1. The freshwater imperative

Water is basic to the human health, welfare and economic development. Water is equally vital for the preservation of wildlife and the natural environment. Freshwater is a central feature of climate, and can be a source of energy, an avenue of transportation, and a means of production and aesthetic inspiration. Its presence or absence governs the nature and placement of structures within the physical landscape and it exerts a major influence on demographic patterns. It is also viewed as a key to economic growth and prosperity.

Freshwater, or that portion of the world's water resources suitable for use by humans and most terrestrial vegetation and wildlife, is a small portion of the global water supply. For domestic and agricultural uses, freshwater generally refers to water containing less than 1 000 mg/l dissolved solids. (Although, depending on the specific purpose for which the water is used, this concentration may be higher or lower; for example, salinity levels in freshwater for drinking purposes should not exceed 500 mg/l, while, for irrigation purposes, they should be less than 2 000 mg/l.) The presence of other contaminants such as toxic substances, disease-causing organisms, nutrients, oxygen consuming substances, and suspended solids also decreases the quality of freshwater for human and environmental uses.

For centuries, this limited volume of freshwater has been augmented for different human purposes using various indigenous and modem technologies. Frederick (1992) points out that freshwater augmentation technologies in 1990 have advanced little in the several centuries since the early achievements of the Romans in transporting water over long distances and the Dutch in manipulating and regulating water levels. Likewise, in Asia, few advances are evident since the development of large irrigation projects in China's Sichuan Province, runoff farming collection systems in Israel's Negev Desert of Israel, and, in the rural areas of Thailand and Indonesia, the indigenous practices of rainwater collection, developed during the past several centuries.

The absolute shortage of freshwater is further compounded by the fact that freshwater is unevenly distributed geographically and seasonally. Thus, the need for augmentation technologies remains. Most recently, decades of water development and management policies have focussed on supply-side management with the construction of large reservoirs, dams and conveyance systems, as well as deep tubewells. Despite these technological advances in freshwater augmentation, the modem era is not only facing tremendous water scarcity, but also a shortage of the capital investment funds necessary to continue the scale of construction likely to be required in the future. Further, conservationists and NGOs are placing ever larger hurdles in the path of these modem water resources development projects, as the damages caused by many past projects have become obvious, even though the previous construction of hundreds of large and small dams and deep tubewells has contributed significantly to the overall well-being of the people and societies in the Asia (WRI, 1994).

This issue of water scarcity, and the associated cost of developing new water resources, has now been placed water at the top of the international agenda. The United Nations Commission on Sustainable Development (UNCSD), at its first meeting to review global progress in the implementation of the United Nations Conference on Environment and Development's (UNCED) Agenda 21, Chapter 18 (Freshwater Resources), called for a comprehensive assessment of global freshwater resources as an initial step in assessing the adequacy and suitability of the world's freshwaters for meeting current and future human demands. In the meantime, water resources managers have begun to focus increasingly on other methods of freshwater augmentation, including a return to the more traditional technologies developed throughout the world. This book, prepared by the United Nations Environment Programme's (UNEP) International Environmental Technology Centre and Water Branch, provides a catalogue of technologies traditionally and currently used in some countries of the Asian region, as an initial step in compiling a global source book on freshwater augmentation technologies. This book is one of five such volumes prepared by UNEP in support of Agenda 21, Chapter 18 and Chapter 34, the latter presenting a detailed plan of action for the assessment and transfer of technologies worldwide.

The per capita water availability in Asia and the Pacific Region varies widely. A recent report of the United Nations Economic and Social Commission for Asia and the Pacific (ESCAP) on the State of the Environment in Asia and Pacific (1995 Draft) pointed out that:

The per capita water availability varies from as high as 200 000 cubic metres in Papua New Guinea to 3 000 cubic metres in Afghanistan, China, India, Korea, Pakistan and Sri Lanka. Countries like Afghanistan, Pakistan and semi-arid regions of Northwest India and Northwest China face growing water scarcities. Likewise, due to growing uncertainty of rainfall and high population growth, local scarcities are increasing in several major cities; e.g., Beijing, Jakarta, Karachi, Madras and Kathmandu.

