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close this bookSourcebook of Alternative Technologies for Freshwater Augmentation in some Asian Countries (UNEP-IETC, 1998)
View the document(introduction...)
View the documentForeword
close this folderPart A - Introduction
View the document1. The freshwater imperative
View the document2. Objectives
View the document3. Organisation of the source book
View the document4. Survey methodology
View the document5. Results of the survey
View the document6. Recommendations of the workshop
View the document7. Information sources
close this folderPart B - Technology profiles
close this folder1. Water conservation technologies
View the document(introduction...)
View the document1.1 Dual water distribution system
View the document1.2 Evaporation reduction
View the document1.3 Coconut pick-ups
close this folder2. Wastewater treatment and reuse technologies
View the document2.1 Sewage reclamation using conventional wastewater treatment
View the document2.2 Sewage reclamation using reverse osmosis
View the document2.3 Wastewater treatment using wetlands
View the document2.4 Wastewater treatment using duckweed
View the document2.5 Wastewater treatment using lagoons
View the document2.6 Other technologies of wastewater treatment and reuse
close this folder3. Freshwater augmentation
View the document3.1 General rainwater harvesting technologies
View the document3.2 Rainwater harvesting for drinking water supply
View the document3.3 Rooftop rainwater harvesting for domestic water supply
View the document3.4 Rainwater harvesting for agricultural water supply
View the document3.5 Rainwater harvesting for irrigation water supply
View the document3.6 Rainwater harvesting for community water supply
View the document3.7 Rainwater harvesting for multiple purpose use technical description
View the document3.8 Open sky rainwater harvesting technical description
View the document3.9 Rainwater harvesting in ponds
View the document3.10 Artificial recharge of groundwater technical description
View the document3.11 Fog, dew and snow harvesting
View the document3.12 Bamboo pipe water supply system
View the document3.13 Hydraulic ram technical description
View the document3.14 Development and protection of natural springs
View the document3.15 Restoration of traditional stone spouts
close this folder4. Upgrading water quality
View the document4.1 Desalination
View the document4.2 Pond sand filtration
View the document4.3 Biological pretreatment of raw water
close this folderPart C - Case studies
View the document5.1 Water conservation and recycling - Gujarat State fertilizer corporation, India
View the document5.2 Traditional methods of soil and water conservation - coconut pick-ups, India
View the document5.3 Use of reclaimed water - Hindustan petroleum corporation limited, India
View the document5.4 Reclaimed city sewage as industrial water - Madras fertilizers limited, Madras, India
View the document5.5 Rainwater harvesting - the Thai rainwater jar
View the document5.6 Daungha rainwater collection water supply project, Nepal
View the document5.7 Conjunctive use of surface and groundwater - Krishna Delta, India
View the document5.8 Artificial groundwater recharge - India
View the document5.9 Integrated water conservation - Bhilai steel plant, India
View the document5.10 Drip irrigation - India
close this folderPart D - Annexes
View the documentAnnex 1 - Additional references
View the documentAnnex 2 - Table of conversion factors for metric and U.S. customary units
close this folderPart E - Institutional profiles
View the documentThe UNEP water branch
View the documentDanish hydraulic institute (DHI)

5. Results of the survey

The results of the survey are presented below in Table 2 in summary form and in greater detail in Parts B and C. Technologies have been considered in four focal areas; water conservation, wastewater treatment and reuse, freshwater augmentation, and upgrading the water quality of natural waters.

Water conservation technologies include: water recycling in industries (i.e., cleaning wastewater for reuse in the same or other processes), dual distribution systems with drinking water in one system and water of marginal quality for non-potable uses in another, and mono-molecular organic surface films on the surfaces of water storage reservoirs to reduce evaporative losses.

TABLE 2. Summary Evaluation of Alternative Technologies for Freshwater Augmentation in Asia.

