Current and future state of groundwater salinization of the northern Elbe-Weser region

M. Azizur Rahman,Jörg Elbracht,Helga Wiederhold,Nico Deus,Eva González

doi:10.1007/s00767-021-00496-w

Abstract

Salinization of the upper aquifer of the northern Elbe-Weser region almost extends to the surface. Chloride content exceeds 250 mg/l and the groundwater is therefore, according to the German Drinking Water Ordinance, not suitable as drinking water. The chloride content in the aquifer originates from early flooding with seawater which occurred during the Holocene sea level rise. Depth and extent of the salinization were mapped by airborne electromagnetic surveys and validated by groundwater analyses. In the transition zone between the marshlands and geest areas, the fresh-saline groundwater interface falls to a depth of > −175 m NHN. Due to the extensive drainage of the marshlands, seepage of fresh groundwater is impeded. Instead, an upconing of the fresh-saline groundwater interface appears due to an upwardly directed hydraulic gradient. Due to climate change, chloride concentrations will increase along the coastlines. Further inland, a decrease of chloride content in near-surface groundwater will occur.

Highlights

Project areaIn coastal areas around the world, including Lower Saxony, salinization of the upper aquifer is a serious challenge for public water suppliers
Present day salinity distribution based on helicopterborne electromagnetic data (HEM) data
The map is based on the fresh-saline groundwater interface modelled by using the HEM data (Fig. 3)

Summary

Introduction

Project areaIn coastal areas around the world, including Lower Saxony (northern Germany), salinization of the upper aquifer is a serious challenge for public water suppliers. A consistent high quality of groundwater is important for maintaining the public water supply. It is a challenge for the agricultural sector, even though a chloride concentration of up to 1000 mg/l is acceptable for watering (Kamphues et al 2007). 1 m NHN and is lower than its natural state This results in an extensive upconing of salinized groundwater within the marshlands. In addition to sea level rise, changing parameters in the water balance, i.e., groundwater recharge, precipitation and evaporation, and the resulting increase of drainage, play an important role (Feseker 2007; Green et al 2011; Rasmussen et al 2013). To prevent deterioration of the groundwater quality, different adaptation strategies are required

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