The impacts of nonlinearities and shifts in ecosystems in optimal groundwater pumping patterns

Abstract

Groundwater management is currently one of the main issues in environmental regulation worldwide. The large depletion and contamination of these resources during recent decades, calls for the implementation of control measures capable of reduce or dampen down the escalating global depletion, which is above 150 Mm3 per year. While several efforts have been done analyzing suitable regulations and measures to control extractions and protect these resources, the impacts of groundwater resources over their dependent aquatic ecosystems is still a pending issue. The large degradation of ecosystems, especially fresh water biota and habitats, requires the protection of specific ecosystems and their habitats. During recent decades, the interest on studying ecosystems has increased exponentially, with much more accurate analysis of the behavioral response of ecosystems to changes in their habitat. A broad literature suggests that the existence of nonlinearities in ecosystem behavior seems to be most precise representation of ecosystem status. Additionally, the existence of shifts in ecosystem’s behavior due to large deterioration of their external conditions appears to be a quite frequent feature. This paper purpose is to include ecosystems as very important elements to be considered in groundwater management. The contribution of this paper is the inclusion of nonlinearities and switches in the ecosystem’ status due to habitat deterioration (groundwater depletion). Using a two-stage optimal control method, we obtain the optimal patterns of irrigation water extractions and water table levels. The results highlight how both the economic value and the ecosystem’ status functions have important impacts on water extractions and groundwater levels. Additionally, the existence of shifts in ecosystem’s behavior affects critically the characterization of the optimal groundwater strategy.