ESR102 - Lecture 6

http://web.pdx.edu/~rueterj/courses/esr102-201001/lecture5.html

Lecture 6: Water resources: local, critical, and renewable February 11, 2010 water requirements for human health and agriculture discuss - Is access to clean water a right? areas of water shortage large water projects ecological restoration to improve water appropriate technology and smaller scale approaches
Review: water amounts and pollution as a major loss recent article in the NYT
1. Water requirements for human health and agriculture Human health just to survive for drinking = 3 liters/(person*day) for hygeine and sanitation = 50 liters in 2000, 55 countries below this level ref Agriculture water uses the most http://www.eoearth.org/article/Freshwater water efficiency for different crops water used for an amount of crop production kg crop/m3 of water depends on many variables such as humidity, crop type, wind track water flows - figure 9 example numbers desert 0.4 g per kg (0.4 grams of plant per kg of water) short grass prarie = 1.1 forests 1 to 1.8 water use efficiency for several products water embedded in food LCA for water and diapers
2. Is clean water a right? different points of view: Wetzel 2001 (limnologist) - clean water is not a "right", it is rather our "responsibility" to look after the environment to maintain clean water stress on human population - goes from desease, economy, food, energy and predicts that after 2000 it will be water will be the most severe stress Amartya Sen : deprivation in human capabilities defines poverty such as a lack of access to water and services freedom from these deprivations is the value that should be counted link GPI - cleaning up polluted water doesn't count in the GPI What are our rights to clean water?
3. Regions of water shortage http://www.eoearth.org/article/Freshwater total availability by country water stress - % of available water withdrawn
4. Large water projects used to tie civilizations together Aztec Mayan Anasazi in Chaco (New Mexico) current water projects California Aqueduct - 1150 km map China South to North project > 1200 km
5. Ecological restoration to increase water available healthy, forested watersheds deliver more water as an ecosystem service leaves intercept the rain plants cover the bare soil surface humus and plant material act as a sponge roots break up the soil and sub-strata to allow water to percolate loss of plants results in a positive feedback for loss of ecosystem water restoring deforested or damaged watersheds can produce water The Nature Concervancy model NY Times article on Niger Wangari Mathai - video (extras/Green Belt Movement/environmental conservation) Greenbelt - short video other examples: rainwater harvesting in India traditional methods of retaining water in small catch dams johads that provide water for stock and also recharge groundwater in 1940's government policies encouraged logging loss of trees meant more erosion and loss of johads viscious cycle - from a negative tipping point trying to correct this by revegetating stream channels and building johads opposite of a tragedy of the commons because: good immediately for those who build it (stock watering) builds a community resource (well water) over longer time and larger spaces Water for People Green Empowerment in San Jose de Bocay, Nicaragua combination project microhydro - renewable energy with some excess capacity allows for enterprise use of power community development lead to protect and reforest the watershed clean drinking water constant source for micro-hydro sustainable farming techniques biomass rice drier agro-forestry training center Rio Calico, Nicaragua Mitigating climate change through reforestation land use changes may improve land use and quality of the resource more reliable water better food security through variety of crops maybe able to tap carbon offsets or credits to pay for reforestation projects
6. Appropriate technologies smaller scale technologies are often very useful examples relating to water: windmill driven water pumps Aeromotor solar (photovoltaic) driven water pumps deep wells need bigger arrays (1 kwatt) shallow wells and shorter distances - smaller arrays (80 watts) shallow water treadle pump Paul Polak - Out of Poverty drip irrigation as installed in Nicaragua importance of this scale of technology (not just for water) individual installations are cheaper and can be funded locally community is involved can be fixed locally can be changed or improved more easily innovation can spread through the adoption of the components in fresh ways