The economic value of flood risk regulation by agroecosystems at semiarid areas

Agroecosystems are anthropized ecosystems that provide food and other benefits to society known as ecosystem services (ES). Among these services is the Ecosystem Service for Flood Regulation (ESFR). This regulation service has been scarcely studied in the scientific literature, which has mainly focused on factors such as land use patterns and intermediate indicators. This implies that key physical aspects that condition the development of floods and their impact on society have been ignored. The aim of this work is to develop a methodological proposal for accurate economic valuation of the ESFR provided by agroecosystems. To this end, the avoided damage method is used, carrying out hydrological and two-dimensional hydraulic modeling combined with cadastral cartography and a depth-damage function. The model thus constructed allows the quantification of the damage reduction associated with different levels of agroecosystem ESFR provision. The urban settlement composed mainly of the municipality of Los Alcázares, and also the Bahia Bella housing estate, from the municipality of Cartagena (Murcia, south-eastern Spain), is used as a case study, as it is located downstream of a predominantly agricultural area recurrently affected by floods. The results show that the value of the ESFR provided by the service-maximizing agroecosystem in the area, citrus crops, is 22.51 € ha-1 year-1 in the case study area, which is comparable with that of natural ecosystems. Furthermore, relationships were established between intermediate indicators and economic losses which, in addition to facilitating the valuation process, show a limit in the flood regulation provisioning of agroecosystems in the face of the most extreme events. This work shows the magnitude of the ESFR that can be provided by agriculture and enables its valuation in areas with similar characteristics. The information obtained can be incorporated into the decision-making process of land and risk management organizations, enabling them to rationalize agricultural spatial planning. This work was supported by the Spanish Ministry of Science and Education: AgriCambio project (Grant PID2020-114576RB-I00 funded by MCIN/AEI/ 10.13039/501100011033). Víctor Martínez-García acknowledge the financial support from the Spanish Ministry of Education and Personal Training (FPU19/05143).