Ecohydrologic separation alters interpreted hydrologic stores and fluxes in a headwater mountain catchment. Issue 20 (6th August 2019)

• Record Type: Journal Article
• Authors: Cain, Molly R.; Ward, Adam S.; Hrachowitz, Markus
• Is Part Of: Hydrological processes. Volume 33:Issue 20(2019)
• Page Start: 2658
• Page End: 2675
• Publication Date: 2019-08-06
• Subjects: conceptual model -- hydrologic connectivity -- plant water sources -- preferential flow -- residence times -- soil water -- tracer -- two‐water worlds hypothesis; Hydrology -- Periodicals; Hydrology -- Research -- Periodicals; Hydrologic models -- Periodicals; Hydrological forecasting -- Periodicals; 631.432
• DOI: 10.1002/hyp.13518
• Languages: English
• ISSNs: 0885-6087

Abstract

Abstract: Recent studies have demonstrated that compartmentalized pools of water preferentially supply either plant transpiration (poorly mobile water) or streamflow and groundwater (highly mobile water) in some catchments, a phenomenon referred to as ecohydrologic separation. The omission of processes accounting for ecohydrologic separation in standard applications of hydrological models is expected to influence estimates of water residence times and plant water availability. However, few studies have tested this expectation or investigated how ecohydrologic separation alters interpretations of stores and fluxes of water within a catchment. In this study, we compare two rainfall‐runoff models that integrate catchment‐scale representations of transport, one that incorporates ecohydrologic separation and one that does not. The models were developed for a second‐order watershed at the H.J. Andrews Experimental Forest (Oregon, USA), the site where ecohydrologic separation was first observed, and calibrated against multiple years of stream discharge and chloride concentration. Model structural variations caused mixed results for differences in calibrated parameters and differences in storage between reservoirs. However, large differences in catchment storage volumes and fluxes arise when considering only mobile water. These changes influence interpreted residence times for streamflow‐generating water, demonstrating the importance of ecohydrologic separation in catchment‐scale water and solute transport. Abstract : Representing ecohydrologic separation in hydrologic models alters interpretations of water storage and the transport of water and solutes at the catchment scale. These changes in internal catchment functioning influence plant water availability as well as the potential for biogeochemical reactions, demonstrating the relevance our evolving conceptual model has on ecological processes.