Already bogged by industrial development, Gujarat’s coastline may become more vulnerable as sea levels rise: ISRO report

coast7Gujarat’s coast is back in news, but for wrong reasons. A new ISRO report for the Ministry of Environment and Forests, Government of India, has found adverse impact on mangroves due to industrial activity along the sea coast. A rise in the sea level may further adversely impact the coastal area, it adds. A report:

A new report by the Space Application Centre (SAC), Indian Space Research Organization (ISRO), Ahmedabad, called “Coastal Zones of India”, has suggested Gujarat – which has the longest coastline in India, of 1,600 km – is becoming increasingly vulnerable because of industrial activity along the coast, on one hand, and rise in the sea level, on the other. Signs of vulnerability can already be visible, with Gujarat becoming one of the four states where there has been “considerable decrease in mangrove vegetations”, other states being Karnataka, Kerala and Andhra Pradesh. On the other hand, the report reveals, “Significant increase in the mangrove area has been noticed for the states of Maharashtra, Goa, Tamil Nadu, Orissa and West Bengal.”

Prepared by the Ministry of Environment and Forests (MoEF), Government of India, the report shows, the quality of mangroves in Gujarat is perhaps the worst in India. “The average height of major mangroves is — Godavari (4.5m), Krishna (4.5m), Bhitarkanika (6m), Mahanadi (6 m), Andaman and Nicobar (7.7 m), Muthupet and Pichavaram (5-6 m), and Gujarat (2-3)”, the report says. Assigning values for healthiness to mangroves in terms of height, it adds, tree height index value 10 metres (m) or more and more is considered healthy for mangroves, 7–10 m is moderately healthy, 4-7 m moderately unhealthy and less than 3 m unhealthy.

Rise/ fall in mangrove cover in India
Rise/ fall in mangrove cover in India

The study says, these facts came to light not just by satellite imagery but by approaching the mangrove assemblages from the adjoining saltpan or port roads. “The area was surveyed on foot. Information on the mangrove diversity, density, height and soil and water samples was collected from the study area”, the report states, adding, among the major reasons for decline in mangrove cover and unhealthy mangroves along the Gujarat coast is that “industrial development along the coast is very fast and it occupies 192.21 sq km.” Further, “Gujarat is a major salt producer in India and salt pan occupies 1115.6 sq km. “

Gujarat mangrove vegetation is observed in the districts of Valsad, Navsari, Surat, Anand, Bharuch, Ahmedabad, Bhavnagar, Amreli, Junagadh, Porbandar, Jamnagar, Rajkot and Kutch. The total mangrove cover in south Gujarat is 81.09 sq km. As for South Gujarat and up north along the sea, the report says,  more area of Bharuch is under mangrove vegetation (62.18 sq km) than Valsad (18.90 sq km) and Ahmedabad (36.32 sq km). In Saurashtra, “Porbandar covers maximum mangrove vegetation (92.05 sq km), followed by Amreli (63.83 sq km). Mangrove vegetation accounts for 24.22 sq km and 10.80 sq km in Junagadh and Bhavnagar respectively. Jamnagar district occupies 149.62 sq km area of mangrove cover.”

coast5In Kutch, “Kori creek occupies the maximum mangrove cover in Gujarat (407.77 sq km).” Further in the district, “the islands of Bocha and the adjoining mangrove areas, including the Bharadi-Mata creek area, support dense mangroves on the fringe areas. Most of the other areas have sparse mangroves. Only one species of true mangrove was found here. The species was avicennia marina. In addition to the true mangrove species, several mangrove associates and salt marsh species were also observed growing in the area. They are suaeda fruticosa, suaeda nudiflora, suaeda maritime, urochondra setulos, cyperus sp., salvadora persica and salicornia sp.”

Pointing towards how the area under mangrove vegetation in Kutch has undergone “a large change in the past few decades”, the report says, “The development of the port has decimated the mangroves on Navinal Island, except for a few patches on the west and east of the port complex. There has been a change in the mangrove area surrounding the Mundra port. The saltpans adjoining it have been reclaimed and even much of the mangrove area has been taken over.”sh1

No doubt, “on the extreme south are present some of the tallest mangroves in the Gulf of Kutch. The heights of the mangrove trees here reach five meters.” And, at another locality, good mangroves are found is the Bharadi-Mata Creek area towards the west. This area is currently far away from the port and thus not under its influence so far. However, the report predicts, “With the approval of the special economic zone in the vicinity, the mangroves of this area are also under threat.”

