7. this problem is from elements of physical hydrology, 2nd edition, by hornberger et al. (johns hopkins press). in an average year, a small (area 3.0 km2) agricultural catchment or watershed receives 950 mm of precipitation. the catchment is drained by a stream, and a continuous record of stream discharge is available. the total amount of surface-water runoff for the year, determined from the stream discharge record, is 1.1 x 106 m3. what is the volume of water (in m3) evapotranspirated for the year assuming no change in water stored in the catchment? a. what is the depth of water (in mm) evapotranspirated for the year (again, assuming no change in water stored in the catchment)? b. c. what is the runoff ratio (quotient of average surface runoff rate and average precipitation rate)?