32 Water Conservation and Management Strategies

Rajesh Singh

Objectives:

•      To learn various water conservation technologies

•      To know various water conservation practices

•      To know various water conservation strategies

32. Introduction

About 70% of earth is covered by water but still water is limited resource and is also threatened worldwide. Good quality, non-saline water is a global asset, most important in satisfying the increasing demand for basic food, fiber and fodder. Decline in per capita consumption of water due to increasing population and drought has led to growing concerns about water scarcity. Also due to urbanization, haphazard industrialization, intensive agriculture, poor waste management practices etc more and pollutants are being discharged in the environment further contaminating surface as well as groundwater. Being, its differential availability in different parts of the word, the agricultural activities account for the largest share, about 70%, followed by industry 22%, domestic need 4% and reservoir account for 4%.

India has the largest rural drinking water supply program in the world and serving almost more than 740 million people. It is expected that around 2020, India will be a “water stressed” country with decline in per capita availability to 1,600 cubic meter/person/year. A country is said to be water stressed when the per capita availability of water drops below 1,700 cubic meters/person/year. The aquifers throughout the world are under stress due to increased pumping from existing wells or development of new wells. Though, the health status of majority of the Indians is far from the satisfaction when compared to the developed nations.

So the challenge is to improve the water quality and quantity in the water bodies. To meet the challenge, management is one of the main priorities to improve the availability of this resource. Water conservation measures are the first-line option for the control and management of water. So what is water conservation?

Water conservation can be described as “Any beneficial reduction in water use or in water losses”. Conservation measures involve reducing the mass emission of drainage water and are include:

i.  Source reduction through sound irrigation water management;

ii.  Shallow water table management;

iii. Groundwater management; and

iv.  Land retirement.

While conservation programs differ from city to city, they are generally designed for the representative customer in a service region. Source reduction plays a major role in dealing with problems caused by the shallow, saline groundwater. In the developing country like India, conservation measures required as large tracts of land to drain in inland basins without adequate disposal facilities.

Balancing competing uses of surface water in stream and off-stream and groundwater, while protecting water quality, is challenging the limited water supplies in a ways that require new solutions for responsible use. Reservoirs, created by damming streams and sometimes pumping water from other surface waters, are often the first choice of water authorities seeking to meet demand due to the apparent quick fix provided by the ease of creating a large amount of storage. However, adverse impacts of impoundments and withdrawals (direct or for pumped storage) are well documented in the literature and include effects on the impounded areas, as well as upstream and downstream reaches.

The United States Geological Survey (USGS) has determined that hydrologic alteration is the primary cause of ecological impairment in river and stream ecosystems. Altering the hydrologic regime can impact water quality, eliminate natural variability, change water and food transport downstream, increase temperature and nutrients, decrease dissolved oxygen levels, and induce cyclical changes in cues for life cycle events of aquatic species. The cumulative impacts of evaporative losses from the tens of thousands of smaller reservoirs are also a concern, with one study in the Upper Oconee Basin in Georgia finding in excess of 10 million gallons/day in additional evaporative loss due to small impoundments alone. Water, the natural resource is become increasingly scarce; so managers often seek policies to reduce demand. It is also essential to introduce various water saving strategies with the purpose to save freshwater resources, decrease discharge of wastewater and facilitate the recovery of chemicals and energy. Optimizing system management and demand can be very advantageous for water utilities.

32.1.Water management

The change in global surface temperature, rainfall pattern, evapo-transpiration, and extreme events and its possible impacts on the hydrological cycle are pertinent to reassess the availability of water resources. It is necessary to implements the water use efficiency programs, which include water supply, water conservation and water recycling, reduce demands on the existing water supplies and delay or eliminate the need for water supply for an expanding population. In order to meet the needs of existing and future populations, the Nation’s water must be sustainable and renewable to protect the habitats and ecosystems. The sound water resource management, which emphasizes careful, efficient use of water, is essential to achieve the objectives of water conservation. “Water management is the activity of planning, developing, distribution, managing and optimum use of water resources under defined water policies and regulations”. The following are the measures to be taken to conserve the water:

32.1.1. Development of water saving technologies

Despite being the fastest developing country; India has poorly managed waterways. Among the developed countries, water leakage (which is not available for billing) is estimated to be < 3%, whereas in India, water leakage/pilferage is 45% at most. Development of new supplies, treatment and distribution infrastructure, and associated costs such as land acquisition and debt servicing can be very expensive in comparison to implementing water conservation/efficiency measures. Dams and reservoirs can cost $4,000 per 1,000 gallons of capacity whereas water efficiency costs between $0.46 to $250 per 1,000 gallons saved or new capacity (GEPD, 2008). The following are six best water utilities practices which can be undertaken them in considering water efficiency as an alternative to development of new supplies (USEPA, 2016).

