On hydrological heterogeneity - Catchment morphology and catchment response

Catchment morphology and hydrological processes are linked through the geomorphic development of a catchment. The relaxation times of hillslope development are often long relative to time scales of climatic change, so that hillslope form may be a reflection more of hydrological regimes in the distant past than current processes. Current morphology, however, often acts as a dominant control on water flow paths and may be used as a clue to current hydrological responses. Studies of the relationship between morphology and runoff routing and runoff production are reviewed, including methods of physically-based flood frequency predictions that combine both production and routing. The relationship between morphology and other sources of spatial heterogeneity in catchment response is examined, including the concept of the "representative elementary area". Some suggestions for further research are made including the development of morphometry based definitions of hydrological similarity for use in regionalisation studies.