Technology

Extend of use

O&M

Level of involvement

Costs

Effectiveness

Suitability

Advantages

Disadvantages

Cultural Acceptability

Comments and Recommendations

Water recycling

Moderate.
Only in the industrial sector

Moderate to high

Private sector. Government for legislation

High investment costs.
Recurrent low

High

Industrial sector

Reduces freshwater needs, waste water amounts, and environmental hazards

High investment. Modifications to processes may be required

Highly acceptable

Has a high potential and should be encouraged. Often makes use of dual distribution systems

Dual distribution systems

Rare

Moderate

Household Government

Capital moderate.
Recurrent low

Depends on quality and availability of alternative source

Where drinking water is scarce and marginal-quality water easily available

Reduces demand for drinkable water significantly

Costly. Can introduce aesthetic problems and health hazards

Low to Moderate

Limited potential in general. Should be encouraged in areas with high water scarcity

Mono-molecular organic surface films

Rare

Low

High involvement from Government

Moderate

Moderate, under research conditions low in practical application

Rural areas, especially in arid and semi-arid regions

Reduces water loss. Prevents mosquito breeding

Un-aesthetic. Loss of recreational value of the water body

Low

Suitability for large water surfaces unknown.
Not recommended

Reuse irrigation water for irrigation

Moderate

Same as O&M for irrigation systems in general

Household, community, Government organizations

Same as for irrigation systems in general

High overall effectiveness

Not suitable in (arid) areas with salinity problems

Overall efficiency of water utilization increases

The quality of the drainage water may be low

Acceptable if the quality is OK

Promising potential.
Further research required on economic techniques for extraction of salt and dilution processes

Sewage water in aquaculture

Moderate to high

Low to moderate

Household, community, government

Low

High

Suitable for the most common species of fish

Low operational costs. Effluent applicable for irrigation

Hygienic problems. Health hazards. Requires large areas of land

Acceptable in most Asian countries

Potential exists and increased use is recommended. Contamination with industrial waste should be avoided

Primary wastewater treatment

Low to moderate for farming. High as initial treatment

Low to moderate

Community

Low

High for irrigation, otherwise low

Rural areas

Low cost. Reduces requirements for further treatment

Aesthetic problems, pollution and health hazards

Acceptable in most areas

Recommended. Water quality monitoring required, when applied for irrigation

Secondary wastewater treatment

High

High

Community, private sector, government

High

High. The effluent will usually be non-polluting

Outside residential areas

Reduce hazards. Water may be reused in agriculture and industries

High costs

Acceptable

Recommended

Advanced wastewater treatment

Low

High

Community, private sector, government

Very high

High

Only when pollutants can not be removed by secondary treatment

Reduces environmental and health hazards

High costs

Acceptable

Recommended

Water treatment by lagoons and wetlands

Low

Low

Community, private sector, government

Low

Low to High, depending on chemical and physical characteristics, flow etc

Where suitable lagoons/wetlands are available

Reduces environmental and health hazards

High costs for land acqusition

Acceptable

Recommended only for organic wastewater after primary treatment. Research required on quantification of impacts

Rainwater harvesting

High

Low

Household, community, (government for promotion)

Low

High

No limitations

Simple technology, low costs, source close to user

Limited and uncertain supply, hygienic problems

High

Recommended

Fog and dew

Low

Low

Household, community

Low

Low

Few areas

Reduces the need for other sources

Low quantities

Acceptable

Low potential

Small scale water storage

Moderate

Low

Community, private sector, government

Low to moderate

Moderate to high

Rural areas, where suitable sites are available, preferably marginal lands

Augments water availability in dry season.
Reduces (flash) flooding

Potential water quality problems.
Requires land

Acceptable

Recommended

Artificial recharge of groundwater

Low

Low, except for deep well injections

Community, government

Moderate to high

Low to high, depending on hydro-geological conditions etc

In areas with appropriate geological and hydrological conditions

Augments dry season supply. Reduces flooding, land subsidence, sea water intrusion

High costs. compared to benefits. Risk of groundwater pollution

Acceptable

Potential exists. Further research required on the effectiveness under different geo-hydrological conditions

Artificial rain

Low

High

Government

High

Low

Areas with clouds but little rain

Can increase rainfall

Expensive The rain may fall outside the target area

Acceptable

Not recommended.

