SLIDE 1
Presented by: Civil Engineering Academy Detention/Retention Ponds - - PowerPoint PPT Presentation
Presented by: Civil Engineering Academy Detention/Retention Ponds - - PowerPoint PPT Presentation
Presented by: Civil Engineering Academy Detention/Retention Ponds Presented by: Civil Engineering Academy Also known as impounding reservoir or retention watershed (CERM Ch. 20). Analysis to determine the proper size of a reservoir or
SLIDE 2
SLIDE 3
Also known as impounding reservoir or
retention watershed (CERM Ch. 20).
SLIDE 4
Analysis to determine the proper size of a
reservoir or dam, or to evaluate the ability of an existing reservoir to meet water demands.
Reservoir sizing Methods (CERM Ch. 20) 1. Non sequential drought method 2. Modified Rational Method 3. Reservoir routing method 4. Stochastic simulation method
SLIDE 5
Formula:
Vn+1 = Vn + (inflow)n – (discharge)n – (seepage)n – (evaporation)n Where: V = storage volume and subscripts n means present data n+1 means the next iteration of data
SLIDE 6
Evaporation
- Can be estimated from analytical relationships or by evaluating
data from evaporation pans.
Evaporation Pan Formula
Where: KP = pan coefficient, typically 0.7–0.8. Ep = evaporation loss ER = ∑KPEP
- Eq. 20.48
SLIDE 7
An evaporation pan with coefficient of 0.8 is used to estimate the
evaporation loss of a reservoir. For one day, it shows an evaporation loss of 0.9. Determine the evaporation loss of the reservoir.
Solution:
ER = ∑KPEP KP= 0.8 Ep = 0.9 ER = (0.8)(0.9 in) = 0.72 in
SLIDE 8
For reservoir sizing, use the mass diagram
method.
SLIDE 9
Six Minute Solutions – Water Resources Prob. 52, Depth
SLIDE 10
- Prob. 52, Depth (continued)
SLIDE 11