The Alaknanda disaster in Uttarakhand in northern India during 15-16 June 2013 is one of the worst human tragedies in recent history. The impact of this event has reminded us once more of the increased and undesirable human interventions on the natural systems. The trigger for this event was an unusual natural process–cloud burst at several locations bringing down 200-400 mm of rains during 13-19 June, followed by lake burst at a couple of glacier snouts such as the Chorabari glacier lying on the slope of the 6,940 m Kedarnath peak and the Milam glacier upstream of the Goriganga and the Kaliganga. Such phenomena are generally called glacial lake outburst flood (GLOF) and they do occur in glaciated regions at regular intervals. However, this event affected a large population living very close to the rivers, which were flooded suddenly at a time when a large number of pilgrims were en route to the Kedarnath temple. The impact of this event could have been easily minimised if we had a little more consideration and understanding of the river processes.
As a part of the Ganga River Basin Management Plan being prepared by the consortium of Indian Institutes of Technology, we submitted a report to the Ministry of Environment and Forests (MoEF) in December 2010, which proposed the concept of ‘river space’ for performing the natural and ecological functions of rivers. River space consists of the ‘floodplain’ and ‘valley margin’ of the river and its width on both sides of the river can be spatially variable depending upon geomorphic considerations. The active floodplain, hydrologically defined as the area inundated by 2.33 year (average theoretical return period) flood, is the ecologically most sensitive zone and supports a wide variety of vegetation and life forms; its complete preservation is one of the prime indicators of good river health. The human dimension of the river space is that this zone should be kept free of habitations as much as possible not only from the river health viewpoint but also from a human risk perspective – a point well illustrated by the recent disaster.
Recognising the fact that “the anthropogenic pressure on ecosystems and environment has tremendously increased, causing irreparable damage to the fragile mountain ecosystems including flow and character of the river,” the MoEF issued a notification dated 18th December, 2012 declaring the 130 km stretch from Gaumukh to Uttarkashi in the Bhagirathi valley as an eco-sensitive zone strictly prohibiting large-scale settlements. Unfortunately, this notification was never implemented by successive governments in Uttarakhand. Although this notification did not include the Alaknanda valley, which was affected most by the recent disaster, this was the first attempt towards identifying river space. Had this been implemented and extended to other vulnerable areas in this region, it could have saved hundreds of lives. It is certainly desirable that we start a serious debate on defining river space and declaring this as a no-go zone.
Another related issue is the impact of the existing/under construction/proposed hydroelectric projects along the several tributaries of the Ganga in this region. The claims of the governmental agencies that the existing dams (e.g. Tehri on the Bhagirathi) helped to reduce the impact downstream have been rubbished by the non-governmental agencies. In any case, the peak flow in the Alaknanda valley occurred later than in the Bhagirathi valley. There are also suggestions that peak flow at Rishikesh and Haridwar could have been earlier in the absence of Tehri Dam but not much higher than what was observed. On the other hand, several under construction hydroelectric projects on the Alaknanda such as at Vishnuprayag and Srinagar not only got severely damaged but probably created additional problems. An important observation by many has been a huge pile of sediments deposited by the river in many areas and it is not clear if these sediments were derived from the hill slopes alone or a part of this was a result of severe degradation due to construction activities around the hydroelectric projects.
The final point is that a proper understanding of river processes must be emphasised in river management and development. The urban development around the Kedarnath temple close to the abandoned channel of the Mandakini river by a landslide a few decades ago reflects extreme ignorance of the ways the rivers work both by the administration and the local community. Such abandonment and reactivation of river channels are known to occur over decadal scales and the identification of such hazards related to river dynamics must figure prominently in the development plans of the mountainous areas close to rivers in a region, which is known to be one of the most fragile mountains in the world.