i.  Water System Management: Supply side and demand side accounting

Why do toilets and lawns drink the same water as humans do? Make the most of water rather than letting it go down the drain or into the street. There are a number of opportunities every day to reuse water. The multi tap supply system plan could make use of various source of water like reservoirs, recycled wastewater and desalinated seawater is necessary for various uses in the house. Plumbing systems are the primary network for transport and control of residential water to and from the home. Plumbing systems distribute potable water within the residence, and dispose of wastewater (both gray water and black water) to sewage systems. Innovative methods can be implemented affordably for minimizing both water use and available water wastes in plumbing system designs. These include selection of efficient plumbing fixtures, appropriate layout and locations of fixtures, and reclaiming grey water for use in landscaping irrigation.

ii.Water Loss Minimization: Leak management

Leakage represents the largest real losses of water for most systems, and may result from a range of conditions, including material weaknesses and physical stresses. Operational problems such as excessive pressure or rapid changes in pressure, corrosion, seasonal stresses leaks at connections and fittings, and accidental or deliberate damage. Leakage should be managed proactively, cost-effectively and economically for effective stewardship of a shared and increasingly scarce resource. To maintain leakage at economically low levels (the amount of leakage that can be feasibly reduced from an economic perspective), a utility should be implemented in leakage management plan and/or water loss control program addressing each of the four pillars described by AWWA: Active leakage control, Optimized leak repair activities, Pressure management, and System rehabilitation and renewal (Figure 32.1).

iii. Metering of consumed water

Domestic water supply using meter and water charge leads efficient use of domestic water and conservation of energy for better livelihood. Measuring water thru water meter is used in industrial and residential uses but is not being practice in irrigation system. In many developing countries, measuring domestic water supply (hot and cold), drainage water and tax accordingly are most commonly practice. Metering utilities should not only implement at end users, but also of all water sources including groundwater, surface water, water purchases, and/or reclaimed water. The detailed information collected from meters can help in identifying unseen sources of leakage and prioritize abatement measures.

The application of water meter done by Navdeep Apartment, a registered cooperative housing society namely “Panchsil Memnagar cooperative housing society limited Vibhag-1” in 1995 achieved the significant reduction in water as well as electric current. Around 76 apartment owners having 270people lived in four block had agreed and decided to distribute water through meter in year 2013. They had decided to collect charges as per use of water to cover their operational expenditure to maintain water supply system. Navdeep experience of water meter proves that before water meter water installed there were electricity bill, which was around 2.3 times (base on electricity consumed). It means that use of water was almost 2.3 times more than current water used. It is beneficial to consumer that it leads to less maintenance charge to them. Ultimately, judicious use of natural resources will lead the sustainability.

iv.  Conservation rate structure

Water utilities estimate the potential demand reductions from pricing water for efficiency before pursuing a reservoir or building an intake, treatment plant, or transmission system. Managing demand through pricing can also be an advantage to the utility in that revenues may remain level or even increase if set to account for elasticity of demand. Inclining block rates (also known as increasing or inclining tier rates) – Conservation pricing can be accomplished with a tiered fee system which includes a base charge for fixed costs and a variable rate for volume of water consumed. Although increasing block rates have been favored in many recommendations as most likely to support conservation-oriented behaviors by end users, some simpler rate structures (such as uniform rates) can send customers stronger conservation price signals, as well.

v. End use water conservation and efficiency analysis

In order to determine which efficient water conservation programs and policies will be most effective in managing demand, a water utility need to understand the makeup of its customer base and conduct a thorough assessment of end use water efficiency measures. The performance based targets are important in determining how to secure savings to offset water supply needs and use water efficiency and conservation as a “least environmentally damaging practicable alternative.”The impact at the single-building level can be huge depending on the type of building and reuse system, the San Francisco Public Utilities Commission (SFPUC) has found reductions of potable water use from 50 to 95 percent.

Water conservation practices can be followed by residential users, industrial and commercial users, and agricultural users. They can also be followed by local utilities and/or regional water supply plants. Low-flow plumbing fixtures and retrofit programs are permanent, one-time conservation measures that can be implemented with little or no additional cost over the lifetime of the fixtures. The most commonly recommended low-flow plumbing fixtures are pressure reduction devices, faucet aerators, toilet displacement devices, low-flush toilets, low-flow showerheads, and plumbing modifications for gray water reuse.

Toilet Displacement Devices: Non-toxic bricks or plastic containers can be placed in a toilet tank to reduce the amount of water used per flush. By placing between one and three such containers in the tank, more than 4L of water can be saved per flush. A toilet dam, which holds back a reservoir of water when the toilet is flushed, can also be used instead of the displacement device to save water.

Low-Flush Toilets: Conventional toilets use 15 to 20L of water per flush, but low-flush toilets use only 6L of water or less. Since low-flush toilets use less water, they also reduce the volume of wastewater produced. A schematic of a low-flush toilet is shown in figure 32.2.

vi. Water conservation and efficiency plan

The idea is to capture water that has been used once, treat it to sub-potable standards, and then reuse it for purposes that don’t require drinking-grade water. Aside from toilet flushing and irrigation, that can also include using the stuff to cool a building and avoid using a costly air conditioning unit.

