Water Resources and Water Pollution

Water Resources and Water Pollution

• Freshwater is an irreplaceable resource that is managed poorly
• Freshwater is relatively pure and contains few dissolved salts, which is vital for most forms of life
• 71% of the Earth’s surface is covered by water, most of it saltwater
• Water is an amazing and irreplaceable chemical with unique properties
• Humans can survive for several weeks without food, but only a few days without freshwater
• Huge amounts of water are needed to supply humans with food and most other things used daily
• Water is important in sculpting the Earth’s surface, controlling/moderating climate, and removing/diluting some pollutants/wastes
• Freshwater is one of the most poorly managed resources, which is wasted and polluted
• Freshwater is available at too low a cost
• A global water crisis is occurring due to over-extraction; unsustainable agricultural practices, industrial water use, and groundwater depletion lead to water scarcity
• Pollution such as untreated sewage, industrial discharge, agricultural runoff, and plastic waste contaminate water sources
• Underpriced water encourages wasteful consumption
• Changing rainfall patterns and increased droughts worsen water scarcity
• Only a tiny fraction (0.024%) of Earth's water is readily available as freshwater in accessible locations such as lakes, rivers, and groundwater deposits
• The vast majority is in oceans (97%), frozen in ice caps/glaciers, or in inaccessible underground aquifers
• The world's freshwater is naturally recycled via the hydrologic cycle, although this system is vulnerable to pollution/unsustainable withdrawal rates

Increasing Freshwater Supplies

• Increase freshwater supplies through a variety of methods, each with its own advantages and disadvantages

Groundwater management

• Sustainable groundwater management involves reducing extraction rates, implementing artificial recharge techniques such as spreading surface water to replenish aquifers
• Employing aquifer storage and recovery (ASR) methods and improving irrigation techniques can reduce water consumption in agriculture

Surface Water Management

• Surface water management constructs dams and reservoirs to store water
• Careful consideration must be given to environmental impacts and displacement of communities
• Water transfer projects can move water from water-rich areas to water-scarce regions; ecological and social consequences need careful assessment

Desalination

• Converting saltwater to freshwater is a viable option
• Desalination is energy-intensive and produces concentrated brine that requires careful management
• Technological advancements are constantly improving the efficiency and sustainability of desalination

Water Conservation and Efficiency

• Reducing water consumption through water-efficient appliances is crucial for water conservation
• Leak detection and repair, xeriscaping (drought-tolerant landscaping), and public awareness campaigns can conserve freshwater resources

Water Recycling and Reuse

• Treating and reusing wastewater for non-potable purposes such as irrigation or industrial processes can significantly reduce dependence on freshwater sources
• Advanced treatment technologies are making this a more viable and safe option

Rainwater Harvesting

• Collecting rainwater for various uses reduces reliance on other water sources
• Can range from simple household systems to larger-scale community projects

Cloud Seeding

• Cloud seeding techniques aim to increase precipitation by introducing substances into clouds
• While still experimental and with varying degrees of success

Using Freshwater More Sustainably

• Approximately 66% of freshwater used globally is wasted
• Reducing this waste to 15% could potentially meet the world's freshwater needs
• Government subsidies often make water artificially cheap for users such as farmers, industries, and households
• This discourages investment in water-saving technologies and promotes wasteful practices, leading to overuse
• Outdated or poorly maintained water infrastructure contributes significantly to water loss
• Lack of awareness/education about water conservation among users leads to wasteful habits
• Producers of chemicals, paper, oil, coal, primary metals, and processed foods consume almost 90% of freshwater used by industries in the United States
• Flushing toilets alone accounts for about one-fourth of home water use

Actions

• Line canals bringing water to irrigation ditches
• Irrigate at night to reduce evaporation
• Monitor soil moisture to add water only when necessary
• Grow several crops on each plot of land (polyculture)
• Encourage organic farming
• Avoid growing water-thirsty crops in dry areas
• irrigate with treated waste water
• Import water-intensive crops and meat
• Redesign manufacturing processes to use less water
• Recycle water in industry
• Landscape yards with plants that require little water
• Use drip irrigation
• Fix water leaks
• Use water meters
• Raise water prices
• Use waterless composting toilets
• Require water conservation in water-short cities
• Use water-saving toilets, showerheads, and front-loading clothes washers
• Collect and reuse household water to irrigate lawns and nonedible plants
• Purify and reuse water for houses, apartments, and office buildings

