Drought of 2004-2007
Drought Event Summary
2004 and 2005 were characterized by dry conditions affecting most of western Europe, but particularly the Iberian peninsula. This period is considered the most severe drought in the hydrologic record of both Portugal and Spain, primarily in the central and southern regions.
Dry conditions remained after drought peaks of July and October of 2005, reoccurring to a lesser extent in the summer of 2006. 2006 also produced a moderate drought in the Baltic region, though this is not the focus of this analysis.
Approx. duration: 7/2004-6/2007
Date of SPI-6 min: 25/2/2006
Affected regions: Iberian peninsula
Drought conditions began during the summer of 2004, with a severe meteorological drought centered in Portugal. Drought conditions returned closer to normal in the Iberian peninsula during the fall of 2004, though precipitation in Italy was significantly lower than typical during this period as well.
By February 2005, climatological drought conditions returned to the Iberian peninsula. This lack of rainfall increased to an extreme in July 2005 and again in October. Drought conditions were almost entirely centered in Spain and Portugal, with the rest of Europe experiencing typical conditions.
Progression of climatological (SPI-6) drought. Climatological drought is defined by the SPI-6, which sums precipitation over the previous 6 months and transforms this value to the standard normal distribution. Negative SPI values (shown in red) represent dry conditions, measured in standard deviations from typical conditions. Percent area in drought is calculated by summing all cells less than the 20th percentile (SPI < -0.84).
In parallel to this Iberian drought cycle significant impacts of drought were reported in other parts of Western Europe, like in France in 2005 (EC, 2007) or in Southern Britain during 2004-2006 (Marsh, 2007; Marsh et al., 2007). Yet, for Portugal and Spain this drought episode, evolving from the winter of 2004/2005 onwards, is considered to be one of the worst events in recent times that caused major socioeconomic impacts particularly regarding hydropower and crop production (García-Herrera et al., 2007; Massarutto et al., 2013; EC, 2006; EC, 2007). In 2005 Portugal declared a calamity status at national level and a temporary "Drought Commission" (Comissão para a seca) was established on governmental initiative (Massarutto et al., 2013). According to EM-DAT the drought disaster from 2004-2005 in Portugal had an estimated economic cost of more than 1.3 billion US-Dollars.
Location of drought impact reports. Darker colors refer to more reported impacts in the EDII. Scroll over each country to see more detail.
Due to the exceptional dry conditions in the hydrological year 2004-05 agriculture suffered from extreme yield losses and even complete failure for virtually all kind of crops, but especially in rain-fed farming (Comissão para a seca, 2005; USDA-Foreign Agricultural Service, 2005, García-Herrera et al., 2007; Gouveia et al., 2009). Cereal production (of both Iberian countries) dropped to only 60% of average (García-Herrera et al., 2007) and, in particular there was a severe shortage of wheat (Gouveia et al., 2009). In Portugal vegetation in the South was most affected by drought stress in 2005 – in a region, which due to its semi-arid characteristics is generally dominated by rainfed agriculture, and with the Alentejo region alone being responsible for more than 80% of the total of wheat production in Portugal (Gouveia et al., 2009). Extremely poor pasture conditions, premature cutting and problems with availability of water in the field threatened livestock farmers. This was also evident in an increased number of abortions of ruminants in Portugal in 2005 (Comissão para a seca, 2005). The costs incurred due to drought impacts in the agricultural sector in 2004-2005 in Portugal and Spain were quantified to 0.5 billion and 2-3 billion Euros, respectively in EC (2007). In both countries rather strict restrictions of irrigation water use became effective in many regions during the growing season in 2005 and also in following years. In many areas the (irrigated) cultivation area was considerably reduced. On the other hand, the prolonged drought episode apparently increased incentives for drilling (illegal) boreholes to access ground water for irrigation in Spain (WWF, 2008).
