Department of Civil Engineering, Indian Institute of Technology, Kanpur
The 2013 Uttarakhand floods: Two faces of a disaster
July 2013: The Himalayan regions of India are geologically fragile and highly eco-sensitive, and hence prone to certain types of natural disasters. Among the Himalayan states, Uttarakhand has been notable for a plethora of such disasters in recent decades, including floods and landslides in almost every monsoon season. Hence, except for the heavy toll of pilgrims and tourists and damages to shrines and property, the severity of the floods in June 2013 in Rudraprayag, Uttarkashi and Chamoli districts may not have attracted overwhelming attention. Indeed, the ravaging floods that occurred simultaneously in Pithoragarh district went almost unnoticed at first, which reinforces the notion that such floods are now considered almost normal in Uttarakhand. It is against this background that we briefly review the ‘hows’ and ‘whys’ of this disaster. But, at the outset, we would like to declare that our own expertise on the subject is limited. The problem is multi-faceted, and our understanding of it is grounded in the environmental studies of National Ganga River Basin (Uttarakhand state lies in this basin) that we have been conducting in the recent years. Natural disasters are ‘natural’, that is they are caused by natural forces beyond human control (and, often, beyond human understanding). But human activities can also affect the magnitudes of such disasters, either positively or negatively and sometimes they may even trigger such events. Hence, broadly speaking, the recent floods of Uttarakhand are a combination of both natural and manmade causes.
NATURAL CAUSES: The floods were essentially caused by heavy rainfall
in Uttarakhand in mid-June, with the monsoon having entered the state about a fortnight earlier than usual. We look at the possible natural causes that may have accentuated the floods.
Early monsoon: The early onset of monsoon caught people unawares (hence causing significant damage to life and property), but there is no plausible reason for the earliness of monsoon to have intensified the floods.
Extreme rainfall event: High rainfall magnitudes are not very rare in Uttarakhand. While we have not analysed the data, rainfall in the affected districts does not seem to have been so high as to suggest an exceptionally rare event.
Widespread rains: The rainfall events before and during the above floods occurred widely over the catchments of Alaknanda, Bhagirathi and other rivers, thereby sending high runoff into these rivers. But such widespread rains in these regions are also not as exceptional as the flood fury suggests.
Heavy rains at the start of monsoon: It seems to us that heavy rains rarely occur in Uttarakhand at the very start of monsoon. Usually, the rains are relatively light and scattered at first, before increasing in magnitude and spread after 2 or 3 weeks. In the present case, however, the monsoons entered the State with a bang, which may have been a factor that intensified the floods. This is because rains cause landslides/landslips due to unstable slopes and loose rocks/boulders, which tend to (partially) block the stream paths; and when these blockages get blown away, the dammed up water disgorges with high flood peaks. Thus, whereas in previous years minor landslides would occur at the start of monsoon, and their blockages get dismantled before the onset of heavy rains, in the present case both minor and major landslides would have occurred simultaneously in mid-June, thereby producing dam-burst like floods.
MANMADE CAUSES: Local anthropogenic factors were certainly a crucial reason for the devastating flood peaks. A large number of commentaries have highlighted several factors of significance – rampant deforestation, slope cutting, blasting of rocks, haphazard disposal of debris, and riverbank constructions. These activities invariably tend to enhance landslides (through weakened rock structures and soil stabilities), increase the runoff rates, and/or disrupt river flows. Such activities are largely related to extensive and growing pilgrimage and tourism in the State. But the increasing number of dams (and barrages) in the region is also considered by many to be a key factor. In our view, there is much confusion about dams. In our opinion dams do have significant adverse effects on river health, but they do not cause or accentuate floods by their mere existence (except when floodgates are operated irresponsibly). The conventional manner of constructing dams–involving rock blasting, careless disposal of debris, deforestation, etc.–may be major factors that promoted the high flood waves in Uttarakhand, but not the dams themselves. In fact, dams may actually provide safety against floods: the Managing Director of Uttarakhand Jal Vidyut Nigam Limited had in fact pointed out that Tehri Dam had actually absorbed the flood wave of Bhagirathi river on June 16th, thereby preventing downstream flood damage.
END NOTE: The remedies for the natural and manmade faces of disasters like the Uttarakhand floods are different in nature. Natural causes cannot be waived away, but we can prepare to face them. Thus, knowing that monsoons may set in vigorously in mid-June, it may be prudent to remove tourists and valuable assets from hazard-prone regions by early June. And, in case of extreme natural events thereafter, locals can be alerted (and evacuated) at short notice through early warning systems. On the other hand, manmade causes are eminently preventable by adopting suitable preventive measures (plus remedial measures where needed). The complete strategy calls for an expert review of both types of problems and a consequent plan of action. We believe that the government has already embarked on such expert assessments and we hope that all issues will be reviewed with an open mind and wide consultations, taking account of factual data, people’s concerns, and the environmental and socio-economic realities of the region.