Water Availability Threshold Management, a relevant tool to reach Zero Net Biodiversity Loss in semiarid mediterranean landscapes in Spain

Antonio Pastor-Lopez and Jose Antonio Perez-Lahiguera, Ecology, Universidad de Alicante, Alicante, Spain, Jose Emilio Martinez-Perez, Unidad de Cartografía Ambiental, Universidad de Alicante, Alicante, Spain

Background/Question/Methods
Biodiversity loss is one of the main ecological problems in most semiarid mediterranean lowlands landscapes in Europe, due to strong modifications in the traditional agriculture water cycle. Unsustainable aquifer management and irrigation developments focused, mainly, on water consumption reduction are driving many habitats to disappearance. These scenarios are very frequent in Southeastern Spain. Water conflicts with agricultural stakeholders are increasing, and successful and feasible planning strategies are urgent.
This research examined land-use and associated water-use changes in Alto Vinalopó County (Alicante province). Scenario of frequent water management conflicts, associated with long time aquifers overexploitation, and paradigm of “how a very ecologically rich area”( just two centuries ago) is losing biodiversity dramatically. Analysis was focused on water consumption data from Jucar Water Authority (Confederación Hidrográfica del Jucar), and GIS spatial changes 1956 to 2018, on irrigation networks fragmentation. Using LIDAR 1m resolution DEM and a combination of QGIS tools ( "r.flow" from GRASS; SAGA toolbox; "Terrain Analysis-Hydrology" menu, and "Catchment area - flow tracing") water accumulation value per pixel was obtained, under different rainfall scenarios. Comparing historical information, and aerial photos in the vicinity of the town of Villena (Alicante) the main water landscape features regression trends were identified. Biodiversity status of the area was stablished using the information available on the Generalitat Valenciana Biodiversity Data Bank on a 1 km side grid.

Results/Conclusions
Many relevant factors affecting ecological functionality were induced since 1992, by modifications in water quantity and quality inputs in these landscapes. Fragmentation, and/or elimination of the traditional (on ground), and the more recent (1970’s concrete) irrigation channels network, compared at a 100 meters and 1 kilometer side pixels, indicated that there were a considerable amount of small sites that still keep the old network complexity and water availability. Water inputs significantly reduced: (a) in channels receiving Water Treatment Plants effluents from 94 to 10 liters per second; (b) flooding to dripping irrigation between 40 to 60 per cent lost (mean water demand per hectare and year : 2328 cubic meters). Results suggest the need to include, in the structural land-use planning, maps of Water Availability Thresholds areas. This will allow rural land planning to meet Zero Net Biodiversity Loss. Planning procedures, must consider ecologically relevant landscapes units, and not just the former "Units of Agricultural Demand". A structural planning of relevant ecological features, must be explored, to effectively conserve them and the associated biodiversity.