Safe, Sustainable, Gravity-Fed Drinking Water – A Model for the Western Ghats
Dr. Jared Buono & R. Thomas (Grampari)
Executive Summary: Everyday throughout the Western Ghats, new wells are being dug and lift schemes are being constructed. As a result many areas are facing declining groundwater levels, increased pumping costs and growing conflict. Sustainable alternatives are needed. Hundreds of villages have traditionally used natural springs as a source of gravity-fed drinking water, but the springs are being threatened because of the recent increase of bore wells, construction, ecosystem degradation and large lift schemes. In response, we are proposing that a spring protection and development programme be instituted in the Western Ghat Development Plan to bring safe and sustainable drinking water to tens of thousands of people.
Project Need: The geology of the Western Ghats presents a unique situation where extensive laterite rock formations sit atop impervious basalt layers. During monsoon rains the laterite allows water to slowly percolate and, after reaching the impervious basalt layers, it emerges from the sides of the mountain. The slow percolation filters the water and ensures a steady supply of pure water throughout the year, long after the end of the rains. Moreover, because these springs occur in areas with high topography, they can be gravity-fed with no energy inputs (see Figure 1). Over the last few decades however, as focus has been placed on drilling new wells, these vital resources have been neglected, constructed on, and in some cases turned into open wells in a misguided effort to increase flow. Further, these laterite caps also supply water to distant locations including base flow in nallas throughout adjacent valleys – in essence they act as water towers of the Deccan Plateau. As such, a new effort is needed to protect and enhance these vital resources.
Project Background: Grampari has been working with several communities in Satara District to protect their natural springs for both drinking water and ecological purposes. To date we’ve designed and built three new spring boxes and replaced or upgraded five others to provide a pure and consistent source of gravity-fed drinking water for hundreds of people (see Figure 2). We now hope to expand this program by creating a larger spring protection campaign.
Potential Scope: This programme has the potential to impact hundreds of villages and tens of thousands of people. A recent survey of the northern part of Satara District indicated that from one mountain alone seven villages, totaling over 3000 people rely on gravity-fed spring water for their drinking water needs. Considering the spatial extent of the laterite in the Western Ghats, we can extrapolate that these springs may be supporting hundreds of communities reaching tens of thousands of people, and therefore has wide applications (see Figure 3).
Project Proposal: Our hope is to create a larger initiative of spring protection that has the support of government agencies and NGOs. We are proposing to host an initial meeting of heads of departments on our campus to share our experiences and demonstrate effective spring protection as well as how many springs have been damaged by lack of technical understanding. This meeting could also inspire cooperation between different departments involved with the Western Ghat Development Plan.
Spring Recommendations: In the last two years of our work on these springs we have made several observations.
1) Most people do not understand how springs work or where this water comes from. Construction in the watershed upstream of the springs can have a negative impact on the amount of water recharging the springs. Annual anthropogenic fire is likely to also have a negative impact on watershed function reducing spring flow. Spring areas should be protected from tree cutting, over grazing, burning and construction to protect the native watershed.
2) Bore wells near the springs can reduce spring flow or destroy them entirely. Buffer distances to protect the springs vary by case but the 500 meter distance outlined in Maharashtra state law should be adhered to (Figure 4).
3) Using heavy machinery or blasting to ‘open’ springs DOES NOT necessarily translate to higher yield – and may actually decrease flow. In addition, this converts a groundwater source to a surface water source and thus makes it prone to contamination requiring treatment (Figure 5).
4) To use a spring as a village drinking water source we recommend a simple yet effective spring box that most masons can construct. It protects the ‘eye’ of the spring, efficiently captures water, prevents contamination, and allows gravity-feeding to village-based water tanks (Figure 6). It can also be modified to ensure ecological flow near the spring to maintain biodiversity of the site.
5) Laterite caps should be protected in general. These rock formations absorb and retain monsoon rainfall and slowly release this water throughout the year. This not only feeds the springs but also groundwater and base flow in nallas in adjacent valleys. They are the water towers of the Deccan Plateau and should be treated as valuable parts of the Western Ghat ecohydrologic system.
1 Modified from: Ollier, Cliff D., H.C. Sheth. 2008. The High Deccan duricrusts of India and their significance for the ‘laterite’ issue. Journal of Earth System Science. Volume 117, Issue 5, pp 537-551.