Modeling the optimal management of land subsidence due to
aquifers overexploitation
E. Esteban, E. Calvo, J. Albiac
University of Zaragoza and AgriFood Institute of Aragon, Spain
A. Dinar
University of California, Riverside, USA
J. Calatrava
Polytechnic University of Cartagena, Spain
G. Herrera-Garcia, P. Ezquerro
Geological Survey of Spain, Madrid, Spain
P. Teatini
University of Padova, Padova, Italy
R. Tomas
University of Alicante, Alicante, Spain
Y. Li
University of Toronto, Canada
The study of land subsidence has recently been expanded due to its increased occurrence and magnitude
worldwide. This paper develops and applies an optimal control model of groundwater extractions under conditions
of land subsidence. We include, in a traditional groundwater management model, two types of negative
externalities associated with land subsidence: damage to infrastructure and to economic activities, and the loss of
aquifer storage capacity. Using a two-stage optimal control method, characterized by two sub-problems corresponding
to the phase before and after the occurrence of subsidence, we find the economically sustainable paths
of groundwater extractions and water table levels under the existence of land subsidence impacts. The theoretical
results indicate that the presence of land subsidence dictates the optimal paths of groundwater withdrawals and
water table levels. The model has been applied to the Alto Guadalentín over-exploited aquifer system in the
Segura River Basin of Spain. The empirical outcomes indicate that by following the optimal paths, groundwater
extractions should be curtailing to avoid reaching the critical water level at which subsidence takes place. Results
suggest that regional net present value of welfare over the planning period, under the two land subsidence
scenarios, is reduced by nearly 1-5%, compared to the no land subsidence scenario. Furthermore, under subsidence,
even with relatively small impacts of both types of externalities, groundwater optimal extractions are
kept at levels that avoid these externalities. These outcomes clearly call for government intervention in order to
reduce groundwater withdrawals in aquifers with propensity to face undesirable subsidence effects.
