Assessing urban water supply from karstic groundwater reservoirs through two hydrological models and the Exploitation Index in the southeast of Spain

Assessing urban water supply from karstic groundwater reservoirs through two hydrological models and the Exploitation Index in the southeast of Spain

Teresa Palacios-Cabrera¹, Antonio Jodar-Abellan², Ryan T. Bailey³, Dámaris Núñez-Gómez², Derdour Abdessamed⁴, Seyed Babak Haji Seyed Asadollah⁵, Pablo Melgarejo²

¹Faculty of Geology, Mines, Petroleum and Environmental Engineering. Central University of Ecuador. teresaalejandrap3@gmail.com

²Centro de Investigación e Innovación Agroalimentario y Agroambiental (CIAGRO), Miguel Hernández University (UMH). Orihuela, Spain.

³Dept. of Civil and Environmental Engineering, Colorado State University, Fort Collins, CO, USA.

⁴Laboratory for the Sustainable Management of Natural Resources in Arid and Semi‑arid Zones. University Center Salhi Ahmed Naama (Ctr Univ Naama). P.O. Box 66, Naama 45000. Algeria.

⁵Department of Civil Engineering, Science and Research Branch, Islamic Azad University, Tehran, Iran.

Abstract:

Nowadays, numerous urban settlements in arid and semiarid areas are supplied by groundwater from adjacent small aquifers. Climate change with expected decreases in averages precipitation values jointly with increases in the frequency of heavy rainfall events does not show a clear pattner to how water resources in karstic aquifers are going to evolve. This work, focused in the Guadalest watershed (province of Alicante, southeast of Spain) assesses the behaviour of four karstic aquifers (the Mela, Beniardá-Polop, Benimantell and Serralla-Aixorta aquifers), whose resources supply urban water consumption for close municipalities. In these aquifers, we estimate groundwater recharge, extractions and their relation within the Exploitation Index (EI) by using the SWAT and SIMPA models, previously calibrated and validated in this watershed, during the period 1980-2016. These groundwater estimations were tested (validated) with field measurements performed by local authorities during the above mentioned period. Thus, in the Mela aquifer an EI of 0.19 was estimated with SWAT and SIMPA while an EI of 0.13 was obtained by local authorities; in the Beniardá-Polop aquifer an EI of 1.43 was estimated while an EI of 1.26 was obtained in the fieldwork; in Benimantell an EI of 0.25 and an EI of 0.22 were estimated and obtained respectively; and finally in the Serralla-Aixorta aquifer an EI of 0.19 and an EI of 0.2 were estimated and obtained respectively. Our results denote that: i) both models simulate correctly groundwater abstractions; ii) assessed aquifers depict a clear reduction of their reserves during the study period which represent an important issue considering that currently groundwater extractions are the unique water source of these populations. Therefore, it will be necessary to design supply strategies for these inhabitants and to carry out them, meeting budget restrictions and avoiding potential water shortages.

Keywords: groundwater; SWAT; SIMPA; Exploitation Index; urban water supply; southeast of Spain.