2.2 - Planning Priorities Of Water Resources Projects.pptx

CHAPTER II WATER RESOURCES PLANNING AND DEVELOPMENT

2.2. PLANNING FOR PRIORITIZING WATER RESOURCES PROJECTS BY:

EMMAN COSME G. VIRTUDAZO KIN B. QUIÑONES

Water resource projects are constructed to develop or manage the available water resources for different purposes. According to the National Water Policy (2002), the water allocation priorities for planning and operation of water resource systems should broadly be as follows:

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Domestic Consumption This includes water requirements primarily for drinking, cooking, bathing, washing of clothes and utensils and flushing of toilets.

Irrigation Water required for growing crops in a systematic and scientific manner in areas even with deficit rainfall.

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Hydropower This is the generation of electricity by harnessing the power of flowing water.

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Ecology / Environment restoration Water required for maintaining the environmental health of a region.

Water resource projects are constructed to develop or manage the available water resources for different purposes. According to the National Water Policy (2002), the water allocation priorities for planning and operation of water resource systems should broadly be as follows:

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Industries The industries require water for various purposes and that by thermal power stations is quite high.

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Navigation Navigation possibility in rivers may be enhanced by increasing the flow, thereby increasing the depth of water required to allow larger vessels to pass.

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Other uses Like entertainment of scenic natural view.

1. Domestic Water Consumption All around the world the water consumption per inhabitant is very various, for instance an American needs in average 500 liters a day, a western European 150 liters and a African only 50 liters a day. Even if these differences tend to decrease with the time no one is equal in the water uses. And another difference is a consequence of the people's way of life, indeed in the countryside people uses less water than in the city. An other example is the age of people because young and old persons use less water than the average. There are several factors to explain this discrepancy. The amount of available water is maybe the most important factor, for instance water is a very precious good in Africa because the water is rare. Another factor is the water price, more richer people are more water they are able to consume. At home, actually the drinking water is only 1 or 2 % of our total water consumption.

How much water is consumed per day?

Spain’s National Statistics Institute reported that average household water consumption in Spain was 137 litres per person per day in 2012. That number far exceeds the minimum required per person, according to the World Health Organisation. It’s clear that water sustainability—the greatest guarantee for its availability—requires responsible consumption and proper management. The following consumption data sheds light on our daily relationship with water: A bath: 150-300 litres Shower: 50-100 litres Flushing a toilet: 10 litres Washing dishes by hand: 23 litres Dishwasher: 20-40 litres. Washing machine: 40-80 litres Defrosting food under the tap: 25-25 litres Leaving the water running for 1.5 minutes while you brush your teeth can use more than 18 litres. • Washing your car with a hose: 200-500 litres. • • • • • • • •

How much water is consumed per day? According to the WHO (World Health Organization): ”The basic need for water includes water used for personal hygiene, but defining a minimum has limited significance as the volume of water used by households depends on accessibility”. First, access needs to be defined. Basic access is the availability of a source of water that is at most 1,000 metres or 20 minutes away that affords the possibility of reliably obtaining at least 20 litres per day per family member.

The WHO uses certain metrics to estimate water needs according to the needs that are being met. For example, basic access allows for consumption, hand washing and basic hygiene, but it doesn’t guarantee laundry or bathing. These limitations have a notable impact on health.

Accessibility of Water

Intermediate access Intermediate access is where people have access to 50 litres per day at a distance of less than 100 metres or 5 minutes, covering laundry and bathing as well as basic access uses. In this case, the impact on health is low.

Optimal access Optimal access allows for the consumption of 100 litres per person per day on average, Supplied continuously through multiple taps and which meets all consumption and hygiene needs.

In conclusion, as paradoxical as it may seem, access to water for human consumption is not always directly linked to availability.

Worldwide, 1.1 billion people have no access to any type of improved drinking-water source. As a result, 1.6 million people die every year from diarrheal diseases (including cholera), of which 90% are children under 5.

Access to 50-100 litres per person per day ensures a low impact on health

Expected population growth (8.1 billion people by 2025), with a high concentration in cities, together with the effects of climate change, threatens to increase social unrest if steps are not taken immediately to support access to water for the entire population.

