Links between water temperatures, ecological responses and flow rates: A framework for establishing water temperature guidelines for the ecological Reserve


Sponsor: Water Research Commission
Leader: Prof DA Hughes
Staff: Dr NA Rivers-Moore (Associate IWR)
Duration: April 2006 - March 2007


Aims and Objectives
Water temperatures are a function of complex interactions between thermal drivers and buffers. The statistical and mechanistic natures of these links have not been adequately established for South African rivers, which have previously been characterised as exhibiting highly variable flows. Future research is required to understand water temperature variability, and associated impacts on aquatic invertebrate communities. Currently water temperature is an optional variable for an ecological Reserve determination, largely due to a lack of available data. Where observed data are unavailable, simple models are recommended to calculate monthly water temperature time series, based on air temperature relationships. It has been demonstrated that such an approach is simplistic, and that this relationship is considerably more complex and often site-specific. Research on the links between water temperature and flow volumes, and how these may be related to biotic response patterns, makes an important contribution to the ecological Reserve determination process. Additionally, simulation models that include flow-dependent terms will add significantly to the decision-making process, providing the capacity to understand thermal changes under flow scenarios.

The aim of this project was to explore the abovementioned issues in greater detail, through a one-year consultancy project for the Water Research Commission. It is anticipated that this research will lead into a larger three-year WRC report on water temperatures and the ecological Reserve. The following five objectives were identified:

    Develop a conceptual model for identifying critical water temperature signature components and how these could be used to develop general temperature guidelines for the ecological Reserve.
    Add to an understanding on possible differences between northern and southern Hemisphere thermal patterns in river systems.
    Review of theoretical effects of natural and modified thermal regimes on aquatic invertebrate communities, and how this could be related to the ecological Reserve.
    Refine water temperature simulation modelling approaches, including spatially dynamic models, and how such models could be linked to existing hydrological models.
    Contribute to the Terms of Reference for solicited WRC project on water temperatures.

Last Modified: Fri, 14 Aug 2015 10:44:25 SAST