The use of participatory object-oriented Bayesian networks and agro-economic models for groundwater management in Spain

This paper describes the development of a participatory decision support system for water management in the Upper Guadiana basin in central Spain where there has long been competition for groundwater resources between the agricultural sector and the environment. In the last few decades the rapid development of irrigation has led to the over-exploitation of the Mancha Occidental aquifer, the main water source in the area; this in turn has led to the loss of ecologically important wetlands. Against this background the River Basin Authority (RBA) has designed a new water management plan aimed at reducing water consumption. The objective of this paper is to evaluate the impact of these measures on both the environment and the agricultural sector. To this end stakeholders have been invited to actively participate in the development of a decision support system (DSS) based on the combination of an agro-economic model and an object-oriented Bayesian network. This DSS has been used to evaluate the trade-off between agriculture and the environment for different management options at different scales. Results indicate that achieving even a partial recovery of the aquifer water levels will require strict enforcement by the RBA of water restrictions on farmers combined with a high offer price for the purchase of water rights. However, compliance with water restrictions inevitably leads to losses in farm income, especially in small vineyard farms, unless additional measures are taken to compensate for those potential losses. The purchase of water rights alone is insufficient to ensure the recovery of water levels; accompanying measures included in the new regional management plan will also need to be undertaken