Towards improved instrumentation for assessing river-groundwater interactions in a restored river corridor

摘要

River restoration projects have been launched over the last two decades toimprove the ecological status and water quality of regulated rivers. As mostrestored rivers are not monitored at all, it is difficult to predictconsequences of restoration projects or analyze why restorations fail or aresuccessful. It is thus necessary to implement efficient field assessmentstrategies, for example by employing sensor networks that continuouslymeasure physical parameters at high spatial and temporal resolution. Thispaper focuses on the design and implementation of an instrumentationstrategy for monitoring changes in bank filtration, hydrologicalconnectivity, groundwater travel time and quality due to river restoration.We specifically designed and instrumented a network of monitoring wells atthe Thur River (NE Switzerland), which is partly restored and has been mainlychannelized for more than 100 years. Our results show that bankfiltration – especially in a restored section with alternating riverbedmorphology – is variable in time and space. Consequently, our monitoring network has been adapted inresponse to that variability. Although not available at our test site, weconsider long-term measurements – ideally initiated before and continuedafter restoration – as a fundamental step towards predicting consequencesof river restoration for groundwater quality. As a result, process-basedmodels could be adapted and evaluated using these types of high-resolutiondata sets.