The increasing water resource scarcity has already affected the water supplies in major cities of Asia. Of 38 major cities, only 21 cities have full water supply services. Others have already faced rationing of water supplies. While cities like Lahore, Jakarta and Manila provide 16 to 20 hours of service per day, Delhi, Rangoon, Karachi, Dhaka, Bombay, Calcutta, Madras and Kathmandu provide only between 1 and 10 hours of service per day (ADB, 1993).

The environmental costs of intensive water development are also escalating. Many coastal communities are facing upstream saltwater intrusions in river systems which threaten their drinking water supply (Postel, 1985). Wasteful use and poor management of water resources impose serious costs as well. Some detailed information available indicate that:

· in the 28 years between 1960-1988, portions of the City of Bangkok have sunk about 1.6 m and the current rate of subsidence for some sections of the City is about 5 cm/year (Phantumvanit et al., 1990).

· heavy pumping for irrigation purposes has caused a drop in groundwater levels of 25 to 30 m in a decade in Tamil Nadu, India (Postel, 1985), and of about 7 to 10 m in Gujarat, India, over a 21 year period between 1966-1981 (Ghosh and Phadtare, 1990).

· in Madhya Pradesh, India, extensive waterlogging of soils due to historic agricultural practices have caused farmers to refer to their once fertile lands as "wet deserts" (Postel, 1985).

· groundwater overdrafts in the northern provinces of China, typified by annual pumping volumes in Beijing that exceed the sustainable supply by 25%, have caused water tables in some areas to drop by up to 4 m/year, and, in Tianjin, by 20 cm every year (Postel, 1985).

A further dimension of the problem is a result of the decreasing assimilative capacities of the rivers and waterbodies in major urban areas. Freshwater used for consumption and production processes are typically drained as wastewater to surface water courses. Usually, during the dry season, these waterbodies are often loaded with sewage and effluent in amounts greater than their carrying capacity. In such situations, water availability is not only constrained due to physical limits, but also due to deterioration in water quality. The Human Development Report (UNDP, 1992) indicated that the majority of the population in developing countries still lack safe drinking water and that more than 50% of the population have no access to potable water.

The unit production cost of water in public water supply systems in the major cities of Asia varies from about $0.01/m³ in Hanoi to about $0.32/m³ in Hong Kong. Nearly 70% of water supply utilities have unit costs below $0.10/m³. The average tariff, estimated from annual water bills in 38 major cities of Asia, ranged from about $0.01/m³ in Shanghai to about $0.47/m³ in Port Vila, with a median tariff of $0.44/m³. However, both the unit production cost and tariff rates do not include the social cost of production or scarcity or opportunity costs of the water. In addition, these costs suggest that water augmentation efforts of the past have largely neglected the environmental costs of rates of withdrawal of available freshwater that exceed rates of replenishment. Indeed, such relatively low costs have encouraged this rapid rate of depletion of water resources in many urban areas.

The costs of water supplied by municipal systems in some urban areas, however, have already started to rise. In the Bangkok Metropolitan Area, the real, per unit rate of water consumed has almost doubled between 1976 and 1989, while the per unit supply cost to the consumer has increased by two and one-half times. The economic costs of groundwater depletion in Bangkok City are realized in the increased costs of pumping water as ground water levels recede, and the costs of providing surface water to substitute for groundwater that has become saline. In addition, there are other costs of too high a rate of water withdrawal, including the costs of land subsidence and related costs of damages to structures, streets, and underground water, sewer, electric and telephone lines, and an increased risk of damage from flooding (Phantumvanit et al, 1990).

In Thailand, the marginal construction costs of all types of irrigation systems installed between 1978 and 1990, rose until the mid-1980s, but declined thereafter in response to a decline in the incremental area brought under irrigation. An economic evaluation of irrigation systems constructed during this period indicated that scarcity, and high rental and opportunity costs contributed to the decline in new irrigation areas (Tiwari, 1994).

