Highland-lowland interactions in a context of global change: challenges and opportunities in land and water resources management in new irrigated lands

• Published in: Pirineos
• Main Authors: Beguería, Santiago, Haro-Monteagudo, David, Palazón, Leticia, García-Ruiz, José M.
• Format: Article in Journal/Newspaper
• Language: Spanish
• Published: Consejo Superior de Investigaciones Científicas 2022
• Subjects: New irrigated land; irrigation modernization; Global Change; water resources; snow; reservoirs; Monegros; Riegos del Alto Aragón; Nuevos regadíos; modernización de riego; Cambio Global; recursos hídricos; nieve; embalses; Journal of Glaciology
• Online Access: https://pirineos.revistas.csic.es/index.php/pirineos/article/view/340; https://doi.org/10.3989/pirineos.2022.177005

The transformation of rainfed agriculture lands into irrigated lands in the central sector of the Ebro Depression has represented a spectacular change in the cultivation conditions of a semi-arid territory affected by scarce and irregular precipitation. However, the new irrigation systems faced serious structural problems from the beginning due to the peculiar design of the irrigation system, the limitations of its objectives, the slow pace with which the infrastructures were built (reservoirs, canals and secondary ditches) and the conditioning of cultivated fields. This work focuses on the study of the limitations faced byRiegos del Alto Aragóndue to the trend shown by water resources and their seasonal distribution as a result of the evolution of temperature and precipitation, the expansion of woody vegetation in mountain areas and the progressive silting up of the reservoirs. For this, the information available on Global Change in the Pyrenees has been reviewed and climatic and hydrological models have been applied. The necessary modernization has improved the irrigation systems and water use efficiency, and has allowed the expansion of much more productive and profitable crops. Paradoxically, modernization has also increased the water demand, and has made necessary to increase the system’s internal reserves through the construction of small reservoirs and ponds. This greater water demand coincides with a decreasing trend in water resources availability, due not only to the increase in average temperature, but also to changes in snowpack accumulation and melting dynamics in the Pyrenean headwaters and to forest expansion in old abandoned fields in the Pyrenean valleys, which reduces runoff generation and streamflow. It is foreseeable that most of these processes will continue or even accentuate in the medium- to long-term due to climate change. In addition, the progressive silting up of the reservoirs reduces the water storage capacity year after year. These processes, which highlight the interactions between ...