Shagorkhali Borobeela Drainage Modelling

Location

South West Region of Bangladesh

Type of Project

Drainage Improvement

Period of Study

1999-2001

Client

Bangladesh Water Development Board (BWDB)

Map showing development scenario in Sagarkhali-Borobeela Drainage Project

Description

Mathematical Modelling and Detail Feasibility Study for Sagarkhali-Borobeela Drainage Project are mainly focused on drainage congestion at two locations lying within the Ganges Kobadak (G-K) Project, i.e, Sagarkhali and Borobeela basin. The Kumar-Nabaganga river system is the drainage system of the entire G-K project. The Sagarkhali and Borobeela basins are connected to Kumar and Nabaganga drainage system respectively. The basin reas of Sagarkhali and Borobeela are 37,500 ha and 21,295 ha respectively. These two drainage systems are inter-dependent and as such integrated study of the two locations was necessary.

The project was taken up under the Fifth Five Year Plan of Bangladesh. The ‘perspective plan’ of the project is to boost the agricultural production, increase farm income and generate employment opportunities in the area. To achieve these targets, it is required to generate improved drainage congestion in the area, create scope for water conservation, improved water management facilities and increased irrigation potentials for the beneficiaries to manage the existing facilities.

An integrated approach through mathematical model has been attempted to identify and solve the Sagarkhali-Borobeela Drainage problems created by canal systems of the G-K project. Mathematical model runs were carried out to establish the option studies, which were earlier identified by socio-economic and environmental studies and validated through People’s Rural Appraisal (PRA) surveys.

The findings from the model runs were presented in the form of flood maps for decision makers and engineers to comprehend the impacts.

In all 11 improvement scenarios have been tested for Sagarkhali basin and 4 options tested for the Borobeela basin. The recommended option for Sagarkhali includes, construction of ungated syphon at Amla and Azampur under the Ganges main canal, re-excavation of Sagarkhali khal, Chapai khal, Kumar river, D1SK and D10SK khal, expansion of existing bridge opening on Chapai khal at Ujangram and construction of footbridges.

For Borobeela Basin the option includes construction of regulator on Alamkhali khal near the outfall with Fatki river, construction of regulator on Haworkhali khal near the outfall with Fatki river, re-excavation of Alamkhali and Haworkhali khal, Fatki river and existing internal khals, re-modelling of Narayankhali regulator on D1N and reconstruction of regulator at the outfall of D4N khal.