Projected impact of climate change and chemical emissions on the water quality of the European rivers Rhine and Meuse: A drinking water perspective.

Low river discharges of the rivers Rhine and Meuse are expected to occur more often and more prolonged in a changing climate. During these dry periods the dilution of point sources such as sewage effluents is reduced leading to a decline in chemical water quality. This study projects chemical water quality of the rivers Rhine and Meuse in the year 2050, based on projections of chemical emissions and two climate scenarios: moderate and fast climate change. It focuses on specific compounds known to be relevant to drinking water production, i.e. four pharmaceuticals, a herbicide and its metabolite and an artificial sweetener. Hydrological variability, climate change, and increased emission show a significant influence on the water quality in the Rhine and Meuse. The combined effect of changing future emissions of these compounds and reduced dilution due to climate change has leaded to increasing (peak) concentrations in the river water by a factor of two to four. Current water treatment efficiencies in the Netherlands are not sufficient to reduce these projected concentrations in drinking water produced from surface water below precautionary water target values. If future emissions are not sufficiently reduced or treatment efficiencies are not improved, these compounds will increasingly be found in drinking water, albeit at levels which pose no threat to human health.

Effects of a drought period on physico-chemical surface water quality in a regional catchment area.

Hydrological drought periods are expected to become more severe in North-Western Europe as a result of climate change. This may have implications for water quality, as demonstrated by declining water quality of large rivers (e.g. Rhine, Meuse) during droughts. However, similar investigations in regional catchment areas are lacking to date. In the present study, we investigated the effects of a drought period on the water quality of the Dommel River, a tributary of the Meuse river in the Netherlands. Water quality during the drought of 2003 was compared to that in reference years (2004-2006) for 18 physical/chemical parameters using ANOVA analysis. It was demonstrated that the drought period of 2003 did not significantly affect water quality, although the origin of river flow during the drought shifted from mainly overland flow to deep groundwater flow and (treated) communal effluents. Significant differences in water quality were noted for some monitoring stations during the study period, which could be related to operational water management such as cleaning of sediment traps in the river and improvements in communal effluent treatment. The results of this study are interesting to water managers in Western Europe as they contribute to understanding the potential impact of climate change on water quality/quantity patterns in regional water systems.