adapting to climate change in urbanizing watersheds ( accuwa )

Adapting to Climate Change in Urbanizing Watersheds (ACCUWa)

SITUATION IN ARKAVATHY BASIN

Veena SrinivasanFellow, Ashoka Trust for Research in Ecology and

the Environment

June 18th 2013

Objective: Comparative study of climate change-water vulnerability and adaptation

in 2 urbanizing watersheds

Arkavathy Watershed: Peri-urban Bangalore, 4,250 sq.km

Noyyal Watershed: Peri-urban Coimbatore,

3510 sq km

CAUVERY BASIN

RiverBasin BoundaryState Boundary

TAMIL NADU

KARNATAKA

KERALA

Arkavathy Watershed Tributary of Cauvery ~1/3 of Bengaluru, 4

Class II towns

Sources of Water Arkavathy River

(almost dry) Import from Cauvery

(limited by Tribunal) Intensive pumping of

groundwater (declining)

Rainwater + wastewater (small)

Challenges in developing theoretical framework and methods

A. Multiple Stressors

B. Multiple scales with missing linkages

C. Multiple Concerns

A. Multiple Stressors:Traditional Natural Science Framework

Water Supply(Quantity and Quality)

StressorsShocksSeasonality

RainfallTemperature

InfrastructurePolicies

Livelihood / Domestic Water Security Outcomes

“Top-Down” View of Water Supply Vulnerability

A. Multiple Stressors:

Both climate models and station rainfall data suggest slight increasing trend in annual rainfall.

< -5%

-5% - 0%

0% - 5%

5% - 10%

10% - 15%

Projected Increase in Rainfall 2035 A1B Scenario

Source: BCCI-Karnataka, 2011

A. Multiple Stressors:

Both climate models and station rainfall data suggest slight increasing trend in annual rainfall

< -5%

-5% - 0%

0% - 5%

5% - 10%

10% - 15%

Projected Increase in Rainfall 2035 A1B Scenario

Source: BCCI-Karnataka, 2011

Arkavathy Basin

A. Multiple Stressors:

0

500

1500

1000

Both climate models and station rainfall data suggest slight increasing trend in annual rainfall

1900 1950 200019751925

Doddaballapur Annual Rainfall (mm/year)

A. Multiple Stressors:

YET inflows into the TG Halli reservoir, which supplies Bengaluru, exhibit a sharp declining trend. (No new upstream dams either)

Inflows into TG Halli Reservoir (mcft/year)

A. Multiple Stressors:Traditional frameworks inadequate

Clearly the approach of blindly applying historical rainfall-runoff relationships to predict future water supply is not valid.

Rainfall Water Supply

A. Multiple Stressors:Need to account for multiple change drivers

A. Multiple Stressors:Need to account for multiple change drivers

Hypothesis 1. Increase in evapotranspiration due to temperature increase => decrease in flow.

A. Multiple Stressors:Need to account for multiple change drivers

Hypothesis 2. Excessive GW Pumping reducing base flow

A. Multiple Stressors:Need to account for multiple change drivers

Hypothesis 3. Increase in “green water use” via plantations decreasing recharge

A. Multiple Stressors:Need to account for multiple change drivers

Hypothesis 4. Unplanned urbanization causing water to collect in a “million puddles” and evaporate

A. Multiple Stressors:set up rival hypotheses

Hypothesis 2: GW Pumping

Hypothesis 3: Eucalyptus Plantations

Hypothesis 4: “Million Puddle Theory”

Hypothesis 1: Temperature rise

B. Multiple Scales – Missing LinkagesClimate variability occurs at the basin scale, whereas vulnerability is

experienced at the household scale.

PoliciesInstitutio

nsProcesses

NS

FP

H

Household Individual

Vulnerability

ContextShocks

SeasonalityTrends

influenceLivelihood / Domestic Water Security Outcomes

Social Scientists “Bottom-up” View of Water Supply Vulnerability

Source: DFID’s Sustainable Livelihoods Framework

B. Multiple Scales – Missing Linkages

Institutions

Infrastructure

No transparency on how water is allocated both within towns, across different towns, and between industrial and city supply during wet and dry periods, so hard to determine how resource variability translates to household vulnerability.

B. Multiple Scales – Missing Linkages

Different areas are vulnerable to different supply variability pathways. E.g. selected pockets get “Cauvery supply” the rest are dependent on groundwater.

Cauvery water supply

Arkavathy water supply

C. Multiple Concerns

Human Well-being

T= 0Present

T= XFuture

Drought/ SeasonalVulnerability

C. Multiple concernsInadequate water supply

Overall- most parts of Arkavathy basin do not receive enough public supply.

(However, different data sources are not consistent.)

C. Multiple concernsInadequate water quality

• Groundwater and surface water highly contaminated

Groundwater samples by taluk (sub-district)

Concentration* (mg/L)Heavy metals Fecal coliform

Cr6+:0.05 mg/lAl3+:0.03 mg/l 0 MPN/100L

Anekal 0-364Peenya Cr6+ = 16-32 0-88Doddaballapur Al3+ = 35 0-300Kanakapura PresentRamanagara Present

C. Multiple concernsDeclining SW availability

In most places the Arkavathy River is completely dry.

C. Multiple concernsDeclining GW availability

1974 1996(14)

(9)

(0)

Water Level (meters below ground level)

Source: Srikanta Murthy, 2011

Sample hydrograph in Yelahanka*

*Although groundwater levels have been increasing in places within the city mainly due to pipeline leakage

C. Multiple Concerns

Human Well-being

T= 0Present

T= XFuture

Resource Unsustainability

T= 0Present

T= XFuture

Drought/ SeasonalVulnerability

T= 0Present

T= XFuture

Chronic Scarcity/ Inequity

Research Methods

Global Climat

e Chang

e

Land, Labor,

Commodity

Markets

Topography, Geology,

Soils

Water Users

Livelihood / Domestic Water / Economic Production / Environment Outcomes

Infrastructure

Land use decisions

Extraction

Adaptation, coping

InstitutionsWatershedTemp and Rainfall

Land useAssets, Income

Water Quantity

and Quality

Available

Wastewater

Need an approach that considers all these

A. Multiple Stressors

B. Multiple scales with missing linkages

C. Multiple Concerns

THANK YOU!!Team MembersIDRC CCWSharachchandra LeleVeena SrinivasanBejoy ThomasPriyanka JamwalShrinivas BadigerDurba BiswasPennan ChinnasamyMeghana EswarT. ZuhailKiruba HaranKarthik MadhyasthaSwati SulganaSanjeev Kenchaigol

InternsMalvikaSayan Tagore Nagaraju Shilpa

Tata Social Welfare Trust ProjectSheetalDeepthi