Surface Water Modelling Centre

Surface Water Modelling Centre (SWMC) an independent trust established by the Ministry of Water Resources, Government of the People's Republic of Bangladesh. The origin of SWMC dates back to 1986 when Surface Water Simulation Modelling Programme, Phase-I (SWSMP-I) was launched by the government with the assistance of United Nations Development Programme (UNDP). The programme was aimed at implementing an advanced computer-integrated technology for simulation of rivers and flood flows in the complex surface water systems of Bangladesh.

The successful completion of SWSMP-I led to SWSMP-II in 1990, funded by the Government of Bangladesh (GOB) and the Danish International Development Agency (DANIDA). SWMC was established for institutionalising the transfer of related technology on mathematical modelling. SWSMP-II was followed by SWSMP-III. Meanwhile SWMC began to emerge as an autonomous trust with the mandate of operating as a commercial organisation to work for national and international clients. SWMC Trust came into being in January 1997 and started operation as a self-administered national organisation under Trust Act. Board of Trustees is the governing body of SWMC and gives policy and guidelines to the management. Thirteen trustees have been drawn from different ministries, departments and organisations of Bangladesh and outside.

SWMC (the then SWSMP-I) entered the arena of mathematical modelling in 1986. Since then the entire Bangladesh has been brought under review by the method of mathematical modelling with the General Model and six Regional Models which are calibrated each year with the latest available data. The General Model includes three major rivers - the ganges, jamuna and meghna and a number of other large rivers covering the main drainage system of the country. These models have been extensively used in numerous water resources planning applications including the component studies of the flood action plan (FAP) which was initiated following the disastrous floods of 1987 and 1988. The country's Flood Forecasting and Warning Centre uses this model on a routine basis for generating flood level forecasts during the flood season. The General Model is also suitable for long term global planning.

The Regional Models cover the entire drainage system of the country's six regions, namely: northwest region, north-central region, northeast region, southeast region, Chittagong area, and southwest region. These models are capable of simulating the fast catchment response from foothill areas across the border, spill characteristics of the rivers, floodplain flows in the depression areas and tidal flows in the estuaries.

These models have been calibrated and verified for the last 10 years. The regional models are being used by both local and international organisations for carrying out water resource planning investigations at pre feasibility and feasibility stages and also for detailed investigation of local problems. In short the regional models provide the only framework of modelling studies in water resource related issues for the country.

SWMC represents one of the most comprehensive high quality computerised water resources, topographic and hydrometric database systems in Bangladesh, which are continuously being updated through collection of routine data from various agencies and also through SWMC's own field campaign. The database contains two categories of data, Temporal and Spatial. Temporal ie time series database comprises hydro-meteorological, climatic, salinity, water quality, sediments, groundwater level data while the Spatial Database comprises topographic data, river cross-section, river and coastal bathymetry, hydro geological, national coverage for rivers, roads and landuse data. As the national custodian of all the models SWMC also possesses other historical water resources planning databases.

Spatial information such as land levels, river coverage and infrastructure are also stored in digital format via a geographical information systems (GIS). SWMC embarked upon developing a central database system, where all types of data would be maintained under a united operating system with the provision of data querying, plotting, extraction and interfacing with advanced GIS software.

In addition to mathematical modelling study, system review, detail structural design and irrigation applications, SWMC is conducting a detailed topographic survey including an inventory survey of the existing hydraulic structures. To ensure precision and accuracy, the survey work is performed with advanced electronic equipment.

In the dry season, shortage of surface water is a significant problem in Bangladesh, which has made it strongly dependent on groundwater resources for dry season water supply and irrigation. During the last few decades, increased groundwater abstraction has led to drying up of wells and reduced crop yields in different parts of Bangladesh.

On the other hand, large surface water irrigation projects have been undertaken. In the context of this development, surface-ground water modelling is becoming one of the significant means of dealing with wide-range water management issues.

The combined use of both surface and groundwater is the current practice for reducing pressure on any particular source. With this objective, SWMC introduced a groundwater management model. It has been utilised for training purposes in the Jamuneshwari Basin Pilot Model study. Now it is being utilised effectively in the Fourth Dhaka Water Supply Project, the Meghna-Dhonagoda Irrigation Project and Pilot Research on Arsenic Contamination of Groundwater in the Sonargaon Thana Area.

Dhaka City has been suffering from waterlogging problems for decades. A moderate to heavy shower of rain can inundate many parts of the city, thus paralysing city life for hours. The situation was severe in September and October 1996 when city dwellers experienced the worst cases of waterlogging. SWMC carried out a pilot model study for establishing a Decision Support System to address the storm water drainage problems in Dhaka City. Storm water flow through the sewers and canals (khals) was simulated under extreme hydrological conditions during this study.

Bangladesh has an extensive coastal zone along the bay of bengal featuring estuaries, coastal plain, offshore islands and the world's largest mangrove forest, the sundarbans. The coastal environment is extremely dynamic as a result of the interaction between the tidal flow from the Bay of Bengal and the huge upstream discharge. Understanding of the coastal environment and its changing pattern is the key to managing the Sundarban's huge natural resources effectively. SWMC has actively participated in a major number of studies on coastal processes like cyclones and tidal surges.

The ecology of the Sundarban is largely governed by the interaction between fresh water from the upstream rivers and the saline water of the Bay of Bengal. Serious ecological changes have been observed recently, which are affecting the forest's natural resources. SWMC carried out a study for FAO/UNDP as part of the Integrated Resources Development of the Sundarban Reserve Forest. The hydraulic modelling study has improved the understanding of the dynamics of the water resources of the region including salinity intrusion and siltation of the estuaries. Linked to the GIS, the model results have been used in an integrated resource analysis and environmental impact study. The effect of seasonal and long-term hydrological trends on ecologically sensitive areas, forests and aquatic resources has been determined, with siltation and saline processes deriving from the model.

The arsenic concentration in groundwater has posed a serious threat to the country. The health of 50 million people is at risk. SWMC in association with other national institutions initiated a three-phase research project. The main objective of the study is to form a basis for modelling the related physical processes and formulate a watershed management strategy using mathematical modelling techniques.

Surface Water Modelling Centre has sustainable technological capability in developing mathematical models of both surface and groundwater systems. The application of SWMC modelling tools covers a wide range of water related issues such as: flood control, flood forecasting, irrigation and water resources management, river morphology, salinity and sediment transport, coastal hydraulics, environmental impact assessment and related infrastructure development. [Masud Hasan Chowdhury and Md Mahbub Murshed]