পানি সম্পদ পরিকল্পনা সংস্থা (ওয়ারপো)

Name of the Project: Assessing Sedimentation in Long-Term Morphological Time-Scale in GBM Delta

1. Introduction

Bangladesh lies at the heart of one of the world's largest and most dynamic river deltas—the Ganges-Brahmaputra-Meghna (GBM) delta. Understanding sedimentation patterns in this complex system is essential for sustainable land formation, floodplain management, and long-term water resources planning. This research initiative is a continuation of the recently completed WARPO-BUET collaborative project, which has studied floodplain sedimentation and various sediment management strategies in the Bangladesh delta based on short-term simulation (one hydrological year) using the Bangladesh Delta Model (BDM). On the basis of that study, the present study will assess sedimentation in the GBM delta over a long-term morphological time-scale.

2. Rationale of the Research

All previous studies related to sedimentation show that sedimentation potential in the floodplains of the GBM delta seems to be very high concerning the delta building process. The results of these studies show the sensitivity of sedimentation analysis on spatial and temporal scales. For a conclusive statement on the sediment distribution, sedimentation potential, and sediment management strategy for the GBM delta, a delta-level spatial-scale and long-term morphological time-scale analysis is required.

All the conclusions in the WARPO-BUET project (WARPO and BUET, 2022) related to sedimentation on the delta floodplains and impacts of sediment management options (e.g., cross-dams and dredging) were made based on short-term (one hydrological year) simulation of BDM. The sediment management options were also assumed to be executed in isolation. The validity of the conclusions over long-term morphological timescales was not assessed, nor were the combined impacts of multiple sediment management interventions. Additionally, the optimal sequence for implementing these options—aimed at maximizing positive impacts and minimizing negative ones—was not explored. The proposed research project is designed to address these research gaps.

3. Research Objectives

This research study has the following proposed objectives related to GBM delta:

• Assess sediment balance considering long-term morphological time-scale
• Assess long-term sedimentation rate on the delta floodplains
• Assess long-term impacts of sedimentation due to various sediment management strategies.

4. Research Methodology

The research will adopt the following methodologies to achieve its objectives:

1. Continuing application of Bangladesh Delta Model (BDM)
2. Additional Validation of BDM with Measured Sedimentation Data
3. Long-term Simulation of BDM
4. Determining an Effective Long-term Sediment Management Strategy.

5. Expected Result

Expected results from the research are as follows:

1. Distribution of incoming sediments in the delta through different rivers, estuaries, floodplains, ocean, and re-entry to the estuarine systems
2. Quantification of sedimentation rate on the floodplain of the delta in long-term morphological time-scale
3. Recommendation on effective sediment management strategy which will be sustainable in a long-term morphological time-scale.

6. Present Progress

Contract of Agreement (CoA) has been signed between WARPO and IWFM, BUET on 24 May, 2025. The project is scheduled to run for 24 months following the signing of the contract. Meanwhile, Technical Committee, and Research Team have been formed to ensure the effective operation of the research project. Additionally, the Inception Report of the research project has been submitted by IWFM, BUET to WARPO in June, 2025. The national workshop on Inception report will be held soon.