Paper ID:082 1st National Conference on Water Resources Engineering (NCWRE 2018) 21-22 March 2018, CUET, Chittagong, Bangladesh www.cuet.ac.bd
RANK BASED HAZARD SEVERITY ANALYSIS AFTER TIDAL RIVER MANAGEMENT (TRM) IN BEEL BHAINA
M. B. Edrish1*, S. Yeasmin1 & S. Rahman2
1, Department of Urban & Regional Planning, Khulna University of Engineering &
Technology, Khulna-9203, Bangladesh, <[email protected]>
1Department of Urban & Regional Planning, Khulna University of Engineering &
Technology, Khulna-9203, Bangladesh, <[email protected]>
2Department of Urban & Regional Planning, Khulna University of
Engineering & Technology, Khulna-9203, Bangladesh. <[email protected]>
*Corresponding Author
ABSTRACT
In Bangladesh, 19 districts are accounted as coastal zone and one-third of the total population lives in the south-west part of the country. To manage the entire area under the coastal zone, many initiatives are taken to control but some doesn’t work at all like Khulna Jessore Drainage Rehabilitation Project (KJDRP). The KJDRP became a great failure for building the embankment around the polder area to trap water which leads to flood, water logging, long-term salinity etc. in the affected area. To get rid of these consequences, general people cut the polder for allowing tidal flow and accumulating sedimentation inside the polders. These allowed the land to upgrade which termed as Tidal River Management (TRM). After cutting these, like other beels, Beel Bhaina became vulnerable to many disasters like river erosion, salinity, water logging, flood, drought following long-term land upgradation procedure. It was found that affected people reported a different kind of hazard in different parts of beel. The detection of hazardous areas and collection of information are conducted according to the ownership and activity of people. Beel Bhaina and its adjacent affected villages Agarhati and Bharat Bhaina in Keshabpur Upazila in Jessore were selected for the study focusing on the questionnaire survey. The objective of the study is to analyze the severity of one hazard which might need attention more than others and also find out the origins of that hazard. On the interpretation of these studies, the ranking procedure was conducted based on people’s opinion, affected area, time duration and economic losses and achieved highest scored hazard. Some hazards like water logging, salinity, river erosion, and drought have become more frequent in the area according to local people which lead to migration and infertility of land.
Keywords: TRM, Beel Bhaina, Hazard, Severity Analysis, Weighted Ranking.
INTRODUCTION
As most vulnerable region in the world, Bangladesh is vulnerable to climate change as well as sea level rise due to a continuous process of land subsidence (Huq et al., 1999). In southern part especially in Khulna Jessore District is facing huge amount of water logging problem in recent years.
Most of the part of that area specially beel area like Beel Bhaina, Beel Khuksia etc are inundated for long time which destroy the land fertility and increase salinity problem for long term. There was scarcity of dry cultivable land. To increase the amount of dry cultivable land, Tidal River Management (TRM) practice has been introduced by local people. Tidal River Management (TRM) is an eco-technological concept and designed to solve the water-logging problem and also improve the environment problem. (Amir et al., 2013). It was not originally conceived as a way to adapt to climate change, the technique employed may offer hope for communities as risk of sea level rise in similar areas (Oxfam, 2011). As unique indigenous ecological knowledge of river management and collective effort of local communities is to raise coastal land to a desired height. Bangladesh Water Development Board (BWDB) learned the concept in 1990s from the local communities and about 31.32 km2 of land had been raised by local communities themselves in Beel Bhaina and Beel Dakatiya applying TRM. (Kibria & Mahmud, 2010). It also found that flap gate is used to control the salinity of water by reducing the discharge of brackish water in agriculture land. In this project, the environmental impact assessment has not been done. (Kibria & Mahmud, 2010).After then, the govt.
took this coping strategy to control river sedimentation. It also increases the navigability of rivers.
Because of coastal embankment, the tidal wetland has experienced severe environmental impairments in this region. (Rejve, 2006). For long term inundated under saline water, it increased the effect of different type’s hazard according to local people. Many people’s land face water logging still now, some response to river erosion, some land near river still face flooding during tidal wave and salinity intrusion is common to all for they face this kind of phenomena all the year round. The main purpose of the study is to identify the most divested hazard which is faced and affected by local people living around and in Beel Bhaina.
