APES – Chapter 21: Water Supply, Use and Management

Case Study: What Is the Value of Clean Water to New York City? - Catskill Mountain Forest provides water to 9 million; New York City owns less than 8% of the forest; the

quality of the water is very good and requires little filtering- Natural filtering has aided in the past (helps reduce the use of treatment plants) - As water infiltrates the ground (soil) and then transfers to groundwater, and then transfers into a stream, it

undergoes natural filtration (physical and chemical) processes > these are called ‘natural service functions’ - In the 1990s, the water supply was becoming vulnerable to pollution due to uncontrolled development in

the watershed; urban runoff and toxins were allowed to seep through soil; EPA warns New York to construct a water treatment plant if the quality did not improve; the plant would cost $6-8 billion along with running costs; therefore, New York chose to try and improve the water quality without a treatment plant

- New York City then built a treatment plant in the Catskill mountains for $2 billion; New York therefore decided to invest in the “natural capital” of the forest > will take a long time to see if the investment paid off

- The Catskill Mountains provide other benefits as well such as trout fishing and other recreational activities - New York has also provided financial incentives to farmers and other residents to help influence them into

keeping the water clean; “valuing ecosystems for the functions they perform” - Numerous other cities have also chosen to invest in watershed protection rather than build treatment plants

Water To understand water, we must understand its characteristics, and roles:

o Water has a high capacity to absorb and store heat. o Water is the universal solvent.o Water has a high surface tension.o Water is the only compound whose solid form is lighter than its liquid form. o Sunlight penetrates water to variable depths, permitting photosynthetic organisms to live below the

surface. A Brief Global Perspective We are facing a growing global water shortage linked to the food supply. Global hydrologic cycle

o Transfers water from the atmosphere, to land, to oceans and back to atmosphereo 97% in oceanso 2% in iceo Only 0.001% in atmosphere

Tommy Hicks

APES – 6th period

At Earth’s surface water can be found in liquid, solid or gaseous form.o Residence time varies from a few days to thousands of years

Amount of water for which all people, animals and plants compete is < 1%o Industrial production increases water useo Mass of water used 1000x total production of minerals

Groundwater and Streams Groundwater refers to the water below the water table

o Where saturated conditions existo Locations where surface waters move into the ground are recharge zoneso Places where it flows or seeps out are discharge zones (points)o Area where water seeps through pore spaces known as vadose zone

Aquifer is an underground zone from which groundwater can be obtainedo When water is pumped from an aquifer forms a cone of depression

Streams Effluent stream

o Flow is maintained during the dry season by seepageo Perennial stream

Influent streamo Entirely above the water table and flows only in direct response to precipitationo Ephemeral stream

A given stream can have reaches that are both or intermittent at varying times of year. Interactions Between Surface Water and Groundwater Should be considered part of the same resource. Nearly all surface water environments have linkages w/ ground water

o E.g. withdrawal of groundwater can lower stream flow or lake levelso Pollution can spread from one source to the other

Water Supply: A US Example Water supply at any point on the land surface depends on several factors in the hydrologic cycle,

o including the rates of precipitation, evaporation, transpirationo stream flowo subsurface flow

Water budgeto A model that balances the inputs, outputs, and storage of water in a system.

o Precipitation - evaporation = runoff Amount of water vapor passing over the US every day ~ 152,000 million m3

o 10% falls as precipitation (66% of which is evaporated or transpired)o Only 34% enters surface or groundwater

Precipitation and Runoff Patterns In developing water budgets for water resources management it is useful to consider annual precipitation and

runoff patterns.o Potential problems can be predicted in areas where average runoff and precip lowo Total storage of runoff not possible because of evaporative losses

Droughts Because there are large annual and regional variations in stream flow, even areas with high precipitation and

runoff may suffer from droughts. Groundwater Use and Problems ½ the people in the US use groundwater as a primary source of drinking water

o 20% of water usedo In many parts of the country withdrawal from wells exceeds natural inflow

Overdraft Nonrenewable resource Problems include damage to river basins and land subsidence

