Make drainage system foolproof to avert disasters

VK Bahuguna

Former Director General, Indian Council of Forestry Research and Education

Flashfloods in the Teesta river basin, triggered possibly by a cloudburst over the Lhonak lake, have caused devastation in Sikkim. Thousands of people have been affected by the calamity, even as the death toll is mounting and the infrastructure has suffered heavy damage. Notably, a study by an international team of researchers had issued a warning two years ago that this lake may burst and considerably impact the downstream region.

The Sikkim disaster, along with those witnessed in Himachal Pradesh and Uttarakhand earlier this year, presents a gigantic challenge for planners and policymakers. The spotlight is on the Indian Himalayan region, which is spread over 13 states and UTs — J&K, Ladakh, Himachal Pradesh, Uttarakhand, Sikkim, Arunachal Pradesh, Nagaland, Mizoram, Manipur, Meghalaya, Tripura, Assam and West Bengal. It covers 5,31,250 sq km, which is around 16.6 per cent of the country’s geographical area.

The Himalayas play a crucial role in preventing the monsoon winds from crossing further north and blocking the dry and cold winds from Central Asia from entering India. The Himalayan region is witnessing an increasing number of natural disasters, resulting in a huge loss of lives and resources. The impacts of climate change, lopsided urban and rural planning and geological and seismic factors are exacerbating natural calamities. To assess the causes and mitigate the disasters, we need to understand the overall pattern of governance and the role played by the people of the region in disturbing the basic fibre of Himalayan geology and hydrology. Himalayas are divided into three zones. The outer Himalayan Shivalik hills, which range from 3,000 ft to 5,000 ft, have cultivation in flat valleys with a high population density. This zone experiences significant silt runoff during heavy rain due to extensive deforestation.

The Lesser Himalayas, which reach heights of up to 15,000 ft, are separated from the Shivalik ranges by a geological fault and are peppered with numerous rivers and streams with deep gorges. These waterways are fed by glaciers that are increasingly being affected by rising temperatures. The Great Himalayas are above the snowline and have most of the glaciers. The Indo-Gangetic plain, referred to as the food bowl of India, is nourished by rivers and is vulnerable to floods and landslides that occur in the Himalayas, impacting the lives of millions of Indians, as we witness every year in Uttar Pradesh, Bihar and Bengal.

At the point of confluence of these mountainous ranges, there are shifts in the alignment of geological systems, leading to the formation of numerous other mountain ranges. Due to the continuous movement of the Indian tectonic plate towards the North-East at the rate of 5 cm per year and its underthrusting beneath the Eurasian plateau, several earthquakes occur. The Himalayan mountain ranges and the Tibetan Plateau were formed after a collision between the Indian Plate and the Eurasian Plate and we need to be prepared upfront for the lurking disasters. Landslides occur due to these earthquakes and severely disturb the geology of the region as well as the courses of rivers, streams and their tributaries. Our planners, policymakers, local social workers, administrators and engineers need to be reminded that tens of thousands of people have died due to earthquakes, landslides and flashfloods in recent decades in the Himalayan region.

Monsoon fury ravaged Himachal Pradesh in July-August. The situation in Uttarakhand is also grim as subsidence is causing damage to roads and houses in Joshimath. The all-weather road for the Char Dham yatra has proved to be a hazard as its method of construction has disturbed the ecology and geology of the hills. Such roads in the Himalayas need to be constructed on pillars rather than cutting the vulnerable slopes. Reports of scientists have indicated that the blocking of the sub-surface water streams and rivulets is the cause of land subsidence in Joshimath. The reckless expansion of Joshimath, situated on unstable debris without solid rocks beneath it, made the disaster inevitable.

While leading a Central Government inter-ministerial team in 1999 after the flashfloods in Rudraprayag, I identified two major reasons for the disasters. First, the obstruction of the drainage system along the hills, and second, the unplanned construction of houses, roads and buildings by both locals and government agencies on geologically unstable and ecologically vulnerable slopes. Due to this, small lakes and streams are formed within the soil, and during heavy rains, they find their way into the sub-surface soil, causing havoc through flashfloods and landslides. Our team had recommended the creation of geological maps starting from the block level, along with a comprehensive inventory of resources. In 2011, the National Rainfed Area Authority sanctioned Rs 6 crore to the Forest Research Institute, Dehradun, for preparing such maps for 275 districts, including the Himalayan region. The resource inventory should be used to prepare development strategies for each town and block, focusing on shifting villages located on vulnerable slopes. Another important recommendation was to ensure the prevention of drain blockages and effective management of sub-surface hydrology. Coincidentally, 14 years after our recommendations, many of the villages we had identified were swept away in the 2013 Kedarnath tragedy.

A case in point for better management of drainage is Nainital. In 1880 or so, landslides claimed the lives of several hundred people; subsequently, the British worked on making the drainage system foolproof. For more than a century, Nainital has been largely disaster-free; however, its stability is at risk, as construction and development have already reached the area’s carrying capacity.

The Centre needs to redefine the development paradigm of the Himalayas and ensure a new strategic vision based on scientific parameters, including translocation of the population, if needed. A plan is needed to make the Himalayan mountain range climate-resilient so that people and nature can coexist. Considering the region’s proximity to the international border, the Army will have to play a key role in implementing such a plan. Complacency will surely invite many more disasters as people often forget to learn from their mistakes.

Join Whatsapp Channel of The Tribune for latest updates.

#Sikkim