Impacts of the 2018 summer drought on the Dutch part of the Rhine river

Abstract

Rivers and river ecosystems provide essential services to the earth’s natural processes and to society. Droughts are a threat to these ecosystems that rely heavily on the availability of water. Especially in areas like the Netherlands, where ecosystems are used to a wet climate, droughts can have severe impacts. In the summer of 2018, the Netherlands experienced one of its most severe droughts. Measures were taken to protect drinking water quality, and research after the drought also mainly focused on impacts on drinking water. No studies have been done on the impacts on river ecosystems. Therefore, this study aims to answer the following research question: What impact did the drought of 2018 have on the Dutch part of the Rhine river in terms of discharge, temperature, pH, dissolved oxygen content, and ammonium concentration? These parameters will serve as indicators of several drought impacts on river ecosystems, namely: habitat loss, heat stress, oxygen stress, and toxicity. Statistical analysis comparing the summer of 2018 to the summers of the years 2009- 2017 found a significant difference on the parameter temperature, but not on any of the other parameters. From this, it is concluded that heat stress was an impact of the 2018 drought, while oxygen stress and habitat loss were not. Toxicity as an effect of ammonium was not indicated by the results of the analysis, toxicity due other toxic compounds not included in this study was proven to be an impact of the 2018 drought as well.