Desalination as a Water Source Seawater is 3.5% salt Desalination- a technology to remove salt from water

o Must be reduces to 0.05% to be fresh watero Requires large amount of energy, tied to fuel priceso Has place value- price increases quickly with transport distanceo Discharge may affect local salinity

Water Use Off-stream use

o Refers to water removed from its source for useo May be returned to source after useo Or consumptive use- water enters tissues, product or evaporates during use and not returned

In-stream useo The use of the river for navigation, hydroelectric power, fish and wildlife habitats, and recreation.o Multiple uses can create controversy

Another problem with off stream use is how much water can be removed w/o damaging the stream ecosystem.o E.g. Aral Sea. Diverting water for agriculture caused sea to dry upo Surface area of sea reduces 90% in 50 years

Aral Sea Salt content of the water has increased Dust storms from dry salt flats Climate changes

o Winters colder, summers warmero Loss of fishing and decline of tourism

Transport of Water Ancient civilizations constructed canals and aqueducts to transport water

o From distant river to where it is needed In modern civilization water moved from areas of abundant rain and snow fall to areas of high usage

o E.g. California moves water from north to southo E.g. New York City has had to obtain water from farther and farther away

Some Trends in Water Use Withdrawal of surface water far exceeds withdrawal of groundwater Since 1980 use has decreases and leveled off

o Suggests improvement in water management and conservation Trends in freshwater withdrawals by water-use categories suggests that:

o 1. The major uses of water are for irrigation and the thermoelectric industry.o 2. Water use for irrigation increased from 1950-1980. It decreased and leveled off from 1985-2000

due to better irrigation efficiency, crop type and higher energy costs.o 3. Water use by thermoelectric industry decreased slightly in 1980, and stabilized in 1985.

Due to reticulating water for coolingo 4. Water for public and rural supplies continued to increase through the period from 1950 to 2000

presumably related to the increase in human population. Water Conservation The careful use and protection of water resources

o Involves the quantity of water used and the qualityo Important component of sustainable water useo Expected that a number innovations will reduce the total withdrawals

Agricultural Use Improved irrigation could reduce agricultural withdrawals by 20 to 30%

o Tremendous savings because ag is the biggest user Suggestions for conservation:

o Price agricultural water to encourage conservation o Use lined or covered canals that reduce seepage and evaporation.o Use computer monitoring and schedule release of water for maximum efficiency.o Integrate the use of surface water and groundwater to more effectively use the total resource.o Irrigate at times when evaporation is minimal, such as at night or in the early morning.o Use improved irrigation systems, such as sprinklers or drip irrigation, that more effectively apply water

to crops.o Improve the soil to increase infiltration and minimize runoff.o Encourage the development of crops that require less water or are more salt tolerant.

Domestic Use Accounts for about 10% of total national water withdrawals

o But concentrated in urban areaso May pose major local problems

Water use can be substantially reduced by:o In semiarid regions, replace lawns with decorative gravels and native plants.o Use more efficient bathroom fixtures.o Turn off water when not absolutely needed.o Flush the toilet only when really necessary.o Fix all leaks quickly. o Purchase dishwashers and washing machines that minimize water consumption.o Take a long bath rather than a long shower.o Sweep sidewalks and driveways.o Using gray water to water vegetation. o Water lawns and plants at cool times to reduce evaporation.o Use drip irrigation and place water-holding mulch around garden plants.o Plant drought-resistant vegetation.o Learn how to read the water meter to monitor for unobserved leaks and record your conservation

successes.o Use reclaimed water

Industry and Manufacturing Use Water conservation measures that can be taken by industry:

o Using cooling towers that use little or no watero In-plant water treatment and recycling

Perception and Water Use Perception of water is based partly on its price and availability.

o If water is abundant and inexpensive, we don’t think much about it. o If water is scarce or expensive, it is another matter.o E.g. people in Tucson pay about 100% more for water than people in Phoenix.