32.3. Watershed management

It is an urgent need to manage the watershed, a meeting point of climatology and hydrology so as to absorb the climatic shocks likely to come from the erratic climatic patterns expected in near future. This can be done only through practicing soil and water conservation techniques for artificial recharge during rainy season and through construction of small percolation tanks for artificial recharge during the dry season. Small water storages or tanks created in the sub-basins by bunding streams and gullies, store runoff water and recharging ground. These practices increase the residence time from a few months to a few years of water in the basins thus increased the percolated water available in the wells even during the summer season of a drought year.

India is well enriched with the knowledge of hydrology science for water conservation. The floods and droughts were regular occurrence in ancient India and this why every region in the country has its own traditional water harvesting techniques that reflect the geographical peculiarities and cultural uniqueness of the regions. The cities of Indus Valley Civilization are well evidenced by the excavations having excellent water harvesting and drainage systems. The basic concept underlying all these techniques is that rain should be harvested whenever and wherever it falls. Rajasthan, a large part of which is covered by the Thar Desert, has had a long tradition of water conservation. The builders of the famous Bundi and Chittorgarh forts had the vision of exploiting the natural catchments in the forts created by undulating hilltops. As long as people have inhabited the drylands and have cultivated crops, they have harvested water. Ephemeral streams (wadis) and water collected in wadi beds and cisterns, supported people’s livelihoods in the arid and semi-arid areas many thousands of years ago, and allowed the growth and development of cities. Millions of hectares of land in the dry parts of the world must once have been cultivated using water harvesting, but, for a variety of reasons, this practice has steadily declined.

The Indian mythology is well documented with the story of one of the disciples of a Rishi named Aruni, when approached by his teacher (Rishi), volunteers himself to go to the field in a raining night for undertaking preventive and corrective measures of the field bund from a possible breach due to heavy rain as it had remained incomplete during the repair work undertaken on previous day. He (Aruni) lies down on the breached portion of the field bund while failing to repair it due to torrential rain thus stopping the flow of water from over the field bund. The teacher very much appreciates it when he finds him over the field next day. So the importance of water conservation was well known to our forefathers of ancient India and it is very much evident from above narration.

32.3.1. Water harvesting

Water harvesting may be defined as “the process of concentrating precipitation through runoff and storage, for beneficial use”. Water harvesting may occur naturally or by intervention. Besides being applied to agriculture, water harvesting may be developed to provide drinking water for humans and animals as well as for domestic and environmental purposes.

Four main groups of water harvesting techniques can generally be distinguished: micro and macro-catchments, floodwater harvesting and storage reservoirs. Typical micro catchment techniques involve the delineation of natural depressions, the construction of contour and stone bunds, systems for inter-row water harvesting, terracing, construction of semicircular (half moon) and triangular (V-shaped) bunds, eyebrow terraces, Vallerani-type micro-catchments, pits, meskats and negarim.

i. Rain Water Harvesting

What is rainwater harvesting?

Rainwater harvesting is a technology used for collecting and storing rainwater from rooftops, the land surface or rock catchments using simple techniques such as jars and pots as well as more complex techniques such as underground check dams. The techniques usually found in Asia and Africa arise from practices employed by ancient civilizations within these regions and still serve as a major source of drinking water supply in rural areas. Commonly used systems are constructed of three principal components; namely, the catchment area, the collection device, and the conveyance system. Rainwater harvesting is discussed in detail in the next module, i. e., module no. 33).

32.3.2. Design of Landscape Detention basin

Through proper planning and design, contour the site into a series of concave landscape basins where essential shade trees are to be located. Providing water retention at shade tree plantings allows for fullergrowth of trees to assist in shading the house for energy conservation.

Xeriscape: It’s probably no surprise that a big jump inhousehold water use occurs in summer because folks are outdoors gardening and watering theirlawns. Traditional commercial landscapes alsoconsume plenty of water. These lush floraldisplays and broad expanses of turf dress up a neighborhood, but many popular landscape plants are real water guzzlers. A relatively new concept in landscaping has cropped up that was created to conserve water.“Xeriscaping,” a term coined (and trademarked) in Denver, Colorado, uses planting and design features that are more suitable to a particular region, whether in the arid West or the more variable climate of the Northeast. Xeriscape is water-wise gardening. It means choosing plants that conserve water and designing landscapes that protect the environment.

Contour Trenching/Bunding: One of the oldest methods of water conservation is digging of contour trenches and contour bunding across the slopes of the ground/field (Fig. 32.3). They have usually been installed to prevent small rills developing into gullies by limiting the area over which runoff collects, with or without sideways diversion into prepared waterways for safe disposal down slope. The barriers, which they provide may, if well maintained, accumulate soil which has been eroded from upslope. During monsoon the rain water flowing across the slopes will get collected in these contour trenches and recharge the area lying below the trenches. This will provide additional moisture to the dry crops sown under rain fed conditions in the respective field.

