An extended riparian buffer strip concept for soil conservation and stream protection in an agricultural riverine area of the La Chevrotiere River watershed, Quebec, Canada, using remote sensing and GIS techniques

The implementation of riparian buffer strips in agricultural areas is regarded as a means to protect watercourses against runoff water carrying sediments and contaminants. In the field, riparian buffers are usually dimensioned to meet the minimum width required by policies and regulations. In the case of the province of Quebec, Canada, regulation stipulates a width of 1-3 m in agricultural watersheds. However, such small riparian strips offer little protection, especially during the spring-snowmelt period when the soil is saturated, infiltration is low, vegetative cover is poor and soil erosion and runoff are the dominant hydrological processes. In this study, high-resolution, remote sensing, raster-based information is used to evaluate an extended riparian buffer strip concept with variable widths of 5-120 m to assess soil erosion and to convert agricultural riverine areas into soil and water conservation areas. For a studied watershed of 108 km(2) in Quebec, this would enable reducing soil erosion in riverine areas from 361 to 1.0 t year(-1) (1.9 to 0.005 t ha(-1) year(-1)), and thereby reducing soil erosion at the watershed scale by 40% (calculated with the Revised Universal Soil Loss Equation, RUSLE). The extended riparian buffer strip concept would require the conversion of 7% of the 29 km(2) of agricultural land.