Comprehensive watershed management and buffer zone planning using spatially distributed modeling (WaTEM)

Soil degradation and environmental impacts due to water erosion is a growing concern all over the world. Regarding the harmful effects of soil erosion there is therefore a need to focus on best management practices (BMPs) in order to mitigate the polluting effects of soil erosion. Buffer zones as a structural BMP can be efficient in terms of retaining sediment transported by water bodies. Therefore, it is important to optimize the placement of buffer zones to effectively protect water bodies. To optimize the placement of buffer zones, landscape planning tools are needed. In this study, the suitability of a spatially distributed model (WaTEM, Water and Tillage Erosion Model) has been evaluated. Rill-eroded and fan-deposited sediments were measured on agricultural slope units including units with and without breakthrough to the stream. Based on the observed data including mass and volume of erosion and deposition there was positive correlation (R2 = 58.0) between rill-eroded and fan-deposited sediments for slope units without breakthrough to the stream whereas there was weak correlation for units with breakthrough to the stream. WaTEM outputs including soil erosion and deposition patterns indicated areas with the highest risk of soil erosion and deposition. These patterns provided visual tools to recognize critical areas. Moreover, model parameterization indicated that WaTEM was able to estimate soil erosion and deposition in the fields and soil deposition in the buffers in the lowest range of transport capacity coefficient (ktc=25) and McCool low as LS algorithm. Our results showed the effectiveness of buffer zone establishment to mitigate the off-site effects of soil erosion and WaTEM was able to predict soil erosion and deposition in the fields and soil deposition in the buffers.

Keywords:

Best Management Practice (BMPs) , buffer zone , modelling , erosion