Village Tanks: Another oldest method of water conservation, a tank is a simple earthen banked rainwater harvesting and storage structure, designed by the early settlers using their indigenous wisdom and constructed with the generous support of native rulers and chieftains over the past several centuries. Since most tanks are manmade, they are usually called reservoirs (Fig. 32.4). Surprisingly these earthen structures have withstood the test of time and survived over many centuries. They are simple technological innovations developed by those people to accommodate their primary needs and adapted to the distinctive Indian climate intense monsoons followed by protracted droughts. The rain water collected and stored in these tanks improves the ground water and charge the open wells located in the vicinity of the tank. The water stored in these tanks, is used for domestic consumption by villagers, fisheries, agriculture purposes.

Improved Irrigation Systems: Agricultural (including forestry) sector is a major water-consuming sector. Under certain conditions, surface irrigation techniques such as level basins can also be very efficient. These methods require precise grading of the topography, high instantaneous flow rates and relatively high levels of automation and management. Micro-irrigation is the slow rate of water application at discrete locations at low pressures, and includes trickle or surface drip, subsurface drip, micro-sprinklers and bubblers. It has made tremendous strides over the past three decades, and has become the modern standard for efficient irrigation practices for water conservation and optimal plant responses. These systems are particularly advantageous on widely spaced tree and vine crops as well as high-value vegetable crops (e.g. under plastic mulches that control weeds, minimize foliar diseases and eliminate soil evaporation). Carefully managed subsurface (buried) drip will probably provide the greatest potential for water conservation because of the potential for reduced losses.

Raised beds and waru waru cultivation: This technology is based on modification of the soil surface to facilitate water movement and storage, and to increase the organic content of the soil to increase its suitability for cultivation. This system of soil management for irrigation purposes was first developed in the year 300 B.C., before the rise of the Inca Empire. The technology is a combination of rehabilitation of marginal soils, drainage improvement, water storage, optimal utilization of available radiant energy, and attenuation of the effects of frost. The main feature of this system is the construction of a network of embankments and canals, as shown in Figure 32.5.

The embankments serve as raised beds for cultivation of crops, while the canals are used for water storage and to irrigate the plants. The soils used for the embankments are compacted to facilitate water retention by reducing porosity, permeability, and infiltration. Infiltration in the clay soils of the region varies from 20‒30 % of the precipitation volume. Thus, clay soils are preferred for this purpose and sandy soils have too great a porosity to retain the water within the beds.

The cultivation takes place in the “new” soils within the raised bed created by the construction of the embankment. Within the bed, the increased porosity of the new soils results in enhanced infiltration, often increasing infiltration by 80‒100% of the original soil. This system permits the recycling of nutrients and all the other chemical and biological processes necessary for crop production. Water uptake by the raised beds is through diffusion and capillary movements using water contained within the beds or supplied from the surrounding canals.

Clay pot and porous capsule irrigation: This technology consists of using clay pots and porous capsules to improve irrigation practices by increasing storage and improving the distribution of water in the soil (Fig. 32.6). It is not new; it was used by the Romans for many centuries. The clay pot system of irrigation, which consists of individual pots or a series of pots connected with plastic tubing, is easy to install, operate, and maintain. This ancient irrigation system has been modernized and reapplied in water-scarce areas.

This low-volume irrigation technology is based on storing and distributing water to the soil, using clay pots and porous capsules interconnected by plastic piping. A constant-level reservoir is used to maintain a steady hydrostatic pressure. Clay pots are open at the top and are usually fired in home furnaces after being fabricated from locally obtained clay or clay mixed with sand. The clay pot method of irrigation should only be used on small plots of up to one hectare because the pots do not usually release the same volume of water. The system is recommended for home vegetable gardens (10 to 20 pots) and for small orchards in rural communities.

Bamboo Drip Irrigation: In Meghalaya (one of the seven Northeastern states in India), an ingenious system of tapping of stream and spring water by using bamboo pipes to irrigate plantations is widely prevalent (Fig. 32.7). It is so perfected that about 18-20 liters of water entering the bamboo pipe system per minute gets transported over several hundred meters and finally gets reduced to 20-80 drops per minute at the site of the plant. The tribal farmers of Khasi and Jaintia hills use this 200-year-old system.

The bamboo drip irrigation system is based on gravity and the steep slopes facilitate in implementing it. Water from an uphill source is tapped and brought to the plantation by a main bamboo channel. Usually these water sources are far off from the plantations and the main bamboo channel runs hundreds of meters in some cases even few kilometers. The water is then regulated through a complex bamboo network of secondary and tertiary channels to all the parts and corners of a plantation, right up to the bottom of the hill. These bamboo networks usually have 4-5 diversion stages before water is delivered at base of the plant. The 18-20 liters per minute of water from the main channel gets reduced to 10-80 drops per minute at end of the network. After this long journey, the water trickles or drips drop by drop at the base of the plant. Sometimes water is diverted to distant houses for domestic use

Percolation Tanks: The best way to provide dry season recharge is to create small storage at various places in the basin by bunding gullies and streams for storing runoff during the rainy season and allowing it to percolate gradually during the first few months of dry season. Such storage created behind earthen bunds put across small streams is popularly known as percolation tank (Fig. 32.8).

