract. The mineral content of. [BOU 05] G. BOULET, La composante biospherique du cycle de l’eau: modeles et utilisation de la télédétection, cours Master Hydrologie, Hydrochimie, Sols et.
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Switch to xours view. In a Mediterranean climate, water resources are scarce in sedimentary basins. In Tunisia, as in other semiarid countries, the revival of traditional floodwater harvesting, such as hydrochimiee reservoirs, can provide water resources for the development of agriculture and agroforestry as well as reduce the use of other valuable water resources such as groundwater.
Since the early s, more than hill reservoirs were built within the mm range of mean annual rainfall. Most of them can limit water loss by runoff and enhance groundwater recharge.
The El Gouazine reservoir in Central Tunisia was chosen within the European Union sponsored project Hydromed because its groundwater balance is highly negative, ranging annually fromm3 in Tunisian hydrological year, conventionally starting in September and ending in August tom3 inthus suggesting an important water loss by infiltration. The hyddrochimie of the present paper consists in studying the hydrochemical behaviour of the hydrochiime to improve the understanding of alluvial groundwater recharge below the hill reservoir.
Water sampling was carried out in May when the reservoir was almost empty 14 samples and in March when it was full 21 samples.
Surface waters were hydrochiime within the open water surface of the reservoir, in a small upstream pond created during road construction, in a temporary affluent river, in a dam seepage and in the downstream riverbed. Underground water samples were collected from three well locations located downstream from the hill reservoir, from 10 hydrochiime well locations and from two downstream pit locations.
All the samples were immediately filtered on site. Total alkalinity was measured by titration with 0.
The total dissolved solids TDS of the surface waters ranged from 0. Reservoir water was less mineralised in the FP than in the DP with an ion concentration factor of 2. The pH was nearly neutral and tended to be higher in reservoir water The silica concentration of the reservoir water was much lower in the DP and in the FP as well. The TDS of the ground waters, located within the watershed, varied from 0.
The pH values were mainly neutral. Silica concentrations demonstrated relatively low variation ranging from 22 to 27 hydrkchimie L-1 in the DP and from 15 to 27 mg L-1 in the FP.
Hydrochimie de la rivière Lot | Annales de Limnologie – International Journal of Limnology
From upstream to downstream of the hill reservoir, the mineralisation of groundwater decreased, suggesting that an upstream mineralised groundwater flow is hydroxhimie by a weakly mineralised reservoir water.
Three groundwater types can be distinguished in relation to the bedrock limestone, marl, gypsiferous marl, gypsiferous mudstone, sandstone.
The first type, weakly mineralised, was represented by three wells from the limestone outcrop.
Courz the lower part of the basin, the third type of groundwater was draining gypsiferous deposits and was dominated by calcium and sulphate ions. The reservoir water belongs to this type. Most underground waters originated from infiltrating precipitation that was not subject to surface or cpurs alteration of its isotopic composition. Groundwater located in the limestone outcrop was less hydroxhimie in stable isotopes.
In the DP, reservoir water showed 2H and 18O enrichment, which is typical for water that has been subjected to surface evaporation. However, reservoir water is weakly mineralised, suggesting that the reservoir was an open system with more mineralised groundwater entering the reservoir and a mixed reservoir water downstream outflowing by infiltration. Downstream groundwater was weakly enriched and less mineralised than upstream groundwater.
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Reservoir water, which was permanently mixed, tends to be meteoric in the FP and evaporated in the DP. Physical and pedological clues indicate that the reservoir was leaking. The layer forms an aquifer resulting from the weathering of the sandstone outcrop and was connected to the downstream alluvial aquifer. The high permeability of the sandy layer partly explained the high water loss of the reservoir. Flowing through clayey materials, which contain variable amounts hhdrochimie easily soluble minerals, such as gypsum, and which are less permeable, the alluvial groundwater was strongly mineralised.
The alluvial aquifer was hyrochimie by shallow groundwater stored in limestone aquifers resulting in a strong decrease of the concentration. The limestone aquifers were highly porous and very transmissive.
They can accumulate a high water content and rapidly recharge or discharge. The meteoric water collected in the reservoir also decreases the groundwater ion concentration leading to the same effect as the limestone groundwater. Download the article in PDF to read it. Groundwater, surface water, soil, hill reservoir, geochemistry, stable isotopes, watershed, Tunisia. Revue des sciences de l’eau17 2— Revue des sciences de l’eau 17, no.