In The Philippines, the cost of water supplied to the agricultural sector has declined over the nine year period from 1975 to 1984. Water fees for irrigation water supplied from groundwater sources decreased from $36/ha to $23/ha, and, for irrigation water supplied from surface water sources, from $36/ha to $14/ha. However, as the water service fees for irrigation water in The Philippines and most other developing countries are not based on the marginal value of water, these prices and trends clearly do not reflect the scarcity value of water in The Philippines or these other countries.

Despite the water shortages in many parts of Asia and other constraints, no incentive mechanisms are currently being actively promoted, either for the conservation of available water or for the technological innovations for augmenting and conserving water in future. Supply side management, dominated by a command-and-control approach, has long dominated the field of water resources management, and the increasingly significant environmental dimensions of the water supply problems have been neglected.

The persistence of water scarcity problems in many countries of Asia suggests two major areas for concentration in terms of freshwater augmentation technologies. First, decision-making criteria, presently based on engineering and pure economic grounds, should be shifted towards a more comprehensive, decentralized and participatory type of management system. Development efforts also should be carried out in an environmentally sound and sustainable way. This requires an integrated approach rather than the continuation of conventional practices.

Second, it is time to look for traditional, low-cost water collection and use systems, which have been practised for centuries, as well as other technological options. Low-cost water collection systems, such as rainwater harvesting, conservation of freshwater through dual distribution system and alternative technological options, have to be perceived as sound bases for developing new sources of water. Technologies related to water conservation, including those concerned with quality and standards, can have long-term impacts on the availability and capacity of traditional sources of water to supply freshwater for human uses (Keenan, 1992). This, no doubt, will add additional costs to the development of new water resources, but can satisfy the need to maximize the use of existing water resources as well as augmentating such sources with previously unexploited water resources using both the modem and traditional techniques. These augmentation technologies include wastewater reuse, water recycling, desalination, dew harvesting, and fog and rainwater harvesting. Nevertheless, application of these technologies are still limited, mainly because of the lack of information on the appropriate technologies available (Table 1).

TABLE 1. Potential Water Quality Problems Related To Alternative Freshwater Augmentation Technologies.

		PROBABLE IMPACT ON WATER QUALITY
TECHNOLOGY		DRINKING WATER	AGRICULTURE	INDUSTRY
RAINWATER HARVESTING
	Erection of Bunds Around Agricultural Farms	-	No problem	-
	Low Lying Pond for Irrigation in Critical Periods	-	No problem	-
	Pond-Sand-Filter Process	Salinity and Iron
	Rain Water Harvesting from Roofs	No problem		No problem
	Open Sky Water Catchment	Hygiene
	Artificial Pond Catchment	Hygiene and salinity	-	Hygiene (food industry)
WATER CONSERVATION
	Recycling	Cultural problems	Hygiene	Depends o n industry and use
	Reduce Wastes	No problem	Salinisation	No problem
	Reduce Evapotranspiration	No problem	No problem	No problem
	Regulated Flow in Agriculture		No problem
ARTIFICIAL RECHARGE OF GROUND WATER
	Direct Subsurface Recharge	Hygiene and toxics	No problem (controls needed)	No problem (controls needed)
	Surface Recharge	No problem	No problem	No problem
DESALINATION		No problem
FOG, DEW AND SNOW HARVESTING		No problem (tastes)
REUSE OF WATER
	Reuse of Wastewater	-	Variable (controls needed)	-
	Reuse of Irrigation Water	-	Salinity
ALTERNATING USE OF SURFACE AND GROUND WATERS		Controls needed	Controls needed	Controls needed
NATURAL SPRINGS		Protection required	Excess water
ARTIFICIAL SAND/ROCK FIXES RESERVOIRS		Variable depending on source	Variable depending on source	Variable depending on source

2. Objectives

The main objective of this project is to address the need of Asian planners for information appropriate to maximize and augment available freshwater resources using appropriate technologies. To achieve this objective, it is necessary to provide water resource managers with information on different technologies used within the Region to augment and maximize freshwater resources, and on specific experiences with these technologies from throughout the Region. The Asian Source Book forms part of the UNEP environmental technology transfer initiative that will ultimately result in the preparation of a Global Source Book on Alternative Technologies for Freshwater Augmentation. Other regional source books are being compiled for Africa, Latin America and the Caribbean, East and Central Europe, West Asia, and Small Island Developing States. These regional books provide a basic source of information for, and form the basis for international cooperation between, developing countries of the world.

