Effect of Precipitation on Buffer Strip Design and Water Quality: Theory, Case Studies, and Economics

Climate change is predicted to increase precipitation intensity extremes, both flooding and drought, and will therefore necessitate the augmentation of many water infrastructure projects, including buffer strips for protecting waterways from agricultural chemical runoff. To quantify the effect of increased precipitation intensity on buffer strip length, both theory and modeling were employed here. First, design equations were used with varying values of precipitation intensity and the buffer strip width quantified. Next, four case study examples from varying climate zones in the US were modeled using the EPA’s Pollutant Load Estimation Tool (PLET) for various chemical constituents and the sensitivity to buffer strip area calculated. The economics of buffer strip and optimal length were also found. It was found from the design equations that buffer strip length was a logarithmic function with rapidly increasing length at low precipitation intensity values but less influence at higher intensity values. In addition, modeling showed that pollutant load decreased quickly with increased buffer area at low values but less so at higher values. Also, the optimal profit of revenue minus cost came at a percent area of buffer strip to croplands area of from 2% to 10%.