CGRG Bibliography of Canadian Geomorphology
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Author : Devito, K.; Creed, I.; Gan, T.; Mendoza, C.; Petrone, R.; Silins, U.; and Smerdon, B.
Date : 2005.
Title : - A framework for broad-scale classification of hydrologic response units on the Boreal Plain: is topography the last thing to consider?
Publication : Hydrological Processes
Issue : 19(8):
Page(s) : 1705-1714.
Abstract
Clearly defined hydrologic response units (HRUs) that incorporate unifying concepts in hydrology—the complete hydrologic cycle and conservation of mass —are required to direct and integrate local, regional and continental scales of hydrologic research and management. The topographically defined watershed or catchment has been championed as the basic HRU. However, catchment studies reveal large complexity and heterogeneity of runoff behaviour, resulting in a multitude of conceptual and numerical model structures. Recent reviews argue that a broad-scale classification of catchments is required to generalize dominant hydrologic processes, direct field methodologies, and apply hydrologic model structure. However, protocols on defining such areas are presently lacking. Traditionally, researchers have disregarded large portions of the landscape in favour of areas amenable to ‘hydrologic study’, by relying on catchments where hydrologic boundaries can be easily defined. These catchments are often small and homogeneous, to ‘control’ for climatic and geologic features, which may have misled non-catchment-hydrologists (or up-and-coming hydrologists and managers) to believe that the first variable to consider in predicting hydrologic response is topography. This approach may provide a false sense of security about the effectiveness of topographically defined catchments as an approach to conduct research, assess regional hydrology, and generalize results to broad landscape scales. Recent reviews clearly illustrate the need for a thorough integration of surface water and groundwater processes, and current research has begun to challenge the assumptions of the dominance of topographic controls on soil moisture distribution and runoff responses. Paradoxically, the principal hydrologic boundary of most watershed studies continues to be surface topography and/or channel networks. As a result, approaches to catchment delineation, and subsequent instrumentation and application of model structures, may not consider the validity of assumptions implied by using topography to define HRUs with respect to dominant hydrologic cycling and mass balance. We believe that asserting the topographically defined catchment as a standard hydrologic unit, or by assuming that the water table conforms to topography, is a methodological approach that has been overstated in importance for regional to national scales of water management.
Bibliography of Canadian Geomorphology