The importance of conceptualizing the dynamics of storage-driven saturation area connectivity in runoff generation has been central to the development of TOPMODEL and similar low parameterized rainfall–runoff models. In this contribution, we show how we developed a 40-year hydrometric data base to simulate storage–discharge relationships in the Girnock catchment in the Scottish Highlands using a simple conceptual model. The catchment is a unique fisheries reference site where Atlantic salmon populations have been monitored since 1966. The modelling allowed us to track storage dynamics in hillslopes, the riparian zone and groundwater, and explicitly link non-linear changes of streamflows to landscape storage and connectivity dynamics. This provides a fundamental basis for understanding how the landscape and riverscape are hydrologically connected and how this regulates in-stream hydraulic conditions that directly influence salmonids. We use the model to simulate storage and discharge dynamics over the 40-year period of fisheries records. The modelled storage-driven connectivity provides an ecohydological context for understanding the dynamics in stream flow generation which determine habitat hydraulics for different life stages of salmon population. This new, long-term modelling now sets this variability in the riverscape in a more fundamental context of the inter-relationships between storage in the landscape and stream flow generation. This provides a simple, robust framework for future ecohydrological modelling at this site, which is an alternative to more increasingly popular but highly parameterized and uncertain commercial ecohydrological models. It also provides a wider, novel context that is a prerequisite for any model-based scenario assessment of likely impacts resulting from climate or land use change. Copyright © 2016 The Authors Hydrological Processes Published by John Wiley & Sons Ltd.
We thank Iain Malcolm of Marine Scotland Science for access to data from the Girnock and the Scottish Environment Protection Agency for historical stage-discharge relationships. CS contributions on this paper were in part supported by the NERC/JPI SIWA project (NE/M019896/1).
- rainfall-runoff modelling
- Atlantic salmon
- conceptual model