Aakash Ganga, our rainwater harvesting program, brings clean drinking water to the doorsteps of rural communities. One of the costly line items of Aakash Ganga is the physical survey of the villages. The physical survey is essential for designing the rainwater collection reservoirs and laying pipes to connect the reservoirs with the rooftops, but it is expensive, time-consuming, and laborious. Volunteers at GISCorps have developed a methodology that utilizes geographic information system (GIS) technology to conduct virtual surveys. While rooftops are digitized using Open Street Map, web maps available on mobile devices are developed using Esri. Their methodology significantly cuts down the costs, time, and labor spent on surveys, and will allow Aakash Ganga to be replicated in villages quickly and cost effectively.
Aakash Ganga involves the installation and maintenance of a series of channels and reservoirs that vary from community to community depending on village-specific aspects. Every village will differ in elevation, number of rooftops, population, density of houses, topography, and soil condition. All of these characteristics will affect how Aakash Ganga is implemented, as we believe that sustainability relies on solutions that suit a community rather than requiring the community to adjust to the solution. Conducting physical surveys to gather this information requires considerable manpower, expenses, and time ─ typically 10-12 weeks. Villages in India don’t have street names and house numbers, which makes identification of physical locations of the reservoirs an insurmountable challenge.
It became evident after the first implementation that a more efficient way to conduct surveys was needed. If we could alleviate the need for physical surveys, we would be able to reduce the time and money spent on planning down to only a fraction of what we were spending. Conducting virtual surveys through the use of GIS images would help Aakash Ganga expand its reach farther and more quickly than we thought possible.
Rooftops in red have an area of at least 1,000 square feet. The homes with red rooftops are large enough to have their own Griha tanka, as they will collect enough water for economic viability. Rooftops in yellow have an area of less than 1,000 Sq. feet, and will share a Griha tanka with adjoining houses.
Image credit to GISCorps
The volunteers at GISCorps developed a methodology using GIS technology and latitudinal and longitudinal coordinates to calculate the rooftop area of each individual house. The rooftop area tells us how much rainwater can be collected from each house and, for example, what the pipe diameters should be. The use of GIS maps also shows possible pathways for laying pipes to transport the collected rainwater from individual house reservoirs (Griha tankas) to the community reservoir (Gram tanka), and how close together the houses are, which is a determining factor in concluding how many Griha tankas are able to fit in the village.
The ability to calculate rooftop areas using coordinates gives us an accurate square footage measurement without even needing to visit the community. It also resolves the issue presented by the lack of street names and house numbers as the locations of every reservoir will have a unique and exact set of coordinates, which will also make monitoring and future maintenance a much easier task.
An interactive platform allows us to view the square footage and coordinates of rooftops and reservoirs.
Image credit to GISCorps.
Image credit to GISCorps.
We combine the GIS technology with elevation data to find the lowest point in the village, which marks the location of the Gram tanka. Building the Gram tanka at the lowest point ensures that gravity will pull the collected rainwater to the reservoirs, alleviating the need for pumps. The Gram tanka is sized to collect the maximum volume of rainwater, and is determined by the average annual rainfall.
The work of the volunteers at GISCorps is expected to reduce the planning period of Aakash Ganga from ten-to-twelve weeks down to only one or two weeks.
Thanks to the efforts of our volunteers, we are developing a standard process for Aakash Ganga that will pave the way for the program to be rapidly replicated anywhere it is needed. Utilizing GIS technology reduces the time and money spent on designing the systems by removing the need of conducting physical surveys, and also simplifies the design process and future expansion as we work to expand our program, ensuring socially equitable distribution and access to water in communities everywhere.
We would like to extend our sincere thanks to the volunteers at GISCorps, whose motivation and tireless efforts have transformed our program. We would not be where we want to be without them.