APR villa complex is located in Bellandur, next to the Devarabisanahalli Lake. The villa complex occupies an area of 110 acres and houses 798 villas. Being a low-lying area, the houses and roads closer to the lake have been facing basement seepage and road flooding issues. This case study looks at how certain individual villas have been tackling this issue with rainwater harvesting.
Based on anecdotal information, rooftop rainwater harvesting has been implemented in about 40 villas as of 2022. Water from the rooftops is directed into wells that have been dug in these villas for groundwater recharge. Motors with / without automatic sensors have been fitted in some of these wells, and the water is used for various non-potable purposes that include washing clothes, cleaning the house etc. Here are stories of some noteworthy individual villas that have successfully reduced seepage with various techniques of rainwater harvesting and groundwater usage.
|Measures implemented at individual villas||Outcome|
|Swathi – rooftop rainwater goes into recharge well. Faced seepage on ground-floor walls. Attached pump to well and used well water for gardening. Planning dual plumbing to use it for flushing and in the washing machine.||Seepage has been reduced to some extent|
|Mumu Pande – faced seepage for many years. Rooftop rainwater goes into 3 wells. Water from these is now being used for all non-potable purposes. In case wells are not pumped, seepage reappears.||Seepage has completely disappeared|
|Shalini – rooftop rainwater is harvested and stored in a sump tank and used for all non-potable purposes||Surface runoff is reduced in volume|
Recharge well in the backyard
In 2017, Biome and ACWADAM conducted a comprehensive hydrogeological study to help understand the shallow aquifer of the area.
Hydrogeology and Aquifers: The study found that the shallow aquifer occurs less than 10 metres below ground level and is about 30 metres deep. This shows that a large quantity of water is present as shallow groundwater in this area. The water table eventually cuts through the surface of the ground close to the entrance of the layout forming the Devarbeesanahalli Lake.
Hydrogeological cross-section along E-W direction
Villa layout: The villa layout is divided into three phases. The study found that the eastern part (placed at a higher elevation) forms the recharge zone, and the western part, containing the Devarabeesanahalli Lake, constitutes the discharge zone of the shallow aquifer. The transition from one zone to another occurs approximately at the 4th lane of phases one and two, causing seepage and even flooding in the areas left of this lane (see figure below).
Recharge and discharge zones in APR on the phase-wise demarcation of the villa complex
Flood mitigation using recharge/withdrawal wells: Simultaneous recharge and discharge of the aquifer by using the water in the shallow aquifer can mitigate the flooding/seepage issue. This will further reduce tanker usage, thus reducing the load on the aquifer even further.
Water quality: The study also found that the TDS of the water varies throughout the layout. However, leveraging the vast area of APR by artificial & natural recharge with rainwater will improve the overall water quality over time.
To mitigate the seepage/flooding issue as well as to become water-sufficient, a housing complex that is sitting on a saturated aquifer like APR needs to reduce its load on the aquifer while making sure it is sufficiently recharged for the dry season. This can be achieved by;
Here’s the detailed case study of Adarsh Palm Retreat villas.