Evidences and characterization of groundwater circulation in dryland piedmonts+ impacts on aquifer recharge. Example of the Andean Piedmont between 19.5°S and 20°S (Northern Chile).

Abstract : A piedmont acts as a transition zone, shaped by an alluvial cover overlying the bedrock, between i) a mountain range area and its lowland+ ii) a high and low precipitation area which generally correlated with the relief in drylands. These transition zones can be associated to significant groundwater circulation, from the mountain front recharge zones towards a downstream aquifer, generally located in the lowlands. Nevertheless, due to several constraints (rugged terrains, significant vadose zone) the density of observation points (e.g. well) in the piedmont is very restricted, whereas a large number of wells (groundwater exploitation) are usually available in the lowlands. Consequently, both groundwater circulation and aquifer recharge in the piedmont cover are poorly addressed and thus often neglected. The Andean Piedmont (between 19,5°S and 20°S - Northern Chile) is located in the Pampa del Tamarugal (PdT) Central Depression. The piedmont cover and the lowlands are composed of late - Cenozoic alluvial deposits (hundreds of meters thick) which contain the Pampa del Tamarugal Aquifer (PTA). In this arid and hyperarid climatic context, the PTA is one of the main strategic groundwater resources in Northern Chile. In order to determine both groundwater circulation and aquifer recharge within the piedmont, we used various approaches such as (i) Time Domain Electromagnetic (TDEM) method to assess resistivity variations with depth+ (ii) stream flow measurements+ (iii) analysis of current springs location and paleogeomorphic features of the piedmont cover and (iv) hydrogeological modelling. This allowed to better constrain the aquifer boundaries with the geological structures+ to identify preferential recharge areas and to highlight a regional groundwater flow patter n in the alluvial cover. This methodology, transposable to other dryland piedmonts, allowed providing a new conceptual model of the PTA.
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https://hal.umontpellier.fr/hal-02122761
Contributeur : Pascale Roussel <>
Soumis le : mardi 7 mai 2019 - 15:07:13
Dernière modification le : mardi 13 août 2019 - 14:30:11

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  • HAL Id : hal-02122761, version 1

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Benoit Viguier, Véronique Léonardi, Herve Jourde, Claudio Moya, Elias Lira, et al.. Evidences and characterization of groundwater circulation in dryland piedmonts+ impacts on aquifer recharge. Example of the Andean Piedmont between 19.5°S and 20°S (Northern Chile).. 43rd IAH International Congress “Groundwater and society : 60 years of IAH”, Sep 2016, Montpellier, France. ⟨hal-02122761⟩

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