Development of a Model to Predict Runoff Water Headloss Through Compost Filter Berms

As a part of a larger study designed to develop compost filter berms i.e., an unsupported mound of compost that intercepts surface runoff from a site, suitable for removing nutrients and sediment from agricultural operations, we evaluated the hydraulic behavior of compost buffers with different masses and particle size distributions subjected to varying water flow rates using flume experiments. For each berm combination, the maximum flow rate the compost berm could sustain before a structural failure occurs was determined for different compost particle sizes. These data were used to develop models to predict headloss through a compost berm as a function of the flow rate per unit width, the median particle size of the compost media, and the buffer dimensions. The developed models perform well with R² values ranging from 0.64 to 0.97 with the majority of values greater than 0.9. The effect of presence of sediments in the flow was also quantified. The results show that headloss increased by 1–2 cm as a result of sediment removal, ranging from 5 to 35%, taking up pore space in the compost berm.