In semiarid regions, an ideal percolation tank with a catchment area of 10 sq. kms or so hold maximum quantity by end of September and allows it to percolates for next 4 to 5 months during winter. Excess of the runoff water received in Monsoon flows over the masonry waste weir constructed at one end of the bund. Ground water movement being very slow, whatever quantity percolates between October and March, is available in the wells on the downstream side of the tank even in summer months till June or the beginning of next Monsoon season.

Check Dams: A check dam is a small, temporary or permanent dam constructed across a drainage ditch, swale, or channel to lower the speed of concentrated flows for a certain design range of storm events. These are masonry structures constructed across local Nalas/Streams to collect and store the flood water during rainy season. A check dam can be built from wood logs, stone, pea gravel-filled sandbags or bricks and cement (Fig. 32.9).These areconstructed in series all along the local streams whichflow during rainy season. The rain water collected andstored in these check dams will improve ground waterlevels in the open wells situated near by providing water supply for agriculture under open wells. The size and shape of a drainage area, as well as the length and gradient of its slopes, have an effect on the run-off rate and amount of surface water. Therefore, all topographic characteristics should be studied in detail before gully-plugging work begins.

Preserve natural plant vegetation:-Preserve natural existing plant vegetation to reduce landscape water use and maximize natural drainage. Retaining native plants on the site as part of the landscape will assist in erosion control and is an affordable means of landscaping.

Augment storm water collection area with rainwater cisterns: Augment surface water basin systems with water collection cisterns that capture roof runoff to optimize storm water collection. Size the cisterns according to roof collection area. Locate catchment cisterns near planted areas to allow for gravity flow irrigation directly to plants. Rainfall is typically a higher quality water source compared to gray water, so it should be considered for irrigating food/herb gardens and sensitive, household potted plants. More complex, large volume, underground cisterns requiring pumps are probably not feasible for single-family affordable housing projects.

Porous Landscape Detention (PLD): Recent regional flood events, recognition of the impacts of developed and rapidly developing areas on water quantity and quality are the main issues requiring special management planning. The use of Storm water Best Management Practices (BMPs) is one way to address these two intertwined issues. Porous Landscape Detention (PLD) is one of the most common types of Storm water Management Facilities utilized (Fig. 32.10). Porous landscape detention (PLD) consists of a low lying vegetated area underlain by a sand bed with an under drain pipe. A shallow surcharge zone exists above the PLD for temporary storage of the Water Quality Capture Volume (WQCV).During a storm, accumulated runoff ponds in the vegetated zone and gradually infiltrates into the underlying sand bed, filling the void spaces of the sand. The under drain gradually dewaters the sand bed and discharges the runoff to a nearby channel, swale, or storm sewer. The major design parameters for a PLD system are the infiltration rate on the land surface and the seepage rate through the subsurface medium.

Fig. 32.10: Porous landscape detention design (Source: Storm water Quality BMP manual)

A low infiltration rate leads to a sizable storage basin while a high infiltration rate results in standing water if the subsurface seepage does not sustain the surface loading. Parking islands, medians and buffers, courtyards, planters, and green roofs are the excellent on sites with minimal space for detention where landscape and storm water quality can be combined. Geotechnical and foundation issues must be carefully considered when selecting and locating porous landscape detention facilities and designing under drains and linings. The area with sufficient water detention facilities can be developed as a constructed wetland basin.

Super absorbent polymer: Superabsorbent polymers (SAPs) are materials that have the ability to absorb and retain large volumes of water and aqueous solutions. This makes them ideal for use in water absorbing applications such as baby nappies and adults incontinence pads to absorbent medical dressings and controlled release medium. The use of super absorbent polymer(SAP) could be the future of irrigation water conservation. The quantity of water retained in soil depends on soilparticles size, as the larger the particle size, the less the ability to attract and retain water, and conversely, the smaller the particle the greater the ability to attract and retain water. Super absorbent polymer (SAP) materials mostly are organic materials with enormous capability of water absorption, essentially dissolution and thermodynamically favored expansion of the macromolecular chains limited by cross-linkages.

Earlier super absorbents were made from chemically modified starch, cellulose and other polymers like poly(vinyl alcohol) PVA, poly(ethylene oxide) PEO all of which are hydrophilic and have a high affinity for water. When lightly cross-linked, chemically or physically, these polymers became water-swell able but not water-soluble. The water absorbency of some common absorbent materials in comparison with a typical commercial SAP samples are given in table 32.1.

Today’s superabsorbent polymers are made from partially neutralized, lightly cross-linked poly (acrylic acid), which has been proven to give the best performance versus cost ratio. SAPs as hydrogels, relative to their own mass can absorb and retain extraordinary large amounts of water or aqueous solution. These ultra high absorbing materials can imbibe deionized water as high as 1,000-100,000% (10-1000 g/g) whereas absorption capacity of common hydrogels is not more than 100% (1g/g). Figure 32.11 shows visual and schematic illustrations of an acrylic-based anionic superabsorbent hydrogel in the dry and water-swollen states (Omidian et al. 2004).

