The Guadalentín River is located in southeast Spain and is a major tributary of the Segura River, one of the largest Mediterranean basins in Spain. Semiarid climatic conditions are characterized average annual precipitation of 250 mm/yr and 17º C of average temperatures. The Guadalentín Basin is characterized by a nearly flat valley bottom with series of well-developed alluvial fans. It is occupied by the Alto Guadalentín aquifer, which is bounded on the northeast and on the south-east by fault systems. The basement beneath the aquifer is composed of several relatively impermeable Paleozoic metamorphic complexes overlain by permeable Miocene conglomerate and/or calcarenite series. The top of the succession comprises Pliocene–Quaternary, low-permeability, compressible conglomerates, sand, silt, and clays. Historically, piezometric levels were near land surface with development of artesian wells and permanent lagoons. Since the 1960s-1970s, the Guadalentín Basin aquifer has has been exploited intensely, leading to a spatially variable continuous piezometric level decrease. Recent drought periods from 1990 to 1995, and 2005–2008 reduced natural recharge and increased pumping in the Guadalentín Basin, which led to an increased resources deficit. The ERS and ENVISAT ground deformation data indicates large scale deformation and in particular the discovery of the highest rates of groundwater-related land subsidence recorded in Europe (> 10 cm/yr). The occurrence of Lorca earthquake that caused 9 fatalities, and the recently published possible correlation with ground water extraction requires more research on this complex phenomenon.
Flat valley bottom with series of well-developed alluvial fans.
Floodings (with over 2000 fatalities documented during the last 250 yr), earthquakes (with 9 fatalities on the May 11th 2011 earthquake), subsidence due to ground water extraction, and erosive processes (piping)