INVESTIGATIONS FOR RESERVOIR PLANNING, SEDIMENTATION & CONTROL APPORTIONMENT OF TOTAL COST OF A MULTI-PURPOSE RESERVOIR

1. RESERVOIR PLANNING

2. CONTENTS:
 Types of Reservoirs
 Investigations for reservoir planning
 Apportionment of total cost of a multi
purpose reservoir
 Reservoir sedimentation & control
 Measures to reduce evaporation losses

3. RESERVOIRS
 STORAGE / CONSERVATION RESERVOIR
 FLOOD CONTRO RESERVOIR
 DISTRIBUTION
 MULTI PURPOSE
INVESTIGATIONS FOR RESERVOIR
PLANNING
ENGINEEING SURVEYS
contour plan…(area elevation & storage-elevation curves
;water spread area, reservoir capacity)
GEOLOGICAL INVESTIGATIONS
HYDROLOGICAL INVESTIGATIONS
runoff patterns, hydrograph of worst flood to find spillway capacity.

4. APPORTIONMENT OF TOTAL COST OF A MULTI
PURPOSE RESERVOIR
 EQUALAPPORTIONMENT
irrespective of diff beneficiaries divided for them
 USE OF FACILITIES
storage vol prov for each function
 ALTERNATIVE JUSTIBLE
economically justible
 REMAINING BENEFIT
estimated benefit of each function
JOINT COST = TOTAL COST – SEPARABLE COST OF INDIVIDUAL FUNCTIONS

5. RESERVOIR SEDEMENTATION
Sediments transported by Rivers :
• BED LOAD (coarse sediments)
• SUSPENDED LOAD (fine)
DENSITY CURRENTS
Heavy turbid water flows along channel
bottom by gravity.
LIFE OF RESERVOIR
Useful life of reservoir is terminated when
its capacity is reduced to 20% of design
capacity.
TRAP EFFICIENCY = Capacity / Inflow

6. PRE-CONST. METHODS
 SITE SELECTION
deep, water tight rock base, less sediment inflow
 RESERVOIR DESIGN
provide entire design capacity in stages & provide adequate no.of outlets.
 CONTROL OF SEDIMENT INFLOW
check dams, vegetation screens.
POST CONSTR. METHODS
 CONTROL OF SEDIMENT DEPOSITION
operation of gates (sluices & head regulators of canals
 REMOVAL OF SEDIMENT DEPOSITION
excavation, dredging, under sluices
 EROSION CONTROL IN CATCHMENT AREA
soil conservation methods
CONTROL OF RESERVOIR SEDEMENTATION

7. MEASURES TO REDUCE EVAPORATION LOSSES
 Construct the Reservoir with less surf area & more depth.
 Grow tall trees on windward side of it to act as wind
blockers.
 Spraying chemicals (cetyl alcohol) acts as thin layer.
 Provide outlets for warm water.
 Develop underground reservoirs.
 Afforestation around th site.