The technology and determination have made rainwater harvesting successful even in the regions with extreme weather. The vast and varied demography of India affects the way rainwater harvesting is being carried out in our country. At some places, the ice storms pose a serious threat to the turbidity of the water storage tanks while dust storms increase the maintenance cost of the RWH system. The degree of impact of the extreme weather conditions must be judged beforehand, to reap the proper benefits from the systems.
Extreme weather conditions are mainly natural but too much human intervention with the surroundings or resources is also responsible to a great extent. In this hardship, focusing on saving precious rainwater through rain harvesting system can help mankind and environment too. But then, it is also a challenge to maintain the RWH system in such extreme weather conditions and keep them running at a satisfactory level.
Our country has a high vulnerability to climatic changes. 65% of India is drought-prone while 12% is flood prone. Then there are areas which are freezingly cold while there are also places with continuous heatwaves. But still, rainwater harvesting system is advised to be installed at every place wherever inhabitants need to be supported.
Extreme Weather Conditions Bestowing Challenges to RWH Systems
Every weather or climate has an impact on the components of the rainwater harvesting system. The general principle of physics – matter expands when heated and contracts when cold, makes the major distortion in the design and functioning of the RWH system. Additionally, each weather extremity brings challenges of their own.
- Heavy Snowfall/Blizzard – snow can freeze the water flowing through the pipes, making the pipes vulnerable for a burst and this hinders the availability of the desired amount of harvested rainwater.
- Flood – flooding can bring a gush of water along with every possible contamination which can make its way through RWH pipes and into the storage tanks. The filtration capacity of the system can be challenged and compromised during floods. Also, the floods can cause the tank overflow problem, adding more to adversities.
- Cyclones – cyclones can destroy the catchment areas and overground storage structures (In the year 2015, Cyclone Pam destroyed an estimated 68% of rainwater harvesting catchments, across Vanuatu, Country in Oceania).
- Typhoons & Dust Storms – The harvested rainwater after a dust storm has higher pH, turbidity, TOC (total organic carbon), Na, Mg, Ca, Cl–, NO3– and SO42- than normal rainwater. Due to strong winds and dilution effect, most of the ion concentrations in harvested rainwater during typhoons are lower than that in normal rainwater.
Component-wise Effect of Extreme Weather
Most of the components of rainwater harvesting systems are exposed to weather conditions, making them susceptible to damage and malfunctioning. Some effects are temporary and get eliminated as the weather turns itself out while some can lead to serious damage to one or more components. During or after the event of bad weather, make sure to check every component for the possible breakage or obstruction.
- Above Ground Tank- the water storage tanks located above the ground are easy to manage but they are open to all possible damage during floods, dust storms, cloudbursts, snowfall. The extreme drop and rise in temperature, at some places, can lead to subsequent cracks and leakage in the tanks. They can be hit hard during cyclones and floods, creating a scarcity of clean drinking water during those desperate times.
- Conduits – the network of water transportation i.e. pipes or conduits can get obstructed during dust storms. This may not be the permanent damage, but this may hamper the flow of a substantial amount of runoff water, into the storage unit. Snow can clog them too, which, then required to be treated to melt the snow back to water.
- The Control Unit – the control units for rainwater harvesting system are used to monitor water levels, the temperature of the water, pump pressure and has a fault diagnosing software. They must be installed in close vicinity to prevent them from freezing in extremely cold weather or heating up in extremely hot weather.
- Header Tanks – the indirect systems have header tanks as one of the components. The header tanks are used to hold some water from the main rainwater harvesting tank and is installed above the appliances such as geyser so it can be gravity fed down to them. They have adverse effects in extremely cold as well as extremely hot weather conditions.
- UV Filters -UV filters are installed to disinfect the collected rainwater, if it is to be used in domestic situations for drinking, showers, hand-washing, etc, or commercially in pressure washers. UV filters are a safe, reliable and energy-efficient source of disinfecting water for aforesaid purposes. These filters can get damage if they are exposed to extremely hot weather. The bulb installed in the filters can be broken with the damaging effect of cyclones or floods or storms.
- Water pumps – Water pumps can get clogged by heavy snowfall, dust storms and can get eroded during cyclones and floods.
- You can add an Aerator in your RWH systems. This device works by producing a steady stream of air that keeps the water moving so that it does not have time to settle and freeze.
- You can also use a heat pump that recirculates hot water into the system.
- Cover or lag the over-ground PVC pipes by the black corrugated pipe which has closed cell spray foam insulation on inside.
- Water in tanks, if allowed to get too warm during hot weather conditions, is likely to permit the growth of undesirable organisms. Hence, install insulation jackets on them.
- Plant vegetation around the system to reduce the impact of heavy floods or dust storms.
- The filters must be environment specific, in terms of the material being used and the capacity to filter out finer substances during dust storms.
- You can also insulate your water tank from the extreme weather by coating it with a heat resistant paint or thermal coating.
- You can put salt down the drain. Salt would quickly melt the snow. Avoid pouring hot water into the drain though, as it might cause bursting of the pipe due to sudden temperature change.
- Thorough cleaning is needed after floods and other extreme weather conditions.
If RWH is the lifeline of your water conservation methods, then it is more important to follow the precautionary steps to have a lesser impact on extreme weather conditions.
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