Scientists sound alarm over rising sea level

AU geo-engineering team conducts study

Guntur: Global warming, land subsidence and shore-line erosion caused by aquaculture ponds are resulting in eustatic sea-level rise. The sea-level rise would result in interface of fresh and sea waters, salinisation of agriculture lands and seriously impair agricultural activities in the lower parts of the AP coastal zone, especially in the twin low-lying Krishna-Godavari delta region. They are considered rice bowl of the State.

A sea-level rise by one metre by 2100 has been predicted by Inter- Governmental Panel on Climate Change (IPCC). It has necessitated identification and protection of vulnerable parts along the coasts. A team of nine members, led by Andhra University professor of geo engineering Kakani Nageshwar Rao, recently made a study of the current rising levels of the sea and the disastrous consequences due to further rise in sea levels and its impact on the Krishna and Godavari deltas.

If the sea level rises as predicted by IPCC, an area of about 532 km, including 150 km in the Krishna-Godavari deltas lying between the shoreline and the 0.6m elevation, would be permanently submerged under the future low tide level. Further an area of about 1,233 km including 894 km area within the Krishna-Godavari deltas lying between the present high tide line (1.5 m) and the future high-tide line (2.1 m) would go under the future inter-tidal zone, affecting the farmlands in over 319 km, aquaculture over 499 km and plantations in over 279 km, besides threatening the survival of 1.29 million people living in 282 coastal villages along the entire AP coast.

Prof Nageshwar Rao told The Hans India that the Union government had come up with the constitution of Integrated Coastal Zone Management to deal with the exigencies of possible repercussions of the sea level rise in future. He said the AP coast was known for frequent tropical cyclones and associated floods and tidal surges causing loss of standing crops, life and property in the region.

The 1977 cyclone that was accompanied by a five-metre storm surge killed about 10,000 people and 20,000 livestock, besides causing enormous damage to standing crops and property in the Krishna delta region. The storm surges in the 1990 and 1996 killed thousands of people and livestock, besides damaging agricultural lands and property in Godavari delta region.

Considering the IPCC 2007 estimates that the global sea levels may rise by about one metre by 2100 AD and the more recent estimates on possible sea level rise of about 1.0 m to 1.5 m, the AU team made as assessment to measure its possible impact along AP coast. If the sea levels rise by 0.60 m above the present, an area of about 565 km lying between the present shoreline and the 0.6 m elevation would go below the low tide including the 150 km area along the Krishna-Godavari delta front coast. Further, the high tide line would shift landward from the present 1.5 m contour to 2.1 m contour.

Therefore, the present area lying between 1.5 m and 2.1 m contours would become a part of the future inter-tidal zone. There are many villages located close to the present high tide limit. An analysis of the village location map in comparison with the contour map showed that as many as 282 revenue villages were located within 2.1 m elevation along the AP coast.

All these villages and 1.29 million people living there would be in danger if the sea level rises by 0.6 m above its present level. Within the Krishna-Godavari delta region the increased sea levels would affect 97 human habitations and 0.57 million people. The sea-level rise might also affect the region indirectly through landward shift of freshwater-seawater interface and consequent groundwater contamination by salinisation.