3. Organisation of the source book

This Source Book contains three main parts. Part A presents an overview of the survey results and identifies the need for the identification of freshwater augmentation technologies in the region. The status and current use of alternative technologies for freshwater augmentation in selected countries within the region are summarised based on information gathered during field surveys conducted during 1995. The methodologies used to obtain the information also are summarized, together with the results of the surveys, additional observations, conclusions, and recommendations about the technologies currently in use to augment freshwater resources. Part B, Alternative Technologies, presents a series of technology profiles which describe in greater detail the technologies currently in use to maximize water use efficiency and to augment freshwater supplies. The information provided in this part is based on an extensive literature review and the field surveys carried out in the region within four selected countries. The different technologies include water conservation, wastewater reuse, rainwater harvesting, artificial recharge of groundwater, and desalination technologies, amongst others. In addition to the technical description, each technology is analysed in terms of the extent of its use; its operation and maintenance; level of involvement; costs; effectiveness; suitability; cultural acceptability; advantages and disadvantages; and any further development of the technology that may be required. Part C contains information on selected case studies identified during the field surveys. The purpose of the case studies is to highlight especially innovative, cost effective technologies that have been successfully adopted within the region.

4. Survey methodology

The approach used in this study is based upon literature reviews, field surveys, and discussions with concerned individuals and professionals. An extensive review of the available literature was made by a group of water experts from the Asian Institute of Technology (AIT), Bangkok, Thailand. In addition to the literature available at the AIT library, information was collected from individuals from within the region. Much of the literature reviewed did not contain complete or quantitative information on the various technologies identified, and a significant portion of the available literature was only available in specific countries or from local sources (e.g., unpublished documents, internal papers, etc.), not readily accessible by the study team. Only references to freely available documents have been included.

Field surveys were carried out in Bangladesh, India, Nepal, and Thailand to supplement the results of the literature survey. The four countries were identified, during the initial phase of the study, as countries within Asia that were leading the region in the development and implementation of freshwater augmentation technologies. Within these four countries, various hydrological regions were identified that represent typical hydrological and social areas of Asia, excluding oil-rich west Asia. For example, the rainwater harvesting technologies used in northern and northeastern Thailand represent technologies that could be applied in the southern China and Indo-China regions. Similar climatic conditions also prevail in Laos, Cambodia and Vietnam. Likewise, the conditions in southern Thailand are similar to those in Malaysia, Myanmar, Singapore, and parts of Indonesia. Nepalese conditions represent those in the mountainous areas of the region (e.g., Afghanistan, Bhutan, China (Tibet), and northern areas of Pakistan and India), while the socio-economic conditions in Nepal are representative of those in the smaller, poorer countries of the region, with large rural populations. Conditions in India, a sub-continent with a wide range of physical, social, cultural and climatic characteristics, have relevance throughout Asia and outside. Likewise, the physical and tropical climatic conditions in Bangladesh are representative of many regions in Asia including Sri Lanka, Myanmar, Cambodia, and Vietnam. Local consultants carried out the field surveys and prepared the case studies in the different countries. The Danish Hydraulic Institute, Bangladesh Regional Office, in association with the Water Expert Group of AIT, coordinated the field survey and compiled the Source Book using information drawn from the country reports. These detailed country reports are available from the UNEP Water Branch, Nairobi, Kenya, together with additional information, photographs and illustrations of the various technologies.

The field surveys were carried out in three stages by survey/reconnaissance teams within each of the four representative countries in the region. In the first stage, information on the use, place of use, and characteristics of use of freshwater augmentation technologies was obtained from discussions with resource persons belonging to universities, research organizations, government departments and NGOs. The available literature on freshwater augmentation technologies was also reviewed. In the second stage, informed persons from government departments, research organizations, universities, and international organizations were consulted for more detailed information on the places and types of use of freshwater augmentation technologies. Finally, site-specific, detailed information was collected through a questionnaire survey and focussed group discussions. Questionnaire surveys of heads of households were conducted in randomly-selected individual households chosen from the total number of households within a specific settlement or village. Individuals included in the focussed group discussions included school teachers; members of the local councils; well known farmers, fishermen and industrialists; and representatives of farmers organisations, etc., as well as officials from organizations such as UNICEF and NGOs directly or indirectly connected with freshwater augmentation technologies.