Artificial Glaciers: The natural glaciers are shrinking due to rising global temperatures and results in water crises. In 2014 a local mechanical engineer, Mr. Sonam Wangchuk, set out to solve the water crisis of the Ladakh. Mr. Wangchuk had a simple idea: he wanted to balance this natural deficit by collecting water from melting snow and ice in the cold months, which would normally go to waste, and store it until spring, just when farmers need it the most. He built a two-story prototype of an “ice stupa”, a cone of ice that he named after the traditional mound-like sacred monuments that are found throughout Asia (Fig. 32.12).

Fig.32.11: A typical acrylic-based anionic SAP material: (a) A visual comparison of the SAP single particle in dry (right) and swollen state (left). The sample is a bead prepared from the inverse-suspension polymerization technique. (b) A schematic presentation of the SAP swelling (Source: Omidian et al. 2004).

33.4. Desalination

What is desalination?

Desalination is a process that removes dissolved minerals including salts from saline water and produces potable water. Desalination is a natural and continuous process and a part of the natural water cycle. Sea water evaporates and returns to earth as desalinated rainwater.

Why desalinate?

Desalination has become increasingly important in the last four decades due to the tendency, in recent years, for the world’s swelling population to dwell in areas where supplies of high quality fresh water sources are less than adequate. Moreover, as there are a considerable number of saline sources available, desalination is becoming an attractive possibility. More than three quarters of the earth’s surface and more than 95% of the world’s water is either salty or brackish, and therefore not potable. Desalination increases the range of water resources available for use by communities. A number of technologies, such as the membrane process, distillation, and vacuum freezing, have been developed to perform desalination. Nearly 60 percent of the world’s desalination systems use distillation, heating the salty water to produce water vapor that is then condensed to form fresh water.

32.5.Extended detention wetland

Wetland Treatment System: A storm water or wastewater treatment system consisting of shallow ponds and channels vegetated with aquatic or emergent plants. This system relies on natural microbial, biological, physical, and chemical processes to treat storm water or wastewater. An extended detention wetland (EDW) is a constructed basin that has a permanent pool of water throughout the growing season and captures the water quality volume (WQv) and releases it over a 40-hour period. Extended detention wetlands are among the most effective storm water practices in terms of pollutant removal, and they also offer aesthetic value (Fig. 32.13). As storm water runoff flows through the wetland, pollutant removal is achieved through settling and biological uptake within the wetland. Flow through the root systems allows the vegetation to remove nutrients and dissolved pollutants from the storm water (California Storm water Quality Association, 2003).Routine harvesting of vegetation may increase nutrient removal and prevent the export of these constituents from dead and dying plants falling in the water. Vegetation harvesting in the summer is recommended annually (California Storm water Quality Association, 2003).

32.6. Management policy

The main issues encountered in water resource management in the region include wasteful usage, low efficiency, and poor management policy. However, Willis et al. (2011) opine that “the determining motives for saving water are key when designing educational urban water saving strategies; hence at the outset, an understanding of consumption and attitudes towards water is vital.” Recently estimated increased cropping intensity to meet world demands will require an increase of 40% in the area of harvest crops by2030, and that the amount of water allocated to irrigation must increase correspondingly by 14% (UNESCO, 2006). This is creating a major paradox and a looming crisis due to limited availability of the required water.

32.7.Water Management Strategies

Water resource management requires a shift in the attitudes and behaviour of the various stake holder to move away from centralized top down planning to community driven location specific, people centric planning. Water-management strategies projects do not depend solely on good engineering and suitable agronomy for their success. Socioeconomic considerations are just as important. Generally same water management strategies are employed without consideration to different parts of a basin. Infect it is necessary to provide a simple framework to visualize water use in a basin and enable formulation of effective, site specific, water management strategies. A water management strategy is a plan or a specific project to meet a need for additional water by a discrete user group, which can mean increasing the total water supply or maximizing an existing supply. Strategies can include development of new groundwater or surface water supplies; conservation; reuse; demand management; expansion of the use of existing supplies such as improved operations or conveying water from one location to another; or less conventional methods like weather modification, brush control, and desalination. Factors used in the water management strategy assessment process include:

1. The quantity of water the strategy could produce;
2. Capital and annual costs;
3. Potential impacts the strategy could have on the state’s water quality, water supply, and agricultural and natural resources and
4. Reliability of the strategy during time of drought.

Calculating the costs of water management strategies is done using uniform procedures to compare costs between regions and over time, since some strategies are recommended for immediate implementation, while others are needed decades into the future. The opportunities for applying new technologies and making other changes in our management of the water resource must be fully assessed and implemented as soon as possible.

The water resources shall be managed in such a manner that will result in the greatest long-term benefit to the people. Various water-saving opportunities exist, since conditions vary from place to place, specific opportunities must be identified individually. All the terrestrial freshwater use takes place within a basin context. Within each basin, there are hydrological, topographical, and hydrological differences between areas or reaches, requiring different water management and conservation techniques. Unfortunately too often this is not done and the same water management strategies are employed without consideration to characteristics of different part of basin. The greatest potential savings are found in areas where significant quantities of return flow from excess water applications are disposed to saline waters without serving further beneficial use. But even in areas where water conservation measures will not save large quantities of water, they may result in energy savings and offer opportunities for environmental improvement through changes in water management.

