Lecture 1 - Introduction Flashcards
Why is Water important?
- No species can live without water
- Plays a key role in shaping the earth’s surface, moderating climate, removing and diluting wastes.
- Takes huge amount to provide food, shelter and other needs.
- It is 71% of our planet
What are water’s unique properties?
- Hydrogen Bonding
- Liquid over wide temperature range
- Changes temperature slowly
- High heat of evaporation
- Great dissolving power
- Filters out ultraviolet radiation
- Adhesion and cohesion
- Expands when it freezes
- Water is also one of few substances found commonly as a solid, liquid and gas.
_____ of water is in oceans
97.4%
precipitation that does not infiltrate the ground or return to the atmosphere.
Surface runoff
amount of water that can be counted on each year as a stable source.
Reliable runoff
the region of land from which surface water drains into a river, lake, wetland or other body of water
Watershed
It is One of the most important source of water.
Groundwater
_____ found within 1km of the surface contains 100 times more water than all the rivers, streams and lakes
Groundwater
Humans use about _____ of reliable runoff
54%
Uses of Water Resources
- Agriculture
- Industry
- Domestic
About ___________ do not have access to regular, clean water supplies.
1 in 6 people (1 billion people)
4 Reasons why there’s too little of water
- Dry climate
- Drought
- Desiccation
- Water Stress
people living or growing crops in areas where little precipitation naturally falls
Dry climate
prolonged periods of below average precipitation.
Drought
drying of exposed soil because of activities such as deforestation and overgrazing.
Desiccation
low per capita availability of water due to increasing population demands.
Water Stress
6 water resources sustainability - facets
- Availability of supply
- Infra for provision and protection
- Infra for quality
- Water supply and excess management
- Local, regional, national and international basis
- Integrated water resources management
Draw the Urban Water Cycle
-see ppt-
7 water management to water supply
- Sources
- Transmission
- Water treatment
- Distribution system
- Wastewater collection
- Wastewater treatment
- Reuse
3 water management to Water excess
- Collection/drainage system
- Storage/treatment
- Flood control components
8 Major impacts of increased runoff (Urban storm water runoff
- Increased stream flows
- Decline in runoff water quality
- Higher runoff with higher pollutant
- Diminished GW recharge
- Increased flooding
- Sanitary sewer overflows
- Damage to stream and aquatic life
- Destroying food sources/habitats of aquatic life
6 Factors affecting urban flood management
- Development with no planning
- High population concentration
- Lack of stormwater and sewage facilities
- Polluted air and water
- Difficulty of water supply against population
- Poor public transportation
How to increase water supply
1) Build dams and reservoirs
2) Transfer water to places it is needed
3) Withdraw groundwater
4) Desalinization
5) Reduce water waste
6) Import food from regions where irrigation is not needed.
Large _____ can produce cheap electricity, reduce downstream flooding and provide a year round source of water, but they completely alter the river ecosystem.
dams
Benefits of tapping groundwater
- Year-round use
- Little water loss
- Often cheaper
Tapping of groundwater costs
- Has tradeoffs
- Water tables around the world are falling
Problems with using groundwater
Water table lowering Depletion Subsidence Saltwater intrusion Chemical contamination Reduced stream flows
Problems using groundwater
Salt water intrusion
Ground will subside
removing salt from seawater by evaporation of water leaving salt behind.
Distillation Desalination
pumping saltwater under high pressure through a membrane to take out salt.
Reverse osmosis desalination
releasing tiny particles into air to produce rain clouds
Cloud seeding
moving ice around world.
Towing icebergs
How to use water more efficiently
- Reduce losses due to leakage
- Reform water laws
- Improve irrigation efficiency
- Water efficient landscaping (xeriscaping)
- Water efficient appliances:
- Reusing of water
Human Activities that affect Water Quality
Sedimentation • Eutrophication • Thermal Pollution • Acidification • Microbial contamination • Salinization • Trace metals and mercury • Pesticides
Sources of water pollution
- Storm water runoff
- Domestic discharges
- Industrial discharges
- Accidental spills
