By CJ Armaan Faisal in Hyderabad
On the other hand, even after a thousand years, the irrigation tanks constructed by the Kakatiya kings are still in use. If proper care is taken and encroachment of the tanks as well as their catchment areas is checked, they would continue to serve for many more years, the experts say.
How is that these old irrigation tanks are still doing good, while the major reservoirs in the state, which are hardly 60 years of age, are shrinking in size?
Panduranga Rao, an expert on the construction technology of Kakatiya era, says they had employed such engineering techniques that made the artificially created water bodies last long. Planning was done keeping in view the future requirements, he said.
“It is but natural that sediments accumulate in the tank in course of time. Engineers of that era constructed scour sluices and ensured that they are operated regularly to wash away the sedimentation,” Rao said.
In fact, the modern dams too have similar arrangements, known as river sluices. However, for several reasons, they were not being used and silt has been building up over the years, reducing the capacity of those tanks, he said.
“Before constructing a tank, Kakatiya engineers calculated the yield of the catchment area and built a tank with two to three times capacity. It was based on the hydrological cycle. Once in three or four years, there used to be floods and the floodwater was stored in the tanks, which had enough space. During the drought period, the stored water was utilised to meet the needs.”
Further, the Kakatiyas interlinked tanks to ensure that no tank is overburdened. Excess water in one tank was channeled to others. Several such tanks were constructed in the region, which are in use even today, he said.
An official, who had worked at one of the major dams in the state, admits that non-use of river sluices was one of the reason for the build-up of silt.
Given the mammoth proportions of modern projects and the amount of silt, the process of clearing it becomes a costly affair. As days go by, silt increases, so does the cost of its removal. “Moreover, even if the silt is removed, the question is where to deposit it. If deposited on the bank, it will again fall in the reservoir,” he said.
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