For more information: www.hydropower.org/congress

Session:

MAY, 2015

GEORGE W ANNANDALE

RESERVOIR SEDIMENTATION MANAGEMENT

Global Overview and Policy Implications

2015 World Hydropower CongressBeijing, China

RESERVOIR SEDIMENTATION MANAGEMENT – Global Overview & Policy Implications

WHAT IS SUSTAINABLE DEVELOPMENT?

“Sustainable development seeks to meet the

needs and aspirations of the presentwithout compromising the ability to meet those of

the future”

Brundtland Commission Report: “Our Common Future (1987)”

RESERVOIR SEDIMENTATION MANAGEMENT – Global Overview & Policy Implications

INTERGENERATIONAL EQUITY

RESERVOIR SEDIMENTATION MANAGEMENT – Global Overview & Policy Implications

Focused on FAIRNESS BETWEEN GENERATIONS

Environmental Stabilization

• A DESIRABLE CONSEQUENCE of Sustainable Development

• NOT THE OBJECTIVE of Sustainable Development

INTERGENERATIONAL EQUITY

RESERVOIR SEDIMENTATION MANAGEMENT – Global Overview & Policy Implications

SUSTAINABLE DEVELOPMENT

RESERVOIR SEDIMENTATION MANAGEMENT – Global Overview & Policy Implications

HYDROPOWER SUSTAINABILITY ASSESMENT PROTOCOL

Multiple Use

• Hydropower

• Water Supply

• Flood Control

Create and Preserve MULTIPLE-YEAR STORAGE

• Reliability of Power and Water Supply

• Creating Intergenerational Equity

MULTIPLE USE

RESERVOIR SEDIMENTATION MANAGEMENT – Global Overview & Policy Implications

GROUNDWATER FOOTPRINTOVEREXPLOITATION: GLOBAL FOOTPRINT = 3.5

Western Mexico

High

Plains

North

Arabian

Persian

Upper

Ganges

North China Plain

279

4820 54

5

Aquifer

Area (AA)

Groundwater

Footprint (GF)