Coming to Mundra port and special economic zone (SEZ) area, which is in the news for mangrove cutting and environmental damage, the report states, “The mangrove vegetation near Mundra is one of the most impacted mangrove assemblages in Gujarat. The area has seen the development of one of the largest private ports in the country. The development of the port has also led to the establishment of a SEZ in the vicinity of the port.“

It underlines, “The development has had a substantial impact on the natural vegetation of the area. The Island of Navinal on which the main port is situated is now devoid of mangrove vegetation except for small patches on the east and west sides. The development of a private railway for the movement of goods has also caused damage to mangrove vegetation.”sh

Though occupying only a small area, the report says, “Its development has led to filling up of several creeks that has stopped the movement of water within the mangroves. The mangrove area, east of Bocha Island represents one of the best patches on the north Gulf of Kutch coast. This area has borne the brunt of direct cutting of mangroves as well as burying of mangroves under sand. Sand that is dredged from the nearby creeks is used to completely bury the mangroves so that there is no need to cut them. This has slowly progressed from the central region and is gradually moving to the outer fringe.”

The only area which has allowed continued growth of mangroves because of very little industrial activity, the report states, is the area next to Jakhau, situated on the western tip of Kutch district. “The height of the mangrove trees in a few areas has reached 8.5 m. The average height in most of the mangrove stands is more than 3.5 meters, which is the lowest average found near Chibli Thar. This mangrove stand is approachable by foot from the adjoining saltpans. The highest average height of 6.5 m is found on the mangrove islands found to the west of Jakhau Creek where there is the least anthropogenic influence”, the report says.

Not only mangroves, the report says, in the Gulf of Kutch, coral reefs, too, “degraded with time as and when industrial development became intensive along the southern coast.” It adds, “Onshore developmental activities affected the coral reefs, coral reefs were dredged for cement industries. Loss in mangrove cover has also resulted in sediment loading in the coral reef environment and has caused degradation to the intertidal corals.”

Coming to coastal vulnerability issues, the report says, “The predicted tide along the Gujarat coast line was used to classify the coastal vulnerability on the basis of tidal range. Tide prediction tool of MIKE-CMAP is used to obtain the predicted tidal elevation of the 23 tidal stations along the Gujarat coast. Very high mean tide is found in Bhavnagar (6.52 m), high mean tide are found in Kandla Harbour (4.84 m), Navlakhi (5.175 m), Sultanpur, Ambheta (5.67 m), Dahej Bandar etc.”

Further, it says, “Moderate vulnerable area are found in Cori creek entrance (2.059 m), Koteshwar, lakhpat, mandvi,Sikka, Okha, Valsad (3.88 m), Dahanu etc. Very mean tide range is found in Godia creek (1.81 m), Porbandar, Veraval etc, and very low vulnerable is found in Miyani (0.98 m)”.

The report says, “Considering the Inter-government Panel on Climate Change (IPCC)-predicted sea level rise of about 59 cm by the 2100, the areas likely to be affected along the Gujarat coast were mapped and the loss of different land use and cover/ geomorphological feature are quantitatively estimated. Risk Level map was prepared from coastal vulnerability index (CVI) and coastal length under different risk categories was quantified.”

Based on predictions of sea-level rise, it says, “about 35.74 per cent of the total coast is under high risk and is mainly around the Gulf of Kachchh and the Gulf of Khambat. The geomorphic features are high tidal mudflats, creeks, estuaries and river mouths. The main reason of the high risk area are due to soft substrate, low to moderate slope and moderate to high shore line erosion rate. About 28 per cent of the coastal segment of the Gujarat coast is under moderate risk and is found mostly along the south of Gujarat coast and eastern portion of Gulf of Khambat and distributed in the remaining area. The rocky coastal area, low to moderate slope and less shoreline erosion are responsible of moderate risk.”

The report further states, “The risk classification shows that about 26.34 per cent of the Gujarat coast is under the low risk category. The low risk area are Saurashtra coast, i.e. from Dwarka to Diu, south of Kachchh i.e. Mandvi to near bustard sanctuary, and distributed in length in south Gujarat and east of Khambhat coast. The main cause of low risk are rocky coast, high slope, and shoreline erosion is very less, although significant wave height is moderate to large.”

Quantifying risks, the report says, “The results show that area under very high risk level is 357.54 sq km, high risk level area is 2628.75 sq km, moderate risk level area is 6694.61 sq km and Low risk level area is 2706.29 sq km. The CVI of Gujarat coast shows the relative potential of coastal changes due to future sea-level rise. Coastal geomorphology and mean tide range are the most important variables in determining the CVI for the Gujarat coast since both variables reflect very high vulnerabilities along nearly the entire shoreline.”

— Rajiv Shah


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