Desalinization

Low

High

Community, private sector

High

High

Coastal area with no other water source or with low-cost energy available

Reduces freshwater needs

High costs

Acceptable

Only recommended where no other source is available

Wastewater treatment and reuse technologies include: reuse of irrigation water by tapping return flows from the drainage system for further irrigation use downstream, the use of sewage effluent in aqua-culture (primarily the use of night soil and fecal-contaminated surface waters for fertilizing fish ponds, and irrigation), primary wastewater treatment (in which organic and inorganic materials are removed from waste water through sedimentation and filtering), secondary wastewater treatment (in which also the non-settleable solids are removed, primarily through biochemical processes, to promote the degradation of organic pollutants), advanced wastewater treatment such as carbon adsorption, microstraining, and desalination, and water treatment by lagoons and wetlands (as a form of secondary wastewater treatment utilizing the naturally occurring processes in these areas).

Freshwater augmentation technologies include: rainwater harvesting from roofs into jars and pots or small dams, fog and dew harvesting to condense air-borne moisture into liquid water for drinking water supplies or irrigation, small-scale water storage facilities including small ponds, tanks, surface reservoirs, and underground reservoirs formed by subsurface obstructions or dams, artificial groundwater recharge using infiltration from the surface or injection via deep wells, and cloud seeding.

Technologies for the upgrading of the quality of natural waters through desalinization include distillation, reverse osmosis and electrolyte systems.

5.1 Bangladesh

From time immemorial, rainwater has been playing a significant role in the socio-economic life of Bangladesh. In fact, the entire agro-economic fabric of the country is built on the particular rainfall pattern (commonly known as the monsoon) occurring ion the country. Nevertheless, very few studies have been carried out on rainwater harvesting. Those that are available are studies by Hossain and Ziauddin (1992), Sarker (1994), and Uttaran (1995). The major constraint on the development of rainwater harvesting technologies is a low education level of the people and the poor economic condition of their households. The past studies have provided few innovations for users in the methods of collection and storage of rainwater. A joint Department of Public Health Engineering (DPHE) and UNICEF programme, that has been working in the southern area of Bangladesh since 1984 to provide better quality drinking water, has been reported that, despite filtering, the water remained salty during the dry season and that people did not want to use it. Of the 90 DPHE-UNICEF sand-filtration facilities serving communities of 50 to 60 users, 45% were found to be idle.

In contrast, rainwater harvesting by the erection of bunds around farms is the most common and one of the earliest methods of rainwater harvesting in Bangladesh. In this method, earthen bunds with height of 30 to 45 cm and width of equal dimensions are constructed around the field. Farmers have learned from experience to match their cropping cycle with rainfall pattern. Rainwater meets around 78% to 97% of land preparation water requirement for aman crops. In saline areas, rainwater is used in the aman paddies to dilute saline river water until the river water becomes sweet. Over the entire aman crop cycle, rainwater meets around 50% of water requirements with the residual being obtained from river water sources.

Variations on this technology exist. In the upland areas of Bangladesh (NC zone- Jhenaighati, Nokla thanas) rainwater is stored in low lying plots usually in between two hills to be used in times of necessary. Plots are irrigated using traditional equipment such as dhoons and hicha. In the CW zone (Jhenaidah thana), rainwater is collected from surrounding lands at higher elevations and carded to storage ponds through a culvert. In saline areas (the Patuakhali, Khulna, Satkhira and Bagerhat districts), lands are located within polders or embankments erected to obstruct intrusion of saline water. In these areas, around three-quarters of the agricultural lands are being used for saline water-based shrimp culture delimiting options for freshwater based agriculture.