RESERVOIR SEDIMENTATION MANAGEMENT – Global Overview & Policy Implications

MULTIPLE USE OF RIVER WATERHYDRO AND WATER SUPPLY – NEED FOR STORAGE

RESERVOIR SEDIMENTATION MANAGEMENT – Global Overview & Policy Implications

CLIMATE CHANGE TWO IMPORTANT VARIABLES

CHANGE IN MEAN ANNUAL RIVER FLOW

CHANGE IN HYDROLOGIC VARIABILITY

RESERVOIR SEDIMENTATION MANAGEMENT – Global Overview & Policy Implications

CLIMATE CHANGEMEAN ANNUAL FLOW INCREASE/DECREASE

RESERVOIR SEDIMENTATION MANAGEMENT – Global Overview & Policy Implications

INCREASED HYDROLOGIC VARIABILITYGREATEST IMPACT ON RELIABILITY OF SUPPLY

RESERVOIR SEDIMENTATION MANAGEMENT – Global Overview & Policy Implications

CLIMATE CHANGEMULTIPLE YEAR DROUGHTS GLOBALLY MORE PREVALENT

Current Conditions

2 2

24 1

v

crit

z cn

Assume 25% Increase

in Variability

Multiple-Year Droughts will IncreaseGreater Need for Storage

RESERVOIR SEDIMENTATION MANAGEMENT – Global Overview & Policy Implications

Increased Hydrologic

Variability due to Climate

Change

Reduction in Yield

To Maintain Reliability of

Supply

• LARGE Reservoir

STORAGE

• LESS SENSITIVE to

Climate Change

HOW TO PREPARE FOR CLIMATE CHANGE:STORAGE NEEDS TO DEAL WITH MULTIPLE-YEAR DROUGHTS

2 2

14

vz c

Storage = 0.6MAF

1.0MAF

2.0MAF

RESERVOIR SEDIMENTATION MANAGEMENT – Global Overview & Policy Implications

IN THE ABSENCE OF STORAGELOW RELIABILITY WHEN VARIABILITY IS HIGH

' 1 vc z

HIGH HYDROLOGIC

VARIABILITY

LOW HYDROLOGIC

VARIABILITY

90%

RESERVOIR SEDIMENTATION MANAGEMENT – Global Overview & Policy Implications

STORAGE IS IMPORTANT

AND WILL BECOME MORE IMPORTANT

DUE TO THE

EFFECTS OF CLIMATE CHANGE

RESERVOIR SEDIMENTATION MANAGEMENT – Global Overview & Policy Implications

GLOBAL POPULATION AND

DAM CONSTRUCTION

Population

Gross Reservoir Volume

RESERVOIR SEDIMENTATION MANAGEMENT – Global Overview & Policy Implications

RESERVOIR SEDIMENTATION –THE STORAGE SPACE ENEMY

RESERVOIR SEDIMENTATION MANAGEMENT – Global Overview & Policy Implications

GLOBAL NET STORAGE IN LARGE DAMS Tota

l N

et V

olu

me

(km

3)

Total

Per Capita

Per

Capita V

olu

me

(m

3/p

ers

on)

RESERVOIR SEDIMENTATION MANAGEMENT – Global Overview & Policy Implications

DUAL NATURE OF RESERVOIR STORAGE RENEWABLE OR EXHAUSTIBLE – A DELIBERATE CHOICE

RESERVOIR SEDIMENTATION MANAGEMENT – Global Overview & Policy Implications

PRESERVING STORAGE SPACERESERVOIR SEDIMENTATION MANAGEMENT OPTIONS

Manage amount of sediment

generated by the catchment

Allow sediment inflows to pass

through or around the reservoir

Remove sediment which

accumulates in the reservoir

Catchment Management

Check Dams

Forestation

Sediment Routing

Sluicing

Density Current

Venting

Bypass

Sediment Removal

Dredging

Excavation

Hydro-suction

Pressure Flushing

Drawdown Flushing

RESERVOIR SEDIMENTATION MANAGEMENT – Global Overview & Policy ImplicationsGross Dam, Colorado

Key Messages

Sustainable Development

Create Intergenerational Equity

Environmental Conservation Desirable ConsequenceNot the Objective

RESERVOIR SEDIMENTATION MANAGEMENT – Global Overview & Policy ImplicationsGross Dam, Colorado

Key Messages

Multiple Use

Multi-Purpose ProjectsHydropowerWater Supply

Need for Storage

RESERVOIR SEDIMENTATION MANAGEMENT – Global Overview & Policy Implications

23

Thika Dam, Kenya

Key Messages

Climate Change

Increased Hydrologic VariabilityLonger Multiple-Year DroughtsGreater Need for Storage Reliable Power & Water Supply

RESERVOIR SEDIMENTATION MANAGEMENT – Global Overview & Policy Implications

Key Messages

Current Resource Depletion

Global Net Loss of Reservoir Storage Space Currently Losing More

Storage than Adding

RESERVOIR SEDIMENTATION MANAGEMENT – Global Overview & Policy Implications

Karahnjukar Dam Spillway, Iceland

Key Messages

Intergenerational Equity

Creating Intergenerational EquityPreserve Storage Sediment Management Existing Reservoirs Future Reservoirs

RESERVOIR SEDIMENTATION MANAGEMENT – Global Overview & Policy Implications

POLICY & LEADERSHIP

Intergenerational Equity

Multiple Use

• Reliable Water and Power Supply

• Need for Storage

Climate Change

• Increased Need for Storage

Prevent Resource Depletion

• Preserve Storage

• Sediment Management

• Create Intergenerational Equity

“Time and time again I have seen NGOs and politicians in rich countries advocate that the poor follow a path that they, the rich, never have followed, nor are willing to follow.” –John Briscoe

John BriscoeWorld Bank Engineer

Dams AdvocateDeceased 2014

RESERVOIR SEDIMENTATION MANAGEMENT – Global Overview & Policy Implications

REFERENCE

Annandale, G. 2013. Quenching the Thirst – Sustainable Water Supply and Climate Change, CreateSpace, Charleston, SC

RESERVOIR SEDIMENTATION MANAGEMENT – Global Overview & Policy Implications

RESERVOIR SEDIMENTATION MANAGEMENT – Global Overview & Policy Implications

DESIGN PHILOSOPHYPARADIGM SHIFT REQUIRED

Conventional Design Life Approach

Planning & Design Construction O&M Disposal

RESERVOIR SEDIMENTATION MANAGEMENT – Global Overview & Policy Implications

DESIGN PHILOSOPHYNEW PARADIGM

Preferred Approach: Life-Cycle Management Approach

Planning & Design Construction

O&M

Refurbishment

Sediment

Removal