Question

2. Hydrologic mass balance (20 points): Use a hydrologic mass balance to solve the following: a. (10) A lake is approximately 15 km in length by 5 km in width. The inflow for the month of August is 3.5 m/s and the outflow is 2.15 m®/s. The total monthly precipitation is 20.5 cm and the evaporation is 8.2 cm. The seepage (infiltration) is estimated to be 1.35 cm. Estimate the change in storage (in mº) during the month of August. b. (10) Assume that you want to use this lake as a water supply source and you can control the outflow in the lake. Under the same conditions (i.e. same inflow, precipitation, infiltration, and evaporation), how much water can you extract in August (volume) while maintaining steady state conditions in the lake?

Answer 1

tham you

Solution ☆ bout= 2,15 ml Qin = 3.5m/sec TRATEGI m Surface area of lake A = 15x5= 75Kry2. dA= 75x106m2 I a) using Hydrologic mass balance P precipitation = 20.5cm=0.20 I-Infitation = 1.350m= 0.0133 mm E> Evaperation.= 8,9 cm=0.0&e At for month of August AZ = 31x86400= 52.6786x106cec Ava Vin - Vout XV= (le inxst+ pxa) - ( Pout At+ TA + Exa) AV = (3.5X26786x10€+0.905x75x106)– (2:15 X2-6786x106 +0.0135x75x106 to.82X75X10) AV= 11.87861X/06 m3 1. b) for steady state, Sout=? AVEO = Pin Xatto.A - Qout At - IĄ - EA Pintst+ PA - FA - EA yout= . 1. At Qout= 315x8.6786x10471205x75x10^-25*1.0.0135X75X106 - 0.082x75x10F 2c786x108 296786X106 17587600 Qout = 1458.7 km = 6.566 m/s & Dout = = 61566 m 216786 X 106