Bibliography

• Aderaldo Silva De Souza, et al. 1982. Irrigación par Potes de Barro: Descripcióndel Método y Pruebas Preliminares, Petrolina, PE, Brasil, 1982, (EMBRAPA-CPATSA Boletín de Investigación No. 10).
• American Public Works Association, 1981. Special Report No. 48: Planning and Evaluating Water Conservation Measures. Chicago, IL.
• American Water Works Association (AWWA), 2013. AWWA Standard G480-13 (First Edition): Water Conservation Program Operation and Management. Denver, CO.
• American Water Works Association (AWWA), 2016. Water Audits and Loss Control Programs (Manual of Water Supply Practices M36), 4th Edition. Denver, CO.
• Barber, R.G., Navarro, F., 1994.The rehabilitation of degraded soils in eastern Bolivia by subsoiling and the incorporation of cover crops. Land Degradation and Rehabilitation. 5, 247-259.
• Brannon, P.L, Harland, R.S., 1990. Absorbent Polymer Technology, Elsevier, Amsterdam, Ch 1-4.
• Buchholz, F.L., (Editor) & Graham, A.T. 1997. Modern Superabsorbent Polymer Technology John Wiley & Sons, November. 0471194115.
• Buchholz, FL., Graham, A.T., 1998. Modern Superabsorbent Polymer Technology, Wiley-VCH, New York, Ch 1-7.
• Bunn, S.E., Arthington, A.H., 2002. Basic principles and ecological consequences of altered flow regimes for aquatic biodiversity. Environ. Manage. 30 (4), 492-507.
• Carlisle, D.M., Wolock, D.M., Meador, M.R., 2011. Alteration of stream flow magnitudes and potential ecological consequences: a multiregional assessment. Front Ecol. Environ. 9.5. 264-270.
• Christa, B., Joshua, K.A., 2017. Growing into Water Conservation? Decomposing the Drivers of Reduced Water Consumption in Las Vegas, NV.Ecol. Econ. 133. 99–110.
• Dabral, P.P., 2002. “Indigenous Techniques of Soil and Water Conservationin North Eastern Region of India”, 12th ISCO Conference, Beijing.
• Donald, G., Cornelis, W. M., Schiettecatte, W.,Water Harvesting and Water-Saving Techniques. Land Use, Land Cover and Soil Sciences-Vol. 5.Water Harvesting and Water-Saving Techniques – DonaldGabriels, Wim M. Cornelis and WouterSchiettecatte.
• Douglas County Colorado, 2016.Standard Operating Procedure (SOP) for Porous Landscape Detention (PLD) Inspection and Maintenance Porous Landscape Detention (PLD) – Sedimentation Facility, Stormwater Quality BMP manual.
• Evans, R.G., Sadler, E. J., 2008, Methods and technologies to improve efficiency of water use, Water Resour. Res., 44, W00E04, doi: 10.1029/2007WR006200.
• Fidelia, N.N., 2012. Super Absorbent Polymer (SAP) and Irrigation Water Conservation.Irrigation & Drainage Systems Engineering. 1 (1), 1000-1002.
• Freeman, M., Marcinek, P., 2006.Fish assemblage responses to water withdrawals and water supply reservoirs in piedmont streams. Environ Manage. 38.3.435-450.
• Georgia Environmental Protection Division. Georgia Water Use and Conservation Profiles (Technical Memorandum).
• Gleick, P.H., 2000. A look at twenty-first century water resources development. Water Int. 25 (1), 127-138.
• Goel, R.S., 2000. (Editor).Environment Impacts Assessment of Water Resources Projects – Concerns, Policy Issues, Perceptions and Scientific Analysis’. Oxford & IBH Publishing Company, India, 413.
• Gould, J.E., 1992. Rainwater Catchment Systems for Household Water Supply, Environmental Sanitation Reviews, No. 32, ENSIC, Asian Institute of Technology, Bangkok.
• Gupta, S., 2012. Drinking Water Quality: A Major Concern in Rural India (Some strategies towards cleaner water and the draft water policy-2012). BARNOLIPI An Interdisciplinary Journal. 1: 2249-2666.
• Gupta,  S.K.,  Deshpande.  R.D.,  2004.  Water  for  India  2050:  First  order  assessment  of  available options. Curr. Sci. 86: 1216-1224.
• http://adm.elpasoco.com/transportation/Documents/Drainage%20Manual/PorousLandscapeDetentionP LDSedimentationFacility.pdf )
• http://edition.cnn.com/style/article/ice-stupa-sonam-wangchuk/index.html
• http://www.rainwaterharvesting.org/methods/traditional/bamboo.htm
• https://permaculturenews.org/2014/02/28/bamboo-drip-irrigation/
• Ignatius, A., 2015. Cumulative effects of small reservoir construction: land cover change, evaporation, and water quality in the Georgia Piedmont, USA. doi:10.1017/CBO9781107415324.004.
