Drought experts met in Brussels on 22 – 24 February to attend the Xerochore Final Conference on Supporting Drought Policies in Europe. Xerochore is an EU funded research project designed to assess research needs and policy choices on drought for the EU. The conference brought together planners, water resource experts, environment specialists, climatologists, and economists to discuss the challenges of drought identification and characterisation, the environmental and socio-economic impacts of drought, and management choices and policy options for drought based on EU Member State and overseas experience.
Drought affects water quantity and quality. As streams and rivers dry up organic matter becomes more concentrated in the water which also becomes warmer due to higher air temperatures. This not only puts stress on our water systems designed to deliver drinking water but also those designed to clean water for drinking and for treating wastewater. Fish and other aquatic species are highly vulnerable to drought conditions due to reduced water flows and increases in toxins such as algal blooms due to warmer temperatures and less freshwater.
Droughts can also have less immediate and direct impacts on our environment. Forests can often suffer during drought due to lack of water, the build up of dry matter in large quantities, and episodes of insect and disease outbreaks. The risk of forest fires increases and ironically, can often be started by lightning from developing rainstorms. Rain falling on areas following forest fires can also wash toxic carbon and nitrate concentrations in drainage flows into rivers and streams, raising concerns over the impact on freshwater biodiversity, and maintaining public drinking water quality.
Droughts may also reduce water in the soil. This in turn can reduce soil fertility and structure, affecting water holding capacity of the soil for plants and growing crops. Fertile topsoil may also be lost where dry soil is blown away where wind speed increases during hot and dry drought conditions. Drought conditions can impose limitations on the productivity of terrestrial ecosystems such as their ability to cycle essential chemicals such as carbon, especially where forests and other vegetation die and peatlands dry out.
Major impacts of drought on biodiversity may include changes in seasonal timings, shifts in the distribution of species, changes in habitat composition and structure as species move northwards, including the expected increase in invasive species and diseases, and the impact of changing land use as agriculture, water, forestry and other countryside industries and interests react to water stress. According to The Status and Distribution of Freshwater Fish Endemic to the Mediterranean Basin, drought is reported as a past threat for 41 species, a present threat for 112 species, and a future threat for 180 species. The disappearance of breeding habitats due to drought is also enlisted as one of the biggest impact threatening the survival of Mediterranean dragonflies.
2010 is the International Year of Biodiversity and natural flow regimes are a key component to maintaining healthy rivers that provide the necessary ecosystems goods and services for a biodiverse environment. This is especially important when prolonged drought exacerbate the effects of changes in river flows on freshwater ecosystems. Water chemistry alike, aquatic organisms can be significantly impacted by reductions in dissolved oxygen, changes in water temperature, concentration of nutrients and pollutants and sediment loads, all of which can have severe impact on downstream fisheries as far as open sea. That said, it is no coincidence that this year World Water Day focuses on Clean Water for a Healthy World and will raise awareness on the importance of water quality for human health and the environment.
Among the many valuable services that healthy ecosystems provide besides preserving biodiversity is the storage of water, a critical factor in coping with droughts. Particular attention should be paid to the role of green or natural infrastructure in increasing resilience to drought – areas such as wetlands, groundwater and lakes, which can help society and the environment cope during periods of water stress. Europe has taken action to improve the status of its rivers but achieving good water quality by 2015 will require that synergies are found between nature conservation and sectoral policies, with special focus on restoring many water regimes. In this context, the Drought Conference also included an EU Science-Policy forum, a closed session with DG Environment, DG Research, and a representative from the European Parliament to discuss the outcomes of the Xerochore project and future policy options for coping with drought in Europe for the future.