Assessing and mitigating the landscape effects of river damming on the Guadalfeo River delta, southern Spain

Abstract

Deltaic systems are sensitive to natural and human-induced changes as they accommodate numerous activities and have high ecological, economic and social importance. Mediterranean deltas are particularly vulnerable to anthropogenic activities, which alter the coastal land availability. This work addresses the morphological evolution of the Guadalfeo River delta (southern Spain) by analyzing the evolution of the coastline position and the sediment volume on the coast. The evolution of the built-up area, the impact of river damming and the artificial nourishment projects conducted on the coast were investigated and discussed. Bathymetric, topographic and sedimentological measurements were performed from 1999 to 2008, and fluvial and maritime data were analyzed. Based on the results, a situation diagnosis was performed using the SWOT (Strengths, Weaknesses, Opportunities and Threats) analysis, and management practices were proposed based on a modification of the SWOT analysis. The results indicate that the river regulation has considerably reduced the sediment input into the coastal system and has prevented the advance of a delta that was prograding before dam construction. River damming has also led to severe coastline retreat and has endangered urban developments near the river mouth; furthermore, artificial replenishments have not been effective mainly due to using too fine sediment. We conclude that the best and most practicable strategy for mitigating erosion problems is to bypass sediment from the reservoir in combination with flows drained by the dam.