Question

hydrology
Have 30mins

Q1) (25 Points) Discharge of total flood hydrograph is given below. Basin area is 100 km2, precipitation intensity is 80 mm/hr and the infiltration rate is 20 mm/hr. If the base flow is 100 m3/sec, then find the unit hydrograph and duration of precipitation. The total flood hydrograph is given in Table 1 and drawn below. Table 1. Total Flood Hydrograph 40 60 80 100 0 20 120 140 160 t(minutes) Q(m3/sec) 100 700 610 520 430 340 250 170 100 Total flood hydrograph is drawn below. AQ(m3/s) Direct flow 100 Base flow 160 t(minutes)

Answer 1

Solution A = 100 kr92 effective Rainfall - 80-20 leff-6 cuchhe Pase floral Direct Rune ff mild unit Hydrograph - hell DRY timinj Qlennel) 100 O booloo 215.51 700 40 610 520 510 420 103.18 150.86 11 60 00 118.53 430 340 , 930 240 150 86.21 140 53 88 25.14 170 u 70 160 100 O Area Dirrect R. H. = value of effective Rainfall - Assuming toted effective depth hcm) v=hA = h&102 x 100x10b = tooxhxto hx 106 ma. Area of D.R. H = 2 ( go + Yn + 2 (Yr ty , t Jy + -- yn.)] Using toopozoidal Rule 10 Co to 20x60 +2 (600+ 5/0 +420 +330 +240 +80 +70) 2784000 m3

21784000 from the equation axlob h=2.784 cm Duration of Rainfall leff mation of Rain feall = 27.89 min. = 2.784 6 20.464 hs