Groundwater resources are traditionally overexploited in arid and drought-prone regions with profitable irrigated
agriculture, and the depletion of this groundwater results from a combination of the physical scarcity
of surface sources and the lack of effective control of use rights on the part of water authorities. This is the
case in the Segura River Basin of southern Spain. As a result, drought risks and structural deficits have steadily
increased over the last 50 years. The Drought Management Plan recently approved by the Segura River Basin
Authority aims to enforce more stringent water supply restrictions from surface sources, but the plan does
not include any explicit policy to handle illegal groundwater abstraction. By using a stochastic risk assessment
model, this paper shows that the implementation of the drought plan will increase the expected irrigation
deficits of surface water and can, paradoxically, lead to higher drought and aquifer depletion risks than
the traditional rules that the new plan replaces.