METHODOLOGY
The whole study was conducted on the basis of focusing three parts. (1) Study area selection, (2) Data collection procedure and (3) Rank Based Hazard Severity
Study Area Selection
Under Gaurighona union, Agarhati Bharat Bhaina village is one of the well-known parts of Keshabpur upazila because of Tidal river management. The project area is situated on beside of Bharat Bhaina north-south and east of the Hari river and Sherpur of Raghunathpur, the west-Bherchi village. It is located on 22°52’00” north latitude and 89°22’00” east longitudes. The main area of this assessment was on the adjacent villages. The total beel area is 600 acres. (Sengupta, 2009)
Fig. 1: (a) Study Area, (b)Location of Tidal River Management Project Site in Gaurighona Union Data Collection Procedure
For ranking hazard severity analysis, Data have been collected from primary data source. Primary data collections are based on questionnaire survey and Participatory Rural Appraisal (PRA). In questionnaire using stratified sampling, the sample size determined was 284 but for lacking of manpower, 100 households were surveyed finally. Data had been collected with the following timeline before implementation of TRM practice October 1997 and after implementing TRM the time line is December 2001 to current.
Rank Based Hazard Severity
Assessment of People’s opinions is giving for different kind of hazard problems. In the study area it is important to find out the most effected hazard which could possibly affected the people. So, in here, it is found that water logging problem gets the highest responses. For TRM practice people mostly feel water logging and salinity problem is emerging. This problem is supposedly reduced after implementing TRM but the problem is still present. Third problem is River Erosion which induces after TRM. This causes loss of land in huge amount than before. Lots of people claimed there are being affected by losing land. For changing the topographical condition and reducing the amount of wet land, there is some place which faces drought problem now and then. Especially in the month of April to June, Flood is also found for tidal surge but the amount is not as noticeable.
Table 1: Hazard severity problem ranking
Problem Peoples opinion Score Remarks
Water logging 95 10 0-10=1
11-20=2 21-30=3 31-40=4 41-50=5
51-60=6 61-70=7 71-80=8 81-90=9 91-100=10
River Erosion 76 8
Salinity intrusion 88 9
Flood 46 5
Draught 57 6
10= Highly importance, 1= Low importance
Assessment is given for different amount of affected area to different kind of hazard problems. Area is very important in assessing the problem severity. In the data view, the water logging and Flood problem in study area is huge than any other hazard. This is because the severity of this problems greater.
Table 2: Problem ranking based on affected area
Problem Affected area (sq. m) Score Remarks
Water logging 11758.27 3 0 to 5000 sq.m=1
5001 to 10000 sq.m=2 10001 to 15000sq.m=3
River Erosion 308.2655 1
Salinity intrusion 5153.45 2
Flood 14281.93 3
Draught 7467.54 2
3= Highly Affected area, 1= Low affected area
Fig. 2: Different hazard affected area identify
This analysis has been conducting with the following PRA techniques (i.e. focus group discussion.).
Assessment is given for different time duration of different kind of hazard problems. The long-time duration may cause loss of livelihood and also production. So, it is important to identify the long term affected hazard. Example like, long term saline water intrusion can cause damage of land fertility and also cause damage to the structure.
Table 3: Problem ranking based on time duration
Problem Time duration (month) Score Remarks
Water logging 3 1 1 month-4 month=1
5 month-8 months=2 9 month-12 months=3
River Erosion 12 3
Salinity intrusion 9 3
Flood 3 1
Draught 6 2
3= Long term affected, 1= Short term affected
Assessment is given for income loss of different kind of hazard problems. The study has been found that around 46% people’s income have negative impact means they lost their income after TRM. So, scoring of these criteria has been selected according to the range of income loss with the percentage of people’s number. Like within TK. 500 to 1000 income loss have been faced by 59% people who responses River Erosion as less loss problem.
Table 4: Problem ranking based on loss of income
Problem Loss (income loss) Score Remarks
Water logging 43.47% 2 TK.500-1000=Less Loss=1 TK.1001-2500=Moderate Loss=2 TK.2500-5000=High Loss=3
River Erosion 59% 1
Salinity intrusion 43.47% 3
Flood 50% 2
Draught 50% 1
3= High amount of loss, 1= Low amount of loss
According to importance of criteria, the weight has been provided. People’s opinion has been collected primarily, affected area is collected with Focus group discussion and secondary data collection, and time duration is collected with focus group discussion and at the last loss of income collected with questionnaire analyzed data.
Table 5: Weighted according to priority basis
Criteria Weight according to priority
Peoples opinion 40
Affected area 30
Time duration 20
Loss 10
So, the final scoring has been provided with numerically to find out the top most important hazard.
