Mahadayi/Mandovi River Valley - Part III

By Mohan Pai

Ecological Impact of the Mahadayi Water Diversion on Goa

The construction work on the Kalasa-Bhandura diversion dam for which the Deputy Chief Minister of Karnataka laid the foundation stone on September 22, 2006 at Kankumbi near Goa-Karnataka border is progressing rapidly. The project is threatening to wipe out this millennia old culture and society. Goa, although a small state, is one of the most prosperous state of the Indian union, paying the highest per capita tax and earn the highest per capita foreign exchange. Mining, tourism, corporate taxes, income tax, excise etc. net about Rs. 8,000 crores an annum to the National Exchequer.

The State of Goa is the smallest of all the States in the country yet, it shows an astonishing diversity of endemic species, habitats and ecosystems. Goa is under the influence of two global biomes - the marine biome of the Arabian Sea and the terrestrial forest biome of the Western Ghats. Within this geographical canvas are a wide range of ecosystems and habitats e.g. forests, Ghats, alluvial plains, coasts, rivers, estuaries, mangroves, wetlands, etc.

Madei river at Ganjem, Ponda taluka, Goa - Pic by Mohan Pai

Madei/Mandovi is the largest river in Goa which drains almost all of northern and central Goa with the basin area of 1,580 sq km or 43% of Goa’s total land area. Any tempering with its headwaters will seriously disturb its natural ecology and will damage the ecosystem of the entire river basin in Goa.
The livelihood of 296 villages in the talukas of Tiswadi, Bardez, Bicholim, Sanguem and Ponda depends on the resources of Madei/Mandovi waters. It will also affect the Zuari river basin which is linked with the Mandovi through the Cumbharjua canal.

The change in the Mandovi’s profile will also adversely alter the ecology of its estuarine, thickly populated islands of Chorao, Diwar, Corjuem, Jua, Cumbharjua, etc.

The Salinity Factor

The fresh water flow from the Mahadayi river in Khanapur taluka maintains the Mandovi. The Mandovi is a tidal estuary which means that it is an extended arm of the sea with tidal salt water intrusion. The fresh water flow keeps the salinity at a certain level. Reduction in the fresh water flow will disturb the fresh water regime by pushing up the salinity to a much higher level.

At present the salt water ingress and the tidal influence is felt 36 km upstream beyond Ganjem or nearly 70% of the river’s length in Goa. Reduction in the fresh water flow from Karnataka would completely alter the river profile by moving the estuarine front deeper even beyond Valpoi.

Out of the total drainage area of 1,580 sq km 509 sq km is affected by salinity and in another 540 sq km local conditions do not permit any water resource conservation schemes and that leaves only 531 sq km drainage in Goa which could be utilised. The increase in the salinity level will have a detrimental effect on Goa’s entire coastal ecosystem not only jeopardising Goa’s khazan lands, mangroves, avifauna, agriculture, fisheries and river navigation but also its drinking water storages and treatment plants at Sanqulim, Opa and other places sharply reducing the drinking water availability in the river basin.

Forests & Wildlife

The Madei river waters sustain the forests and the wildlife of the Madei Wildlife Sanctuary in Sattari taluka, Bhagawan Mahavir Wildlife Sanctuary and Molem National Park in Sanguem taluka and Bondla Wildlife Sanctuary.

Tree Frog - Pic by Mohan Pai

The reduction in the Mahadayi waters will not only decimate this area (448.5 sq km) but will result in decimating surrounding forests since the whole belt is one contiguous belt of wilderness.

Gaur or Indian Bison, the State Animal of Goa

Agriculture

The whole of Sattari taluka depends on the waters of Madei for its agriculture including the centuries old method of ‘Puran Sheti’ and the Vasant Bhandaras - lift irrigation employed by most of the villages. These 27 odd villages will face a total ruin.

