Green roofscaping can help tide over urban water crisis

We have successfully graduated from constructing rainproof houses to building entire rainproof cities that are proven heat-traps. It is high time that smart-homes are redefined as those that are environmentally smart as opposed to being merely electronically smart. Harvard scientist James Anderson projects we have barely five years to prevent an environmental disaster. Unless transformational action is taken immediately, a number of rain-repellent cities in various parts of the world are poised to be “water-free” zones, a la Cape Town and Chennai, in the near future.  

Highlighted by absence:
While governments and dedicated NGOs are battling hard to introduce schemes for rainwater harvesting (RWH) in urban areas in countries like India, the most overlooked areas also seem to be the most obvious ones:  

What would urban buildings harvest if cities cannot attract rain first?
How can they attract rain?
No less importantly, what do they need to do to ensure that they do not repel rain?

Undiluted water reality:  No RWH or water body rejuvenation scheme can work unless the approach is holistic to attract, harvest and not repel rain. Any planning must use this integrated 3-part solution in order to succeed.  Afforestation is an essential remedy for the planet's climate crisis but it is too broad to be considered as a specific water solution for urban areas.

Desalination has been a fantastic success in countries like Israel, but while it can be applied to many coastal cities (and distributed to other areas), more eco-friendly and economical solutions are still evolving, including efforts to tap sea-air moisture.

Integrated approach: The Planet Symphony's holistic Urban Roofscaping Project (URP) greens the roofs both literally and figuratively. It can enable urban areas to:
Attract rain
Harvest rainwater
Not repel rain
Prevent flooding in and outside the premises
Ensure purer air
Cool temperatures down by nearly 1.5°F (1°C)
Relieve stress
Reduce energy bills and
Most importantly, minimise greenhouse emissions

What does it include?
1Attract rain: It is well-known that greenery is essential for rain. But that is only one part of the picture. Given that most urban areas have become concrete jungles, they have adversely altered local (and larger) weather patterns in a number of ways. To increase even the probability of rain in such cities, the topmost points of every building have to literally be greened. In other words 50-75 per cent of the rooftops of every building that is higher than the trees nearest to it must be covered with at least potted plants (even if not with terrace gardens). The science behind this is actually simple - forests do not get rain merely because they have trees but their highest points are green. Likewise, concrete buildings that dwarf trees are rain-repelling heat-traps.

Though this has never been viewed as a comprehensive necessity for urban areas to attract rain, governments can now mandate this as compulsory for every building along with RWH and initiate, support or subsidize this initially in impoverished areas. The change has to be transformational across the board to improve every city's chances of increasing rain. (Of course, green roofscaping does not preclude greening other areas within the premises.)
2Harvest rain: Newer, scientific RWH solutions can ensure that months of drinking water supply can be harvested within a few hours of good rains by ensuring the filtered water first goes into storage sumps and surpluses are injected into both traditional and recharge wells to raise the overall water table.

 While residents and businesses can take care of this within their premises, local administration, NGOs and corporate leaders must drive the installation of millions of recharge wells in roads and public areas, ideally one every 90-100 feet, as collectives in Bangalore are already doing. organisations like Rain Centre, Chennai,  are endeavouring to persuade Governments to re-examine current Storm Water Drain systems and ensure that the majority of precious rainwater is injected back into the ground within the urban area instead of dumping most of it into rural areas in the form of wastewater or into the sea. It clearly is an effective insurance against flooding too.

3Don't repel rain: It is no less important to green the roofs with solar panels. Only this can ensure that steps 1 and 2 are not undone by continuing to rely on greenhouse contributors like coal for energy, as that is the guaranteed recipe to aggravate the climate crisis. Governments and private players can accelerate this by ensuring lower prices, following the Los Angeles model or the high potential African model of pay and use solar solutions in collaboration with financial institutions, mobile phone companies and solar energy providers.

In short, solar and wind should no longer be viewed as alternative energy but become the main sources to power the planet's needs.  

Additional benefits:
The URP can also:  
A. Purify urban air:
Plants on roofs are undoubtedly great option to bring down air pollution levels,which have already reached record levels in several cities and contribute to 7 million deaths a year, as per WHO estimates. While 22 of the top 30 are in India.

B. Cool temperatures:
A modeling study in Canada found that adding green roofs to even 50 percent of the available surfaces in downtown Toronto would cool the entire area by 0.2 to 1.4 °F (0.1 to 0.8 °C).

C. Reduce energy bills & emissions:
Cooler temperatures will certainly reduce the stress on  air-conditioners in many areas and thereby emissions as already mentioned.

D. Relieve stress:
Several studies have shown that roof greening actually relieves stress for residents, especially those who are a part of maintaining the plants.

Win-win situation:
While this type of holistic approach is almost the only solution for many cities and towns, the good news is that in most cases, it is only a one-time investment with minimal maintenance that will more than pay for itself, sooner than later. For instance, solar installations reduce energy bills and even bring back monies when surpluses are given back to the main power grid by residents.  Likewise, water harvesting means independence from profiteering private water players in many cities and filling the roofs with greenery means a host of other benefits listed above. The biggest good news however is that citizens would primarily be doing this for their own benefit and that of their succeeding generations.  The key is to be preemptive, preventive and proactive, rather than regretfully reactive to the urban environmental crisis.