The polders also have the potential to revolutionize the drinking water supply systems in the saline areas (the greater Khulna, Satkhira, Patuakhali, Barisal and Noakhali districts) through the construction of "sweet water ponds" which are replenished by rainwater in the monsoon. In southern portion of Hatya and other remote islands in the Bay of Bengal, where there are very few tubewells, rainwater from these ponds is found to meet nearly 80% of the drinking water requirement in the monsoon season. In the saline area of the SW zone, rainwater meets 44% and 7% of drinking water requirement in monsoon and dry season, respectively. Ponds and tubewell water meet remaining 31% and 25% of monsoon season water drinking water requirement. Rainwater meets 49% of cooking water requirement in the monsoon season and is not used at all for bathing. On the other hand, in the NC zone, rainwater is not used for drinking purposes but, instead, is used for cooking (6%) and bathing/washing (11%). The bulk of the drinking, cooking and bathing/washing requirement is met from tubewells. In the NW zone, only 2% of the inhabitants reported using rainwater, for bathing only, as their entire requirement for drinking and cooking water is met from tubewells and, to some extent, from ponds/rivers and other surface waterbodies.

One of the oldest method of rainwater harvesting in Bangladesh is the use of roof-tops for collecting rainwater which is conveyed through a gutter to a pot, or motka, for immediate use or to a storage place for use later on. The water stored retains its colour and taste for around two months after monsoon, after which, the water gradually becomes contaminated with toads, mosquitos, cockroaches, etc. Previously, fish such as Koi, Singh or Magur (Anabas testudinews, Heteropreutes sp., and Clarias batrachus) were grown in the pots to eat the larvae of mosquitos and other insects. However, as these fishes discharge their own excreta in the water, which also degrades the quality of water, use of fish to maintain water quality is fast decreasing. Occasionally, alum or other locally made flocculant aid, like burnt shell, is used to purify the water. Water purifying tablets are very infrequently used.

Of the many industrial uses of harvested rainwater, one of the commonest is fish culture. In north Bengal and in Mymensingh, ponds are completely dried prior to the monsoon. The soil is enriched with lime and cow dung, and the water is treated with potash, to prepare the ponds for fish cultivation. In other areas, water is kept in the ponds at levels of 1 to 1.5 m prior to the monsoon. In saline areas like Hatiya, the same pond may be used for drinking water supply purposes. No soil treatments are applied to these ponds. In Sherpur District (Jhenaigati thana), rainwater is stored in embankments and used for fish culture. In the NC zone, excess water flowing out of the embankments passes through a net so that fish cannot escape from the pond.

5.2 India

The National Water Policy of India states that water is a prime natural resource, a basic human need and a precious national asset. It recommends that water resources planning be done for hydrological units, such as drainage basins or sub-basins. As far as possible, the projects should be planned and developed as multipurpose projects. Provision for drinking water should be given priority over other uses of water. The integrated and coordinated development of surface and ground waters and their conjunctive use should form an essential part of all water resources development projects, with recycling and re-use of water being an integral part of water resources development. Emphasis is placed on the preservation of the quality of the environment and ecological balance in planning, development and operation of water resources projects. The National Water Policy stresses the use of freshwater augmentation technologies as one means of alleviating India's chronic water shortages.

Water conservation may be achieved by modification of technologies and industrial processes in order to reduce the rate of water consumption. Better maintenance, interception and recovery of process water, and recycling can significantly contribute to water conservation efforts. Use of water of lesser quality, such as reclaimed wastewater, for cooling and as fire water can be an attractive option for large and complex industries to reduce their water costs, increase production and decrease the consumption of energy. This conserves better quality waters for potable uses. These technologies can be further complimented dew water harvesting or by constructing "dew ponds". The climatic conditions of some parts of Assam in Brahmaputra Valley and in hill areas hold promise for use of dew ponds. Public information programmes also contribute to water conservation in urban areas.