Tucson residence use less water per person per day Sustainability and Water Management

From a water supply use and management perspective, sustainable water use defined as:o use of water resources by people in a way that allows society to develop and flourish into an indefinite

futureo W/o degrading the various components of the hydrologic cycle or the ecological systems that depend on

it. Sustainable Water Use General criteria:

o Develop water resources in sufficient volume to maintain human health and well-being.o Provide sufficient water resources to guarantee the health and maintenance of ecosystems.o Ensure minimum standards of water quality for the various users of water resources.o Ensure that actions of humans do not damage or reduce long-term renewability of water resources.o Promote the use of water-efficient technology and practice.o Gradually eliminate water pricing policies that subsidize the inefficient use of water.

Groundwater Sustainability Sustainability involves a long term perspective

o For groundwater even longero Effects of pumping might not be seen immediatelyo Long-term approach involves balancing withdrawal with recharge

Water Management Management of water resources is a complex issue that will become more difficult as demand for water

increases in the coming years.o Especially in areas like the Southwestern US and other semi arid regions

Options for minimizing potential problems:o Alternating water supplies and managing existing supplies bettero `Towing icebergso As price goes up many innovative programs are possible.

Variable Water Source Approach >>

A Master Plan for Water Management

New management philosophy is that surface water and groundwater are both subject to natural flux with time. o In wet years, there is plenty of surface water, and the near-surface groundwater resources are

replenished.o During dry years, specific plans to supply water on an emergency basis must be in place and ready to

use. Advanced planning may include

o Drilling to wells that are presently isolatedo Reuse of waste watero Develop surface water and use groundwater in dry yearso In wet years pump excess surface water underground to recharge groundwater

Water Management and the Environment Often a good deal of controversy surrounds water development

o Dams, canals, wetlands modificationo Resolution of development involves input from a variety of government and public groups

Wetlands Wetlands is a comprehensive term for landforms such as salt marshes, swamps, bogs, prairie potholes, and

vernal pools.o Common feature is that they are wet at least part of the yearo Have a particular type of vegetation and soil

Wetlands - defined as areas that are inundated by water or where the land is saturated to a depth of a few cm for at least a few days per year.

Three major components used to determine the presence of wetlands are: o Hydrologyo Type of vegetationo Type of soil.

Natural Service Functions of Wetlands Freshwater wetlands are a natural sponge for water.

o Reducing flooding. Many freshwater wetlands are important as areas of groundwater recharge or discharge. Wetlands are one of the primary nursery grounds for fish, shellfish, aquatic birds, and other animals. Wetlands are natural filters that help purify water. Wetlands are often highly productive and are places where many nutrients and chemicals are naturally cycled. Coastal wetlands provide a buffer for inland areas from storms and high waves. Wetlands are an important storage site for organic carbon. Wetlands are aesthetically pleasing to people. Wetlands Freshwater wetlands are threatened in many areas.

o Over the past 200 years > 50% of all wetlands have disappeared, 90% of freshwater wetlandso Diked, drained or filled o SF bay estuary considered the most modified by human activity

Mississippi River delta includes major coastal wetlandso Historically maintained by floodingo Accretion processes counter natural subsidenceo If accretion decreases area of open water increases and wetland in reducedo Levees block sediments and costal wetlands are being lost

Restoration of Wetlands Number of projects have attempted to restore wetlands.

o In freshwater marshes recovery linked to availability of water

o Salt marshes more complexo EPA of 1969 states if wetlands destroyed by development must be replaced elsewhere

Constructing wetlands to clean up ag wasteo Natural ability to remove excess nutrients, break down pollutants, and cleanse water.o In Florida, human-made wetlands designed to intercept and hold nutrients so they don’t damage the

Everglades. Dams and the Environment Dams and their accompanying reservoirs generally are designed to be multifunctional structures.

o Used for recreational activities o Generating electricity o Providing flood controlo Ensuring a more stable water supply

Often difficult to reconcile various uses at a given site. The environmental effects of dams include the following:

o Loss of land, cultural resources, and biological resources in the reservoir area.o Larger, dams and reservoirs produce a potential serious flood hazard should they failo Storage behind the dam of sediment that would otherwise move downstream to coastal areas.o Downstream changes in hydrology and in sediment transport that change the entire river environment

and the organisms that live there.o Fragmentation of ecosystems above and below a dam.o Restrict movement upstream and downstream or organic material, nutrients and aquatic organisms.