Water: Actions to Reduce Water Footprints

• Waste less water and subsidize water conservation
• Do not deplete aquifers
• Preserve water quality
• Protect forests, wetlands, mountain glaciers, watersheds, and other natural systems that store and release water
• Get agreements among regions and countries sharing surface water resources
• Raise water prices
• Slow population growth

Individuals: Actions to Reduce Water Waste

• Turn off sink faucets while brushing teeth, shaving, or washing to prevent unnecessary water waste
• Repair water leaks can conserve water
• Wash only full loads of clothes or use the lowest possible water-level setting for smaller loads to save water
• Use recycled (gray) water for watering lawns and houseplants; reusing greywater is a highly efficient way to reduce freshwater consumption for non-potable uses such as irrigation
• Use drip irrigation and mulch for gardens and flowerbeds, minimizing evaporation and runoff; mulch helps retain soil moisture

Reducing the Threat of Flooding

• Areas may have too much freshwater because of natural flooding by streams, caused mostly by heavy rain or rapidly melting snow
• A flood occurs when freshwater in a stream overflows its normal channel and spills into an adjacent area, called a floodplain
• Floodplains include highly productive wetlands, helping to provide natural flood and erosion control, maintain high water quality, and recharge groundwater
• Floods have aided some of the world's most productive farmlands by depositing nutrient-rich silt on floodplains
• They help recharge groundwater and refill wetlands, supporting biodiversity and aquatic ecological services
• Floods also kill thousands of people and cost tens of billions of dollars in property damage
• Human activities have contributed to a sharp rise in flood deaths and damages
• One such activity is the removal of absorbing vegetation, especially on hillsides
• Draining and building on wetlands is a significant human activity increasing the severity of flooding
• The flooding of New Orleans during Hurricane Katrina in August 2005, occurred because of the degradation or removal of coastal wetlands

Reducing Flood Damage Prevention

• Prevention forests on watersheds
• Preserve and restore wetlands in floodplains
• Tax development on floodplains
• Use floodplains for recharging aquifers, sustainable agriculture and forestry

Reducing Flood Damage Control

• Straighten and deepen streams (channelization)
• Build levees or floodwalls along streams
• Build dams
• Wetlands act as natural reservoirs, absorbing water
• Rivers/streams peak flow is reduced, lessening the severity of downstream flooding with wetlands
• Vegetation slows water flow
• Plant roots bind soil, reducing erosion and increasing the land's capacity to absorb water
• Forests and other vegetated areas act as natural barriers
• Intact topsoil absorbs water more effectively than bare soil
• Vegetation helps maintain topsoil, preventing erosion that can clog waterways and increase flood risk

Dealing with Water Pollution

• Water pollution is defined as any change in water quality that can harm living organisms or make the water unfit for human uses such as drinking, irrigation, and recreation

Point Sources

• Single, identifiable sources that discharge pollutants into bodies of surface water at specific locations
• Examples include factories, sewage treatment plants, drain pipes, ditches, sewer lines, underground mines, oil wells, and oil tankers
• Located at specific places, which are relatively easy to identify, monitor, and regulate
• More-developed countries often have laws to help control point-source discharges of harmful chemicals

Nonpoint Sources

• Broad and diffuse sources where pollutants enter water from a wider area rather than specific points
• Examples include chemicals and sediments from cropland and runoff from urban streets, parking lots, lawns, and golf courses
• Controlling nonpoint source pollution is more challenging, and less progress has been made

Groundwater

• Because of the difficulty and expense of cleaning up a contaminated aquifer, preventing groundwater contamination is the only effective way to deal with this serious water pollution problem

Solutions

• Find substitutes for toxic chemicals
• Keep toxic chemicals out of the environment
• Install monitoring wells near landfills and undergoing tanks
• Require leak detectors on underground tanks
• Ban hazardous waste disposal in landfills and injection wells
• Store harmful liquids in aboveground tanks with leak detection and collection systems
• Pump to surface, clean and return to aquifer (very expensive)
• Inject microorganisms to clean up contamination (less expensive but still costly)
• Pump nanoparticles of inorganic compounds to remove pollutants (still being developed)

Conclusion

• Addressing global water challenges requires a multifaceted approach
• Must consider the availability of usable water; methods for increasing freshwater supplies
• Must consider the sustainable use of water resources, flood mitigation strategies, and effective solutions for water pollution
• Each of these areas presents significant challenges and opportunities for innovation and collaboration