Biswas presents on Freshwater Resources in Bangladesh

At the 11th Conference on International Perspective on Water Resources and the Environment, held in Dhaka, Bangladesh, January 4-6, 2023, Nishan Kumar Biswas (617/UMBC) presented a talk on understanding the stresses on freshwater resources in Ganges Delta due to climate change and human impact using satellite observations. This conference was organized jointly by Environmental & Water Resources Institute, American Society of Civil Engineers and Institute of Water and Flood Management, and Bangladesh University of Engineering and Technology, Dhaka, Bangladesh.

Dr. Biswas presented on this topic as a part of NASA Earth Information System (EIS) - Freshwater, an open-science initiative. Part of his presentation focused on inland and coastal flooding in Ganges-Brahmaputra-Meghna delta, particularly in Bangladesh. During his visit to Dhaka, Dr. Biswas interacted with six government agencies to provide them with a better understanding of how they can benefit from NASA open-source models, datasets, and software. 

We followed up with Dr. Biswas to learn more about his research and findings.

A: We have been seeing that the terrestrial water storage (TWS), or the amount of water stored in lakes, rivers, soil moisture and groundwater, has been decreasing over time. It mainly started happening when Bangladesh has promoted heavy and unplanned groundwater abstraction to expand the dry season cropping (around the 1980s). In the same region, we also found that precipitation is decreasing and with that the dry season discharge of major rivers. This scenario worsens after having sea level rise in the Bay of Bengal, which is pushing the saltwater edge to the inland due to a decrease in the availability of upstream freshwater resources. 

A: Within the country, extensive and unplanned irrigation in many parts is the major human impact we have been seeing. The Ganges-Brahmaputra-Meghna basin is so big, and only 7% of the watershed area lies within Bangladesh, the most downstream country. So, the impact of upstream dams/barrages and other natural flow regulation activities that disrupted the flow of the transboundary rivers are also considered as the human impact. Groundwater resources along with surface water have been decreasing and saltwater is being pushed; thus, access to drinking water has been hampered in the southwest part of the country. Shifting from agriculture to aquaculture in the southwest region has been impacting the country's recent agricultural production.  

A: From the use of NASA datasets and software, the country can benefit in two ways. First, using all the remote sensing datasets, the relevant agencies can detect the key hydrological changes and take steps accordingly. For example, from MODIS satellite-based annual land cover maps, we found that the coastal land loss from 2000-2020 is around 500 km². From the MODIS Leaf Area Index (LAI) dataset, it was observed that the dry season cropping (locally known as "Boro") has increased significantly across the country. The second and the ultimate benefit from NASA EIS that Bangladesh can gain is a relative quantification of impact due to climate change and human impacts. This will help the government to understand that the impact has been caused by human activities across the delta, and they can take actions to minimize further impact on currently available freshwater resources.  

For more information about this study, Dr. Biswas provided these two helpful links: 

Nature comment article on the groundwater issue in Bangladesh:  https://www.nature.com/articles/d41586-022-03373-5

NASA EIS Veda dashboard story on this study: https://www.earthdata.nasa.gov/dashboard/eis/discoveries/eis-coastal-risks.