Table 6: Scoring on problem based on different criteria
Problem Ranking of criteria Final score
Peoples opinion Affected area Time duration Loss Score
Water logging 10 3 1 2 530
River Erosion 8 1 3 1 420
Salinity intrusion 9 2 3 3 510
Flood 5 3 1 2 330
Draught 6 2 2 1 350
Final Scoring= Peoples opinion˟40+ Affected area˟30+ Time duration˟20+ Loss˟10
From the calculation it is found that the final score is highest for Water logging and lowest for flood.
Table 7: A comparison among hazard based on Final score
Problem Score Ranking
Water logging 530 1
River Erosion 420 3
Salinity intrusion 510 2
Draught 350 4
Flood 330 5
RESULTS AND DISCUSSIONS
Overall findings from the study have been gathered to identify the core reason why hazard become main concern for Beel Bhaina adjacent living community after TRM. The findings are given below:
After TRM, River Erosion problem has been introduced. In recent years 61.1 sq. m is being gone to river bed. Mostly these lands come from settlement.
In Beel area, the elevation has been only emerged the point of river water entrance and its some adjacent areas.
All the year round the land becomes flooded with saline water through swage gate of Beel Bhaina but after rainfall the Hari river supply fresh water
The amount of respondent outside the Beel area also affected by River Erosion.
Water logging and Flood is reduced but salinity, river erosion increased.
For changing topographical condition and reducing wet land, some place faces drought problem now and then.
The time duration for Boro rice with water logging is quiet adjusting.
Water logging problem getting highest response among all kind of hazard not only in public response but also other secondary issues of assessment.
Specific Water Logging Problem Analysis
For high scoring of water logging problem, the analysis has been conducted more precisely than other problems. The reason behind this problem is the low elevation for specific area. For 18 years of siltation in Beel area, there very few areas have been enabled to emerge. In far most the siltation in first 2 years is marvelous but after that the process is slow. The elevation has been only emerged the point of river water entrance and its some adjacent areas. The inside area has been untouched but at some point, the elevation is around 1m. (Data source: Terrain website)
After implementation of initial TRM practice, BWDB appointed SWMC (Surface Water Modeling Centre) for monitoring and evaluation of TRM. They worked for 27 months since February 2000 to April 2002. Beel Bhaina has been cut unplanned way as like Beel Dakatia. In November 1997, local people decided to open the Beel Bhaina of the Hari River System and the embankment was cut in two places. One of these cuts was closed towards the end of 1998 but cut again in February 1999. In the process, Beel Bhaina started to function as tidal basin. Both cuts are closed in 2001 (Alam, Undated).
During this period about 600-acre land of the Beel area reclaimed from severe water-logging (CEGIS, 2003). After monitoring of 27 months, the SWMC had left the Beel. This long time Beel have not being monitored or maintained the siltation process. So, this cause slows the siltation process. There is another analysis showed the data that the land has been emerged near the river area. To make the progress speedy there is need systematic management and control of sedimentation.
Figure 4: Land elevation with contour line and affected study area
For water logging there is a possible reason found in flow direction map in figure that the flow of water come from upper portion of Beel. This may be caused for Beel Khuksia. Beel Khuksia is still under developed which cause water flow directed to middle space of Beel Bhaina. In river basin one at a time only one Beel should be used as a tidal basin for TRM. (Shampa and Paramanik, 2012) this will help to maintain the biodiversity of other Beel. But in this case Beel Bhaina and Beel Khuksia both are being used as TRM practice which may cause these phenomena.
Before and After TRM Overall Problem of Water Logging
From different timeline, water logging affected in different land use in differently. 48.1% agriculture present in Beel Bhaina in between 2 villages. But with time the amount is changing. It is decreasing
around 3.5% and this also cause reduction in settlement. This data provides the understanding that water logging problem reduce with time. Within available area of use, this problem is losing its tale.
Table 8: Overall Problem of Water Logging Before and After Tidal River Management Type of
land Overall problem before
water logging Total Overall problem after water
logging Total
Yes No Yes No
Agriculture/
shrimp 48.1 4.7 52.8 44.58 8.44 53.02
Settlement 40 1.2 41.2 38.55 2.41 40.96
Commercia l
6 0 6 4.82 1.2 6.02
Total 100 100
Deposition in the basin is high at close to the opening and less at the furthest end of the basin, which varies from few 10 of cm to more than 2 m at Beel Bhaina (Ullah and Rahman, 2002). After closing of Beel Bhaina tidal basin, the Beel has been brought under agriculture practices. However, the uneven sedimentation is causing drainage congestion in some parts of the Beel (Paul and Nath, 2011).
