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Module 2: Water Use and Conservation

• Changes in Urban Streams• Water Reuse• Household Water Use• Local Issues with Water Supply• Conservation Opportunities• Water Use Regulations

Robert PittDepartment of Civil and Environmental Engineering

University of AlabamaTuscaloosa, Alabama 35487

Long Island barrier island development, NY

Moscow, Russia, fountains and kids in urban water

Navasink River, NJ

Barton Springs, Austin, TX

River Walk, Austin, TX

Confluence Park, Platte River and Cherry Creek, Denver, CO

Dangers of urban waters are well known

But ….. stormwater can be considered a valuable resource in many situations.

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Kitazawa Stream, Tokyo

Kitazawa Stream is an example of a severely degraded urban stream in Tokyo that has undergone extensive modification. The stream watershed is 10.5 km2 and has a population of about 150,000 people. The rapid urbanization in Tokyo since the 1950s has resulted in a severe decrease in groundwater infiltration during rains. This has caused decreased groundwater levels and decreased the associated natural recharge into urban streams. By the 1960s, there was almost no natural flow in Kitazawa Stream during dry weather. The only flows present in the stream was wastewater from homes. The stream was therefore of extremely poor quality, creating an unsafe and nuisance condition. In addition, the increased development caused frequent flooding.

The local government authority therefore diverted the stream into an underground culvert. The aboveground area was converted into a promenade with extensive plantings. Recently however, local residents have requested the addition of a steam along the promenade. A very small flow (0.02 m3/s) of treated wastewater has been pumped from 11 km away to create this new stream (a “two-storied watercourse”). The following shows the changes that Kitazawa Stream has undergone as the watershed has developed. This new steam, however small, has created a very important element in the lives of the residents of this heavily urbanized city. Special community organizations have been established to plan and manage the area.

The history of Kitazawa Stream, Tokyo suburb (Fujita 1998)

The history of Kitazawa Stream, Tokyo suburb (Fujita 1998)

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The history of Kitazawa Stream, Tokyo suburb (Fujita 1998) The history of Kitazawa Stream, Tokyo suburb (Fujita 1998)

2824.0Toilet flushingC

29518 gal/day/acreLawn irrigationB

3631.0Bathing, laundering, auto washing

A

76.5Consumption by humans, food preparation, general kitchen use

AA

Percentage of Total Water Use

Rate of Use (gal/person/day)

UseClass

Distribution of Maryland Residential Water Use and Required Quality (Mallory 1973)

>10,000 (none)240240701Total coliform bacteria (MPN/100 mL)

Near saturation (AA)4455Oxygen, dissolved (minimum)

6 to 9 (AA)6667pH (pH units)

25 (B)30302015Color (color units)

25 (none)15-208-153-80-3Turbidity (NTU)

50 (none)3010--Suspended solids

250 (A)1500500500150Total solids

Typical average residential stormwater quality and highest use without treatment

CBAAAConstituent (mg/L)

Maximum Concentrations Allowed by Maryland for Different Reuse Categories, Compared to Typical Residential Stormwater

Runoff (Mallory 1973)

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As shown on these tables, residential area stormwater can be used to meet at least class A water needs, except for suspended solids, turbidity, color, and coliform bacteria. The solids, turbidity and color levels are likely to be adequately reduced through storage and associated settling, plus possible post-settling filtration. The most serious impediment for the reuse of stormwater in residential areas is the bacteria levels. 2.2requiredRecreational

impoundments: body contact (bathing)

2.2requiredRecreational impoundments: boating and fishing only

23requiredRecreational impoundments: no public contact

2.2requiredLandscaped areas: parks, playgrounds, schoolyards

23requiredLandscaped areas: golf courses, cemeteries, freeways

Total coliform bacteria criteria (MPN/100 mL, median of daily observations)

Secondary treatment, coagulation, filtration, and disinfection

Secondary treatment and disinfection

Use of reclaimed water

California Reuse Guidelines (Metcalf and Eddy 1991)

Metcalf and Eddy (1991) state that primary treatment (similar to settling in a storage tank) reduces fecal coliform bacteria by less than 10%, whereas trickling filtration (without disinfection) can reduce fecal coliform levels by 85 to99%. Chemical disinfection is usually required to reduce pathogen levels by 99.9+%, as likely needed to meet the above bacteria criteria for even the most basic water uses. Because of the risks associated with potential pathogens, reuse of stormwater in residential areas should only be considered where consumption and contact is minimized, restricting on-site reuse to classifications B and C, and only after adequate disinfection and site specific study to ensure acceptable risks.To further minimize risks, only the best quality stormwater (from a pathogen perspective) should be considered for reuse, such as roof runoff.

It is possible to determine the likelihood of supplying needed irrigation water and toilet flushing water (reuse classifications B and C) from the stormwater generated from roof runoff by conducting an urban water budget. This budget requires a knowledge of all water sources and uses, and the associated quality requirements.

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Available Freshwater Resources Small Fraction of all Water

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Typical US Water Use (gallons/person/day)

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Water Regulations and Conflicts

“Water flows uphill towards money.”Old western US saying

“Whiskey’s for drinking – water’s for fighting about.”

Mark Twain

Riparian water law is a common-law idea

• Owner of land has the right to withdraw water that is adjacent to the land.

• Water must be returned in a relatively unpolluted condition to ensure that downstream users do not have their water rights violated.

• The water must be used on land adjacent to the water source, not exported (reasonable use doctrine now allows irrigation).

• Evolved through practical use.• Practiced mostly east of the Mississippi River

where sufficient water resulted in few conflicts.

Appropriation water law adopted from Roman civil law

• Owners of land may be denied the right to withdraw water if a more beneficial use is found.

