The research group is made up of professors Javier Miró, María José Estrela, Vicente Caselles, and Igor Gómez, from the Department of Geography (Faculty of Geography) and the Department of Earth Physics and Thermodynamics (Faculty of Physics). The study presents new and denser spatial data (890 series) processed, bigger than previous studies, thanks to new methodological procedures, which has allowed a more detailed study of climate change. This is why a more accurate approach to the current situation of the headwaters of the Xúquer and the Segura has been made.

Results show that significant trends are not important at the coast although negative trends have been detected at the inland headwaters, like the Segura River, and particularly the Xúquer River and its tributaries such as the Cabriel. The Xúquer situation is very serious since there is a loss of 20% of the annual rains in its headwaters –right in the point where it joins to the Alto Tajo–, and at least of 10% or 15% in the rest of the interior and centre of the basin.

Rainfalls have however increased –or have not changed– at some points in the south of the Gulf of Valencia due to torrential rainfalls and thunderstorms in this Mediterranean region. Moreover, dry spells –number of days without rainfalls– have increased in both basins, and moderate rainfalls, which are more beneficial, have decreased in favour of extreme ones.    

A loss of more than 200 mm per year –the average goes from 1,000 – 1,200 mm to 800 – 1,000 mm– has been registered in the upper side of the Xúquer, where 1,000 mm are usually surpassed. Right in the source of Xúquer, where annual rainfalls are most registered and close to the source of the river Tajo, there is a loss of 300 mm per year.

There is also a loss of 100 mm per year in the upper side of the Segura, in the area between Albacete and Yecla, in some northern points of Castelló, and in inland points of the Xúquer basin. Losses of between 50 and 100 mm are thus registered in much of the area of the Vinalopó River.

On average, the hydrographical basin of the Xúquer has lost 50 mm throughout the studied period and the hydrographical basin of the Segura, 10 mm.

Nevertheless, annual rainfalls have increased up to 100 mm in some points closer to the mouth of the Xúquer –especially Alzira, Cullera, and Tavernes de la Valldigna–. In some other points in the south of the Gulf of Valencia and north of Alacant –as well as in some points in the middle area of the Segura and its mouth– rainfalls have increased, but in a weaker way. However, most of these punctual increases are not statistically significant due to rains have been torrential and irregular throughout the year.

Furthermore, the number of days without rainfalls in a year has increased up to 10 days in botch basins. Summer and winter are thus the seasons that register major negative trends of rainfalls. Summer storms are decreasing during summer itself and are hitting during spring and fall.  

These results are very important for proper planning of future policies on water and spatial planning in Valencia and Murcia regions.