Talk, Fourth BHS International Conference, Cranfield, UK: 2016-08-30 - 2016-09-01
Abstract:
Recent field and modelling research has acknowledged the hyporheic zone as connecting interface between river and groundwater systems, and its functional significance to river ecosystems. However, our understanding of the interacting factors driving hyporheic exchange at large scales (i.e. from segment to landscape) is fragmentary and further evidence is needed to link local hyporheic exchange flows across scales. Therefore through a critical review of recent literature, we have developed a conceptual model of the hyporheic exchange that details how drivers operating at catchment, valley and reach scales are responsible for spatial and temporal variations in exchange. This work is based on a conceptual understanding of surface-groundwater interactions from published reviews and field studies on hyporheic exchange placed within a hierarchical river processes framework. First the factors that influence the presence and hydraulic functioning of the hyporheic zone were identified, and evidence gathered on their cumulative impact at stream and catchment-scale. Then, data across 8 UK catchments were collected from public and private repositories and analysed in order to identify indicators of hyporheic exchange.. Statistical tools such as Principal Component Analysis and clustering technique were used to develop unsupervised decisional systems that define potential hyporheic exchange at different scale. This approach was tested using field-site information from recent literature studies. The outcomes of the study will benefit fundamental research in hyporheic zone by providing an integrated approach of the drivers of hyporheic exchange across spatial and temporal scales. It will also benefit river restoration and catchment management through the identification of areas characterized by hyporheic exchange sites and therefore defining the methods and criteria for maximizing hydrological and ecological benefits. Finally the hierarchical approach will help foster a cross-scale perspective of the hyporheic zone that will highlight possible catchment-scale solutions to reach-scale problems.