Apparent Changes In Rainfall Extremes and Possible Changes In Soil Erosion and Sediment Yield

Abstract

There is much interest and concern about expected changes in various climatic variables and impacts of such changes on a wide range of water resource and other variables. The possibility of changes in short-duration rainfall extremes is of particular interest to persons concerned about soil erosion and sediment yield. This paper presents evidence that annual rainfall extremes for durations from 15 minutes to 12 hours have shown no consistent change in recent years in Ontario; however, monthly extremes have appeared to increase during the spring and fall. Possible impacts of these and further changes in rainfall extremes on soil erosion and sediment yield have been explored by means of a field-scale model. Results reveal that soil erosion can be expected to increase substantially more in response to increases in spring rainfall extremes than to similar increases in summer extremes. Sediment yields can also be expected to increase substantially as a result of increases in spring extreme rainfalls; but increase in summer rainfall extremes may not result in much change in sediment yield.