If one travels across the landscape of South India, one comes across innumerable lakes which dot the landscape. These are right across the dry country and are used primarily for agriculture. Often many of the larger ones have more than one village associated with them in the periphery. And there are many temples which would be associated with these lakes in general. These lakes were (and still are) meant to trap the rainfall which flows down the elevation and store it for agriculture. These lakes are all man made and there are no natural lakes in our area.
So if we ask ourselves the question as to when these lakes were created, we can find that many go back to almost a millennium in time. Most are more than a few centuries old and perhaps less than half a percent of them would be less than a century old.
These lakes were created by impounding a stream with an embankment called a bund. Almost all the lakes have an embankment which is not straight like a dam but created as a long curved arch pointing upriver. The curvature should give the bund additional strength.
These lakes have the embankment side which is generally steep but the rest of the sides are very gradually sloping. The old practice, much before the coming of canal irrigation, was to cultivate on the shore, following the receding water level with the approach of summer. This ensured that the slope was very gradual. In hilly country, cutting slopes and increasing the sediment base of the lake was done to get a flat bed useful for paddy cultivation.
With the ability to make canals, the flat and very gradually sloping foreshore perhaps became less important, because the water was diverted into larger areas downstream. And with the growth of the population, urbanization and construction crept closer to this shoreline. This again made the shorelines steeper because people either cut it or filled the slopes to elevate the ground.
So if we take the case of the fastest growing city at one time in India, Bangalore, one can see what is happening to the lakes. As the city grew, it engulfed the lakes. Many were drained for development to happen. The irrigated fields were all converted to properties and sites. And some lakes were just engulfed. Due to the severe malarial epidemic in the last century, vector control measures were focussed on reducing mosquitoes and this translated to draining all the lakes close to the growing city or those engulfed by it. At that point of time with the medical technologies available then, there perhaps were no alternatives than to eliminate the disease vector. So a large number of lakes were drained and eliminated.
With increasing concerns on the water situation, including ground water, as the city grew, the government setup the Lakshman Rao Commission in the mid eighties to look at what should be done with the lakes which had lost their irrigated areas. With much forethought, the committee recommended that the lakes should not be drained but repurposed. So many of them came to be what they are today: an urban tank like lake, with a peripheral walking path and a garden around. And benches and pergolas, where people can sit and chat. The biggest casuality in this change was the gradually sloping foreshore and margin which our engineers failed to understand the importance of, because biology awareness is so poor in our society.
Now, these lakes both with and without the irrigated area can be called wetlands. Wetlands are areas marginal between land and water characterised by hydric soils and hydrophytes. They host their own unique community of birds which are well adapted to a life in or near water. The changes and the loss in the wetlands around Bangalore has resulted in an enormous decline in bird populations in the wetlands around Bangalore. The decline could be by some ninety percent compared to the early nineties or thereabouts.
Birds have inspired and fascinated man from times immemorial. Their flight, song and colour have charmed poets and writers to include them in their works. But in spite of all this admiration, they have still attracted the attentions of a different kind. They have been often hunted, and often indiscriminately without restraint, especially when firearms became common and often for entertainment. And so was it here in India too, until the Wildlife Protection Act was passed in 1972. It was a landmark act which changed the way wildlife was treated, and though primarily targeting the larger vulnerable mammals, included other persecuted wildlife too. The newly arising sentiments of the time and the Act brought about a dramatic change across the region and wildlife conservation became an accepted thought. Much of the people who are active today are this post wildlife act generation whose schooling happened after the early seventies.
Wetlands are highly productive ecologically and support life far in excess to equivalent areas of land. In the Bangalore area for example, some forty percent of the bird species are supported by wetlands which account for hardly two and a half percent of the land area. Many of the wetland birds are long distance migrants coming form near and within the Arctic Circle. Some of them would be covering an excess of some twenty four thousand kilometres every year in their migration journeys. Many sport exclusive lifestyles and feeding strategies. And they are threatened in our urban areas and periphery because of the spoilage of the habitat. Though India is a signatory to many conservation treaties and has ratified them, there is need for bird conservation to reach local situations.
Why worry about birds one may ask. It is because they have some very unique traits apart from being very charming, that should endear them to be within our surroundings. Birds are the most highly metabolising animal group, with body temperatures which could be as high as 43 deg C. And they require lots of energy to fly. So per unit bodyweight birds consume a lot of high calorific food. If the food is contaminated by the pollutants and toxic materials that we put out, they are most likely to be affected the first. So they serve to give out a warning to all that we do! This is perhaps the only warning for synergestic effects of the chemicals we put out. And some of the most major damages to the life around us caused by us, have been studied because of birds. Remember the Canary which was being carried into coal mines?
//KRISHNAMB. 20th July 2022. This draft is not formally edited and would require some editing perhaps.
~ in good faith, krishnamb.
~ making time free is culture!
~ making free time is culture!
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