GUWAHATI, July 6? About four years back The Assam Tribune carried a newsitem titled Guwahatians burying their own city. The story was about the adverse impact of hill cutting. Today, when a move to politicise hill cutting in the name of providing land to the thaluas (indigenous people) and the ?landless?, is on, we feel it our duty to remind the people of the same things we wrote about four years back. The Assam Science Technology and Environment Council (ASTEC) conducted a study on hill slope destabilisation and its impact on urban drainage planning between May 1993 and October 1997 taking the Navagraha-Noonmati area of the city as the area for case study under the project. Dr Pradip Sarma of Cotton College Geography Department was the principal investigator of the project, while Dr Ranjan Saikia of the same Department was the co-investigator of the project.
During the study, it was found that suspended sediments in the surface run-off had been increasing every passing year in most of the gullies and the slopes selected for study. In certain areas, like Anandanagar, near Jyotinagar, suspended sediment was found to be more than 500 grams per litre of surface run-off. This was because of two factors? significant amount of rainfall and the destabilisation caused to the hill slopes by the newly settled areas in the steep slopes. The study revealed that more than 2.8 mm of rainfall occurred in a single hour on August 11, 1993 in the area under study . The average mean hourly rainfall between May and September in the area, was found to be between 2.36 mm and 2.88 mm. This amount of rainfall is enough to cause tremendous damage to the hill slopes of the area.
The slopes of the hills in this area range from 5? to 60?. Newly settled areas approaching towards steeper slopes in the recent years, were found to be causing more destabilisation of the hill slopes and thus setting in motion the process of soil erosion in the hill areas and siltation in the plains, finally leading to the clogging of the drains and burying the roads and other built-up areas. Of the area under study, it was found in some localities, like Jyotinagar and Anandanagar, that silt deposition in the basin areas per rainy season, was more than 20 centimetres? i.e. 8 inches.
Though the rate of siltation was found to be less in other areas, the average rate of siltation in foothill areas under study was estimated to be not less than 3 centimetres? i.e. over one inch, in a year. Taking to The Assam Tribune here today, Dr Pradip Sarma said that the depth of the soil layer over the city hills ranges between 8 and 10 metres only. If it is allowed to be washed away at the rate/rates mentioned above, for the narrow individual interest of the land hungry people, the day is not far when houses on the hills, irrespective of the technology used to build them, will start tumbling down like houses of cards resulting in tragedies in a series which will shock the entire humanity.
Finally, the beautiful hills, Guwahati now boasts of, will wanton themselves as barren rock domes like in many South Indian places. And by this time, the entire civilisation of Guwahati will get itself buried, he warned. Dr Sarma?s above observation may sound bombastic for some people, but, for them we have the examples of Uzanbazar Happyvilla area, R G Baruah Road areas, Zoo-Narengi Road areas, Christianbasti area, Kahilipara area, and Fatasil Ambari etc. areas, among othes, to substantiate the assertion made by Dr Sarma.