2. Irrigation Irrigation water use includes water that is applied by an irrigation system to sustain plant growth in agricultural and horticultural practices. Irrigation also includes water that is used for preirrigation, frost protection, chemical application, weed control, field preparation, crop cooling, harvesting, dust suppression, and leaching salts from the root zone.

Water use for Irrigation

Agriculture is by far the largest water use at global level. Irrigation of agricultural lands accounted for 70% of the water used worldwide. In several developing countries, irrigation represents up to 95% of all water uses, and plays a major role in food production and food security. Future agricultural development strategies of most of these countries depend on the possibility to maintain, improve and expand irrigated agriculture Water is a resource that may create tensions among countries down and upstream. Irrigated agriculture is driving much of the competition since it accounts for 70-90% of water use in may of these regions.

3. Hydropower By taking advantage of gravity and the water cycle, water have tapped into one of nature's engines to create a useful form of energy. Today, harnessing the power of moving water to generate electricity, known as hydroelectric power, is the largest source of emissions-free, renewable electricity in the worldwide.

Converting moving water to electricity Hydroelectric power plants generate electricity using the energy from flowing water, called ‘linear kinetic energy’, and energy from pressure, called ‘pressure potential energy’. The water has to move with sufficient speed and volume to spin a propeller-like device called a turbine, which in turn rotates a generator to generate electricity.

To increase the volume of moving water, impoundments or dams are used to collect the water. An opening in the dam uses gravity to drop water down a pipe called a penstock. The moving water causes the turbine to spin, which causes magnets inside a generator to rotate and create electricity.

Converting moving water to electricity Hydropower can also be generated without a dam, through a process known as run-of-the-river. In this case, the volume and speed of water is not augmented by a dam. Instead, a run-of-river project spins the turbine blades by capturing the kinetic energy of the moving water in the river.

Generators at Hoover Dam. Photo: Cobolhacker/Wikimedia Commons

Some steps are being taken to move fish around the dams, such as putting them in barges or building fish ladders, but success has been limited. Downstream fish passage can also be a challenge since young fish can be chewed up in the turbines of the dam as they head towards the ocean.

Fish ladder on John Day Dam in Oregon. Photo: U.S. Army Corps of Engineers

Although the generation of hydropower does not emit air pollution or greenhouse gas emissions, it can have negative environmental and social consequences. • Dams that have flooded areas with live vegetation can emit methane, a powerful global warming gas, as that organic material decomposes. • Hydropower projects can reduce the flows in rivers downstream if the upstream flows are trapped behind a reservoir and/or diverted into canals that take the water off stream to a generation unit. • Dams can also block the migration of fish that swim upstream to reach spawning grounds. • Lowering the flows in a river can alter water temperatures and degrade habitat for plants and animals. • Less water in the river can also reduce oxygen levels which damage water quality. • Water is typically stored behind a dam and released through the turbines when power is needed. This creates artificial flow patterns in the downstream river that may be very different from the flow patterns a river would naturally experience.

4. Ecology / Environment Restoration Restoration ecology is the study of renewing a degraded, damaged, or destroyed ecosystem through active human intervention. Restoration ecology specifically refers to the scientific study that has evolved as recently as the 1980s. Land managers, laypeople, and stewards have been practicing restoration for many hundreds, if not thousands of years (Anderson 2005), yet the scientific field of "restoration ecology" was first identified and coined in the late 1980s by John Aber and William Jordan.

The Society for Ecological Restoration defines ecological restoration as an “intentional activity that initiates or accelerates the recovery of an ecosystem with respect to its health, integrity and sustainability” (SER 2004).

The practice of ecological restoration includes wide scope of projects including: erosion control, reforestation, removal of non-native species and weeds, revegetation of disturbed areas, daylighting streams, reintroduction of native species, as well as habitat and range improvement for targeted species. The term "ecological restoration" refers to the practice of the discipline of "restoration ecology".

5. Industries Energy is needed to pump, treat, transport and desalinate water. It is also obvious that water is needed to produce electricity in hydropower plants. However, many are unaware that almost all thermal power plants (coal, nuclear, solar-thermal, geothermal, biomass, natural gas combined cycle power plants), can also require huge amounts of water, especially for cooling purposes. Thermoelectric power plants are caused for 40% of the freshwater withdrawn every year in the US and for 43% in Europe, just as much as the agriculture sector. Although most of the water is not consumed and is returned to the water source, these huge volumes of water withdrawn by the power sector have an impact on the ecosystem and on the water resources of a region.

