Determine the minimum surface area in acres of an irrigation
reservoir so that
the drawdown over August is no more than 10 ft. the drainage basin
feeding into the
reservoir, including the reservoir itself, is 100 mi 2. Assume that
35% of the rain falling on the
basin runs off the reservoir. Assume groundwater flow into and out
of the basin is negligible.
Determine the irrigation water needed from the evapotranspiration
requirement from beans
growing on 40mi 2 at 35 o North latitude. The reservoir must also
supply a continuous 50 cfs of
water for instream flows to protect fish and aquatic life. The
evaporation pan coefficient for
this area is 0.800. For the month of August, Temp = 68F; precip =
2.0 inches and Pan
Evaporation = 7.9 inches. Draw a figure and clearly, show the mass
balance on the figure.
Hint: use the mass balance equation: inflow-outflow = change in
storage
Change in storage = reservoir area * change in height.
Change is height is given so use the mass balance, calculate the
change in storages and calculate
reservoir area.
Precipitation = 2inch=0.16666ft
Let area of reservoir be Ar ft2
Total drainage area(including reservoir area)=100mi2=100*(5280)2 ft2= 2787.84*106 ft2
evaporation from reservoir= 7.9 * 0.8 inch= 6.32inch = 0.52666 ft
total evaporation loss from reservoir in agust= 0.52666Ar ft3
total precipitation inflow in reservoir in agust=0.35*0.166666 * 2787.84*106 =162.6175*106 ft3
total loss in stream from reservoir in agust=50*60*60*24*31=133.92*106 ft3
max permessible drawdown= 10 ft
So,
change in storage from reservoir=total precipitation in reservoir in agust - total loss in agust
drawdown * reservoir area =162.6175*106 - (133.92*106+0.52666Ar )
10* Ar =28.6975 * 106 - 0.52666Ar
Ar =2.726* 106 ft2 = 62.5842 acre ANSWER(min area of reservoir needed).
Determine the minimum surface area in acres of an irrigation reservoir so that the drawdown over...
The water elevation of Lake Ontario is 246 ft and a surface area of 4.69x106 acres. The annual inputs and outputs to the lake are 40.0 inches of precipitation, 36.3 inches of evaporation, 3.0x104 cfs of runoff, 2.45x105 cfs of stream inflow, and 2.70x105 cfs of outflow. Groundwater flow into Lake Ontario is minimal and considered negligible in water balance. a) Make a tabulated water budget showing the inputs and outputs in metres per year and calculate the change in...
Daily water balance is done for a lake (300 acres of surface area) that is used as water supply resource for a community. During the previous 24-hr period the average inflow was 200 cfs, the average outflow (including water extracted for public supply) was 80 cfs, total precipitation was 2 in. and the pan evaporation near the lake indicated a net reduction of 0.3 in. Infiltration losses of the soil and bottom of the lake have a constant infiltration rate...
A lake with a drainage area AD has a surface area of AL and an average depth of zL. The long-term rates of precipitation and evapotranspiration for the portion of the drainage basin are PD and eD, respectively. For the lake itself the average rate of precipitation and evaporation are PL and eL, respectively. Average rate of stream outflow is Q. There is no groundwater inflow or outflow to the basin. a. Identify the units (Length[L], Time [T], Mass [M],...