Numerical simulation of the surge generated by the 1977 Andhra cyclone

Abstract

Three different numerical models are used to simulate the surge generated by the 1977 Andhra cyclone. In each of these we simulate the effect of three days of wind-stress forcing before landfall of the cyclone at the Andhra Pradesh coast. the analysis area in the first model includes the entire Bay of Bengal north of 6°N and utilizes a curvilinear boundary treatment to represent the coastlines. the second model is a coastal zone model extending along the east coast of India, again utilizing a curvilinear treatment of the coastline. In the third model, which again covers the entire Bay of Bengal, the coastlines are represented by a conventional stepwise procedure. Using available data on the Andhra cyclone as a guide in representing the effect of wind-stress forcing in our models, we compare the predicted rise in the sea-surface elevation obtained from each of these with estimates based on reports received from Andhra Pradesh after the disastrous flooding in that region. Each of the three models produces a qualitatively similar surge response. the slight quantitative differences are explained in terms of the different boundary treatments. the predicted peak surface elevation above mean sea-level compares well with the estimated 5 m reported along part of the Andhra Pradesh coast south of Masulipatnam.