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| CLOUDBURSTS: Nature's Fury | | |  Dr. Pragya Khanna
We have been hearing about the Clouds Bursting every now and then, especially in the hills leading to extreme hydrometeorolgical conditions like heavy debris flow, landslides and eventually the blockade of river channels, which consequently wreak havoc downstream.
Going by definition, a cloudburst is sudden abundant rainfall. It is an abrupt insistent and violent rainstorm falling for a short period of time limited to a small geographical area. Generally cloudbursts are associated with thunderstorms. The air currents rushing upwards in a rainstorm hold up a large amount of water. If these currents suddenly cease, the entire amount of water descends on to a small area with catastrophic force all of a sudden and causes mass destruction. This is due to a rapid condensation of the clouds. They occur most often in desert and mountainous regions, and in interior regions of continental landmasses.
Cloud burst is actually a situation when the inter-molecular forces between the water molecules get very high due to the rapid decrease in the temperature or excess of electrostatic induction in the clouds causing the lighting to remain inside the cloud only, which causes hyperactive energy inside the cloud.
The water molecules get denser and denser and get condensed but do not leave the cloud due to excess of electro forces. As the water concentration gets higher and higher, the weight gets heavier and so the water no longer is able to maintain force with the clouds and hence it precipitates. Sometimes this happens when the cloud is ready to rain and the ground below is scorching hot. Or maybe a very warm current of air is blowing under the rain cloud. Either of these events causes a strong updraft of warm air. Raindrops find it very hard to fall through a current of rising air. When they start down, they are whisked up again. If this goes on unabated for any length of time, the cloud gets an overload of rain. The drops that should have fallen are returned back up and new drops are being formed all the time. Finally something happens to change the situation. The weight of rain is able to break through or maybe the updraft suddenly stops for some reason, then all the raindrops new ones and old come tumbling down at once. At such a time it seems as if the rain clouds have burst open.
The topographical conditions like steep hills favour the formation of these clouds. In such areas the devastations occur on large scale as water flowing down the steep slopes brings debris, boulders and uprooted trees with great velocity damaging any structure that comes in their way. This leads to flash floods/ landslides, house collapse, dislocation of traffic and human casualties on large scale.
Most places in India have to deal with around 20 mm of rain in a day during the monsoon. However, Uttarakhand, the mountain state that reeled under extreme devastation caused by floods in 2013, received 220 mm rainfall. Rainfall of such intensity can lead to flash floods within a few minutes.
The scale of damage due to floods in such situations cannot be estimated but is certainly immense. The loss of human lives above all, and the destruction of public and private property haunt the residents for many years.
Today, the world is facing severe issues as a result of climate change. Cities all over the world are increasingly plagued by flooding resulting in large damages to private and public space. After a number of massive cloudbursts in recent years, I think this is high time for India to start preparing for climate change and the impact of future extreme weather.
Maintaining a holistic mindset in the interest of the human and animal life and environment in particular is of vital importance, both in the short and long run. The main problem being faced is of increasing urbanisation, particularly in Asia where more and more people are moving to the cities. Meanwhile, they are shifting from low to middle income and demanding better standards of living. This puts massive pressure on urban expansion and infrastructure build-up, creating an urgent and pressing need for holistic urban planning and city solutions.
Take for example Uttarakhand and Himachal Pradesh, the two hill states in the Himalayan range, so far the worst hit by the extreme rains that struck northern India in the wake of monsoons during past couple of years. Heavy rainfall has wreaked havoc on the region because of the fragile nature of the Himalayan range and poor soil stability in its steep slopes. But it is man-made factors that have compounded the scale of the disaster. Unabated expansion of hydro-power projects and construction of roads to accommodate ever-increasing tourism, especially religious tourism, are also major causes for the unprecedented scale of devastation.
The cloudburst concretisation plans as adopted by certain developed nations must be practiced like the ones used in Copenhagen which are based on a few simple principles. The new cloudburst infrastructure is generally used for separating rainwater from smaller events to take the load off the sewers and wastewater treatment plants. From a socioeconomic perspective, this has proved to be more feasible compared to conventional pipes, underground retention volumes and a completely new separate system. Cloudburst streets collect and transport water away from vulnerable areas. Retention streets are typically located a bit further upstream from a low-lying vulnerable area and retain the water through the large storage volumes created. Adjacent to the cloudburst streets, areas with secondary streets are transformed into green streets with swales or permeable pavements that retain the water in the area and to some extent infiltrate it, thus helping to recharge the groundwater aquifers. Central retention will be created in public spaces such as parks and parking zones. In areas where the water simply cannot be handled on terrain, large underground cloudburst tunnels up to three metres in diameter are built instead of cloudburst streets.
These are though long term expensive plans, however in the meantime certain preventive measures can be adopted to mitigate this destruction led phenomenon. Experts say promotion of the hilly places as tourist destinations is coming in way of sustainable development.
Looking at the various causes of damage in Uttrakhand or hilly zones, it is seen that sanctioning/installation of power projects without making survey and studying results in this type of destruction; furthermore construction of unplanned buildings, hotels, industries etc. in hilly areas without thinking of global warming and other side effects on nature and increase in the number of vehicles plying on these mountainous tracks has led to increase in nature's fury.
We need to act on certain aspects as fast as we can in order to prevent the future disasters and averting such catastrophes. We need to grow more trees in the hills and hills must be saved from environment contamination. Lesser number of transportation in the hill area can help to avoid pollution.
We need to provide the infrastructure, roads, and building as per the hill environment. The buildings should not be allowed near the banks of rivers. We must develop good techniques to get the weather forecast. State of art medical facility must be available at these locations, also there is need to use latest technique to save trees and maintain the overall environment. We need to have establishment of disaster management groups in all such areas and people must follow their instructions. The construction of new roads should be discouraged with proper maintenance of old ones; vehicles moving with fuel other than CNG should be discouraged in order to reduce pollution; all vehicles should be equipped with basic tools to aid them in case of any disaster. All drivers and their assistants should be trained in basic first aid and life saving techniques. Further, they should be connected via radio to the main head quarters and relay any information that might help contain a situation. There should be regular checkpoints along the way to provide assistance if needed. And last but not the least; the pilgrims/tourists should be made aware of the risk to life and property in undertaking such a journey and not treat it lightly.
Above all, the natural beauty must be maintained.
Mountains, like the rest of our environment have been made fragile by our actions. It is time we remedied it. Our constructions should be cohesive with the nature of the land we build on, not against it. Any project which affects our ecosystem adversely should be stopped. It can never help us in the long run. |
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