Mitigation possible

The Narod and Baral river basins in the Rennell's Map

BARAL is the most important distributor of the Ganges River on its left bank inside Bangladesh.  The other two branches on its left bank were Narod and Ichhamoti. Narod's source near Rajshahi town was naturally delinked during nineteenth century. Ichhamoti died only a few decades back, after the flood embankment along the left bank of Ganges River was imposed over it.  Baral also was affected by this, when a three vent regulator was imposed over its off-take near Charghat to check floods in the Natore and Pabna districts.
Bangladesh Water Development Board (BWDB) had two projects to intervene in the Baral basin areas. The Ganges Left Bank Embankment Project stretched through Godagari, Paba, Charghat, Bagha, Lalpur and Ishwardi upazillas, with 68 km embankment, 32 km canals and 3 regulators. The Baral Basin Development Project in Natore, Bagha, Lalpur, Baraigram, Bagatipara and Charghat upazillas had 195 km canals and 13 regulators. Those projects were to benefit 1,59,514 ha and 1,09,000 ha areas, but instead, they brought disaster in the Baral basin. The 3 vent head regulator at Charghat was the main reason for this disaster.
The Baral River alignment from its off-take passes from the high banks of the Ganges at an elevation 18m from mean sea level (MSL), towards the sloping grounds of the Chalan Beel. At its outfall in the Gumani River in Faridpur upazilla of Pabna district, the ground elevation is only 10m from MSL. The Baral River has several branches on its way down. Its 1st branch, the Musa Khan River, originates from its left bank at Hapania. It is an artificially cut navigational canal towards the north which joins the Narod and Hoja rivers. Its 2nd branch, the Nandakuja River, originates near Atghori from its left bank. Baral's total flow is now shifted to this branch, whereas the original flow towards Bonpara is now dead. Nandakuja, on its way towards northeast, receives the flow of Narod River and turns southeast to fall in the Gaur River at Gurudaspur. The Baral through Nandakuja is about 120 km long. Baral's another flow path from the right bank of Nandakuja River can be located near Ahmedpur, upstream of Bonpara Natore highway. This branch is now called the Old Baral River. This channel receives no flow from the Nandakuja, but joins the original Baral, and with the local drainage collections flows towards Chatmohor and to its outfall in Faridpur upazilla.
The present situation is more than a kilometer long off-taking channel in front of the 3 vent regulator of Baral and is heavily silted up. So, only overtopping flow from the Ganges is possible during floods. This 3 vent regulator was built in 1985. In 1995, a 5 vent regulator was built at Atghori. This regulator had definite purpose to divert Baral's flow to its original path where a one vent regulator has been put to limit its flow. But it had no success. A few kilometers downstream of the Atghori regulator, historical evidence of left out debris at several places show that attempts were made earlier to redirect the flow towards its original path, but failed. With this prevailing situation it appears that there is no chance of rejuvenating any of the old channels of Baral.      
The environmental impacts of the BWDB projects were heavy, particularly on the ecology and economy. Water flow to the Chalan Beel areas by the Atrai River from the north was stopped during autumn, winter, spring and summer by erecting earthen dams and using the water for irrigation. The Baral received no flow from the Ganges from October to May. The Musa Khan canal could feed both the downstream of Narod and Hoja Rivers by receiving flow from the Baral River, but restricting flow of Baral by its off-take regulator turned the Musa Khan into a narrow stream and caused the death of those two rivers. As a result, water bodies and fish stock in the Chalan Beel areas were reduced massively. Livelihood of a large section of people depending on those water bodies, animals and plants of the area was affected severely.
Floods in the Chalan Beel areas and in the Baral basin were reduced by the BWDB projects but there were severe environmental impacts. The people started campaigns locally for mitigation of their problems, and were supported by the environmentalists of the country. Several demands were made by the campaigners, particularly removal of the regulators on Baral, but BWDB is unlikely to accept them. A simple solution is possible. If the bed-flow level of the off-take regulator is reduced and its gates removed for a round-the-year inflow, the kilometer long silting in front of the regulator towards the Ganges can stop, and perennial flow can return. If perennial or environmental flow is achieved, major problems in the Baral basin will be mitigated automatically.

The writer is Chairman, Institute of Water & Environment.     E-mail: [email protected]