Castilla-La Mancha (CLM) is one of 17 regions in Spain, being the third largest in surface area (79,463 km2) and more sizeable than some countries of the European Union (EU), such as Belgium, Denmark, and Ireland. However, the population density is one of the lowest i.e. 22.9 habitants/km2. This situation is best explained by the particular distribution of the Spanish population, which tends, with the exception of Madrid, to be concentrated in coastal regions. The interior regions of Spain have traditionally supported agricultural production while industry and tourism are more commonly established in coastal areas. The water demand of coastal regions restricts the availability of water resources in interior regions. CLM generates an important volume of both surface water and groundwater resources. Nevertheless, more than 70% of these resources are appropriated to uses outside of the region. This aspect would not be relevant if the water demands of CLM were covered, however, in spite of being the allocating river basin, the region is experiencing critical water shortages. These water shortages impede economic growth, and fail to insure water availability to some populations.
Most of the territory of CLM experiences a semi-arid climate, with cold winters and warm summers. The distribution of precipitation is irregular and scarce throughout the year, with frequent periods of drought. In the regional southeast of CLM, desertification processes are on the rise. This encroachment advances from the provinces of Murcia and Almeria, which are the two most affected in Spain (CES, 2006).
The agricultural area of CLM consists of approximately 3,400,000 ha, 450,000 ha of which are irrigated land (PNR, 2000). In spite of being a low percentage (13.2%), lower than the national average of 20.9%, irrigated land plays an important social and economic role in the region. It enlarges the profit value of farms and contributes a greater degree of economic security to farmers. More than 90% of the regional water consumption is attributed to irrigated lands, which provides insight into the importance of implementing efficient water use in this sector (MAPA, 2006).
The main irrigable areas of CLM are intentionally situated close to groundwater sources, given that the greatest part of the surface water resources are appropriated to other uses in the regions of Comunidad Valenciana, Region de Murcia, Extremadura, Andalucia and Madrid. The aquifers included in the Hydrogeological Units (HU) 04.04 Mancha Occidental, 04.06 Campo de Montiel and 08.29 Mancha Oriental, are the main sources of water for more than half of the irrigated land area in the region. The rapid conversion of great areas into irrigated land during the last 30 years, along with a lack of planning and obsolete legislation, has permitted for the volume of water of extraction to exceed the volume which can be naturally replenished. As a result, two out of three aquifers have been declared overexploited and the third aquifer is on the brink of a similar plight.
This situation could be solved if CLM had a great enough water volume to supply its demands, or would reduce demands by more efficient irrigation. The second option would negatively affect the social and economic structure of the region, especially in the countryside, where a high percentage of the population would be forced to emigrate. An increase in water availability is needed for CLM. However, this outcome is not favored by neighboring regions, as from their points of view this would imply a reduction in the water that would be available for their uses.
The prospect of greater water resource shortages, greater dependency of regional agriculture on irrigated land, the overexploitation of natural resources, and the proliferation of land desertification has resulted in the establishment of several institutions, in CLM, that try to collectively solve problems. In an effort to integrate the management of water resource problems, the following agencies participate: public agencies, research centers, private companies and irrigation associations.
Through the Regional Water Research Centre (Centro Regional de Estudios del Agua, CREA), the University of Castilla-La Mancha (UCLM) is the institution that designates the greatest number of technical and human resources to resolving water resource problems. The principle objective of researchers of CREA is to achieve sustainability and to obtain the maximum efficiency in water use in the region.
The aim of this study is to show the methods introduced to try to solve the problems of a region of semiarid climate with limited legal availability of water resources to cover demand. The latest technologies are being applied to obtain the maximum efficiency in the sustainable use of water for irrigation. This process includes up to studies directed to quantify the availability of water in the future, due to the effect of climatic change, down to the evaluation of the irrigation systems in plots, to verify optimum operation and appropiate use by farmers.
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