Saving rivers, saving life
Lifeline should not dry up like this; should not be polluted and encroached upon.
SINCE time immemorial, rivers have been playing a significant role in shaping our culture, settlements and economic activities. Majority of the landmass of the country has also been developed from river sedimentation, and it is estimated that about 20,000 kilometers of rivers have crisscrossed the country which constitutes 7% of its total area. These rivers are crucial for sustaining life and livelihoods for millions of people. However, increasing human activities at regional scale are compounding the situation. Without considering environmental consequences, the rivers are being encroached upon which should have dramatic impact on entire Bangladesh. The Ganges system in Bangladesh supports some 40 million inhabitants. People in the Ganges dependent area (GDA-roughly 37% of total land area) solely rely on this mighty river for freshwater means. The river also plays crucial role in maintaining ecological balance of the largest mangrove in the world, the Sunderbans. A vast literature suggests that the Ganges system is dying due to a number of anthropogenic activities both inside and outside of the country. For instance, according to Water Development Board some 24 rivers are already dried up due to reduced flows in the rivers which created manifold problems in the region including death-rattle situation for people for subsistence. Apart from this, increasing salinity both in surface and groundwater is making the total environment very critical. In order to maintain and restore ecological sustainability, Bangladesh has to consider a number of measures to revitalise the Ganges river systems in no time. Otherwise, the situation may turn to a tragedy in the event of global environmental change. Here are some options for restoring the Ganges system which are based on a number of field visits and research outcomes using advanced technology. Let us explore the factors making the GDA to be more vulnerable to environmental change. First of all, land formation in southwest region is relatively newer, and majority of the lands have been created by river sedimentation. On the basis of land evolution, the region can be divided into two, e.g. moribund and active delta. The moribund part is relatively older than the active one, which is characterized by rivers choked with sand and able to carry much water when the Ganges is in high flood, but the lands are high plains well above normal flood level. In contrast, active delta is illustrated by low elevation of land and the delta building process is still continuing. When the river enters into plain, its loses its gradient, and the main course bifurcates into two or more branches, meaning that distributaries and tributaries are highly dependent on their source flows. If any changes occur in the source flow, then it affects the river's normal state. Secondly, control of rivers in the Ganges dependent area was started as early as in the British period. For instance, Bhairab river, a tributary of Jolangi, used to drain in the moribund delta. The river's main flow was diverted by the then district collectorate of Nadia. Consequently, the upper Bhairab became dead within 50-60 years and the lower Bhairab lost its source to flow in full pace. In addition, at least 54 culverts were built on the Bhairab without considering any technical study. As the rivers in South Asia carry huge silt, construction of polder or embankment should have to account silt management which seems very rare in the country. This problem was further aggravated through the construction of cross-dam over Jolangi by India, unplanned construction of polders by Water Development Board in the 1960s and encroachment by local elites. The Kobadak, which was a distributory of the Bhairab also lost its fierce due to upstream withdrawal at Jolangi and is gradually dying. The dying of Mathabanga, Bhairab and their tributaries inhibited delta forming process, hence the land could not be elevated. As a result of river dying, the 2000 flood caused huge damage in the southwest region. Afterwards, people on their own also constructed levee around homesteads and agricultural lands to save their property from flooding. Consequently, the floodplain remains much lower than the adjacent water bodies. These can be explained as contributing factors for severe water-logging in Jessore, Khulna and Satkhira region. In the active part of the delta, the rivers are relatively younger and play a crucial role in delta forming process. The Gorai is the major distributary of the mighty Ganges which is now facing severe water shortage due to low flows of its source. Since a number of rivers are hydraulically connected and mainly depend on the Ganges flow, changes in the Ganges flow is severely affecting delta forming process and greatly contributing to the rapid increase of salinity in river waters. Dying of rivers is also responsible for immature land. Furthermore, the delta is subsiding at a rate of 4-5 mm/year. Hence, the sea level change driven by climate variability would delicate the situation in the absence of effective planning for the region. Remote sensing estimation of sediment load in the Ganges revealed that sediment concentration has been increasing since 1990s which can be attributed to soil erosion in the Himalayan region. Increasing sediment load may alter river systems in many ways. For instance, whenever normal flow interrupts by structural intervention, particularly by barrage or dam, this results in decreased flow. In response, sediment gets settled on the river bed and thereby accelerates accretion. The Ganges river system is facing the same problem according to a recent study published in The Daily Star on January 22. In order to revitalize the river systems in the area, a barrage is crucially needed. Water Resource minister also pointed out the necessity of the barrage on 24 February, 2009. A barrage would not only be useful for mitigating water crisis but also be helpful to maintain navigation routes, repelling salinity and be able to meet growing demand of waters for domestic, industry and agricultural purposes. In addition, the siltation problem can be minimized by keeping the silt flowing into the Bay of Bengal which can be useful to curb sea level change. Moreover, the government can save good amount of money that is used for dredging purpose. It is necessary to point out that there are about 34 structures on the Ganges from its headwater until Farakka. If water is diverted well above Farakka, then it is very likely to have less amount at the point we are entitled to receive. Bangladesh has to be self reliant to tackle climate induced changes in water resources by constructing a barrage on the Ganges. A model study has already been done with 15 crore taka, but there is no sign of implementation. We are about to invest huge resources for the development of climatic adaptations, the construction of a barrage on the Ganges could be a measure to save GDA. A unique opportunity to revive the river system is that, excavating new canals or rivers is not at all needed; we just need to restore existing water ways by dredging. China's massive economic development is based on three rivers e.g. Yangtze, Pearl and Mekong. In the planning process, China introduced smallest geographical unit to divide river reaches into upper, middle and lower, and the development is then oriented to these units. In our case, geographical component is completely missing, if we can incorporate this concept in river basin management, then this may produce splendid outcomes. Individual watershed management should be introduced, and this can be done for the entire country. For instance, dredging of old Brahmaputra may reduce bank erosion in the Jamuna and water diversion by it may help the Shitalakhya to receive more water. Water from the Jamuna can also be used to feed the Dhaleshwari which would eventually assist the Buriganga to survive from consistent environmental damage. Strong regulations are a crying need to restrain people living in the bank area. Since people in Bangladesh live very close to river banks, over exploitation of resources make the banks unsteady in terms of settlement of sediments. Effective management of huge sediment flow in the region may be useful to act as natural defense against sea level rise. Tidal River Management (TRM) has become a popular means of water management in southwest region. This system may not work efficiently throughout the region. Hence, considering ground elevation and drainage types, TRM can be encouraged, where appropriate. We observe that silt by dredging is normally stored next to the water course; this is a serious flaw of river management. Once dredging is completed, local musclemen may encroach the area with different structures overnight. This situation is very much visible in the Turag and Tongi rivers which made the course shortened. This type of management must be avoided. On top of everything, we have to have strong political commitment to save rivers, hence save millions of lives. China already announced to construct a dam on the Yarlung Tsanpo in Tibet which should be a grave concern for our rivers. However India announced to stop the construction of Tipaimukh barrage. Construction of dam by China would bring another death-trap for Bangladesh. Many protests have been made against Tipaimukh, but we are mum of spelling out anything against the Chinese plan. We should refrain ourselves from blame-game. Once we blamed the British, then Pakistan, now India. What about making our foot-hold strong? We are to construct embankments, polders to save lands from sea level rise but at the same time, a barrage on the Ganges is also indispensable to save 37% area and 40 million people of Bangladesh. This would certainly assist us to transform southwest region into economically vibrant, ecologically healthy, and turn the environment congenial and pleasing. Whatever the situation would be, we should make our own defense by keeping these rivers alive by any means.
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