Many people vehemently against building new dams.o But if present water use practices continue we will need new dams.o Few acceptable sites for damso Expensive to build and operate, many people don’t want tax dollars spent on subsidized water.

Canals Water from upstream reservoirs may be routed downstream by way of natural water ways or canals and

aqueducts.o Not hydrologically the same as creekso Smooth, steep banks; water moves fasto Canals can spread and carry disease

Schistosomiasis Removal of Dams Recent dam removals include

o Edwards Dam in Maine o Marmot Dam in Oregono After removal both river saw return of fish as they migrated upstream

Large fish runs transport nutrients upriver from ocean to forest ecosystems.

Trapped sediment behind dams must be dealt with in dam removal.o If released quickly it could damage downstream ecosystem and fill pools.o Slower release minimizes damage.o Matilija Dam in Ventura County cost $300,000 to build but 10 times that to remove.

Removing dams is simple in concept but involves complex problems relating to sediment and water. Channelization and the Environment Channelization of streams consists of straightening, deepening, widening, clearing, or lining existing stream

channels.o Engineering technique that has been used to control floods, improve drainage, control erosion, and

improve navigation Adverse environmental effects, including the following:

o Degradation of the stream’s hydrologic qualities; nearly all riffle flow, resulting in loss of important fish habitats.

o Removal of vegetation along the watercourse, which removes wildlife habitats and shading of the water.o Downstream flooding where the channelized flow ends.o Damage or loss of wetlands.o Aesthetic degradation.

Case study in problems w/ Channelizationo Kissimme River in Floridao Meandering river turned into straight ditcho Failed to provide flood protection, damaged wildlife habitat, water quality problems and aesthetic

degradation.o In 1990 efforts to restore river began.

The Colorado River: Water Resources Management and the Environment The history of the Colorado River emphasizes linkages among physical, biological, and social systems that are at

the heart of environmental science.o Major river of the southwestern USo Ends in the Gulf of California

The Colorado River For its size has a modest flow but is one of the most regulated and controversial bodies of water in the world.

o Total flow was apportioned among various users in 1922o No water allowed for environmental purposeso Water rarely flows into the Gulf, all stored and used upstream.

Damaged delta Two largest reservoirs- Hoover Dam and Glen Canyon Dam

o Stored about 80% of total in the basino Represents a buffer of several years water supply.o Changing hydrology of the river changed other aspects

Rapids, sediment load, and vegetation Record snowmelt in the Rocky Mountains in 1983 forced the release of water from Glen Canyon Dam

o Three times normal but similar to spring floods before the dam was built.o Beneficial to the river, highlighted the importance of floods in maintaining a natural state.

As an experiment “flood” waters released in 1996o Two weeks at full floodo As a result 55 new sandbars formed and 75% of existing sandbars increased in size, rejuvenated marshes

and backwaters.o Hailed a success; hoped that what was learned can help restore other river impacted by dams.

Global Water Shortage Linked to Food Supply Both surface water and groundwater are being stressed and depleted:

o Groundwater in the United States, China, India, Pakistan, Mexico, and many other countries is being mined

used faster than it is being renewedo Large bodies of water—for example, the Aral Sea—are drying up.o Large rivers, including the Colorado in the US and the Yellow in China, do not deliver any water to the

ocean in some seasons or years. As human population grows there is growing concern that there won’t be sufficient water to grow the food to

feed 8-9 billion people.o Food shortage linked to water resources a real possibility. o Water also linked to energy (fuel to pump) as energy cost goes up so does cost of food.

Solutiono Control human population growtho Conserve and sustain water resourceso Need to be proactive now before significant food shortages develop.