Low cost natural dredging

Dredging can be conducted in natural ways such as applying Bandalling techniques which use locally available materials like bamboo, wood etc

Bangladesh is spending huge amount of   hard-earned money to control flood, river bank erosion and to increase depth of navigational channels but people of this poor country are getting poor benefit . We got a lot of very good experience of increasing depth of  river Jamuna-Brahmaputra, the Ganges-Padma, Meghna, Surma and Kushiyara from time immemorial ( from British period) by Bandalling  and vessels/ships/steamers could ply safely during dry season in those alluvial and meandering rivers. A joint study by prof.  Md. Mansur Rahman & Prof. Anisur Rahman of BUET in collaboration with Prof. Hajime Nakagawa & Prof. Taisuke Ishigaki of Disaster prevention Research Institute of Kyoto University, Japan with the assistance of  River Research Institute, Faridpur in 2004-05   found that dredging is very expensive (about 10 times) as compared with the Bandals in order to maintain navigational channels. There conclusion was—Bandals are much cheaper method as compared with dredging option to provide required flow depth for  safe navigation. Dredging in alluvial rivers like Jamuna-Surma-Kushiyara-Padma/Ganges are not sustainable even for one  season. Towards the development of sustainable solution to maintain the navigability, BANDALs or combination of  Bandals and dredging may provide the desired solution.  Channel depth could be increased 8 to 10 ft by Bandalling . In the alluvial rivers with erodible boundaries the bank erosion is drastic and channel width increases in an order of several hundred meters per year  . As a result the major rivers in Bangladesh are shifting their courses every year creating acute problems at the local and national levels. To minimize these sufferings based on the working principles of BANDALs, an idea is developed so that it can be used to stabilize rivers’ courses for long term basis in a step by step manner. River flow are suddenly disturbed by Spur-dyke-Like structures   and consequently their responses are big against such interventions. Therefore water courses cannot be stabilized for long term basis. The gradual encroachment towards the lateral directions using  BANDALs  create less disturbance to the rivers and the rivers  can get sufficient time for it’s  adjustment and new bank line development. The study concluded—BANDALs   have positive impact for the increase of navigational flow depth  in alluvial rivers. The out put of the research for the stabilization of river  courses can solve the problems of Bangladesh that is more or less inherent due to the complex geographical location at the lower riparian of the catchment. From experimental and theoretical analyses, it is found that BANDALs are capable for flow diversion towards the main channel leading to deep navigational channel formation. On the other hand  flow velocities are reduced near the river bank lines that ensure  bank protection. In addition to this , the local scours around these structures are much less than it is the case of impermeable Groins. Therefore Bandals would be less expensive  solution over conventional methods. Another important feature  of Bandal is that the lateral interventions can be extended gradually that can be possible using conventional structures, such as Groins, Revetments.

Prof. AKM   Saiful Islam of  IWFM, BUET  wrote an article in the daily Independent on 30th August  about Flood control where  he sincerely opined-- Dredging can be conducted in natural ways such as applying  Bandalling techniques  which use locally available materials like bamboo, wood etc. Other low-cost natural dredging options can be explored  to improve  water conveyance capacity  of the river and reduce flood peaks .   

The  experts of  Dutch DHV  reported in 1988 for allocation of fund Tk. 20.00 lacs  to 2.00 crores per year for BIWTA conservancy & Pilotage department but the Authority could not pay attention to this low-cost natural dredging which is about  10 times less than dredging. Dredging is essential I do emphasize on continuous dredging also. For the last 3 years BIWTA C&P department was not able to install Bandals in Jamuna and Surma-Kushiyara rivers due to various obstructions  and hindrances resulting in the channels got huge sediments and safe navigation hampered a lot . The Authority is doing penny wise—pound folish decision about the very conventional Low-cost natural dredging i.e. Bandalling  systems for their ignorance and unholistic consideration for improvement of navigational channels in Jamuna/Brahmaputra, Ganges/Padma, Upper Meghna, Surma & Kushiayra alluvial rivers. Where BUET IWFM, IWM of BWDB, RRI, experts of Japan, India and the old  experienced Officers of CPD, BIWTA are in the same opinion that to save money and to control flood, river bank erosion and to increase depth of main channels BANDALLING is very essential in the begining of November every year till 31st March . I would like to request the Ministry of Shipping, BIWTA and BWDB to reconsider the  Low-cost Natural Dredging=Bandalling with Bamboo, Bamboo-made mats, jute ropes, wood, small trees, etc which is very(R) effective for our poor developing nation .

Last year I had the opportunity to be a very small project Director of   Protection river bank erosion by Bandalling  under Ministry of Science & Technology at the request of DG of RRI Dr. Engr. Lutfor Rahman where we submitted the project proposal to install/erect  Bandals in 3 spots of Barishal, Patuakhali & Khulna and estimated cost was 65.00 Lacs taka but sanctioned only 2.00 lacs taka . Since our honourable P.M. has given emphasis on research but the MoST was kind enough to sanction only taka 2 lacs for which NOAMI got 20% and other expenditure are almost half of the 2 lacs taka. So how could we do better work with such meagre amount.  I think our benigh Govt. will look into the matter. Ameen.