THERMAL POWER PLANTS Background Thermal power plants generate around 80 percent of the electricity produced in the world, by converting heat into power in the form of electricity. Most of them heat water to transform it into steam, which spins the turbines that produce electricity. After passing through the turbine, the steam is cooled down and condensed to start the cycle again, closing the so-called steam cycle.

Although power plants require water for several processes (steam cycle, ash handling, flue gas desulfurization systems, among others) most of the water requirements – usually about 90% of the total – are for cooling purposes

THERMAL POWER PLANTS

Why is cooling necessary? Thermoelectric power plants boil water to create steam, which then spins turbines to generate electricity. The heat used to boil water can come from burning of a fuel, from nuclear reactions, or directly from the sun or geothermal heat sources underground. Once steam has passed through a turbine, it must be cooled back into water before it can be reused to produce more electricity. Colder water cools the steam more effectively and allows more efficient electricity generation

THERMAL POWER PLANTS

In conclusion, Power plants across the country contribute to water stress. This tremendous volume of water has to come from somewhere. Across the country, water demand from power plants is combining with pressure from growing populations and other needs, and is straining our water resources—especially during droughts and heat waves. The state power authority warned that several thousand megawatts of electrical capacity might go offline if the drought continued to persist.

6. Navigation Navigation of rivers to transport people and goods precedes historical record. However, within the last few centuries, navigation structures have significantly augmented the ability of industry to transport goods to and from inland ports. In many cases, improvements in river navigation have provided an economical method of transporting large quantities of grain, petroleum, coal, metals and ores, fertilizers and chemicals, forest products, and other cargo, but the improvements have not come without a cost.

Navigation structures have been necessary to increase river depths, eliminate meandering, and reduce water velocities in existing rivers. These structures are often expensive in monetary, societal and environmental costs. Navigation dams form a deep, low velocity reservoir in locations where passage was once impractical because the river was too shallow or currents were too swift. Multipurpose dams are often used to provide a steady supply of water in times when flows would normally be low.

River Morphology and Sediment Transport In general, natural rivers are almost never straight. Straight channels develop secondary currents that meander between riverbanks. At the points where the secondary currents are strongest, erosion develops, and at the points where the currents are weak, deposition occurs. The secondary circulation patterns in the river cause bends to develop in the river. The newly formed bends accentuate the strength of the secondary currents. At the bends, higher velocity water is restricted to the outside of the bend. Consequently, most erosion occurs on the outside of a river bend and most deposition occurs on the inside of the bend. Given that the channel bed consists of erodible material, and that the channel does not have an excessively large sediment load, the originally straight channel becomes more sinuous, and a meandering river develops.

Meander Formation

(i) original channel is straight with uniform cross section (ii) alternating pattern of erosion and deposition develops as a result of secondary currents (iii) secondary currents intensify and banks erode (iv) curvature of stream increases, intensifying outer bank erosion and inner bank deposition (v) meanders are fully formed and do not increase in size, but they continue to migrate.

River Navigation

Canal lock and lock-keeper's cottage on the Aylesbury Arm of the Grand Union Canal at Marsworth in Hertfordshire, England

Lock on the River Neckar at Heidelberg in Germany

A lock is a device used for raising and lowering boats, ships and other watercraft between stretches of water of different levels on river and canal waterways. Locks are used to make a river more easily navigable, or to allow a canal to cross land that is not level. Later canals used more and larger locks to allow a more direct route to be taken.

Locks on the Rideau Canal, Entrance Valley, near Parliament Hill, Ottawa, Canada

When a stretch of river is made navigable, a lock is sometimes required to bypass an obstruction such as a rapid, dam, or mill weir – because of the change in river level across the obstacle.

In large scale river navigation improvements, weirs and locks are used together. A weir will increase the depth of a shallow stretch, and the required lock will either be built in a gap in the weir, or at the downstream end of an artificial cut which bypasses the weir and perhaps a shallow stretch of river below it. A river improved by these means is often called a Waterway or River Navigation

7. Other Uses

Natural views of Body of Water

Plitvice Lakes, Croatia

Halong Bay, Vietnam

7. Other Uses

Natural views of Body of Water

Iguazu Falls, Brazil and Argentina

Cao Cristales, River of Five Colors in Colombia

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