Source Book : A Journey From Madras Through The Countries Of Mysore Canara And Malabar by Dr.Francis Buchanan.
Dr.Francis Buchanan starts his journey in the afternoon of 23rd April 1800 from that portion of Madras occupied by European houses. This must be around Fort.St.George I think. The weather was very hot and dry. However, he finds the country containing little waste land as good crop of rice was raised. ‘In some places, the industry of the native causes a verdure that is highly refreshing’ is how he complements to hard work of the farmers. He says that the roads are good and the tiled houses have a better appearance than those of Bengal. However he doesn’t seem to like thatched roof.
There were many resting-places (Sumaithangi kal) along the road. Also Choultries were common and he says they evince an attention not found in Bengal.
Leaving on the road to Poonamalee he reaches Condturu (Kundrathur) and is wonder struck by the irrigation. Numerous small canals from the Saymbrumbacum (Sembarambakkam) tank convey constant supply of water and fertilize the area without trouble of machinery. They yield every year two crops of rice. Compare this state with our present day situation.
On 24th April 1800 he arrives at Saymbrumbacum tank (Sembarambakkam). He describes the tank in great detail. He says that the tank is formed not by digging, but by shutting up with an artificial bank an opening between two natural ridges of ground. It is about 7 or 8 miles in length and three in width. It receives supply of water from river Chir-nadi (Palar) and several small streams. When water overflows it will break down the bank by falling over it, and sapping its foundations. To prevent this Codies (sluices of stone) were constructed. The sketch from his book is reproduced here. Picture A is cross section of the Cody and Picture C shows the pillars. These Codies (கோடி மதகு/கலிங்கல்) are twenty or thirty feet wide and are lower by some feet than the other part of the bank. They are fortified with large stones in a sloping direction so that water rushes without undermining the bank, into a canal. While this sort of arrangement we can see even today the ingenuity of our ancestors in saving water and still preventing incidence of 2015 kind is described by him. Whenever there is plenty of rain they create a temporary barrier on top of the sluices for those few feet which the sluices are built. They have stone pillars on top of the sluices. A temporary wall is formed of mud, sticks and straw and placed between the pillars, so as to confine the water till it rises as high as the top of the bank. People watch this night and day and break the temporary wall if there is additional rain which may endanger the whole tank. At this point let us remember 2015 incident when Sembarambakkam lake water was let out suddenly resulting in the flooding and death of many in Chennai. We have something to learn from our ancestors.
Another marvelous thing he describes is about the structure used to let out the water. To let water for irrigation sluices lined with cut stone or bricks placed under the bank on a level with the surrounding country are used. (Pic-B). The inner end of the sluice is covered by a flat stone in which a circular opening is cut. This opening can be shut or opened by a plug fixed to a bamboo and secured in its place by two pillars of stone which raise above level of water.
What about the capacity? According to him “Saymbrumbacum tank is said to be sufficient to supply with water the lands of thirty-two villages (should the rains fail) for eighteen months.”. Astonishing isn’t? When we compare the status of water bodies now, our generation should hung head in shame. He also says that five thousand persons were employed in agriculture in those villages. He further says that such a reservoir is of inestimable value. If our forefathers with limited technology can maintain a reasonable buffer against drought why not we with modern technology?