Agricultural water sources can be supplemented by small structures (pick ups) built across seasonal or perennial streams to check the flow of water at appropriate locations by constructing bunds using locally available materials like stones, boulders or even mud bunds turfed with a grass locally available (Maane hullu). Use of these structures results in water storage, groundwater recharge, prevention of soil erosion, and availability of water for other activities in areas where water would typically not be available for much of the year. In contrast, in the Krishna Delta, large demands for water from the Nagarjuna Sagar Reservoir have reduced the volume of freshwater reaching the Delta, and it has become necessary to utilize the groundwater supplies. In order to achieve an acceptable quality, however, groundwater must be used conjunctively with the limited surface water resources in a mix of 28:72, groundwater: surface water. Blending these waters should result in the conservation of storage in the reservoir of about 751 Mm3 for the first stage and 1 016 Mm3 for final stage, for a year with average inflows. In a more general sense, technological developments in the pumping methods and well construction have resulted in large-scale exploitation of groundwater throughout India which exceed the natural rate of replenishment of these resources. Thus, replenishment of the groundwater reservoirs by artificial recharge is essential.

TABLE 3. Water Evaporation Retardation (WER) Projects

States

Implemented for

Reservoirs/Lake

Surface area in acres

Year

Average Project period

Major Projects. Tamil Nadu

Madras Metro Water Supply

Cholavaram Red Hills

760 3200

1988-89

3 months

Andhra Pradesh

Hyd. Metro Water Works






Division -I

Himayatsagar

1500

1986

4 months


Division - II

Osman Sagar

1000

1987



Division - IV

Manjira

3500

1988


Maharashtra

Irrigation Dept.

Chulbandh

300

1988

3 months


Nagpur

Kolar

1000

1989


Gujarat

Govt. of Gujarat

Aji Dam

300 each

1986

6 months



Fulzar


1987




Sasoi


1988




Nyari






Bhadra




Rajasthan

PHED. Kankorli

Rajsamand

1200

1985

6 months


PHED. Udaipur

Pichola

300

1986




Fatehsagar

300

1987



PHED. Bhilwara

Meja Dam

350

1988



PHED. Jaipur

Ramgarh Lake

300

1989



J.K. Inds. Ltd.

Rajsamand

1200




Hind Zinc Ltd.

Udsisagar

300





Tidi Dam

350




Lakshmi Cement


300



Other Project Sites







PHED. Dhar

Dhar Res.


1988

2 months

M.P.

PHED. Seoni

Seoni Res.





Gwalior Rayons

Noda Res.




Rajasthan

PHED. Ajmer

Foy Sagar


1986



PHED. Sirohi

Sirohi Res.


1986

3 months


PHED. -

Dungarpur Res.


1988



PHED. Pali

Pali Res.




In many parts of the country, which have to face the vagaries of the monsoon, dependance on groundwater has increased tremendously, particularly in those areas where surface water resources are either lacking or inadequate, and storage of surface water is uneconomical because of high evaporative losses. Water loss due to evaporation has led to serious problems including acute shortages of drinking water for human consumption in some parts of India. Considering the huge loss of precious water, use of Water Evaporation Retardants (WER) on open surfaces of lakes and reservoirs is now being promoted by various State Governments and Local Authorities. Various substances capable of forming mono-molecular layers on a water surface have been investigated, and fatty alcohols in their pure form were found to be most suitable and effective in retarding evaporation with no known side effects. Water savings resulting from the prevention of evaporative losses using cetyl and stearyl alcohol have been reported to be as high as 50%, but are generally between 20% and 40%. Table 3 shows a list of projects where the evaporation retardants have been used.

In India, rainfall is confined to about four months in a year and is inconsistent both in space and time, causing severe drought. In this context, whatever the source water used, irrigation is a must for agriculture in the country. However, there is an urgent need for efficient use of present available water so as to irrigate the maximum possible gross cropped area. In India, sprinkler irrigation is being adopted in hilly terrains, for irrigation of many plantation crops. The use of sprinkler systems, which mimic natural rainfalls, was introduced in the State of Hariyana in 1970, and other states like Rajasthan, Uttar Pradesh, Karnataka, Gujarat, Maharashtra have since implemented sprinkler irrigation systems. In the State of Hariyana, it has been found that, the use of sprinkler irrigation has saved about 56% of water for the winter crops of Bajra and Jawar, while for cotton it has saved 29% as compared to the traditional gravity irrigation. Drip irrigation systems, a variation on piped irrigation that delivers water directly to the root zone of the crops, are of very recent origin, and are used on a limited scale in Tamil Nadu, Karnataka, Kerala and Maharashtra mainly for irrigation of coconuts, coffee, grapes and vegetables. Experimental studies on sugarcanes, banana and other fruits have shown a very high profitability in addition to water conservation.

