Overcoming water scarcity through Rain Water Harvesting

Mayengbam Bhavananda *

Outline

Even though Manipur enjoys substantial amount of rainfall every year, water scarcity is a common phenomenon during lean seasons. The inability of water utilities to provide piped water in urban and rural areas has compelled majority of households to look for informal water sources. This informal sector which has sprung up to cater the under and un-served population is characterised by high prices and dubious quality nevertheless, it remains indispensable to the vast majority of the population.

The present water crisis in Ukhrul district in Manipur is an example of inability to provide safe drinking water to the population by concerned water utilities. This impact primarily falls on the poor, who are deprived from both the economics of scale and government subsidies, and they have to pay an excessive price.

To illustrate this, the access to water by under and un-served population in Imphal is generally by means of purchasing from water tankers, carts or water vendors. The cost of 500 liters of water in Imphal, depending on distance from water source is Rs.175 to Rs.200, which is extremely higher than that of the urban utility providers.

In search for a cost-effective, sustainable and renewable approach, this paper makes an attempt to highlight the enormous challenges faced by water utilities and look at potential of Rain Water Harvesting (RWH) to close the gap between supply and demand in a sustainable way.

Background to water scarcity in developing countries

Although, we live in a planet covered by water, more than 97 per cent of it is saltwater and nearly 2 per cent of it is in the form of ice and snows. This leaves less than 1 per cent for agricultural and domestic use. It is pertinent to mention that 0.3 per cent of the fresh water is in lakes, rivers and wetlands. This amount includes water in plants, animals and in the atmosphere (Kingsolver, 2010). These figures illustrate universal challenges, ranging from the availability of water resources to its distribution to people in remote locations.

Global statistics indicates that over a billion people live in a region of severe water stress and one of the targets of the Millennium Development Goals is to halve the proportion of people without sustainable access to safe drinking and adequate sanitation by 2015. However, this target seems daunting, considering the present water supply situation in developing counties as many communities in these countries have never had access to piped water supply.

In general, a typical piped water supply system includes a source intake, a raw water transmission main, a treatment plant, a treated water transmission main, and a water distribution network (World Bank, 1986). Of these components, the distribution network is usually the most expensive, representing more than half the total cost. It is also the most difficult component to design.

The inability of governments to maintain and extend distribution systems to urban agglomeration in developing countries is mainly due to the shortage of funds, as these countries are among the poorest in the world with more than 80 per cent of the funds primarily comes from external loans or grants (UN-Habitat, 1989).This problem is further aggravated by surge in demand due to factors of population growth and increasing concentration of population in urban centres.

The increase in population density creates huge demands of potable water in urban centres which in turn requires extensive measures and high cost in conveying water from remote locations and its distribution (Vairavamoorthy et al, 2008). The water utilities in many developing countries also suffer from aged distribution systems (Ciuche, 2005).

The problem is further compounded by inappropriate pipe sizes being used, corrosion of the pipes and low quality fittings causing leakages in the distribution system which in turn causes intermittency and low pressure and their inability to upgrade and repair the system due to shortage of funds. Brihante (2010) posits that a good distribution system on average has a leakage of 10 to 20 per cent; however this percentage could be as high as 40 to 80 percent in a badly maintained system, especially in developing countries.

Rain Water Harvesting

While the infrastructural aspects of piped water distribution systems are integral to their effectiveness, the way primary source of water is managed and administered has also significant impact on the final product. In this regard, the following section highlights a sustainable and alternative approach to quench the thirst of common people through Rain Water Harvesting (RWH) in our state.

Manipur is a small province in the north eastern corner of the country and has a total area of 22,347 Sq. km and has a population of 2,388,634 with Imphal as the capital city. The city is now undergoing a transformation and structural readjustment through Jawaharlal Nehru National Urban Renewal Mission (JNNURM) under the agies of Ministry of Urban Development and Poverty Alleviation. One of the missions of the JNNURM is to focus on water supply and sanitation, solid waste management, road network, urban transport and redevelopment of old city areas.

Rain Water Harvesting (RWH) is one of the optional reforms under JNNURM and the main objective behind making RWH mandatory in all building is to recharge ground water aquifers or to store rain water for direct use by occupants of the buildings. With the increase in urban population and increase in per capita use of water due to economic growth, the water utilities in the state are increasingly finding it difficult to supply water in adequate quantities to the common mass.

