Drought in Water Abundant Finland - Data and Tools for Drought Management

Droughts pose a risk to all societies, even those with abundant water resources. Climate change will affect this risk, and societies should adapt accordingly. Though Finland has a low drought risk, recent droughts have had a clear impact, especially on agriculture and water supply, but also forestry, hydropower, and ecosystems. While Finland's water governance and water security are generally at a good level, drought has so far gained little attention and operative drought management plans and strategies are absent. This dissertation studies drought risks in Finland and provides recommendations on how to improve drought management. Drought risk can generally be understood as a combination of three factors: vulnerability, exposure, and hazard. Several drought indices, models, and weather data generation are used in the dissertation to better understand drought hazard and to quantify drought frequency, severity, and other characteristics of drought events in Finland. The dissertation also considers how drought hazard might change due to climate change. The results are discussed in relation to different sectors and within the broader water governance context in Finland. The results from the drought index analyses provide detailed information on drought characteristics in Finland. The findings show that choosing the best drought indices for different contexts is difficult, emphasizing the need to use several indices. For the Sirppujoki basin case study (a river basin in southwestern Finland), 20 different standardized drought indices were calculated for two drought events of 2002–2003 and 2018 as well as for the years 2040–2069. In addition, weather data generation coupled with hydrological modeling was tested for the basin. This dissertation reveals that drought risks will likely increase due to climate change, predominantly in the south and southwest Finland. Based on evapo-transpiration-dependent indices, drought events are predicted to increase especially during the growing season. This is particularly worrying for the agricultural sector, since only a few percent of fields have irrigation systems. However, the climate scenarios have a large variation, emphasizing the need for more research as well as flexible climate change adaptation. To address the growing drought risk in Finland, adaptation measures against drought impacts are suggested. A national drought strategy, together with bot-tom-up drought management plans, would mitigate the increasing drought risks. These should be accompanied with a systematic drought management process with an early warning system.