Grant, Gordon. 1987. Assessing effects of peak flow increases on stream channels: a rational approach. In: Callaham, Robert Z.; DeVries, Johannes J., tech. coords. Proceedings of the California watershed management conference; 1986 November 18-20; West Sacramento, CA. Rep. 11. Berkeley, CA: Wildland Resources Center, Division of Agriculture and Natural Resources, University of California: 142-149.
Current methods for assessingcumulative watershed effects of forestpractices employ arbitrary limits on thepercentage of basin drainage area affectedwithin certain time periods. Data to supportsuch limits are sparse, making these managementstrategies questionable. A more defensibleprocedure uses the magnitude of flow increasesthat can be accommodated by downstream channelsbefore channel instability occurs. For a givenchannel cross-section and particle sizedistribution of bed material, the effectivedischarge reouired to entrain bed material of aparticular size can be calculated and referredto a discharge to determine the allowableincrease in flow. This, in turn, can be usedto set the upper limit on total basin,compaction area. An example of this proceduredemonstrates that streams with differentchannel geometries and bed materials havedifferent intrinsic sensitivities to peak flowincreases.