1. Storage Reservoirs for Urban Water Supply/Chapter 9 LowLift Intake Conduit Treatment High Lift ConveyanceConduit DISTRIBUTIONRESERVOIR Distribution Supply Pipe SEASONALRESERVOIR WELL FIELD

2. Storage Function (stabilize flow) seasonal reservoir stabilizing varying seasonal supply distribution reservoir stabilizing a varying demand Outflow Peak Inflow 01 year Demand curve (Outflow) Pumping flow (Inflow) Maximum demand 0 24 hours Inflow Curve store release I>OSTORE O>IRELEASE

3. How much storage capacity needed? Cumulative Net Storage S = cum. net storage (L 3 ) O t = O t, volume of reservoir outflow (draft) over t (L 3 ) I t = I t, volume of reservoir inflow over t (L 3 )

4. Illustration of Sequent-Peak method for Seasonal Storage, Linsley et al. 1989 zero reference

5. Reservoir Storage Capacity (contd) Carryover reservoir (Example 9.1)Example 9.1 I = varying river flow over critical period (2-3 yrs) O = demands and losses Cannot assume pattern repeats for analysis Distribution reservoir (Example 9.2)Example 9.2 Operating storage only I = steady pump flow O = varying demand from distribution grid over 24 hr critical period Pumping rate = daily demand/pumping period Can assume pattern repeats for analysis

6. Reservoir Storage Capacity (Graphical and Analytical Method)

7. Reservoir Storage Capacity (contd)