The importance of groundwater in urban India

S.VishwanathAdvisor

Arghyam

Urban India 2001

• 285 million (27.8%) of 1.02 billion

• 5161 cities• 35 metros - million plus• 388 large towns• 4738 small and medium < 10 lakhs

• Projected 368 million by 2012

Photo : Norma Angelica Hernandez Bernal

Groundwater.....provides for the poor , since the poor are usually not connected to the piped water supply

Water from a recharge well

What does urbanization do to urban groundwater?

•Increase it in the core area through leaking pipes (50%) and uncollected sewage

•Impair quality through point/non-point pollution•75% of surface water is polluted by untreated

municipal waste water

Typology

• Lithology determines typology

• Coastal• Hilly• Hard Rock• Alluvial• Arid

Groundwater dependence

• 75 % of urban areas in alluvial areas depend on groundwater

• 80 % of cities in hard rock areas depend on external surface sources of water

• - Ankit Patel,S. Krishnan

But water is a state subject..

Karnataka

• 223 towns• 46 completely dependant on groundwater• 137 partially dependant on groundwater

• Bangalore (pop- 6.6million) for example has 20 to 40 % dependence on groundwater but is counted as non groundwater dependant

The issue in cities

• Exploding water demand in cities

• Problems of urbanization : water shortage and flooding

• Need to manage water in cities holistically

Case study of a city as an example

• New paradigm required• Multiple sourcing of water• Source control for flood management• Institutional coordination• People’s participation in solution’s• More space for ‘softer’ solutions like education

Realities

Water tanker Bore well

Water in the city

Lakes and tanks :261 in 196081 in 199755 in 2000

Lake development authority created to preserve and enhance surface water bodies in city

The Cauvery river basin Bangalore

Groundwater use

• Impacts surface flows – The Arkavathyriver, 4000 sq km catchment, is now dry.

• 150 MLD supply source is now finished• This water now must come from

groundwater within the city or from another surface source

Surface water

• 800 mld is pumped 300 meter high• 80 MW of energy is used• 200,000 bore wells pump groundwater

from 100 to 300 metre depths• ? MW of energy

• The gw energy nexus

Local hydrologic cycle

The change

• Before construction After construction

• Runoff 15 90 (75)• Percolation 10 5 (-5)• Evapo-transpiration 75 5 (-70)

Rain barrel : Does storing water from rain reduce pumping of water?

What should be the quality of recharge water?

Sub-optimization is inevitable

Price will determine use

• Bangalore – Rs 72/ KL for industrial water• Resulted in resource substitution – about

100 mld less demand on BWSSB , which presumably came from groundwater

• Open well Rs 3/per KL• Bore well Rs 15-18 / kl• Cauvery iv stage Rs 48 per KL

The monitoring..

• Each connection is metered• Each bore well pays Rs 50 /- a month as

sanitary cess . Can bore wells be metered and volumetrically priced?

• Will people manage groundwater better if it is cheaper than piped supply?

The construct of the problem determines the solution

• Mulbagal town : 70,000 population• Arghyam initiative for IUWM• Grey area according to the CGWB• Mines and Geology suggests 600 feet as

g.w. depth• Studies indicate g.w. at 20 feet depthBGL

in a well defined shallow aquifer enough for Mulbagal’s needs

Energy cost

• Approx 60 % of the muncipality’s budget goes for energy charges towards pumping costs annually

Sustainability

• Socially-• Technically• Institutionally- Where are the urban gwi’s?• Legally- Where is the law? • Economically- What is the incentive?• Ecologically- How do we protect aquifers

and base flows?