Population Change and Fresh Water

1. Population Change and Fresh Water “Water and other natural resources interact with rates of population growth in affecting economic development. Population growth is most likely to hinder growth in output per person where water and arable land are scarce or costly and the ownership of water, land other natural resources is poorly defined.” Cohen p. 325 EEP153, spring 2005

2. Population Change and Fresh Water • Guesstimates on water availability (Joel Cohen); • Water availability/scarcity under different population projections (PAI, Outlaw and Engleman); • Water quality and water-related diseases with/without MDGs (P.Gleick); • Threats to fresh water ecosystems from human activity (G. Daley); • Actions and policies to conserve and manage water – “soft-path solutions” (P. Gleick); • Small-scale and traditional irrigation (examples from Sandra Postell – read!). EEP153, spring 2005

3. Population Change and Fresh Water How much fresh water? • Renewable groundwater (infiltration) + water from rain, snow, hail and sleet (runoff) = natural water supplies that people can count on from nature. • Est. total = 41,000 cubic kilometers per year. • Est. available total = 9,000 to 14,000 cubic kilometers per year in groundwater + capacity to capture runoff in reservoirs, pipelines, wells…. • Highly unevenly distributed across the planet and seasonally; capacity to store is vital where rain is concentrated in few months. EEP153, spring 2005

4. Population Change and Fresh Water Water withdrawals: • Agriculture, 70% • Industry, 23% • Domestic needs, 8%. On average, 42% of withdrawals are “discharged” to rivers/streams/coastal waters. Great potential to expand fresh water supply through recycling if discharged waters are not too contaminated. EEP153, spring 2005

5. Population Change and Fresh Water Millennium Development Goals for Water (UN and WSSD, 2002): • Halve by 2015 the proportion of people without sustainable access to safe drinking water. (est. 1.1 billion in 2000) • Halve by 2015 the proportion of people who do not have access to basic sanitation. (est. 2.4 billion/40% of world population in 2000) EEP153, spring 2005

6. Population Change and Fresh Water Water quality – • Major issue for human health (biological and chemical pathogens); • Major issue for aquatic ecosystem health. Water-related diseases

7. Population Change and Fresh Water Soft-path solutions to water scarcity“Society’s goal should be not the use of water, but improved social and individual well-being per unit water used.” (Gleick) • focus on water management, productivity & conservation rather than supply; • small-scale, decentralized and lower-cost facilities; • apply economic tools like prices and markets. Examples from: • Domestic water use: • Irrigation water use: • Industrial water use:

8. Population Change and Fresh Water Thinking big about small-scale irrigation – compelling reading! • 1.2 million treadle pumps in Bangladesh, for high water table –low cost, simple design, ease of repair, popular marketing (film stars) • Flood-recession and river-based farming in SSA, combined with small pumps and tubewells to tap shallow groundwater - age-old practice in Africa, Nile and Niger Delta • Harvesting the rain for dryland farming in India, China, NE Brazil, SSA – tanks/small reservoirs, “runnoff agriculture” – channeling rainwater toward fields, small dams & percolation ponds. EEP153, spring 2005

9. Population Change and Fresh Water Actions and policies to increase available fresh water supply/improve water productivity/conserve water: • Vegetarianism! • ……. • ……. • ……. • ……. • ……. • ……. EEP153, spring 2005

10. Population Change and Fresh Water Soft-path solutions to water scarcity (Gleick) “Society’s goal should be not the use of water, but improved social and individual well-being per unit water used.” • focus on water management, productivity & conservation rather than supply; • small-scale, decentralized and lower-cost facilities; • apply economic tools like prices and markets. Examples from: • Domestic water use: low flow toilets & showers, drip irrigation, recycle bath water… • Irrigation water use: precision-application sprinklers & drip, better weather info., drought-tolerant crops… • Industrial water use: recycle withdrawals

11. Population Change and Fresh Water “Today’s problems are to get the right amounts of water in the right places at the right times, and to get the most use from the available fresh water. If population growth continues in the future, present water shortages could become more severe in many regions, and people could encounter limits set by aggregate renewable freshwater supplies….Obvious improvements in recycling, pricing and the efficiency of delivering and using water could postpone water shortages.” Cohen 328 EEP153, spring 2005

12. Population Change and Fresh Water Example of conservation: In Israel, where most people are remarkably well fed, the 1986 withdrawals were 447 (compared with 560 est. requirement for non-vegetarian diets) cubic meters per person, 88% of the renewable fresh water available per person. Most Israelis ate and drank well, and some went to the swimming pool from time to time, by producing goods and services that they exchanged for food grown in other countries. What food they grew at home, they grew with a maximum of water efficiency, using drip irrigation and recycled water. Foreign aid, particularly from the US, contributed to the infrastructure that made this efficiency possible. (Joel Cohen) EEP153, spring 2005