Excel Formulas for Calculating the Volume of Storm Water Detention Ponds

Storm water detention ponds or retention ponds are needed when development takes place on a watershed, because the storm water runoff rate and amount typically increase due to the development. Download spreadsheets containing Excel formulas to make the calculations of volume needed for storm water detention ponds using three different hydrologic models. Parameters needed in the calculations include watershed area and watershed time of concentration, peak storm water runoff rate, and runoff depth, for both pre-development and after development watershed conditions. The Gereralized Model, the Loss of Natural Storage Model, and the Rational Hydrograph model for calculating volume of detention ponds are covered in this article.