Optimality Versus Viability in Groundwater Management with Environmental Flows

Abstract

The protection of environmental flows is a main challenge pursued by water regulating agencies in their groundwater management policies. A stylised hydro-economic model with natural drainage is used to compare the outcome of the optimal control approach in which environmental flows are introduced as an externality with the viable approach in which environmental flows are modelled as a constraint to satisfy. The optimal and viable paths for the water table, water extraction for irrigation and environmental flows are analytically derived together with their long term values. We show how results are sensitive to some key parameters like the discount factor and the monetary value of the externality in the optimal control approach. We show how the value of the environmental flows target in the viable approach can be derived from the optimal control approach. Numerical simulations based on the Western La Mancha aquifer illustrate the main results of the study.

Ecosystem Shifts: Implications for Groundwater Management

“…Lower groundwater withdrawals, when environmental objectives are included in the model, is an expected result already reported in the literature (Pereau et al 2019;Esteban and Dinar 2016). However, our results show a decreasing pattern followed by a sharp increase in extractions.…”

“…The main political implication of our results is that policy regulations are mandatory if a social planner internalizes the protection of aquatic ecosystems. This is indeed an obvious outcome that has already been stated in the literature (Esteban and Albiac 2011;Roumasset and Wada 2013;Gutrich et al 2016;Esteban and Dinar 2016;Pongkijvorasin et al 2018;Pereau et al 2019). However, our findings involve new implications based on the inclusion of ecosystem dynamics in groundwater management.…”

“…Several studies have included ecosystems as relevant elements in groundwater management (e.g., Roumasset and Wada 2013;Gutrich et al 2016;Esteban and Dinar 2016;Pongkijvorasin et al 2018;Pereau et al 2019). However, to the best of our knowledge none of them have specifically included the possibility of tipping points involving regime shifts in the ecological systems.…”

“…2) we assume that groundwater withdrawals for ecosystems (environmental flows) are marginal. A potential sophistication of the model could be the inclusion of ecological withdrawals as stated by Pereau et al (2019).…”

Groundwater Exploitation and Illegal Behaviors in a Differential Game

“…Parameter values used are from Western La Mancha aquifer and are shown in Table 1. These data are widely used in the literature (among others, [9,12,22]).…”