At the conclusion of the field investigations, a Workshop and Expert Group meeting was organised in Kathmandu, Nepal, between 5 and 9 November 1995. In addition to the local consultants who conducted the field surveys, experts and others involved in water resources management and development from throughout Asia were invited to discuss the findings of the study. The Draft Source Book was reviewed and new ideas were received in four focal areas; namely, rainwater harvesting, water conservation and recycling, water quality improvement, and groundwater recharge. It should be noted that rainwater harvesting has been defined in its broadest sense as any process whereby (i) crops or plants are grown by exploiting runoff or directly impounded waters, (ii) human water needs are satisfied by waters drawn from catchments either within or outside an individual household, (iii) fish and other aquatic livestock are cultured using waters drawn from individual catchments or runoff, and (iv) processing and manufacturing water requirements are satisfied by utilizing rainwater in whatever form it is available.

4.1 Bangladesh

Field surveys in Bangladesh were carried out by the Intermediate Technology Development Group, a non-governmental organization (NGO). Survey teams were sent to each of the five ecological and water planning zones exist within Bangladesh (e.g., the North-Central, North-East, North-West, South-Central-West, and South-East zones). Information on the various technologies was obtained from literature surveys, field visits, questionnaire-based interviews, and focussed group discussions with agency officials and project beneficiaries. Rainwater harvesting was identified as the main, and perhaps only, freshwater augmentation technology being practised regularly in Bangladesh.

4.2 Nepal

Field surveys in Nepal were carried out by D&M Associates, a consulting company specialising in water, environment and sanitation issues in Nepal. Information on the various technologies was obtained from literature surveys, field visits, and interviews and discussions with agency officials and project beneficiaries. Five technologies for freshwater augmentation were identified as being in common use in Nepal; namely, the use of stone spouts and pokharis, spring development and protection measures, rainwater harvesting, bamboo-piped water supply systems, and hydraulic rams.

4.3 India

Field surveys in India were carried out by Prasad Modak and Associates of Bombay, a consulting organisation specialising in water and environmental issues. A literature survey, and interviews and discussions with concerned personnel, were used to prepare sixteen case studies of various freshwater augmentation technologies commonly used within India. The technologies identified included the adoption of industrial water conservation practices, use of reclaimed wastewater, recycling of process water, water harvesting for drinking water supply, traditional soil and water conservation practices, roof-top water harvesting, conjunctive use of surface and ground waters for irrigation, use of evaporation retardants, artificial recharge of groundwater, and use of water sprinkler and drip irrigation technologies.

4.4 Thailand

Field surveys in Thailand were conducted by the Water Experts Group of the Asian Institute of Technology, Bangkok, and by Dr. Sacha Sethputra of the Khon Khaen University. Technologies surveyed in Thailand includes rainwater harvesting for agriculture and domestic use, particularly in the northern and northeastern portions of Thailand, and desalination. A detailed case study of the Thai Rainwater Jar, which has become popular in the Indo-China region, was prepared.

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).

6. Recommendations of the workshop

The participants in the Workshop:

· Felt that the source book would be of immense value to policy makers and practitioners in the field, realizing the depletion of water resources now and in the years to come.

· Suggested that the source book should highlight the sensitivity and limitations of the technologies mentioned. Recommended that the cost of the technologies should differentiate the capital and operation and maintenance costs.

· Recommended that the source book be disseminated to existing networks on water, health, and the environment (e.g., ENSICNET, CEHANET, INFORTERRA, etc.) rather than through new networks.

· Recommended that the source book have a specific section on water quality and a discussion of water quality issues related to the various technologies for fresh water augmentation in the Introduction.

· Agreed to recommend that every country introduce and adopt a Ground Water Act if one does not already exist.

TABLE 6. Summary of Freshwater Technologies and Related Issues.

