About 90% of the geographic area of 706 villages and eight towns in Andhra Pradesh fall under the Coastal Multi-Hazard Zone (CMZ), and hence, highly vulnerable to inundation due to sea erosion.
This means 3.2 million people and their assets in these villages are at high risk, while 5.1 million people pertaining to the rest of the villages are partially affected and are under moderate to low risk.
In fact, more coastal villages between East Godavari and Nellore are exposed to multi-hazards facing threats from coastal inundation, said a study by scientists of Hyderabad-based Indian National Centre for Ocean Information Services (INCOIS) of the Ministry Of Earth Sciences (MOES).
The study revealed that there has been an alarming rate of erosion and accretion or accumulation of sediments across AP in the last 48 years till 2019, with the highest erosion recorded in a stretch of 66.3 km along West Godavari, East Godavari and Krishna districts, predominantly due to the dynamic coastal process.
Moderate erosion was recorded in a stretch of 33.9 km and low erosion was recorded in 180.3 km at a few stretches between Nellore and Visakhapatnam. The remaining stretch of 662.9 km was recorded under accretion.
Coastal stretches under the Krishna-Godavari delta including East Godavari, Krishna, West Godavari, Guntur, Prakasam and Nellore districts are low lying and hence, found to be highly vulnerable, where as Visakhapatnam, Vizianagaram, Srikakulam and Prakasam districts were comparatively less vulnerable as they were comparatively on a higher plane.
An analysis of coastal villages with CMZ reveals that 1,420 census villages and 15 towns were falling under CMZ associated with 8.3 million people, said the study led by INCOIS director T. Srinivasa Kumar, along with senior scientists T.M. Balakrishnan Nair, Sudheer Joseph, P.A. Francis, P.C. Mohanty and R.S. Mahendra.
They observed that East Godavari (18%), West Godavari (10%), Guntur (11%) and Krishna (30%) districts were showing a high percentage of CMZ area due to lower elevation and higher long coastlines exposed to sea making them highly vulnerable for extensive inundation.
The current study used the extreme water levels recorded by the tide gauzes for the past century and published data to enhance probabilistic trends in 100-year recurrence intervals. The CMZ estimate demarcated the potential flooding areas due to oceanogenic disasters using high-resolution topographic data up to two km by using satellite, aerial and remote sensing information.
The validation of the Hudhud cyclone-induced storm surge inundation was also strongly corroborated with the corresponding CMZ scenario as useful in coastal disaster management and disaster reduction and preparedness. But, scientists warn that the actual inundations could be much more.