Optimal Groundwater Management Model in a Two-Aquifer System

An optimal model is developed for determining the well sites and their pumping rates from the upper aquifer and lower aquifer in a two-aquifer system, which is designed to prevent the water quality in lower aquifer from contamination of the polluted upper aquifer by observing a set of constraints determined by the drawdowns between the upper and lower aquifers. The physical model of the complex simulation area may be simplified as a two-aquifer system, which consists of an upper phreatic aquifer and a lower confined aquifer with a leaky stratum between them. First, a numerical quasithree-dimensional mathematical equation is introduced to govern the flow of the two-aquifer system. Second, the generation of the response matrix in two-aquifer system is presented by separating the numerical quasithree-dimensional mathematical equation into three equations. Then the objective management strategy for the upper and lower aquifers is designed to construct a linear programming model, the optimal groundwater management model, with its constraints through the response matrix approach in a two-aquifer system. The developed model with data from Qiqihar City, Heilongjiang Province, China is used for allocating the withdrawal amount optimally among wells in the upper and lower aquifers without reducing the water quality in the lower aquifer and satisfactory results are obtained.