GROUNDWATER RESERVES ESTIMATE USING MONTE CARLO SIMULATION OF RIO CLARO AQUIFER

Abstract

Vertical Electrical Sounding and Monte Carlo simulation were used with the purpose to establish the amount of groundwater stored in the Rio Claro Aquifer, in the municipality of Rio Claro. The vertical electrical sounding was chosen because one important variable to calculate permanent reserve is average value of saturated thickness of the aquifer. This variable is usually obtained from well data. However, in the municipality of Rio Claro the well data of the Rio Claro Aquifer are scarce, thus making difficult to obtain a reliable value of saturated thickness. Considering that the variables “aquifer area”, “specific yield” and “groundwater level variation” are also used in the calculation of the permanent and regulating reserves, and because “specific yield” and “groundwater level variation” were obtained only from the wells, the Monte Carlo simulation was chosen to estimate values of permanent and regulating reserves. The cumulative distribution curves of the permanent and regulating reserves, as derived from the simulation, were used to generate some scenarios for the water consumption of the Rio Claro Aquifer, which is of great utility for the management of water resources. One interesting result of Monte Carlo simulation is the chance of the regulating reserve being lesser than the water demand of the current population of the municipality for a period of one year is of only 5%.