ABSTRACT
ABSTRACT: The structure and the hydrodynamic properties of the weathering profile of a granitic area (53 km2 Maheshwaram catchment, state of Andhra Pradesh, India) were characterized in detail and mapped from observations on outcrops, vertical electric soundings, and data from borewells. The structure of the weathering profile results from a multiphase process: an ancient weathering profile was partly eroded down to its fissured layer. It was later re-weathered more or less parallel to the current topographic surface. The hydrodynamic properties of the weathered-fractured layer of the profile are characterized using hydraulic tests at different scales and a comprehensive hydrodynamic model is proposed. A water budget approach is developed to estimate specific yield and natural recharge in the aquifer with significant seasonal water table fluctuations. Water table fluctuations are due to distinct seasonality in groundwater recharge. These techniques constitute a first step towards the modelling at catchment scale in hard-rock aquifers.
