Climate Change Induced Salinization of Drinking Water Inlets along a Tidal Branch of the Rhine River: Impact Assessment and an Adaptive Strategy for Water Resources Management

Matthijs Van Den Brink,Gertjan Zwolsman,Ymkje Huismans,Meinte Blaas

doi:10.3390/cli7040049

Abstract

This study presents the results of an impact analysis of climate change on salinization and the long-term availability of drinking water resources along the river Lek, a tidal branch of the Rhine delta, and a potential mitigation measure. To this end, a one-dimensional modelling approach was used that enabled studying 50 years of variation in discharge and tide in current and future climate. It was found that all locations are increasingly vulnerable to salt intrusion caused by the combination of sea level rise and decreasing river discharges. This affects both the yearly average chloride concentration and long duration exceedances of the threshold value of 150 mg/L. It was also found that diverting a higher fresh water discharge to the Lek of several tens of cubic meters per second reduces the risk of salinization at the upstream inlet locations. However, the increased influence of seawater intrusion on the drinking water inlets cannot be fully compensated for by this measure. The potential gain of the extra water for the drinking water inlets along the Lek has to be balanced against the impact of this measure on water levels and stream flows in other parts of the river system.

Highlights

The Netherlands constitute a densely populated part of the Rhine–Meuse delta
The vulnerability of the drinking water inlets to salt intrusion is indicated by exceedance of the maximum allowable chloride concentration in drinking water in The Netherlands (150 mg/L)
The vulnerability of the drinking water inlets is analysed in three steps

Summary

Introduction

The Netherlands constitute a densely populated part of the Rhine–Meuse delta. Due to an annual precipitation surplus of 300 mm and border crossing discharges of the Rhine and Meuse rivers (averaging at 2200 m3 /s and 230 m3 /s respectively), fresh water supply has not been an issue before long. The country’s limited elevation and the proximity of the sea make The Netherlands vulnerable to seawater intrusion and salinization of freshwater inlets. Seawater intrusion in river deltas is largely governed by two variables, both subject to climate change: . Climate projections for The Netherlands show an estimated sea level rise of 0.15 to. 0.40 m in the year 2050, and an increase of 0.25 to 0.80 m by 2085, compared to the reference year [1].

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Results

Conclusion