3 A lake has a surface area of 800000 mA2 For a given month

3. A lake has a surface area of 800,000 mA2. For a given month (30 days), the lake has an inflow of 1.5 mA3/s and an outflow of 1.25m 3/s. The water level in the lake was raised by 1.0 m. The total precipitation for the month is 22.5 cm. Assume that seepage loss is negligible. Determine the evaporation loss (in cm) for the lake.

Solution

Here we have,

Surface area of lake,A = 800,000 m ²

Inflow rate, I = 1.5 m³/s

Outflow rate, O = 1.25 m³/s

Change in level of lake = 1.0 m increse

Precipitation for the month = 22.5 cm

Seepage loss is negligible

By considering the mass balance concept,we have

>> Inflow + Precipitation - Evaporation loss - Outflow = Change in storage

>> (1.5-1.25)*(60*60*24*30) +(22.5/100)*(800,000) - E *800,000 = 1.0 *(800,000)

E = Evaporation Depth,in m

>> E = 0.035 m = 3.5 cm

Evaporation loss of 3.5 cm occured in lake.