CGRG Bibliography of Canadian Geomorphology
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Author : Church, M.
Date : 1997
Title : Regionalised hydrological estimates for British Columbia: first approximation of scale events.
Publication : Report for Resources Inventory and Data Management Branch, British Columbia Ministry of Environment, Lands and Parks, Victoria, British Columbia
Issue :
Page(s) : 47 p.
Abstract
Surface runoff is affected by climate, physiography, land cover and geology, To the extent that these factors exhibit regional coherence, so does runoff. However, in the stream gauging network the principal factor imparting variability to data of streamflow (Q) is the varying size of the gauged drainage basins. In order to be able to examine the true regional hydrology, it is necessary first to discount the effect of drainage basin area (Ad). This is not simply a matter of examining specific runoff (Q/Ad), since there are various non-additive effects associated with the integration of flow from successively larger areas. This report describes a systematic analysis of the scale effect in runoff data in British Columbia. Consistent scale factors are identified province-wide by conducting analyses in a group of initially imposed regions. Discounting the scale effects yields a runoff factor, k, which is in effect a scale-corrected estimate of specific runoff. The k-factor can be determined for individual stations, so the provincial map of k does not depend on the initial, arbitrary regionalisation. Maps are presented for mean annual flow and for mean annual flood. The scale effect behaves differently for the tow flows. k-factor maps can be used to reconstruct runoff estimates for arbitrary locations anywhere in the province, and they form the rational basis for commencing analysis of the effects of the underlying governing factors listed above. Since estimates are derived of the probable errors associated with k-factor estimates, the precision of the results may be specified. The maps presented in this report probably do not reflect the true hydrological fields across the province. The gauging records are not well constituted for regional anaysis because the network is poorly distributed (both regionally and in respect of the distribution of drainage basin areas), because flow records cover varying periods, and because there remains room to improve the analysis. The displayed fields reflect regional variation at the scale of about 100 km. This resolution is consistent with provincial scale regional analysis, with strategic water resources planning requirements, and with global modelling of environmental change. It is not compatiable with needs to make reliable estimates of flows in individual ungauged basins for purpose of water resource allocation or for site-specific water or stream management purposes. For such purposes, more detailed sub-regional analyses, which preserve a greater measure of local variability, are required. But in may parts of the province - especially the north - the fundamental inadequacy of the gauging network limits the useful additional resolution that could be gained.
Bibliography of Canadian Geomorphology