Lecture 19 - Outline Aquatic Resources Freshwater...

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Unformatted text preview: 3/24/2011 Outline Aquatic Resources Freshwater Recognition of water as an important environmental issue of the 21st century How much water is available for use? – Hydrological cycle – Renewable portion of water – Importance of groundwater ENV200H1S March 24, 2011 Global availability of water Canadian usage of water Basic daily water requirement 1 “The availability and management of fresh water are becoming one of the greatest environmental, social, and political challenges of the 21st century” - Canadian Commissioner of the Environment and Sustainable Development 2 Water promises to be to the 21st century what oil was to the 20th century: the precious commodity that determines the wealth of nations lth Fortune Magazine, May 2000 Of all the social and natural resource crises we humans face, the water crisis is the one that lies at the heart of our survival and that of planet Earth - UN World Water Development Report 2003 3 “to many analysts, emerging water shortages in many parts of the world – along with the related related problems of biodiversity loss and climate change – are the three most serious environmental problems the world faces during this century” I predict that the United States will be coming after our fresh water aggressively within three to five years, I hope that when the day comes, Canada will be ready 4 Peter Lougheed, former Premier of Alberta “As air is a sacred gas, so is water a sacred liquid that links us to all the oceans of the world world and ties us back in time to the very birthplace of life” David Suzuki Miller & Hackett, 2008 5 6 1 3/24/2011 The 2005 Millennium Ecosystem Assessment found that water-based ecosystems are the waterworld’s most degraded natural resource. Seventy major rivers around the world are near maximum extraction levels to supply water for irrigation systems and for reservoirs, including the Colorado, Ganges, Jordan, Nile and TigrisTigrisEuphrates rivers. The Importance of Water All living things need water You are about 60% water by weight Moderates climate Sculpts the land Removes and dilutes wastes and pollutants Waterways template for settlement patterns 7 8 Water on Earth “Water, water everywhere, nor any drop to drink” The Rime of the Ancient Mariner - Coleridge About 97% Earth’s water is salty Fresh water is distributed unevenly 2025: 1/3 human population will live in areas lacking fresh water areas What can be done about this? Water is continuously cycling through the environment 9 How much water is readily accessible? (similar accessible? (similar to Fig. 9.4) 10 Hydrologic Cycle Ocean Atmosphere Land Ocean The earth's water supply remains constant, but humans alter the cycle of that fixed supply. 11 12 2 3/24/2011 Global hydrologic cycle is driven by: Net evaporation over oceans Net precipitation over land Surface Water Streams, rivers, lakes, ponds, reservoirs, wetlands Runoff replenishes surface water Watershed Area of land drained by a single river Drainage basin 13 Groundwater Use and Problems Groundwater 14 Supply of fresh water found under Earth’s surface Stored in underground aquifers aquifers Discharged into rivers, springs, etc… Usually considered nonrenewable Out of sight OneOne-fifth of Earth’s freshwater supply Jurisdictional boundaries boundaries 15 Ogallala Aquifer 16 16 Oak Ridges Moraine Source: USGS 17 18 3 3/24/2011 Dump Site 41 Renewable Water Renewable water supply is a simplified upper limit to the amount of water consumption that could occur in a region on a sustained basis Annual water budget = precipitation precipitation - evaporation 19 If more water is withdrawn than is replenished by natural processes, the excess is essentially "mined" from reserves (fluxes maintain pools). These can be recent local aquifers or ancient ancient sources of underground "paleowater". The water tables under some cities in China, Latin America and South Asia are declining at over one m.y-1. 20 20 Only 1% of the waters of the Great Lakes are renewed each year by snow melt and rain. The remaining 99% represents meltwater from the last ice age 21 Canada 22 Residence Time in Earth’s Water Compartments Canada holds 20% of the world's fresh water (enough to flood the entire country to a depth of more than 2 m), but has only 7% of the world's fresh renewable water 23 24 4 3/24/2011 Water is Unequally Distributed Per capita water supply Mean Annual Precipitation Supply (m3.c-1.y-1) Country Canada 120,000 Brazil 45,000 Australia 19,000 United States 11,000 France 3,000 China 2,000 India 1,000 25 26 continental disparities in water availability versus population Defining Basic Needs Countries with less than 1,700 m3.cap-1.y-1 are characterized as water-stressed Countries with less than 1,000 m3.cap-1.y-1 are characterized as water scarce Asia supports 60% the world’s population with only 36% of the world’s water resources1 China with 22% of world’s population has only 8% of world’s fresh water2 www.unesco.org 2World Watch Institute water is temporarily unavailable at particular locations choices must be made among uses (personal consumption, agriculture, industry or wildlife) there may not be enough water to provide adequate food, economic development is hampered severe environmental difficulties 1 27 In 1997, 270 million people lived in 11 water stressed countries while 166 million people lived in 18 countries experiencing water scarcity. Based on UN Population projections, by 2025 the number of water stressed countries will rise to 15 and be home to 2.3 billion people. The number of countries experiencing water scarcity will double to reach 39, or 1.7 billion people 28 basic daily water requirement In 2000, 61 countries with (BWR)1 50 L.c-1.d-1 (drinking, sanitation, cooking)1 BWR does not take into account other uses of water (e.g. agriculture, ecosystem protection, industry) and translates into ~ 20 m3.c-1.y-1 a total population of 2.1 billion people, were using less than the BWR. By 2050 somewhere between 2 billion people in 48 countries (at best) and 7 billion people in 60 countries (at worst) are likely to be water-scarce Compare this with Canada where we use ~350 L.c-1.d-1 1WHO/UNICEF: Global Water Supply and Sanitation Assessment. 2000 30 5 3/24/2011 And we really use water! Canada ranks 28th among the 29 nations of the OECD in terms of per capita water consumption (for all uses). Only Americans use more water per capita than Canadians. Excessive consumption in Canada is attributed to lack of widespread water conservation practices and water pricing that does not promote efficiency 31 Even within areas of similar hydrology, water plays out differently across the planet Phoenix Arizona and Lodwar Kenya are hydrologic sister cities Each receives about 16-18 cm of precipitation per year In each, population has outstripped the ability of the surrounding watersheds to meet “needs” (wants?) How does each “understand” water? Postel, Sandra Facing Water Scarcity Conference Board of Canada 1600 m3.c-1.y-1 =~4400 L.c-1.d-1 32 Phoenix has ample water for drinking, bathing, swimming, watering lawns, misting the patios at local ‘watering’ holes. Per capita water use exceeds exceeds 1000 L.day-1 Lodwar women and children walk for water, carrying as much as they can balance on their heads. Per capita water use is about 10 L.day-1 33 In Lodwar, water is understood to be scarce with that scarcity adding drudgery and insecurity to everyday life. In Phoenix, there is little real understanding of water. Its scarcity is masked leaving an illusion of plenty in a waterscarce environment How much water does it take to maintain a golf course in the desert? 6 ...
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