Khazan fields - intricate system of dykes & sluice gates - Pic by Mohan Pai

Khazan lands are saline floodplains covering an area of about 17,500 ha which have been reclaimed over centuries (Historical records of the 6th century mention Khazan lands) by constructing an intricate system of bunds (dykes) and sluice gates. Khazan lands are ecologically, economically and socially very important for agriculture and piscine culture. This unique system is based on the ecology of the area that includes the present level of salinity of the water. About 2,000 ha are under dense mangrove vegetation. The mangroves help protect the outside of the mud and laterite bunds that enclose the Khazan. Mussels, clams, oysters, crabs and prawns are harvested and the fish and shellfish sustain a large population of indigenous and migratory birds. Reduction in fresh water flow will push up the salinity to a much higher level which may result in the Khazan lands becoming unproductive, affecting thousands of people depending on the Khazan lands.

Khazan field - Sluice gate - Pic by Mohan Pai

As a result of shortage of water staple produce of rice, pulses and cereals may get affected. The plantation crops such as cashew, coconut and arecanut which are largest plantation crops in Goa are bound to suffer. The largest size of cashew plantations are located in the Madei/Mandovi river basin in the talukas of Sattari, Bicholim and Bardez. The area under arecanut is 2,000 hectares and almost half of it is in Ponda taluka.

(Kulagar in Sattari - Kulagars are hill slope terraces where arecanut and coconut plantationsalong with climbers like betel leaves, pepper, etc. are cultivated. Banana, mango, jackfruit, pineapple, kokum, chillies, turmeric are also being cultivated in kulagars) - Pic by Mohan Pai

Other plantation crops grown in Goa are the bamboo, the banana and mango, bhirand or kokum is also an important plantation crop which forms a part of daily diet. It is used as a garnish to give an acidic taste to curries and vegetable as well as in the preparation of cooling kokum syrup during the hot summer months.

River Navigation

The Mandovi estuary is navigable round the year up to about 45 km from the mouth upstream and is one of the two main waterways of Goa mainly used for transporting iron ore barges of capacity 1,000 - 1,500 tons and transported to the Mormugao Port for export. The depth of estuary varies from 8-10 m at the mouth to less than 2 m.

Mouth of the River Mandovi - Barge carrying iron-ore - Pic by Mohan Pai

Fisheries

Fishing is a major industry in Goa and over 40,000 people are dependent on fisheries for their livelihood. Out of 11 talukas of the state, fisherman fro 8 talukas are involved in fishing. Fish curry and rice is a staple food of Goan people.

Fisherwomen of Britona - Pic by Mohan Pai

The inland catch from the rivers was 3,749 tonnes as against the total catch of 73,135 tonnes (2001). There are landing centres for inland fisheries all along the banks of the Mandovi. The reduction in the water level and the deeper ingress of salt water will affect the fishing due to barriers to fish migration and this will reduce the fish catch. The tourism industry in Goa depends on the local fish produce which will definitely face problems.
The mangroves will be also affected and the shellfish breeding will be depleted and the aqua farms along the river banks also will face problems.

Tourism

Goa’s sandy beaches are major tourist attraction. Goa is an international tourist destination and tourism is the most important component of Goa’s economy providing employment related opportunities to the local population. Tourist arrivals amounted to 2.3 million in 2005 exceeding the local population by almost a million. Number of hotels and resorts, residential dwellings, commercial establishments, beach side entertainment centres/eat outs have changed the landscape of the coastal strip with activities that follow such a coastal tourism.

Tourists at Calangute - Pic by Mohan Pai

The Government has laid special emphasis on creating an attractive image for this international destination by developing infrastructure and diversifying a beach oriented tourism to other forms of tourism such as heritage tourism, eco-tourism, adventure and aqua-sports, etc. And there is an attempt to shift developmental activities towards hinterlands and backwaters as well as the Western Ghat forests in the form of eco-tourism. The other tourist attractions are the wildlife sanctuaries and the waterfalls of Dudhsagar which is a main tourist attraction as well as Surla waterfalls and Vajra Sakhala waterfalls in Chorla Ghat which will be reduced to a trickle due to reduced waters.

Watersports - Northern beaches of Goa - Pic by Mohan Pai

Seismic threat

Karnataka’s project with as many as 11 dams to be located within an area of 50 km radius have been planned in an area much prone to earthquakes. Two large dams - Supa reservoir and Codasalli are just 50 and 35 km away respectively from the Mahadayi project area. Since the project area is bordering Goa, Goa will also be very vulnerable for any seismic disturbances.