GROUNDWATER AND CLIMATE CHANGE GROUNDWATER AND CLIMATE CHANGE

MANAGING THE WATER BUFFERMANAGING THE WATER BUFFER

Albert TuinhofAlbert TuinhofGroundwater Development and Management Groundwater Development and Management

GW-MATE SpecialistGW-MATE Specialist

AGW-NET Training of Trainers on Groundwater Management AGW-NET Training of Trainers on Groundwater Management Dar es Salaam - November 16-20, 2009Dar es Salaam - November 16-20, 2009

• Adaptation Options for Climate Change Impacts on Groundwater Resources (World Bank, SKM – 2009)

• Groundwater and Climate in Africa (Hydrological Sciences Journal, volume 54, number 4, August 2009) – Richard Taylor, Antonis D. Kousis and Callist Tindimugaya

• CPWC: Cooperative Panel/Program on Water and Climate (since 2003)

• Managing the Water Buffer (Acacia Water, Meta Meta, BGR – 2009)

MAIN BACKGROUND MATERIALMAIN BACKGROUND MATERIAL

CLIMATE CHANGE IMPACTS ON GROUNDWATERCLIMATE CHANGE IMPACTS ON GROUNDWATER

- Recharge- Discharge- Storage- Quality

- Temperature- Precipitation- Evapotranspiration - Sea level rise- Soil moisture

RECHARGE : CLIMATE CHANGE MESSAGERECHARGE : CLIMATE CHANGE MESSAGE

Doll and Florke (2005): global scale 2% increase against 4% increase in rainfall

70 % decrease in the western part of Southern Africa and >30 % increase in the Sahel

Estimates not appropriate to scale down to country or basin/watershed level

(IN)DIRECT CLIMATE AND NON-CLIMATE FACTORS(IN)DIRECT CLIMATE AND NON-CLIMATE FACTORS

RECHARGE

•Precipitation: main driver: not only the magnitude but also intensity, frequency, seasonality

•Temperature and CO2 may affect evapotranspiration > portion of rainfall that infiltrates

•Changes in river flow will affect infiltration (and discharge)

• Land cover and land use <> climate change

• Non climate factors: land use changes, population growth, poor management

CLIMATE CHANGE IMPACTS: CLIMATE CHANGE IMPACTS:

Global estimates give regional trends , not appropriate to scale down to country /basin level.

Climate factors (direct/indirect) and non-climate factors

Changes in natural climate variability

IMPLICATIONS FOR GRW DEPENDENT SYSTEMSIMPLICATIONS FOR GRW DEPENDENT SYSTEMS

Impacts of droughts and floods on

• Rural and urban water supply

• Agriculture

• Ecosystems

What are climate change impact <> groundwater related issues in yr country??

CLIMATE CHANGE ADAPTATIONCLIMATE CHANGE ADAPTATION

• Managing grw. recharge• Management of grw. storage• Protection of grw. quality• Managing demands for grw.• Managing grw. discharge

Managing groundwater recharge

Protecting groundwater

quality

Managing demand for

groundwater

Managing groundwater discharge

Managing groundwater

storage

Adaptation: management responses for grw. dependent systems to risks associated with climate variability and climate change

• Building the adaptive capacity for grw. management

• Management Aquifer Recharge: MAR

• Managing the Water Buffer: 3R

No regret measures

EXAMPLE : MGT OF RECHARGE AND STORAGE EXAMPLE : MGT OF RECHARGE AND STORAGE

MARMAR

building infrastructure and/or modifying the landscape to intentionally enhance groundwater recharge

Recharge enhancement provides additional storage

Therefore…..Storage!!Therefore…..Storage!!

There is a need for small scale, low tech, low cost, sustainable solutions!

Some figuresSome figures

• Surface water storage per capita– Ethiopia 43m3

– South Africa 750m3

– North America 6150m3

• Village ponds or domestic rainwater storage could add 5m3 per person

• Each additional 10mm groundwater recharge could add 200m3 per person

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Storage = buffering Storage = buffering

3R concept – Recharge, Retention and Reuse• Local (cisterns) and subsurface storage (active

use of aquifer) of surface water for both water- and food security

• Its not about allocation scarce water but to catch and retain water and extend the chain of use and reuse as possible within a basin

• Introduce buffer management at scale – basin by basin. Not piecemeal/scattered

• Subsurface storage largest potential in terms of m3 13

EXAMPLE : MGT OF RECHARGE AND STORAGE EXAMPLE : MGT OF RECHARGE AND STORAGE

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EXAMPLE : MGT OF RECHARGE AND STORAGE EXAMPLE : MGT OF RECHARGE AND STORAGE

EXAMPLES KITUIEXAMPLES KITUI

SAND DAMSAND DAM

Subsurface storage

Abstraction well

HOW IT WORKSHOW IT WORKS

• Dam drops the flow velocity and results in sedimentation and percolation of water

• Increasing the water availability by storing water in the riverbed and banks

• Increased availability of water for domestic and other uses such as livestock, irrigation and regeneration of natural vegetation

IMPACTS OF SAND DAMS IN KITUIIMPACTS OF SAND DAMS IN KITUI

Vulnerability Categories

Vulnerability indicators Before dam construc-

tion

After dam construc-

tion

Agriculture# of cash crops 1.5 2.8

% irrigated crops 37 68

Special aspects

Water collection Domestic (minutes)

140 90

Water collection Life Stock (minutes)

110 50

Gender Average walking distance women to water (km)

3 1

Economic Income (US$./year) 230 350

Health % households suffering from malnutrition

31.6 0

Every Body has the right to be buffered