Abstract:
Uniformly raising the land inside a beel and maintaining proper drainage capacity of the
river are the two mam objectives of TRM, However, it is observed that sedimentation
inside the beel is nol uniform in Beel Kedana and East Beel Khuksia due to the lack of
social and technical limitations in TRM operation The present practice of TRM operation
is to construct a link canal to connect the beel with the river. This results in sediment
deposition at the mouth of the link canal, preventing further sedimentation inside the beel
Tnthis study sediment management options for uniform silt depOSItion in tidal basins have
been alentified in a participatol)' approach, Three options for sediment management inside
the tidal basins have been identified through FGDs and consultation with the local
stakeholders, In Option-l, each beel is divided into 1hree compartments by constructing
embankment around the compartment and allowing sedimentation in the compartments one
after another. In Option-2, embankments are constructed along both banks of the main
khals through the beel and cutting the embankment part by part gradually from upstream to
downstream. TnOption-3, all existing khals are connected with the river at the same time by
constructing link canals, i.e, allowing sedimentation in the whole basin al the same time,
Technical feasibility of these options has been assessed by a cohesive sediment transport
model using MIKE21 FM modeling system,
Net deposition in East Beel Khuksia and Beel Kapalia for the three options IS evaluated.
The net deposItion volume after 4years in the OptlOn-l, Option-2 and Option-3 are 3,58,
4.51 and 2.6] mlilion m' respectively in East Beel Khuksia, and 3.40, 3.43 and 2.45 million
m' respectively in Beel KapaJia. Maximum deposition was observed for Option-2. The net
s<"hment deposition and areal extent of deposition increase after dredging of kbals So, for
uniform sediment deposition inside the tidal basin, dredging of khals Inside the heel under
TRM operation is required within three to four months. It is also seen that the maximum
and minimum net deposition occur for Option"2 and Option-3 respectively in both beels,
Besides, net deposllion volume is higher in Easl Beel Khuksia than Beel Kapalia because
EastBeeJ Khuksia is located at the downstream of the Han river,
•
The total costs of opemtion for TRM In East Beel Khuksia and Beel Kapalia have been
estimated. The minimum cost is required for Option.2 in both beels.
Stakeholder consultation VIlIS carried out to finalize the acceptable option(s) fur sediment
management inside -thetidal basin. After detailed discussions and consideration of different
aspects of sediment management, it is appears that Option-2 is preferred by most
stakeholders in the area.