TABLE 4. Water Loss Under Various Irrigation Methods.


Temperate Climate

Hot Climate

Surface Irrigation

30 - 45%

35 - 50%

Gate pipe Irrigation

15-20%

20 - 25%

Sprinkler Irrigation

6-9%

10 - 20%

5.3 Nepal

Although Nepal has one of the world's largest per capita water resources, most of the population does not have easy access to safe drinking water and, at times, there are acute shortages of water for all economic purposes. Urban settlements are mostly affected by the shortage of water whereas, in the rural areas, the problem is linked to lack of accessibility of water. The main sources of water in the country are rivers and springs in the hilly regions, and shallow and deep groundwaters in the Terai. Due to the shortage of water from the municipal supplies in the urban settlements, primarily in the Kathmandu Valley, there is a trend toward illegal extraction of underground water using shallow and deep wells, thereby lowering the water table and leading to the possibility of land subsidence and foreseeable tectonic effects. Associated problems are the decline in the yield and productivity of wells and the increasing incremental cost of lifting water from ever-increasing depths. For these reasons, Nepal has identified freshwater augmentation technologies to protect both water quantity and water quality to the extent possible.

Alternative technologies include the use of traditional technologies such as stone spouts and Pokharis, which were the only sources of water in the Kathmandu Valley in the past. However, there is a need to conserve and restore the ponds, aquifers, wells and stone spouts which have been neglected. Conservation and restoration of stone spouts and Pokharis is related to spring development and protection. Spring protection technologies are widely used in the central and eastern hills of Nepal. These are simple and ideal technologies for use where yield of the source is very low and water is drawn at the source itself. Likewise, rainwater harvesting has been popular where there are neither springs nor streams nearby to fulfill the water demand of the community.

Various distribution systems have also been developed in Nepal based upon traditional technologies. For example, bamboo piped water supply systems are not very common, but may prove an ideal system for remote areas where GI and HDPE pipes and fittings are not available and only bamboo is easily available and cheap. Use is also being made of hydraulic rams to pump water using the hydraulic power of the water itself, thus eliminating the need for diesel or electrical power to drive water pumps. The principle advantages of this system are its simplicity and lack of an energy cost in the operation of the system. This system is suitable in places where there is plenty of water, and the area to be supplied is situated at a lower level than the source area.

5.4 Thailand

Freshwater augmentation is practised in Thailand for three main purposes; namely, for agricultural, industrial, and domestic uses. The status of freshwater augmentation technologies in Thailand is summarized in Table 5. The two most common and successful technologies are recycling of harvested rainwater in irrigation systems and rainwater harvesting for domestic rural water supply purposes. Technologies that are related to domestic rural water supply are shown in Table 6. Important issues related to the technologies are also summarized.

TABLE 5. Status of Freshwater Augmentation Technologies in Thailand.

APPROACH

RAIN-FED SYSTEMS

MODERN SYSTEMS

TRADITIONAL SYSTEMS

INLAND FISHERY

INDUSTRY

RURAL

Recycling to maximize the use of existing resources

Planting suitable crops (e.g., deep rooted beans) Planting cover crops

Well-known engineering techniques

Recycling among several small systems

Bottom dwelling fishes used to clean fish ponds

Well-known, engineering techniques

Experimental desalination

Systems to augment existing sources

Traditional contour bunding

None known

Traditional bamboo or earthen weirs found throughout SE Asia


None known

Several facilities used (See the following Table).