A method for estimating stored sediment volumes by check dam systems at the watershed level: example of an application in a Mediterranean environment

Purpose: In this paper a quick, easy and accessible methodology to estimate the sediment volume trapped behind a fully filled check dam system is proposed. As it is well known, check dams play an important role in the sediment balance between watershed and coastline. However, on a large scale, especially in those contexts where a great number of structures was installed, detailed surveys and measurements of sediment storage capacity would be extremely time-consuming and costly in terms of both economic efforts and human resources. Methods: To this aim, the proposed method considers only four easy-to-obtain morphometric parameters to combine with the number of check dams. The method was calibrated on a sample of 912 check dams located in seven long-term studied watersheds and, therefore, validated in a sample of three regulated Spanish catchments with an independent dataset. Results: At watershed level, the comparison between the calculated and estimated values showed a good capability of the method in evaluating the sediment volume trapped by the 912 studied check dams (RMSE ≈ 16,900 m3; R2 > 0.9). The validation revealed encouraging results with estimation errors below 25%. Conclusion: The use of this accessible and easily usable method could represent a supporting tool for planning, monitoring and assessment of the environmental effects of control works. Moreover, these results are useful to carry out actions aimed to mitigate natural hazard and environmental as well as socio-economic problems of the watershed-coast system (e.g. shoreline retreat and morphological instability of the urban and tourist areas).