Local Perceptions, Ruslefac Mapping, and Field Results: The Sediment Budget of Cocagne River, New Brunswick, Canada

Résumé En

Erosion and sedimentation in water courses represent a major and costly problem everywhere on the planet. Perception of local actors of the state of the river can be a useful source of information to document the river’s changes. The main objective of this study consists of understanding how multiple data sources can be used for identifying the most sensitive areas subject to erosion and sedimentation in a watershed. To achieve our objective we combined three complementary methods: conducting interviews, estimating the most sensitive soil loss areas using the Revised Universal Soil Loss Equation for Application in Canada (RUSLEFAC) and taking measurements of environmental variables (turbidity, deposition rate, particle size, water quality, rainfall). The information gathered from the interviews allowed us to determine which areas were the most affected (e.g., either erosion or deposition). However, we observed that there were some differences between the areas identified by the participants and those obtained from the RUSLEFAC and in situ measurements. Among these differences, participants identified sites which were the results of misuse or bad practices (e.g., ATV). By contrast sensitive sites for erosion, as identified using RUSLEFAC, are instead areas of steep slopes, located near the river without forest cover. The in situ measurements were very helpful in establishing background values for turbidity but also for comparing quantitative information (e.g., particle size) with what was reported in the interviews.