• Government agencies “appropriate” the water.• Water right can be taken away if better use found,

or lost if abandoned.• Water can be used away from the source.• Common in western states where water is much

more scarce.

Increasing Recognition of Water Rights to Protect the Natural Environment

• Loss of fisheries, wetlands, lakes, and other ecological assets are shifting the balance of power governing water use, away from agriculture and towards protecting the natural environment.

• Australia’s Murray-Darling river basin states have agreed to allocate 25% of the river’s natural flow to maintaining ecological health in the system.

• 10% of the water from the Central Valley Project in California is to go for maintaining fish and wildlife habitat.

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34 Countries in Africa, Asia and the Middle East are Classified as Water-Stressed

• Occurs when a country’s renewable water supplies drop below about 1,700 m3 per person.

• At this level, it becomes difficult for a country to collect enough water to satisfy all the food, household, and industrial needs of the population.

• These countries then begin to import grain (requires about 1,000 tons of water to produce a ton of grain).

• Poor countries have the vast majority of the water-stressed populations and they can ill afford imported grains.

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About 40% of the World’s Population live in Water Basins Shared by more

than two Countries

Biggest potential problems in Middle East:• Jordan River (Israel, Jordan, Syria, and

Lebanon)• Nile River (Egypt, Sudan, Ethiopia, Zaire,

Uganda, Tanzania, Burundi, Eritrea, Kenya)• Tigris-Euphrates Rivers (Iraq, Syria, and

Turkey)

King Hussein declared in 1990 that water was the only issue that could

take him to war with Israel

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“The national security of Egypt is in the hands of the eight other

African countries in the Nile basin.”Boutros Boutros-Gali, when he was Egypt’s Minister of State for Foreign Affairs

Saudi Arabia uses Fossil Groundwater for 40% of their needs

• Groundwater depletion more than 5 billion cubic meters per year and rapidly growing.

Water Issues Increasingly Responsible for Armed Conflict

• Dispute over the headwaters of the Jordan River helped spark the 1967 Arab-Israeli war.

• Bypass canal project in southern Sudan one factor in continuing civil war.

Current Serious Water Conflicts

• Israel’s unrestricted use of groundwater from the Jordan River basin in occupied territories.

• Egypt-Sudan agreement totally allocates Nile River downstream flow without reference to upstream needs.

• Construction of dams in Turkey reduce Euphrates water to Iraq to as little as 10% of normal flow, and to 60% for Syria.

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More than 2,000 International Treaties Relating to Common Water Basins

Common basins make up 60% of the land in Africa and South America

• US and Canada Great Lakes Compact • The Nile Water Agreement (Egypt and Sudan)• India and Pakistan share development of the Indus

River.• India and Bangladesh agree to maintain minimal

flows in the Ganges.• US and Mexico agree on flow conditions in

Colorado and Rio Grande Rivers.• Argentina and Brazil agree on management of the

Paraná River.Gonick and Outwater. The Cartoon Guide to the Environment.

Formula for “Survival”

(Population) X (Demand) must be <1(Sustainable Supply)

Malthus 1766 - 1834

“A decade ago, a fish Malthusian might have predicted the end of salmon as a food. Human ingenuity seems to have beaten nature once again.”

Forbes 1990

Bailey, Earth Report 2000.

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Environmental Trends Shaping the New Century

State of the World 2000

• Population growth• Rising temperature• Falling water tables• Shrinking cropland per person• Collapsing fisheries• Shrinking forests• Loss of plant and animal species

Time and Scale of Environmental Concerns (Graedel)

Problems in Our Future(recovery periods for individual actions)

• Short Term (< 100 years):

Tree fallsLand slidesOil spillsSlash and burnForest firesFloodsTsunamisVolcano eruptionAcid rain

• Long-Term (>100 years):Heavy metal depositionGroundwater exploitationOzone depletionMeteor strikeClimate change

Water Supply and Water Quality

• Conservation easiest to develop and cheapest new water source

• Water quality problems becoming better understood

• Habitat destruction becoming recognized as serious issue

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Development or Reservation?Development:Atmospheric nitrogen, electric steel, cement, marble, brick, lime, iron, coal, fruit, lumber, and cotton.

300,000 horsepower

Coosa-AL navigation = 10 railroads

Reservation:Falling, wasting as I flow.A mighty brimming river.My commerce tied,my strength untried.Fix me now or never.

W.P. Lay. River Problems of Alabama. 1915

“Nearly the entire spectrum of conservation and efficiency options cost less than the development of new water sources.”

Sandra Postel 1996

Estimated Costs of Water Management Options

100 – 150 Desalination of seawater

55 – 85Development of marginal water

45 – 70Desalination of brackish water

30 – 60Treatment and reuse of wastewater for irrigation

5 – 50Reducing demand through conservation/efficiency

Estimated cost range (cents/m3)

World Bank 1995

In El Paso, pricing and educational efforts are credited with a substantial reduction in water use. Conservation meets about 15 to 17% of the city’s future water needs. Besides slowing the rate of depletion of the groundwater supply, the conservation measures cost about 8% less than the cost of existing water supplies (about $135 per 1,000 m3).

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John Boland, Johns Hopkins University, Abel Wolman Lecturer

WorldWater, January 2003

WorldWater, January 2003 WorldWater, January 2003Hydroplus, July 2003

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Hydroplus, July 2003 Hydroplus, July 2003

“Nature has no reset button”State of the World 2000

Homework Problem• Determine the water use in your household, by

category, for a 5 day period. • Identify the water classification for each category,

and sum the total water needs by category.• How can conservation and/or reuse reduce your

household water needs?• What secondary benefits may occur with reduced

water supply needs and associated decreased wastewater discharges?