Långsiktig trendanalys hur grundvattennivåer reagerar på nederbörd i Gårdsrydsfältet, Nybroåsen

Sammanfattning: Ground water are referred to one of Sweden’s most essential natural resources and constitutes an important part of the water management in Sweden, especially for the smaller municipalities. The ground water recharge in pore aquifer is mainly controlled by the difference between evapotranspiration and the amount of precipitation. The impact of climate change on ground water recharge was considered as a gap of knowledge with the release of IPCC’s fourth assessment report in 2007 and have just recently undertake research by scientists. The publications of scientific papers regarding this subject has increased and shows different and uncertain results. SGU has concluded that for both moraine and esker reservoirs, the annual average ground water table will fall in southeast Sweden as a result of climate change. This appears to occur in both emissions’ scenario RCP 4,5 and RCP 8,5. The objective of this study was to contribute knowledge concerning ground water recharge in eskers by quantifying the relationship between ground water levels and the amount of precipitation in an unconfined esker (Nybroåsen), outside Nybro, SE Sweden. Ground water level and precipitation data between 1970 and 2019 were obtained from Nybro Energi and SMHIs data observation stations, respectively. A correlations analysis was performed between average seasonal ground water level and the amount of seasonal precipitation, for autumn and spring during the years 1970–1989 and 2000–2019. The analysis demonstrates a moderate relationship during spring between 1970–1989, probably due to snowmelt and the percolation of accumulated precipitation. During spring in the 2000s, the analysis demonstrates a very weak relationship probably due to changes in temperature patterns during winter observed by SMHI in the country Kalmar, in which milder winters and the absence of ground frost have become more common. The analysis demonstrates a very weak relationship during autumn because of the meteorological and hydrological factors that inhibit ground water recharge until December.