The writer is the  river researcher and former director of BIWTA.

[email protected]  

 

Low cost natural dredging

Dredging can be conducted in natural ways such as applying Bandalling techniques which use locally available materials like bamboo, wood etc

Bangladesh is spending huge amount of hard-earned money to control flood, river bank erosion and to increase depth of navigational channels but people of this poor country are getting poor benefit . We got a lot of very good experience of increasing depth of river Jamuna-Brahmaputra, the Ganges-Padma, Meghna, Surma and Kushiyara from time immemorial ( from British period) by Bandalling and vessels/ships/steamers could ply safely during dry season in those alluvial and meandering rivers. A joint study by prof. Md. Mansur Rahman Prof. Anisur Rahman of BUET in collaboration with Prof. Hajime Nakagawa Prof. Taisuke Ishigaki of Disaster prevention Research Institute of Kyoto University, Japan with the assistance of River Research Institute, Faridpur in 2004-05 found that dredging is very expensive (about 10 times) as compared with the Bandals in order to maintain navigational channels. There conclusion wasBandals are much cheaper method as compared with dredging option to provide required flow depth for safe navigation. Dredging in alluvial rivers like Jamuna-Surma-Kushiyara-Padma/Ganges are not sustainable even for one season. Towards the development of sustainable solution to maintain the navigability, BANDALs or combination of Bandals and dredging may provide the desired solution. Channel depth could be increased 8 to 10 ft by Bandalling . In the alluvial rivers with erodible boundaries the bank erosion is drastic and channel width increases in an order of several hundred meters per year . As a result the major rivers in Bangladesh are shifting their courses every year creating acute problems at the local and national levels. To minimize these sufferings based on the working principles of BANDALs, an idea is developed so that it can be used to stabilize rivers courses for long term basis in a step by step manner. River flow are suddenly disturbed by Spur-dyke-Like structures and consequently their responses are big against such interventions. Therefore water courses cannot be stabilized for long term basis. The gradual encroachment towards the lateral directions using BANDALs create less disturbance to the rivers and the rivers can get sufficient time for its adjustment and new bank line development. The study concludedBANDALs have positive impact for the increase of navigational flow depth in alluvial rivers. The out put of the research for the stabilization of river courses can solve the problems of Bangladesh that is more or less inherent due to the complex geographical location at the lower riparian of the catchment. From experimental and theoretical analyses, it is found that BANDALs are capable for flow diversion towards the main channel leading to deep navigational channel formation. On the other hand flow velocities are reduced near the river bank lines that ensure bank protection. In addition to this , the local scours around these structures are much less than it is the case of impermeable Groins. Therefore Bandals would be less expensive solution over conventional methods. Another important feature of Bandal is that the lateral interventions can be extended gradually that can be possible using conventional structures, such as Groins, Revetments. Prof. AKM Saiful Islam of IWFM, BUET wrote an article in the daily Independent on 30th August about Flood control where he sincerely opined-- Dredging can be conducted in natural ways such as applying Bandalling techniques which use locally available materials like bamboo, wood etc. Other low-cost natural dredging options can be explored to improve water conveyance capacity of the river and reduce flood peaks . The experts of Dutch DHV reported in 1988 for allocation of fund Tk. 20.00 lacs to 2.00 crores per year for BIWTA conservancy Pilotage department but the Authority could not pay attention to this low-cost natural dredging which is about 10 times less than dredging. Dredging is essential I do emphasize on continuous dredging also. For the last 3 years BIWTA CP department was not able to install Bandals in Jamuna and Surma-Kushiyara rivers due to various obstructions and hindrances resulting in the channels got huge sediments and safe navigation hampered a lot . The Authority is doing penny wisepound folish decision about the very conventional Low-cost natural dredging i.e. Bandalling systems for their ignorance and unholistic consideration for improvement of navigational channels in Jamuna/Brahmaputra, Ganges/Padma, Upper Meghna, Surma Kushiayra alluvial rivers. Where BUET IWFM, IWM of BWDB, RRI, experts of Japan, India and the old experienced Officers of CPD, BIWTA are in the same opinion that to save money and to control flood, river bank erosion and to increase depth of main channels BANDALLING is very essential in the begining of November every year till 31st March . I would like to request the Ministry of Shipping, BIWTA and BWDB to reconsider the Low-cost Natural Dredging=Bandalling with Bamboo, Bamboo-made mats, jute ropes, wood, small trees, etc which is very(R) effective for our poor developing nation . Last year I had the opportunity to be a very small project Director of Protection river bank erosion by Bandalling under Ministry of Science Technology at the request of DG of RRI Dr. Engr. Lutfor Rahman where we submitted the project proposal to install/erect Bandals in 3 spots of Barishal, Patuakhali Khulna and estimated cost was 65.00 Lacs taka but sanctioned only 2.00 lacs taka . Since our honourable P.M. has given emphasis on research but the MoST was kind enough to sanction only taka 2 lacs for which NOAMI got 20% and other expenditure are almost half of the 2 lacs taka. So how could we do better work with such meagre amount. I think our benigh Govt. will look into the matter. Ameen. The writer is the river researcher and former director of BIWTA. [email protected]