Spatial and temporal rainfall changes in the Jucar and Segura basins (1955-2016): Fine-scale trends

摘要

A daily rainfall database covering the Jucar and Segura river basin authorities (east Iberian Peninsula, Spain) with high spatial density without gaps (890 series) has been created for the complete period 1955-2016. This has allowed a trend analysis of precipitation and dry/wet spells with a better spatial detail and coverage of key headwaters sectors than previous studies in this area. Results show significant negative trends for precipitation prevailing in Jucar area (an annual average loss of 51mm), especially towards its north interior headwaters. For this last one the annual loss exceeds 200mm (20% of precipitation). By contrast, certain pre-littoral sectors and most of the Segura area are remaining out of these negative trends (some local positive trends). However, the dry spells length and the number of dry days have increased in a generalized way (Jucar and Segura basins) with rainfall concentration in time and space. The decrease of moderate rainfall with greater precipitation effectiveness and weight in the key interior headwaters is the most significant. On the contrary, there has been an increase in extreme torrential rainfall (with poor effectiveness and high risk) at points on the coast and pre-littoral towards south of the region. These results are linked to a change in the frequency of three basic synoptic types identified in the region as rainfall origin.