Question

1. Consider a drainage basin having 60 percent soil group B and 40 percent soil group C. Five years ago, the watershed land use pattern was ½ wooded area with good cover and ½ pasture with good condition. Now, the land use has been changes to 1/2 pasture land, and 1/2 residential area (1/4-acre lot). Estimate the volume (In inches) of increased runoff due to the land use change over the past 5-year period for a storm with 6 in of rainfall under the dry antecedent moisture condition (AMC I). (15 points)

(Hint: assume soil and landuse are randomly inter-mixed. So for pre-development, you have 4 landuse-soil combinations. After land use change, you have 4 landuse-soil combinations. Try to use Excel for P_e calculations)

Answer 1