Juan Garcia R. Large losses of rainwater in Spain.
Newspaper Information Page 20, 23/06/2008 , Alicante , Spain .
In a country where the regime of rainfall is so variable and the average annual precipitation is considered moderate such as Spain , highlights the importance of establishing the mechanisms needed to achieve a greater grade of rainwater harvesting. In February 2008, Spain suffered the worst drought in recent decades in the area of the Mediterranean not had a very dry winter for 77 years, the volume of water reservoirs in the country at the beginning of February stood at 23352 hm3 for a 43% of the capacity of the reservoir.
In mid-April, the drought continues, the reservoirs have recovered a little, water reservoirs in the country was 26 068 hm3 for 48% of the capacity of the reservoir. The month of May is behaving as very wet, the observatory of the Meteorological Station of the Ebro, located in Tarragona has recorded a cumulative monthly rainfall of 229 mm, reporting that the month of May is the rainiest in the lower Ebro since 1880, reaching the Ebro river water flow up to around 1800 m3/second, also in Valencia located in the Mediterranean in an area of low rainfall was reported in May as wet, with an average value of accumulated rainfall of 132 mm, so there is a great variability of rainfall regime in Spain.
In early June rains accumulated in the country during the month of May has made it possible to increase the volume of water reservoirs, reaching a value of 32,585 hm3, which represents 60% of the capacity of the reservoir. When comparing the volume of water reservoirs in mid-April with the accumulate volume at the beginning of June there was an increase in the volume of reservoir of 6517 hm3, representing an increase of 12% capacity of the reservoir.
The historical average annual rainfall of Spain are of 684 mm and the average accumulative rainfall in the country in the past 45 days are higher than 150 l/m2, which are considered high for the time period analyzed in mid-April to start June, despite the heavy rains, increased water retained in the reservoirs is still insufficient, given the huge losses of runoff, as has been regulated only less than 10% of rainfall, which reflects that we still have problems with increasing use of rainfall during periods of plenty, to cope with the lack of water in the dry season, so it is necessary to regulate more runoff and increase the number of reservoirs in different basins, the lead water surplus to deficit basins and other sub-basins, clean accumulate materials in reservoirs to increase the volume of usable water, combating floods, make more rational use of water and increase aquifer recharge, reforestation, protect watersheds and controlling water quality.
Despite the abundant rains in Spain in the time period analyzed, the water shortage in the medium term continues in the Mediterranean area, as increased water reserves in aquifers, but a watershed in that region, integrated by the basins: South, Segura, Jucar and Cataluña, only collected less than 5% of the capacity of reservoirs in the country, is not included in the Mediterranean coastal region analysis of water reserves in the reservoir basin Ebro, since these stocks were formed in Spain Continental and not in Mediterranean Spain and tend to mask the reality of lack of water by passing through the area.
On many occasions periods of drought and rains appear one after the other, so we must develop a plan for simultaneous fight drought and floods and for the rational use of surface and underground water, with the aim of achieving greater use of the rains, so that we were less exposed to change of the weather and the units can be reached harvests more stable and lower production costs per ton of agricultural production, reduce economic losses as a result of drought and floods and ensure a stable water to the population, tourism, agriculture and industry. We must develop an investment plan and measures for reservoirs has run into each basin depending on the potential of each basin and user demand, as it reviewed the actual use we have in each reservoir in order to determine the volume of water available and the quality of water in each case, because now we have some reservoirs that guarantee very little usable water.