Households are often compelled to use pond water, tube wells or take the service from Alternative Service Providers (ASPs) such as water tankers, carts, and water vendors to supplement their water demands due to huge gap between supply and demand.

There upon, in search to find a suitable solution to close gap between supply and demand, this paper looks at the potential of Rain Water Harvesting (RWH) in Manipur. Manipur enjoys sufficient amount of rainfall with an average annual rainfall of 1467.5 mm however, we have failed to tap this renewable resource, thereby creating an artificial scarcity of water during lean seasons. If an adequate policy is initiated by the government, thousands of people could be benefited though RWH and this artificial scarcity could be overcome.

Rainwater harvesting is a means of taking water out of the hydrological cycle for either human or agricultural use. The rainfall is intercepted and collected on prepared watersheds (Mayengbam, 2010)

Basically, there are two types of rainwater harvesting schemes - those designed for agricultural use and those designed for human use. Rainwater catchment schemes intended for agricultural use require large catchment areas. In this case, use of the ground surface is the obvious choice. However, water for human use should be more convenient and cleaner than water for agricultural use. Roofs are an obvious choice for a catchment surface as their elevation protects them from contamination and damage which are common to ground surface catchments. Tanks located close to homes highlight the convenience of this system (World Bank, 1986).

Besides, small scale RWH does not involve the existing water right. And it has become one of the economical and practical measures for providing supplementary water supplies with its easy system installation. It can be a supplementary water source in urbanized regions for miscellaneous household uses such as toilet flushing, lawn watering, landscape and ecological pools (Handia et al, 2003).

In many developing countries, it even serves as a major water supply source (Thomas, 1998). Other than storing rain water for later uses, it is also capable of providing some detention capacity for flood attenuations in some regions (Kumar et al, 2005). Rainwater harvesting system has been regarded as a sound strategy of alternative water sources for increasing water supply capacities (Motsi et al, 2004).

Supply and disposal chain of water

In simple words, rain water harvesting is an activity involving collection of rainwater and storing it for use. It is not a new concept and mankind has been using this system of collection since centuries. In this modern world many new techniques of harvesting have been developed but the basic concept still remains the same. In principle, the rain water collected can be stored for direct use or can be recharged into the groundwater.

Rain is the first form of water in the basic hydrological cycle, hence is a primary source of water to mankind. Rivers, lakes and groundwater are all secondary sources of water which also depend on rainwater for their recharge (Mayengbam, 2010). In present era, we depend entirely on such secondary sources of water.

In the process, we have forgotten that rain is the ultimate source that feeds all these secondary sources and have remain ignorant of its value. Water harvesting means understanding and appreciating the value of rain, and making optimum use of it at the place where it falls. The collection of rain water can be undertaken through a variety of ways and some the ways are –

• Collecting runoff from rooftops
• Collecting runoff from local catchments
• Capturing seasonal floodwaters from local streams
• Conserving water through watershed management

These techniques can serve the following purposes:

• Provide drinking water
• Provide irrigation water
• Increase groundwater recharge
• Reduce storm water discharges, urban floods and overloading of sewage treatment plants

Conclusion

Presented above is the concept and theory of how RWH should work therefore, this is not an untested idea. There have been pilot projects in different parts of the world where water scarcity is a problem. In India too, under JNNUM, pilot projects on RWH have been initiated in different cities and many state government have amended their existing building codes to incorporate RWH mandatory.

This reform has already been initiated in New Delhi and since June 2001, the Ministry of Urban Development has made RWH harvesting mandatory in all new buildings with roof more than 100sq. m. and all plots with an area of more than 1000 sq. m. that are being developed. Further, Central Ground Water Authority has made RWH mandatory to all institutions and residential colonies in notified areas and banned drilling of tube well in notified areas.

Similarly, other states like Kerala, Madhya Pradesh, Uttar Pradesh, Andhra Pradesh, Tamil Nadu etc. have amended their Building rules to incorporate RWH in new constructions. Therefore, if we have to overcome water scarcity in a sustainable way, the state government needs to formulate suitable polices to incorporate RWH mandatory in all new protects and grass root initiatives with pilot projects are required to quench the thirst in water stress regions.

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* Mayengbam Bhavananda wrote this for Hueiyen Lanpao (English Edition)
The author is an Architect specialized in Urban Environmental & Infrastructure Management
This article was posted on March 19, 2011.

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