Geohazards in the east Siang district of Arunachal Pradesh, India: Need for geoethical approach for integrated flood mitigation strategies

Abstract

The East Siang District represents one of the multi-hazard prone districts of Arunachal Pradesh, India covering an area of approximately 4,005 km2drained by the mighty trans-boundary river Siang. It is located in the foothills of the Himalaya and shows wide variation in lithology and topography. Pasighat census town, established in the year 1911, is the headquarter of the district which falls in zone III of the seismic hazard zonation map of North-Eastern region of India, and can experience peak ground acceleration of the order of 200–250 cm/s2. Flash floods, landslide dam outburst floods (LDOFs) are the major geo- hazards in the district that causes heavy destruction of life and property. Other geohazards include landslides, hailstorm and forest fire spread across the year. The LDOF in Tibet on 11 June 2000 caused death of many people living in the downstream areas of the East Siang district. It also affected more than 10,000 people, submergence of villages and standing crops, and collapse of bridges in Arunachal Pradesh and Assam. The occurrences of flash floods have risen in the past decade causing partial damage to the township of Pasighat. A large numbers of rural link roads, culverts, suspension bridges and wooden bridges have been collapsed due to landslides, flash floods and LDOF time to time. In view of the fact that, Siang is trans-boundary river, temporal coverage in real time and at frequent intervals is ‘thus’ required for continuous monitoring of behavior of the river in relation to incessant rains, cloudbursts and on-going neotectonic activity. A geoethical approach is needed in establishment of integrated flood mitigation strategies by effectively using adequate technologies and sharing of scientific knowledge at trans-boundary levels.