A section of the National Highway between Dimapur-Kohima near the Chumukedima Police Check Gate. Heavy landslide along with mud and rock fall had occurred during the current monsoon season.
The up-gradation of the present two lane NH-38 (28) to four lane carriageway has been under active demand of the state Govt. and finally the Govt. has announced approval of the project by GOI as fulfillment of a long cherished dream. The State Govt. and the public alike has highly and widely acclaimed the project to be a boon to the state looking at the brighter side only but totally unmindful of the darker side of impending danger and hazard that would be the consequential result of high hill cutting. One wonders whether prior detail geological and soil analysis has been carried out to take up such a risky project. My suggestion is to maintain two carriageway of two lanes each under separate road profile (the present NH-38 and a split NH-38 Kohima-Dimapur via New land) without disturbing the present almost stabilized NH -38. I am therefore writing this open letter to cause a deeper study of the structural geology of the region for feasibility of undertaking the four lane project to avoid a blunder.
Geologically, the entire NH-38 lies within the region of highly unstable young Himalayan mountain chain extension known as Barail range consisting tertiary rock called Disang series vulnerable to landslide that is further being aggravated by unabated onslaught of human activities making it ready to trigger landslide and mud slide at any given situation.
By simple definition, landslide is the gravitational movement of a mass of rock, earth or debris down a slope. According to geologist, landslides commonly occur in region where high permeable soil lies on top of low permeable bottom soil. Although the action of gravity is the primary driving force for a landslide to occur, there are other contributing factors affecting the original slope stability. Land slide occur when stability of a slope changes from stable to an unstable condition.
A change in stability of a slope can be caused by number of factors acting together or alone among which are (1) Natural- ground water, (2) Less or absence of vertical vegetation, vegetative structure, soil nutrient and soil structure, (3) erosion, (4) weakening of slope through saturation, (5) earthquake, (6) human activities.
For the past many years we have been living with hardship due to landslides in the NH-38 during every monsoon. Only on very few occasions was there no landslide in the NH -38 between Kohima-Dimapur. However, the vulnerability of the NH -38 to landslides has become more pronounced in the recent years due to increased human activities in the uphill periphery of the highway. It is only few weeks past we have witnessed the worst road block in history between Kuki Dulong and the Setekima (Patkai) bridge due to mud slide from the upper terrain of the highway. This time the mud slide and debris were triggered by storm water runoff upon the human activities in the uphill region. It will continue every monsoon as long as there are human activities of deforestation and cultivation in the upper terrain that is impossible to stop.
The proposed four laning would involve massive earth cutting for widening of the road face raising the height in the uphill side up to few hundred feet may be even five- six hundred feet in many places. In the process of the earth cutting, heavy machineries and even dynamite blasting shall be required that would cause cracks in the settled soil strata due to vibration. Further, once the road is opened to traffic, vehicular traffic would cause further vibration slowly resulting in shifting of the soil equilibrium. Creating such a high steep cut slope shall caused destabilization of equilibrium of the soil strata that would yield to pressure and show sign of bulge that ultimately will give way to causing massive slide. Such block sliding of few hundred feet high terrain would completely choke and block the whole carriageway. We are now experiencing such high cut slope sliding near Botsa in the NH-61. The concept of dual carriageway (split National Highway) in the hill region instead of four lanes was mooted by me at the sectoral core group meeting in the MORTH during my service tenure. I have raised this same issue in our state but it turned out to be only a voice in the wilderness having no taker.
Having two Double Lane carriageway would insure flow of continued life line to the state capital and beyond to its people even if one of the roads remains closed by landslides or other eventualities. Further, opening a new highway traversing Northern Angami region via Nuiland will bring commercial, economic and social development and progress of the region traversed by the road that was erstwhile undeveloped area. On the other hand as stated earlier, attempting to make the present NH -38 into four lane shall more confound the present problem with massive landslide instead of mitigating it during the monsoon rain as besides the action of natural forces there well be increased and unabated human activities on the upper terrain of the road due to agriculture, trekking of firewood, boulder extraction, depletion of vegetation etc.
In the larger interest of public to keep the Capital and the State connected with the rest of the country at all season of the year, I make this humble submission to cause a serious thought that detail geological, soil and practical analysis of the project be made first to avoid any blunder that would jeopardize our lifeline.
Geologically, the entire NH-38 lies within the region of highly unstable young Himalayan mountain chain extension known as Barail range consisting tertiary rock called Disang series vulnerable to landslide that is further being aggravated by unabated onslaught of human activities making it ready to trigger landslide and mud slide at any given situation.
By simple definition, landslide is the gravitational movement of a mass of rock, earth or debris down a slope. According to geologist, landslides commonly occur in region where high permeable soil lies on top of low permeable bottom soil. Although the action of gravity is the primary driving force for a landslide to occur, there are other contributing factors affecting the original slope stability. Land slide occur when stability of a slope changes from stable to an unstable condition.
A change in stability of a slope can be caused by number of factors acting together or alone among which are (1) Natural- ground water, (2) Less or absence of vertical vegetation, vegetative structure, soil nutrient and soil structure, (3) erosion, (4) weakening of slope through saturation, (5) earthquake, (6) human activities.
For the past many years we have been living with hardship due to landslides in the NH-38 during every monsoon. Only on very few occasions was there no landslide in the NH -38 between Kohima-Dimapur. However, the vulnerability of the NH -38 to landslides has become more pronounced in the recent years due to increased human activities in the uphill periphery of the highway. It is only few weeks past we have witnessed the worst road block in history between Kuki Dulong and the Setekima (Patkai) bridge due to mud slide from the upper terrain of the highway. This time the mud slide and debris were triggered by storm water runoff upon the human activities in the uphill region. It will continue every monsoon as long as there are human activities of deforestation and cultivation in the upper terrain that is impossible to stop.
The proposed four laning would involve massive earth cutting for widening of the road face raising the height in the uphill side up to few hundred feet may be even five- six hundred feet in many places. In the process of the earth cutting, heavy machineries and even dynamite blasting shall be required that would cause cracks in the settled soil strata due to vibration. Further, once the road is opened to traffic, vehicular traffic would cause further vibration slowly resulting in shifting of the soil equilibrium. Creating such a high steep cut slope shall caused destabilization of equilibrium of the soil strata that would yield to pressure and show sign of bulge that ultimately will give way to causing massive slide. Such block sliding of few hundred feet high terrain would completely choke and block the whole carriageway. We are now experiencing such high cut slope sliding near Botsa in the NH-61. The concept of dual carriageway (split National Highway) in the hill region instead of four lanes was mooted by me at the sectoral core group meeting in the MORTH during my service tenure. I have raised this same issue in our state but it turned out to be only a voice in the wilderness having no taker.
Having two Double Lane carriageway would insure flow of continued life line to the state capital and beyond to its people even if one of the roads remains closed by landslides or other eventualities. Further, opening a new highway traversing Northern Angami region via Nuiland will bring commercial, economic and social development and progress of the region traversed by the road that was erstwhile undeveloped area. On the other hand as stated earlier, attempting to make the present NH -38 into four lane shall more confound the present problem with massive landslide instead of mitigating it during the monsoon rain as besides the action of natural forces there well be increased and unabated human activities on the upper terrain of the road due to agriculture, trekking of firewood, boulder extraction, depletion of vegetation etc.
In the larger interest of public to keep the Capital and the State connected with the rest of the country at all season of the year, I make this humble submission to cause a serious thought that detail geological, soil and practical analysis of the project be made first to avoid any blunder that would jeopardize our lifeline.
T. Meren Paul
Retired Transport Commissioner
