A catchment has four sub-areas. The annual precipitation and evaporation from each of the sub-areas are given below. Assume that there is no change in the groundwater storage on an annual basis and calcu- late for the whole catchment the values of annual average (i) precipitation, and (ii) evapo- ration. What are the annual runoff coefficients for the sub-areas and for the total catch- ment taken as a whole? Sub-area ABCD Area Mm 10.7 3.0 8.2 17.0 Annual precipitation mm 1030 830 900 1300 Annual evaporation mm 530 438 430 600