Water: Hydrological Cycle and Human Use Hydrologic Cycle Fresh Water Water Resources Storm Water Water Stewardship

Chapter 7 WaterChapter 7 Water –some facts some facts Chapter 7 Watersome facts Fresh water Fresh water –Has less salt than 1000 ppm –Only.77% of water is accessible fresh water –Is a renewable resource Water covers 71% of the Earth’s surface Water covers 71% of the Earth’s surface

Earth’s water:

Hydrologic Cycle Hydrologic Cycle

Hydrological terms Evaporation Evaporation –Water vapor, humidity, relative humidity Condensation Condensation Purification: water is purified through the processes of evaporation and condensation Purification: water is purified through the processes of evaporation and condensation Hadley cells create major weather patterns Hadley cells create major weather patterns –Chinook winds, rain shadows rain shadowsrain shadows Infiltration-runoff ratio Infiltration-runoff ratio Watershed, percolation, Watershed, percolation, ground water, water table, aquifer

Hadley Cells are the low-latitude overturning circulations that have air rising at the equator and air sinking at roughly 30° latitude. They are responsible for the trade winds in the Tropics and control low-latitude weather patterns. Hadley Cells are the low-latitude overturning circulations that have air rising at the equator and air sinking at roughly 30° latitude. They are responsible for the trade winds in the Tropics and control low-latitude weather patterns. ( (

Human Impact On the Water Cycle 1. Changing the Earth’s surface- deforestation, overgrazing, urbanization and overcultivation lead to less infiltration and more runoff 2. Pollution- a. chemicals and wastes in the air, water and on land b. Increases from an increase in runoff 3. Withdrawing water supplies

Domestic Use of Water

Using Fresh Water Quantitative issue: do we have enough? Quantitative issue: do we have enough? Qualitative issue: Is the water safe? Qualitative issue: Is the water safe? Nonconsumptive use: electric power, home use, and some industrial use Nonconsumptive use: electric power, home use, and some industrial use Consumptive use: irrigation and agriculture Consumptive use: irrigation and agriculture

Water Usage:

Sources for Humans Ground water (40%) and surface water (rivers,lakes and reservoirs- 60%) Ground water (40%) and surface water (rivers,lakes and reservoirs- 60%) –Wells –Municipal water supplies Dams create reservoirs then water is piped to treatment plants, also used for power and irrigation Dams create reservoirs then water is piped to treatment plants, also used for power and irrigation Wastewater is collected by a sewage system and then treated before going into natural waterways Wastewater is collected by a sewage system and then treated before going into natural waterways

Treating Water

Overdrawing Water Sources Shortages Shortages Ecological effects Ecological effects –Dams affect ecosystems –Wetlands are drying up –Estuaries increasing in salt content Falling water tables  diminishing surface waters Falling water tables  diminishing surface waters Land subsidence, sinkholes Land subsidence, sinkholessinkholes Saltwater intrusion Saltwater intrusion Saltwater intrusion Saltwater intrusion

Aral Sea: 1989 and 2003

Obtaining More Water Dams: used to control runoff and generate electricity Dams: used to control runoff and generate electricity –Aswan High Dam example Aswan High Dam Aswan High Dam –Three Gorges Dam Project Three Gorges Dam Three Gorges Dam –Some dams have been dismantled Wild and Scenic Rivers Act protects rivers Wild and Scenic Rivers Act protects rivers American Rivers organization American Rivers organization American Rivers American Rivers Tapping more groundwater Tapping more groundwater

Yangtze River – before and after dam

Three Gorges Dam in China

Using Less Water Irrigation changes Irrigation changes –Surge flow method –Drip irrigation –Treadle pumps Tiered pricing for water use, flush taxes Tiered pricing for water use, flush taxes Home repairs/local conservation Home repairs/local conservation Xeriscaping Xeriscaping Xeriscaping Gray water recycling systems Gray water recycling systems Presently, no US policy restricting water use Presently, no US policy restricting water use

Irrigation

Desalting Water Microfiltration – reverse osmosis Microfiltration – reverse osmosis Distillation Distillation Desalinized seawater for irrigation will be costly Desalinized seawater for irrigation will be costly

Storm Water Changing the infiltration-runoff ratio exacerbates salt water intrusion, land subsidence, and falling water table problems Changing the infiltration-runoff ratio exacerbates salt water intrusion, land subsidence, and falling water table problems Increased flooding Increased flooding Stream-bank erosion Stream-bank erosion Increased pollution Increased pollution↓ Storm water retention reservoirs WellsTrenches