Due to low stream flows throughout the Iberian Peninsula many of the (multi-functional) surface water reservoirs had been heavily depleted at the end of the summer in 2005; this fact increased tension in water management and led to large political and social unrest (García-Herrera et al., 2007). The low water availability was also a major problem for terrestrial and aerial firefighting when Portugal faced again devastating wildfires: regardless of efforts, the summer of 2005 was the second worst (after 2003) in recorded wildfire history with 325,000 ha burned (Massarutto et al., 2013). In terms of water resources, Algarve was at that time the most affected region in Portugal, with two important dams below usable capacity levels as well as significant saline intrusion in its most important aquifer (EC, 2006; Comissão para a seca, 2005). In late August about 100,000 people in municipalities across Portugal were affected by limitations in water supply (Comissão para a seca, 2005; EC, 2006). There was a suspect that a remarkable number of Hepatitis A and Salmonellosis cases had been related to the use of alternative (emergency) water supply systems (Comissão para a seca, 2005). Portugal spent in total 23 million Euros on drought mitigation measures regarding only water supply (EC, 2007). Also 118 small villages in the Pyrenees suffered strong water restrictions during the summer of 2005 and supply by cistern trucks was necessary for 60 villages (Ministerio de Medio Ambiente, Medio Rural y Marino, 2008) as well as for several cities within the Douro basin in Central Spain (Confederación Hidrográfica del Duero, 2007).
The extremely low river flows between December 2004 and June 2005 directly affected Iberian hydropower production which in 2005 decreased to only 40% of the average and both countries were forced to massive imports of fossil fuel resources to compensate this by thermoelectric production (García-Herrera et al., 2007). Portugal had to use additional fossil fuel worth 182 million Euros with another expense of about 28 million Euros for annual CO2 emissions licenses in 2005 (EEA, 2010). Due to drought impacts in the Energy sector in 2004-2005 Portugal and Spain incurred costs of 261 and 713 million Euros, respectively (in EC, 2007).
Reported impacts on ecosystems in Portugal include deterioration of water quality, increased algal bloom and eutrophication of surface waters, and increased salinity of groundwater including significant saltwater intrusion in the Algarve region (Massarutto et al., 2013). In some streams, fish populations were severely depleted due to extreme low flow conditions prevailing in the severe drought year of 2005 (Comissão para a seca, 2005). In particular, increased mortality and likely local extinction of an endangered and endemic freshwater fish species from Guadiana river basin was observed (Cardoso & Carrapato, 2007 in Massarutto et al., 2013). Fish kill was also observed in Spain (Ministerio de Medio Ambiente, Medio Rural y Marino, 2008). It seems that the reduced freshwater flows also had effects on estuarine fish species (Dolbeth et al 2008, Martinho et al 2007). Further, there are some indications of adverse effects on grassland and wetland bird species (Massarutto et al., 2013). Carnicer et al. (2011) studied increasing defoliation and tree mortality trends observed for Southern Iberian forests over the last two decades in relation to the two severe drought episodes (1990-1995 and 2005-06).
Corresponding to the clear peak of the climatological drought in the summer of 2005 , the great majority of recorded impact reports in the inventory refers specifically to 2005. However, a few notable incidents in the following years were reported. Those concern mostly water management issues and drought impacts on freshwater ecosystems in different regions of Spain (see Ministerio de Medio Ambiente, Medio Rural y Marino, 2007), like e.g. fish kill and hosepipe bans, but also local cuts in domestic supply. Due to the sustained drought conditions the important Entrepeñas–Buendía reservoir system in the Tagus basin (constructed for hyperannual management) was neither in 2005 nor in 2006 able to satisfy demand, thus managers were obligated to reduce flow to both the Tagus River and the depended water transfer system to the Júcar and Segura basins; this, like in previous droughts, resulted in conflicts and political ramifications at the national level (Lorenzo-Lacruz et al., 2010). Finally, just before rains in spring 2008 brought significant relief for most of the country, Barcelona had taken the unprecedented step of importing a tanker of emergency water from Marseilles (WWF, 2008; Demuth, 2009; EEA, 2010). In addition, this emergency situation prompted the construction of a new water transfer scheme from the Ebro river to Barcelona (WWF, 2008).
Impact Detail Table
|Drought Event||Country||Start Date||End Date||Impact||Impact Category||Impact Description||NUTS 1||NUTS 2||NUTS 3||Reference|
|2003 Europe||Deutschland||5/2004||2.4||Increase of pest/disease attacks on trees (please specify species in the description field!)||Since the middle of Mai 2004 mass propagation of Phyllaphis fagi was observed in consequence of the summer drought in 2003.||Rheinland-Pfalz;|