World Water Week 2010

Workshop 2: Shortcutting Historical Pollution Trends

September 9, 2010

Daniel Stellar

Assistant Director, Columbia Water Center

The Crucial Link between Water Quantity and Quality: The Scope of the Problem and

Implications for Solutions

Outline

Motivation Context/Examples Case Study Quality –Quantity Interactions Solutions

Motivation Explicitly draw out the link between water quality and

quantity

Demonstrate how interventions which affect water quantity can also improve quality, thereby “shortcutting historical pollution trends”

Context Many ways exist to provide safe, high quality water Limiting source pollution Providing treatment

These methods are resource constrained by, money, energy and /or regulatory environments

In some cases there is also a conservation- oriented, quantity-based solution

Quality problems are not always triggered by external pollutants – they can be caused by depletion of quantity

Examples of water quality-quantity tradeoffs Groundwater Excessive pumping of groundwater leading to decreased quality,

through saltwater intrusion and increasing concentration of TDS’s Israel / Palestine - Gaza Coastal Aquifer Cyprus

Surface water Overuse of river water reduces flows leading to increased

pollution concentrations Iraq –Tigris River US / Mexico – Rio Grande River

Context

Water scarcity exacerbates pollution and degradation

Reducing depletion of water resources improves water quality and access

Columbia Water Center is working on all 3 of these areas directly and indirectly. By addressing the root problem of water scarcity we are driving solutions to pollution and access.

3 Nested Water Crises

Case study: Gujarat Semi-arid region Relatively hot and dry, with

low average annual rainfall

Significant ongoing groundwater depletion

Energy use heavily subsided by state. Groundwater depletion so severe that

value of subsidy exceeds farmers income from crop

Example: Gujarat Water levels falling with regard to

mean sea level

In our sample, 82 % of wells reported the appearance of salt in their water over the last 5-15 years. Other changes in water quality include fluoride (30 %) and dust (30 %).

Other studies demonstrate increasing levels of salt and a high level of fluoride in water sources across Gujarat.

Example: Gujarat Project description:

Target agricultural use and water-energy nexus

3 part campaign, including education, analysis of technology options and incentive-based system Reforming energy subsidy can

encourage conservation by farmers

Revenue neutral approach emphasizing incentives for conservation instead of pricing or taxing

Example: Gujarat Possible results: Water savings of up to 10-30%

Reduction in energy use leads to stabilization of groundwater tables at a higher level, reducing risk of catastrophic saltwater intrusion

Gradual increase in groundwater tables, eventually leading to improved quality of groundwater

In this case, quality problem can be avoided by addressing quantity problem.

Quality – quantity interactions

“Pure” Water Quality Problems

•Charles River, MA, USA

Water Quality Problems with Strong Quantity Component•Gujarat, India•Rio Grande

As scarcity increases, so does importance of quantity-quality tradeoffs, and there is a greater role for conservation oriented reforms

Ganges River Yangtze River

Solutions When might a conservation-oriented, quantity based

approach work? Subset of Water Quality Problems with Strong Quantity

Component

Water scarce environment Significant ongoing use of water Agriculture is driving water use Efficiency gains are possible

“Pure” Water Quality Problems

Water Quality Problems with Strong Quantity Component

Conclusions In some cases, water quality problems are caused or

exacerbated by insufficient water quantity In a subset of these cases, conservation-oriented approaches

aimed at restoring quantity may be the most appropriate solution

Water scarcity is likely to exacerbate importance of quality-quantity tradeoffs

Recognizing these issues, and addressing them directly, can allow for shortcutting of historical pollution trends

Thank you!