Recently, major rivers of India as well as certain rivers of Odisha were in spate which caused enormous damages and sufferings. Prime Minister Narendra Modi advised Chief Minister of Bihar Nitish Kumar to investigate the cause of unexpected flood in the Ganga river which caused extensive damages through its back water. Similarly, the river Subarnarekha is still in spate and causing havoc with in the plains of Baleswar district.
Considering the incidences of flood in India, it can hardly be denied that the authorities have failed to manage the river systems of the country. Most of the rivers of our country are either of inter-country or inter-State rivers. Every river has tributaries and sub tributaries in their upstream side and also branches sub-branches, and tertiary branches in downstream side. Every river system can be divided into three major segments. First segment includes the principal catchment areas of the river from where the major volume of water is collected and drained. The catchment area is also known as watershed area. The management of watershed area is most important. The fate of a river always depends upon the scientific management of the ecological system of the concerned river. Similarly, every major river has a number of tributaries and every tributary has its own watershed or catchment areas. The catchment area of the principal river and other catchment areas of every tributary of such principle river should be brought under the ambit of scientific management. The watershed areas of each river and tributary should be treated as protected area. The destruction of valuable biological sphere maintained by nature invites soil erosion, landslides, denudation of earth and avalanches; which usually silt up the main and principal stream of the river and the rivulets including branched and sub-branched rivers of the principal one.
The mainstream beyond the watershed areas comes under the second segment of the river. All the debris carried from the watershed areas through stream gets deposited in the riverbeds of the principal as well as in the subsidiary rivers of the main river. When the principal river stream is silted up for any reason, the water carried from watershed areas is not or cannot be limited within the stream of the river system and goes beyond the limits of the river boundary and forms the back water in the valleys and coastal plains. Again, the banks of the rivers are not managed properly. There are very limited plant species to stabilise the bank soil from soil erosion. The destruction of riverine ecological systems built by nature is another cause of soil erosion of coastal plains and valleys which ultimately carries it to the main stream of river and becomes responsible for siltation of river beds and formation of back water in the plain lands of valleys and coastal plains.
Further, urbanisation along the river banks is growing fast. All the urban debris and garbage of cities and towns are thrown in to the river beds and the rivers are now performing the sewage systems of our urbanized civilizations. Furthermore, several festivals in a year are going on in the urbanized areas along the river course. The garbage obtained through these rituals is dumped in to the river streams. This not only pollutes the river water, but also causes siltation of river beds, which ultimately forms back water in the plain lands of valleys and coastal plains.
The third and last segment is river mouth of all rivers which are most vital regions of all the rivers of the globe. The surplus water of the river systems is drained out into the ocean through the river mouths. The silt carried by the stream is deposited within this regime and creates a floating soil base, where is a very rich soil. Most evergreen types of ecological system of plant community and animal community are noticed here. If handled scientifically and through sound ecological principles, in the long run, a river mouth can be made free from getting choked by silt and garbage. When river mouth is not free, the water within the stream-bed of that particular river swells up, causing flash flood. Not only the main stream of river, but when all the river branches and branchlets are silted up and their mouths at the edge of ocean are choked for any reason, flood becomes inevitable.
let us take the case of Subarnarekha, which is usually, creating flood havoc in Odisha only because of lack of proper management of whole river system. This is an interstate river. The river originates from Chhotanagapur plateau in Jharkhand and flows for considerable distance in the West Bengal and for very short-stretch of distance along the border between Odisha and West-Bengal. But it further returns to Odisha at laxmannath village being very close to Jaleswar town and then it drains into the Bay of Bengal. The daily tide always affects its mouth and forms a luxuriant estuarine mangrove forests within the boundary lands of Odisha. The revenue villages under Jaleswar, Bhograi and Balliapal of Baleswar district are always affected by the flood water of this river. There is a long-standing proposal between the Governments of Odisha, Jharkhand and West-Bengal to use the excess water of the river for irrigation and hydel power generation. But, so far it has not been worked out fully due to sluggishness of the State Government of Odisha. Here, the river Subarnarekha cannot be blamed. It can in long way solve the irrigation as well as the power shortage problems of eastern India provided the authorities make suitable plans.
The plateau of Chhotanagpur is the watershed area of river Subarnarekha, which was once very rich in forests of tropical Sal species. Due to lack of proper watershed management of the plateau, the erosion of soil becomes a common feature, which causes the perpetual siltation of the river bed of Subarnarekha and becomes the cause of back water within the region. Now, the Subarnarekha becomes the main cause of sufferings of north Baleswar as the course of Subaranarekha has been silted up and the river mouth is partially non-functional. The formation of backwater is inevitable. The writer served within this region for pretty long period and has personal knowledge on the problem. The region is the agro-economic hub of Odisha.
Several small to big ports are raising their heads within the coast of Odisha. Besides, rampant commercial activities are going on without sufficient thought to ecological safety. The writer is a man of coastal zone and knows how the people of the sea coast spend their days and night during the flood situation.
The Ganga is a largest and longest river of India which is the lifeline of India and runs from north to east crossing several metro cities, towns, industrial belts and other economic hubs. The length of the river is 2,506 km. The entire river course is highly polluted and silted up. The river mouth within is choked up for various commercial activities.
(The writer is a former senior forest officer and an environmentalist. Tel no 9937460649)