Large-scale drought: a pan-European view of the hazard, impacts and adaptation

Large-scale drought: a pan-European view of the hazard, impacts and adaptation

Henny A.J. Van Lanen, European Drought Centre / Wageningen University

*Scroll to the bottom to see the video in streaming*

Drought is one of the most costly weather-related natural hazards. Droughts regularly occurred in Europe and had major socio-economic and environmental impacts. For example, the estimated costs of the 2003 drought are about € 8.9 billion. We show that different drought types (meteorological, soil water and hydrological) need to be distinguished to understand the impacts and to adapt to these. Such understanding is required for an adequate drought management and drought policy making.

The influence of climate on the development of meteorological, soil water and hydrological (groundwater and streamflow) drought is illustrated for the temperate-humid and cold continental climates (climate control). We illustrate that in addition catchment control (e.g. groundwater response) has major effect on drought characteristics.

We show some recent databases that provide information on major droughts across Europe over the last 50-60 years. The European Drought Catalogue lists monthly information on proportion of the area under drought in 24 homogeneous regions where streamflow was below a threshold. The European Drought Reference (EDR) database provides detailed historical information regarding major historical European drought events. Each drought event is summarized using climatological drought indices, hydrological drought indices, and user-generated drought impacts. Recently, a database has been published that gives the characteristics per European region of properties of meteorological drought (duration, severity, largest area covered). These databases are essential to answer the question, if drought has become more severe in Europe. We show that in general annual river flow became higher in northern Europe and lower in southern Europe over the last half a century. However, the streamflow in August decreased in most of Europe (except Scandinavia). A multi-model analysis confirms that decline in August flow also likely happened in south-eastern and eastern Europe, where access to observed river flow is very restricted. We illustrate that trends in drought characteristics are dependent on the length of the time series, start and end year.

Maps of Europe show that the frequency of meteorological droughts will increase in multiple regions in Europe in the near future (2041-2070). This applies to more areas, if not only the precipitation, but also the change in evaporation is considered. An analysis using reasonably-performing models in the past, points out that hydrological drought in snow-affected river basins will decrease, but in other basins it will increase, particularly during the dry season. We demonstrate that the influence of climate change on duration and severity of hydrological drought is dependent on possible adaptation. If people could adapt to the gradually changing hydrological regime, then impact of climate change will be substantially smaller.

Impacts of historic drought from text sources for different sectors have been systematically collected. About 5000 impacts have been stored in the European Drought Impact Inventory (EDII). Logistic regression has been applied to connect these impacts to drought severity. We will show the likelihood of occurrence (risk proxy) of drought impacts for four different sectors (Agriculture & Livestock farming, Energy & Industry, Public water supply, Water quality) dependent on the meteorological drought severity. Clear differences occur across countries and among impacted sectors, e.g. Agriculture & Livestock farming is more impacted in the Mediterranean, whereas the Energy & Industry sector is more affected at the mid latitudes. Among others this outcome has been discussed in Drought Dialogue Fora (DDFs) at different scales (river basin, national, European Union). Vulnerability factors have been identified. Maps have been compiled. We will illustrate that about 30% of the European population is living in regions that have a high to very high vulnerability.

The high risk associated with drought in many European regions requires a pro-active risk management rather than a reactive crises management that was common in the past. A WMO/GWP template is available that describes the different steps to achieve at a national drought policy and Drought Management Plans (DMPs). Drought policy options have been identified for different cases in Europe. We will illustrate a few of these for Portugal, where the potential of these options have been ranked against policy goals (i) contribution to drought mitigation, (ii) economic viability, (iii) social acceptance, (iv) environmental implications, and (v) technical feasibility. Except increasing public awareness, none of the options supports all five policy goals. A key element in a DMP is, how an ongoing drought is managed. An example is provided that describes that the following key elements are needed: (i) monitoring hydro-meteorological variables, (ii) weather forecast, preferably with lead times up to a month or more, (iii) hydrological modelling, (iv) impact modelling to explore the effects of potential measures to reduce the impacts, and (v) decision support systems. This information is the basis for the regular (e.g. weekly) meetings of the Drought Management Committee (stakeholders, water managers, policy makers) to decide on the best measures using a prior-ranking that has to be set before the drought starts.

We will conclude with some research challenges about trend studies, drought projections, forecasting, impact collation, drought management including its context, and the influence of people. We make clear that there is no one-size jacket that fits all to reduce drought risk. An interdisciplinary scientific approach is required as part of a drought dialogue with all groups around the table directly from the beginning.

Download the video!

• High resolution Download
• Medium resolution Download
• Low resolution Download