Characterisation of Aquifers in Bolivia

In the Central Valley of Cochabamba (Valle central de Cochabamba) about 1 million of inhabitants are concentrated (Figure 1). The urban expansion and the semiarid weather (i.e. limited offer of surface water) led to the population to exploit the groundwater resources. Hence, there is an actual concern about the health of the local aquifers. Groundwater overexploitation and pollution threats from anthropogenic activities are the main hazards to the local aquifers. One main aquifer in Central Cochabamba that is facing all the aforementioned issues is the Chocaya basin. The Chocaya basin is located 15 kilometres northwest of Cochabamba city. It is surrounded in the north Ordovician rocks that forms the Tunari range (west Andes). In the southeast and southwest it is bounded by Quaternary fluvial and alluvial sediments that forms the central Valley of Cochabamba. Despite large volumes of groundwater is exploited and transferred to Cochabamba city, the local hydrogeology is not well known (e.g. geometry of aquifers, type of sediments, layering and depth to basement). Moreover, the unregulated and rapid urbanization is threatening the groundwater recharge, and on the other hand, pollution from domestic waste is jeopardizing the local aquifers The geophysical surveys performed in the study area will provide key information for delimiting the aquifer geometry in the Chocaya basin, and as a consequence in the near future sustainable land use can be stablished in the study area. About 35 TEM soundings and more than 4 km of ERT were performed.