HESS Opinions "Integration of groundwater and surface water research: an interdisciplinary problem?"

Abstract

Abstract. Today there is a great consensus that water resource research needs to become more holistic, integrating perspectives of a large variety of disciplines. Groundwater and surface water (hereafter: GW and SW) are typically identified as different compartments of the hydrological cycle and were traditionally often studied and managed separately. However, despite this separation, these respective fields of study are usually not considered to be different disciplines. They are often seen as different specializations of hydrology with a different focus yet similar theory, concepts, and methodology. The present article discusses how this notion may form a substantial obstacle in the further integration of GW and SW research and management.The article focuses on the regional scale (areas of approximately 10 3 to 10 6 km 2 ), which is identified as the scale where integration is most greatly needed, but ironically where the least amount of fully integrated research seems to be undertaken. The state of research on integrating GW and SW research is briefly reviewed and the most essential differences between GW hydrology (or hydrogeology, geohydrology) and SW hydrology are presented. Groundwater recharge and baseflow are used as examples to illustrate different perspectives on similar phenomena that can cause severe misunderstandings and errors in the conceptualization of integration schemes. The fact that integration of GW and SW research on the regional scale necessarily must move beyond the hydrological aspects, by collaborating with the social sciences and increasing the interaction between science and society in general, is also discussed. The typical elements of an ideal interdisciplinary workflow are presented and their relevance with respect to the integration of GW and SW is discussed.The overall conclusions are that GW hydrology and SW hydrogeology study rather different objects of interest, using different types of observation, working on different problem settings. They have thus developed a different theory, methodology and terminology. However, there seems to be a widespread lack of awareness of these differences, which hinders the detection of the existing interdisciplinary aspects of GW and SW integration and consequently the development of a truly unifying interdisciplinary theory and methodology. Thus, despite having the ultimate goal of creating a more holistic approach, we may have to start integration by analyzing potential disciplinary differences. Improved understanding among hydrologists of what interdisciplinary means and how it works is needed. Hydrologists, despite frequently being involved in multidisciplinary projects, are not sufficiently involved in developing interdisciplinary strategies and do usually not regard the process of integration as such as a research topic of its own. There seems to be a general reluctance to apply a (truly) interdisciplinary methodology because this is tedious and few immediate incentives are experienced.The objective of the present opinion paper is to st...

Promising new baseflow separation and recession analysis methods applied to streamflow at Glendhu Catchment, New Zealand

“…The feeling that catchment drainage can be treated as a single continuum of hydrological behaviour has probably prevented recognition of the disparate natures of the quick and slow drainages. This may be a symptom of the fact that surface water hydrology and groundwater hydrology can be regarded as different disciplines (Barthel, 2014). Others however are crossing the divide by examining geological controls on BFIs (Bloomfield et al, 2009) and relating baseflow simulation to aquifer model structure (Stoelzle et al, 2015).…”

Index‐Based Characterization and Quantification of Groundwater Dynamics

“…Their purpose was usually to monitor the impact of such activities, rather than to observe natural fluctuations. This can be seen as a general problem associated with groundwater time series and a fundamental difference to surface water hydrograph analysis (Barthel, 2014). We have accounted for this by a careful visual analysis of the hydrographs used and removal of those with strong indications for anthropogenic influences.…”

“…Additionally, it is not clear a priori which subsurface processes contribute to the signal. In other words, a streamflow time series can be seen as the output of a gray box system, while groundwater time series pierce a small and unknown volume within the gray box, where it is unclear what portions of the system contributes to that particular volume (cf., e.g., Barthel, 2014, for elaborate discussion). As a result, groundwater time series can take a variety of shapes and forms that are unseen in streamflow (cf.…”

Assessment of regional inter-basin groundwater flow using both simple and highly parameterized optimization schemes

“…Another important challenge with regard to integrated-water-resource-management, in particular at the regional scale, is that most of the currently existing hydrological models do not contain dynamic physically based coupling between surface water and groundwater or unsaturated zone and evapotranspiration processes (Jing et al 2017). Even if the groundwater component is included in the models, they are often calibrated using only surfacewater observations (Barthel 2014) or applied under a steadystate assumption (Sonnenborg et al 2003;Meyer et al 2018), mainly due to the high computational burden of transient description. The importance of considering dynamic groundwater flow for the proper representation of the hydrological processes at the catchment scale has been emphasized by many researchers (e.g., Brunner et al 2008; Ghasemizade and Schirmer 2013;Jiang et al 2017).…”