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PURPOSE OF SURFACE WATER STORAGE. STORE A DESIGN VOLUME OF WATER CREATE A DESIGN LAKE SURFACE AREA CREATE A UNIQUE HABITAT FOR FISH AND / OR WILDLIFE. SURFACE WATER STORAGE OBJECTIVES. PROVIDE A DEPENDABLE SOURCE OF WATER FOR THE PURPOSE PROVIDE AN ECONOMICAL SOURCE OF WATER FOR THE PURPOSE.
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PURPOSE OFSURFACE WATER STORAGE • STORE A DESIGN VOLUME OF WATER • CREATE A DESIGN LAKE SURFACE AREA • CREATE A UNIQUE HABITAT FOR FISH AND / OR WILDLIFE Pond Planning.ppt
SURFACE WATER STORAGE OBJECTIVES • PROVIDE A DEPENDABLE SOURCE OF WATER FOR THE PURPOSE • PROVIDE AN ECONOMICAL SOURCE OF WATER FOR THE PURPOSE Pond Planning.ppt
Top-of-Dam What kinds of storage must be considered in planning a reservoir? Principal Spillway Pond Planning.ppt
WHAT FACTORS MUST BE CONSIDERED IN STORAGE VOLUME? • USEFUL STORAGE VOLUME • SEDIMENT • LOSSES TO EVAPORATION FROM THE SURFACE • LOSSES TO SEEPAGE • FLOOD HANDLING VOLUME Pond Planning.ppt
Top-of-Dam Freeboard Storage Large Flood Storage Emergency Spillway Small Flood Storage Evaporation and Seepage Storage Useful Storage sediment storage Principal Spillway Pond Planning.ppt
WHAT FACTORS AFFECT THE AVAILABLE WATER SUPPLY? Pond Planning.ppt
WHAT FACTORS AFFECT THE AVAILABLE WATER SUPPLY? • PRECIPITATION ON THE WATERSHED • EVAPORATION ON THE WATERSHED • INFILTRATION ON THE WATERSHED • WATERSHED AREA Pond Planning.ppt
WATERSHED WATER BALANCE THIS APPLIES TO THE WATERSHED AREA Pond Planning.ppt
RESERVOIR WATER BALANCE THIS APPLIES TO THE RESERVOIR SURFACE AREA Pond Planning.ppt
OVERALL WATER STORAGE BALANCE HOW WILL THIS BE AFFECTED BY WATERSHED SIZE? HOW WILL THIS BE AFFECTED BY RESERVOIR SURFACE AREA? Pond Planning.ppt
Pond Storage CalculationProblem Solving Pairs • Compare two small ponds • Both hold 10 ac-ft of water • Pond A has an average depth of 8 ft • Pond B has an average depth of 4 ft • Both lose 6-inches of water per year to evaporation and seepage • How much water volume does each pond lose? Pond Planning.ppt
EFFECT OF WATERSHED SIZE ON STORAGE • WATERSHED TOO SMALL • NOT ENOUGH RUNOFF • WATERSHED TOO BIG • TOO MUCH RUNOFF • EXPENSIVE SPILLWAY • TOO MUCH SEDIMENT • 3X Minimum Size Pond Planning.ppt
HOW WILL RESERVOIR TOPOGRAPHY AFFECT STORAGE? • SLOPE OF THE UPSTREAM VALLEY • DEPTH OF THE VALLEY AT THE DAM SITE Pond Planning.ppt
Reservoir TopographyToo Flat • Too much surface area • Too much shallow water • High water loss to seepage • High water loss to evaporation Pond Planning.ppt
Reservoir TopographyToo Steep • Less water storage for given depth • More earth work for given depth • High cost per unit of stored water Pond Planning.ppt
Evaluating a Proposed Site for an earthen reservoir • FOUNDATION AND FILL MATERIAL • ROCK • GRAVEL • SAND • SILT • CLAY • ORGANIC MATTER Pond Planning.ppt
Evaluating a Proposed Site for an earthen reservoir • FOUNDATION AND FILL MATERIAL • ROCK good structure • GRAVEL good structure • SAND good structure • SILT easily eroded • CLAY good water sealing • ORGANIC MATTER easily decayed Pond Planning.ppt
3 1 EARTH DAM CROSS-SECTION W 2 1 H 1 Core Trench 1 10 Ft. min Pond Planning.ppt
EARTH DAM CROSS-SECTIONZONED FILL Pond Planning.ppt
Drop Inlet Pipe Spillway h ANTI-SEEP COLLARS Pond Planning.ppt
Anti-seep collars being installed on a principal spillway pipe. Pond Planning.ppt
Principal Spillway Inlet Pond Planning.ppt
Emergency Spillway Pond Planning.ppt
FLOOD ROUTING Inflow - Outflow = Change in Storage Peak Inflow FLOW Inflow RATE Peak Outflow Outflow TIME Pond Planning.ppt