Tidal basins to control riverbed sedimentation are not only used in tidal rivers in the southwest delta of Bangladesh. It is also found similar water management practices in the Netherlands, the United States and Belgium in tidal rivers. In some cases, it is also found an economically and environmentally sustainable alternative to dredging or pollution control. (Die, 2013). Some Study provide positive response on this matter. Uttaran and communities involved in the project worked with the institute of water modelling to conduct a detailed technical study and monitoring survey on one of the TRM sites, Bhaina Beel, and found that TRM had helped increase river flow and depth and had reduced the incidence of water logging. (Oxfam,2011)
CONCLUSIONS
The research was conducted to identify the impact on Beel Bhaina after implementation of TRM. The assessment of People’s opinions and analyzing the claim of arising different kind of hazard. In the study area it is important to find out the most effected hazard which could possibly affected the people. Not only the data was analyzing in the base of people’s opinion but also data was justifying with other factors. So, the result came up as water logging and it was proved that water logging I the main reason which imposed the hazardous situation. TRM have long term affect in human life as well as climate change. It catalyst the hazard very gradually.
REFERENCE
SAlam, AT, Undated. River Management in Bangladesh: a people's initiative to solve water-logging.
Amir, SII; Khan, MSA; Khan, MMK; Rasul, MF and Akram, F. 2013. “Tidal River Sediment Management–A Case Study in Southwestern Bangladesh,” World Academy of Science, Engineering and Technology International Journal of Civil, Environmental, Structural, Construction and Architectural Engineering Vol:7, No:3.
CEGIS. 2003. Monitoring and Integration of the Environmental and Socioeconomic impacts of implementing the Tidal River Management option to solve the problem of drainage congestion in KJDRP area, Center for Environmental and Geographic Information Services (CEGIS), Dhaka, Bangladesh.
Die, LD. 2013. Tidal River Management Temporary depoldering to mitigate drainage congestion in the southwest delta of Bangladesh; Wageningen University, Netherlands.
Huq, S; Karim, Z; Asaduzzaman, M and Mahtab, F. 1999. Vulnerability and Adaptation to Climate Change for Bangladesh. 10.1007/978-94-015-9325-0.
Kibria, Z and Mahmud, I. 2010. “Tidal River Management (TRM): Community Struggle for Indigenous River management and Climate Change Adaptation in Southwest Coastal Region of Bangladesh,” in Rivers & Communities, Uttaran, Dhaka, Bangladesh, issue 1, Volume 1,
Oxfam. 2011. “Review of Climate Change Adaptation Practices in South Asia”. Available at:
http://www.oxfam.org/sites/www.oxfam.org/files/rr-climate-change-adaptation-south-asia-161111- en.pdf. [Accessed 7 January 2016].
Paul, A; Nath, B and Abbas, R. 2013. Tidal River Management (TRM) and its implication in disaster management: A geospatial study on Hari-Teka river basin, Jessore, Bangladesh, International Journal Of Geomatics And Geosciences, Volume 4, No 1.
Rejve, K. 2006. Changes In Livelihood Pattern Of Inhabitants In Waterlogged Areas In South-West Region In Bangladesh. Master Degree Thesis, BRAC University, Dhaka, Bangladesh. Available at:
http://dspace.bracu.ac.bd/xmlui/handle/10361/1383 [Accessed 11 January 2016]
Sengupta, S., 2009. In Silt, Bangladesh Sees Potential Shield Against Sea Level Rise. [Online]
Available at: http://www.nytimes.com/2009/03/20/world/asia/20bangla.html?_r=2&ref=earth&
[Accessed 19 February2018].
Shampa, MI and Pramanik, M. 2012. Tidal River Management (TRM) for Selected Coastal Area of Bangladesh to Mitigate Drainage Congestion, International Journal of Scientific and Technology Research, 1(5), 2012, 1-6.
Terrain 2016.Zonums: Free software tool [online]. Available at:
http://www.zonums.com/gmaps/terrain.php?action=sample. [Accessed 12 February 2016]
Ullah, WM and Rahman, R. 2002. Tidal River Management: A Sustainable Solution to Drainage Congestion in the Coastal Region in BAPA (ed), Bangladesh Environment, Dhaka, 2, pp 1022-1032.
