A 1200 ha watershed has the agriculture area as given below. Table 7.11) Ver the C C (7 ) (ha) Runoff Coefficient GP01 Agricultural Area Flat: Sandy loams, cultivated Flat: Tight clay, woodland Hilly: Tight clay woodland 450 1822 Sandy Heavy 25 Readers Srce mal Matched O 450 300 0-0 DOO Heavy Apcal Area cured Sandylom, Sud woodland They woodland sulted Sandy . a) Use given table to find the appropriate runoff coefficient. The maximum length of travel of water in the watershed is about 4500 m and the elevation difference between the highest and outlet points of the watershed is 35m. The maximum intensity-duration-frequency (IDF) relationship of watershed is given by : i = 6.311 70.1523 (D+0.5) 0.945 Where i intensity (cm/hr) T Return period (years) D Duration of the rainfall (hours) NOTE: Use Kirpich equation to calculate time of concentration (T) b) Estimate the 20-year peak runoff from the watershed. c) Agriculture area of the watershed went under some changes. Estimate the 20-year peak runoff from the watershed if "Flat: Tight clay woodland agriculture area has decreased to 100 ha and is converted to "Flat: Sandy loams, cultivated". While "Hilly: Tight clay woodland" did not change. A 1200 ha watershed has the agriculture area as given below. Table 7.11) Ver the C C (7 ) (ha) Runoff Coefficient GP01 Agricultural Area Flat: Sandy loams, cultivated Flat: Tight clay, woodland Hilly: Tight clay woodland 450 1822 Sandy Heavy 25 Readers Srce mal Matched O 450 300 0-0 DOO Heavy Apcal Area cured Sandylom, Sud woodland They woodland sulted Sandy . a) Use given table to find the appropriate runoff coefficient. The maximum length of travel of water in the watershed is about 4500 m and the elevation difference between the highest and outlet points of the watershed is 35m. The maximum intensity-duration-frequency (IDF) relationship of watershed is given by : i = 6.311 70.1523 (D+0.5) 0.945 Where i intensity (cm/hr) T Return period (years) D Duration of the rainfall (hours) NOTE: Use Kirpich equation to calculate time of concentration (T) b) Estimate the 20-year peak runoff from the watershed. c) Agriculture area of the watershed went under some changes. Estimate the 20-year peak runoff from the watershed if "Flat: Tight clay woodland agriculture area has decreased to 100 ha and is converted to "Flat: Sandy loams, cultivated". While "Hilly: Tight clay woodland" did not change
