Goa has been facing an odd conundrum of excessive flooding during the monsoons, with the smallest amount of rainfall inviting sardonic comments like “Let’s get out the boat today” and “Are we swimming to school/work?”
At the same time, there are areas of Goa that suffer severe water shortage, and one observes a myriad water tankers making their way to various habitations.
In these challenging and uncertain times, Nisha Mary Poulose, an architect and regional planner, may have an answer to the looming crisis, as she is driven by commitment to regenerative practices to support humans and the environment in a sustainable and ethical fashion.
Sharing her insights on rainwater management at the Museum of Goa recently, Nisha said, “I work with communities, government authorities and technical experts to use nature-based systems to solve our problems, fostering a mindset of abundance rather than scarcity.”
Rainwater management is about making the best use of rainfall, right from its point of impact, enabling it to provide sufficiently to meet all human needs as well as those of other elements of the environment.
Nisha explained that the water systems originate from the headwaters. These would include waterfalls, rapids, springs and streams. These streams are seen sometimes only during the monsoons.
“This is important because we need to know these areas are springs and streams,” said Nisha. When hills are cut or pathways are built across these streams and springs, the water system is disrupted.
The hydrological systems comprise the bottommost layer i.e. the bedrock, then comes the fractured zone, following which you have vacuums that fill with water and are known as deep aquifers. Then there are the unconfined shallow aquifers below the topsoil. The surface water bodies are lakes, ponds, etc.
Many large apartments and luxury villas have resorted to using bore wells, which result in water being drawn from the unconfined shallow aquifers into the deep aquifers as they are drained.
Open wells normally have water from the unconfined shallow aquifers, while bore wells reach for the water in the deep aquifers. Rainwater, surface water bodies like lakes and water from the unconfined shallow aquifers are the best sources for human consumption.
Bore wells contain hard water, because as the water goes deeper, it loses minerals and becomes harder.
Many large apartments and luxury villas have resorted to using bore wells, which result in water being drawn from the unconfined shallow aquifers into the deep aquifers as they are drained.
Nisha said, “So even if the unconfined shallow aquifers are full, when people start digging bore wells, the wells start emptying. And that is something that we are facing in Goa today.”
We are creating a system which will collapse on itself and on us.
Nisha Mary Poulose
Recharge surfaces and recharge wells are conduits to recharging the unconfined aquifers, but we must never recharge directly into the open well or bore well.
This would allow pollutants entry into the water at these deeper levels and bypassing the natural patterns on the surface of the earth would create an imbalance in the ecosystem.
With empty aquifers and no topsoil, all you are left with is rock interspersed with vacuums. The structural integrity of the rock is compromised easily, leading to its collapse.
The cutting down of trees is extremely detrimental to the stability of nutrient-rich topsoil which is essential to sustain life on the planet.
With empty aquifers and no topsoil, all you are left with is rock interspersed with vacuums. The structural integrity of the rock is compromised easily, leading to its collapse.
“We are creating a system which will collapse on itself and on us,” said Nisha.
Urbanisation has created large concretised areas, preventing rainwater, the purest form of water we have, from going into the ground.
The natural systems of water must be protected from pollution, and rainwater must be made to flow as slowly as possible as soon as it touches the ground. Spaces must be delegated for the collection and percolation of water.
Urbanisation has created large concretised areas, preventing rainwater, the purest form of water we have, from going into the ground.
Bioswales on sloped land, linked to an interconnected network of retention ponds and rain gardens, will let excessive rainwater collect and filter into the ground.
These bioswales are layered with gravel, rocks, mesh and other material, and topped with soil and indigenous plants. Plants that are seasonal or require little water should be used.
Trees are vital to this system, preventing the erosion of topsoil and making these areas extremely fertile. The roots of the trees aid the flow of water deeper into the ground.
A perforated pipe is added in case of a flood, which prevents overflowing of the bioswale.
Trees are vital to this system, preventing the erosion of topsoil and making these areas extremely fertile. The roots of the trees aid the flow of water deeper into the ground.
This low-cost, biodiversity-promoting solution can be adjusted according to location, for example, recharge and retention ponds for flat regions and just recharge pits for smaller sites.