Locating new production wells using a probabilistic-based groundwater model

Abstract

Groundwater models provide an efficient means to evaluate the sustainability of new groundwater production wells. An important component of any groundwater modeling analysis is the quantification of the prediction uncertainty. This analysis incorporates uncertainty analysis techniques within the groundwater modeling environment to predict regions within a groundwater basin that have a low probability of excessive drawdown and groundwater contamination. The analysis focuses on the quantification of a basin-wide water-balance, generation of a spatial distribution of lithology, locating a nearby total dissolved solids (TDS) plume, and construction of an accurate groundwater flow model. Thousands of Monte Carlo realizations are simulated to determine the most probable parameter sets based on an objective function that minimizes the error between simulated and observed hydraulic head. Only those simulations with small error are used in a subsequent analysis to investigate 77 potential well locations near the city of Fernley, in northern Nevada. The final result is a map depicting the probability that a production well has either excessive drawdown and/or encroachment of the TDSs plume.