TECHNOLOGY	SOURCE WATER/USE	EXTENT OF USE	EFFECTIVENESS	CAPITAL COST	OPERATING COST	MAINTENANCE COST	SKILLS REQUIRED	EQUIPMENT REQUIRED
RAINWATER JARS	Rainwater/domestic use	Extensive	Very high	$16/m3	0	$6/m3/year	Minimal	Small construction equipment
RAINWATER TANKS	Rainwater/domestic use	Less extensive	Medium	$24/m3	0	$8/m3/year	Minimal	Small construction equipment
SHALLOW WELLS	Groundwater/domestic use	Extensive but declining	High	$120/well	0	0	Minimal	Manual tools for digging and concrete work
IMPACT WELLS WITH HANDPUMPS	Groundwater/domestic use	Sporadic	Low	$200/well	0	0	Minimal	Homemade digging equipment and handpump
DEEP WELLS WITH HANDPUMPS	Groundwater/domestic use	Extensive	High	$16000/well	0	$80/year	Minimal	Drilling rig, piping and handpump
DEEP WELLS WITH ELEC. PUMPS	Groundwater/domestic use	Extensive, upgrade of Impact Wells	High	$2 400/well	up to $200/year	$80/year	Minimal	Drilling rig, piping, electric pump and accessories
PONDS	Rainwater/domestic use	Sporadic	Low	$3/m3 of earth moved	0	$20/year	Minimal	Traditional tools for earthwork
SPRINGS	Groundwater/domestic use	Sporadic	Low	$4 000/km of pipe	$1 000/year	$200/year	Medium	Tools for concrete work and piping
PIPED WATER, VILLAGE SUPPLY	Groundwater/domestic use	Extensive, upgrade of Deep Wells	High	$12 000 to $56 000/system	$1 000/year	$1 000/year	Medium	Tools for concrete work, piping, pumps, tanks, valves and other accessories
WEIRS	Streamflow/domestic and agricultural use	Extensive	High	$12 000/unit	$80/year	$80/year	Medium	Tools for wood and concrete work and some earthwork
SMALL RESERVOIRS	Streamflow/domestic and agricultural use	Extensive, but few sites remain	Low	$160 000/unit	$960/year	$80/year	Medium	Tools for woodwork, bamboo, gravel and stone

7. Information sources

BBS 1993. Statistical Year Book of Bangladesh, 1993, Government Printer, Dacca.

Department of Health s.d. Manual for Caretakers of Village Pipe Water Supply Systems (Medium and Small Sizes), Rural Water Supply Division, Department of Health, Bangkok 2535. Department of Health s.d. Manual for Caretakers of Village Pipe Water Supply Systems, Rural Water Supply Division, Department of Health, Bangkok 2535.

Hossain, M.D. and Ziauddin, A.T.M. 1992. Rainwater Harvesting and Storage Techniques from Bangladesh, Waterlines, January 1992.

NESDB 1992. Manual for Preparation of Master Plan for Provision of Drinking and Domestic Water for Villages in Each Province, NESDB.

NESDB 1992. Status of Drinking and Domestic Water in Rural Areas, NESDB Division of Rural Development Coordination.

Office of Public Health s.d. Manual for Management of Village Pipe Water Supply Systems, Sanitary and Environmental Health Division, Office of Public Health, Chiangrai 2535.

Thongtip, S., Pacharin, L., and Wichien, K. 1995. Esan Women and Water Management, Research and Development Institute, Khon Kaen University (in That).

Water Resources and Environment Institute 1986. Manual of Weir Construction, Khon Kaen University, Thailand (in Thai, English, Laos and Cambodian).

Water Resources and Environment Institute 1991. Small Scale Water Resources: Clean Water and Sanitation, Khon Kaen University, Thailand (in Thai).

Water Resources and Environment Institute 1991. Manual of Small Weir Design, Khon Kaen University, Thailand.

Water Resources and Environment Institute 1991. Manual for Construction of Farm Ponds, Khon Kaen University, Thailand.

Water Resources and Environment Institute 1991. Manual for Construction of Impact Wells, Khon Kaen University, Thailand.