• Jain, R.C., 2017. Strategies for sustainable ground water management in face of climate change in India. Workshop proceeding on Water conservative and its related issues.
• Malesu, M.M., (Editor); Oduor, A.R., (Editor); Odhiambo, O.J., (Editor)., 2007. Green Water Management Handbook.Rainwater Harvesting for Agricultural Production and Ecological Sustainability. Nairobi: The World Agroforestry Centre. URL.Accessed: 09.05. 2012.
• Modal, R.C., 1978. “Pitcher Farming is Economical,” World Crops, 30. 3. 124.
• Mohammad, J., Zohuriaan, M., Kourosh, K., 2008. Superabsorbent Polymer Materials: A Review Iranian Polymer Journal 17 .6. 451 – 477. Superabsorbent hydrogels, Website of the leading Iranian manufacturer of superabsorbent polymers; Rahab Resin Co., Ltd.; www.rahabresin.com, available in 10 September 2007.
• Molden, D.J., Sakthivadivel, R., Keller. J., 2001.Hydronomic Zone for developing basin water conservation strategies (Research report 56).
• Nader, C., Mary, H., 2007. Conservation Technologies for Affordable Housing, Energy Efficiency and Water Conservation Design Guidelines.
• New    York State Public Service Commission, 2016. PSC Directs Water Utility to Develop Conservation Plan for Rockland County.
• Olmstead, S.M., Stavins, R.N., 2007. Managing Water Demand: Price vs. Non-Price Conservation Programs.
• Omidian, H., Zohuriaan, Mehr, M.J., Kabiri, K., Shah, K., 2004. Polymer chemistry attractiveness: Synthesis and swelling studies of gluttonous hydrogels in the advanced academic laboratory, J. Polym Mater, 21, 281-292.
• Oweis, T., D. Prinz. A., Hachum. 2001. Water Harvesting: Indigenous Knowledge for the Future of the Drier Environments. ICARDA, Aleppo, Syria.40.
• Pawar, A.T., Shelke, S., Kakrani, V.A., 2005. Rapid assessment survey of earthquake affected Bhuj block of Kachchh District, Gujarat, India. Indian J. Med. Sci. 59: 488-494.
• Richter, B.D., Braun, D.P., Mendelson, M.A., Master. L.L., 1997.Threats to Imperiled Freshwater Fauna. Conserv.Biol. 11.5.1081-1093. doi:10.1046/j.1523-1739.1997.96236.
• Robert, G., Evans, E., John, S., 2008.Methods and technologies to improve efficiency of water use.Water Resources Research, 44, W00E04, doi: 10.1029/2007WR006200.
• Rockland County (New York), 2016. Website: Task Force on Water Resources Management. http://rocklandgov.com/departments/planning/task-force-on-water-resources-management/.Accessed November 29.
• Ronald, B.R., 1976. Water Conservation in California, Bulletin No. 198. World Public Library Association.
• Ruffino,  L.,  2009.  Rainwater  Harvesting and  Artificial  Recharge  to  Groundwater.  Brussels:  SAI Platform. URL.Accessed: 09.05.2012.
• Senthil, K.K., 2013. Indian Waters: Past and Present. Hydrology Current Research. S10.
• Shrikant, D.L., 2011. Importance of Percolation Tanks for Water Conservation for Sustainable Development of Ground Water in Hard-Rock Aquifers in India. Environmental Engineering “Water Conservation”, edited by Manoj K. Jha, ISBN 978-953-307-960-8.
• Singh, R.A., Gupta, R.C., 2002. “Traditional land and water management systems of North-East hill region”, Indian J. of Traditional Knowledge, 1. 32 – 39.
• Texas Water Development Board, 2017.Texas State Water Plan. Austin, TX.
• Tripathi, K.P., 2016. Field Bunding: Foremost Rain Water Management Measure. Water Conservation and Management in India. Civil Division Board, Annual Technical Volume Vol. II.
• U.N. Educational, Scientific, and Cultural Organization, 2006.Water, a shared responsibility, Rep. 2, World Water Assess.Programme, Berghann, New York.
• US Environmental Protection Agency, 2010.Control and Mitigation of Drinking Water Losses in Distribution Systems. Washington, DC.
• US Environmental Protection Agency. 2016. Best Practices to Consider When Evaluating Water Conservation and Efficiency as an Alternative for Water Supply Expansion. (www.epa.gov).
• USEPA, Cleaner Water Through Conservation, Washington B.C., 1995 (Report No. EPA-841/B-95-002).
• Willis, R.M., S.A., Panuwatwanich, K., Williams, P.R., Hollingsworth, A.L., 2011. Quantifying the influence of environmentaland water conservation attitudes on household end use water consumption. J. Environ. Manag. 92 (8), 1996-2009.
• Zheng, D., Yin, Y., 2010. Eco – reconstruction in Northwest China, Water and Sustainability in Arid Regions: Bridging the Gap between Physical and Social Sciences, Springer.