Drought in Belgium
The figure below shows the expected trend of drought and precipitation surplus. The red line represents the average precipitation total of the last 90 days of whole Belgium. The green and the blue line show the trend of the wettest and driest periode of the same but past time span.
The following map shows the spatial distribution of the aridity index. The aridity index is calculated by the standardised index of the cumulative rainfall of the past 90 days (SPI-3). The index is divided into three classes: "wet/dry", "very wet/very dry" and "extremely wet/extremely dry". These classes refer to a climatic reference period from 1981 until 2010. These periodes return empirically every 10 to 30 years, 30 to 50 years and more than 50 years. The forecast of the aridity index is claculated with the cumulative rainfall of the last 80 days and the forecast of the cumulative rainfall for the coming 10 days. The forecast is provided by the European Centre for Medium-Range Weather Forecasts (ECMWF).