Dhaka city water logging hazards: area identification and vulnerability assessment through GIS-remote sensing techniques.

Water logging is one of the most detrimental phenomena continuing to burden Dhaka dwellers. This study aims to spatio-temporarily identify the water logging hazard zones within Dhaka Metropolitan area and assess the extent of their water logging susceptibility based on informal settlements, built-up areas, and demographical characteristics. The study utilizes integrated geographic information system (GIS)-remote sensing (RS) methods, using the Normalized Difference Vegetation Water and Moisture Index, distance buffer zone from drainage streams, and built-up distributions to identify waterlogged zones with a temporal extent, incorporating social and infrastructural attributes to evaluate water logging effects. These indicators were integrated into an overlay GIS method to measure the vulnerability level across Dhaka city areas. The findings reveal that south and south-western parts of Dhaka were more susceptible to water logging hazards. Almost 35% of Dhaka belongs to the high/very highly vulnerable zone. Greater number of slum households were found within high to very high water logging vulnerable zones and approximately 70% of them are poorly structured. The built-up areas were observed to be increased toward the northern part of Dhaka and were exposed to severe water logging issues. The overall findings reveal the spatio-temporal distribution of the water logging vulnerabilities across the city as well as its impact on the social indicators. An integrated approach is necessary for future development plans to mitigate the risk of water logging.

Does anthropogenic upstream water withdrawal impact on downstream land use and livelihood changes of Teesta transboundary river basin in Bangladesh?

This article evaluates the impact of upstream water withdrawal on downstream land use and livelihood changes in the Teesta River basin, using a combination of geospatial and social data. Results show that water bodies gradually decreased, indicating a low volume of water discharge from upstream of the Teesta River basin due to the construction of several barrages. During the study period, a significant change in the area of water bodies was observed between 2012 and 2016, from 881 to 1123 Ha, respectively. The cropland area increased because farmers changed their cropping practice due to water scarcity and floods. Trend analyses of riverbank erosion and accretion patterns suggest an increase in accretion rates compared to the rate of riverbank erosion. A household survey was conducted using a self-administered questionnaire where 450 respondents have participated (farmers: 200 and fishermen: 250). Survey results show that most of the farmers (65.5%) and fishermen (76.8%) think that the construction of upstream barrages caused harm to them. The majority of farmers and fishermen feel water scarcity, mainly in the dry season. We found that a large number of participants in the study area are willing to change their occupations. Furthermore, participants observed that many local people are migrating or willing to migrate to other places nowadays. Our study also found that farmers who face water scarcity in their area are more likely to change their location than their counterparts, while those who face problems in their cultivation are less likely to move. On the other hand, upstream barrages, fishing effects, and getting support in crisis significantly predict fishermen's occupation changes. We believe our results provide essential information on the significance of transboundary water-sharing treaties, sustainable water resource management, and planning.

Dhaka landfill waste practices: addressing urban pollution and health hazards.

Two Dhaka, Bangladesh, landfills are explored to understand how management practices impact environmental quality and public health in the surrounding areas. A combination of research methods is used, such as geospatial buffer zone analysis, semi-structured observation checklist and qualitative interviews, to gain an understanding of the waste transportation, leachate percolation, and adverse health and environmental effects. A multi-ring buffer zone and ground truth method were applied through ArcMap for the spatial distribution of landfill-adjacent environmental features. Qualitative interviews were conducted with landfill officials and nearby residents. Findings reveal that landfills are situated very close to residential areas, water bodies and agricultural lands, exposing them to various health and environmental hazards. Improper solid waste management practices of the landfills cause adverse environmental effects by leachate percolation, waste incineration and vector breeding. Adjacent dwellers suffer from bronchial diseases, pneumonia, diarrhoea, itching problems, headache and appetite loss. The existing solid waste management system requires managerial and technical modifications to reduce the associated environmental pollution and health hazards.

Environmental sustainability assessment due to stone quarrying and crushing activities in Jaflong, Sylhet.

Quarrying and crushing activities constitute a major threat to the environment and occupational health of the workers in Jaflong, Sylhet. This study aims to determine the environmental sustainability of stone quarrying and crushing activities considering four dominant environmental components, viz. physicochemical parameters of water, PM2.5 and PM10, sound, and land use land cover (LULC). Water quality was measured in a seasonal variation, and air and sound data were collected in an 8-h period of every weekday of 2 months while LULC data were also collected from 1999 to 2019 with 5 years of interval. Water quality index (WQI) and cluster analysis were applied to classify the pollution sources while inverse distance weighting (IDW) and weighted overlay were used to show the vulnerable zone. All the parameters were considered with the established limit of WHO. WQI detects that the sampling stations located near the quarrying site were responsible for the deterioration of the water quality. Cluster analysis identified that the S8 and S10 sites were heavily susceptible to air and sound pollution. IDW and WO ranked the south-western lower stream and tribal village located at the north-western side as moderately to highly polluted. Correlation analysis illustrated that the values of air and sound parameters were concentrated above the permissible limit. Besides, LULC change revealed the significant lowering trend of vegetation and water bodies whereas it shows the upward trend of barren land and settlement. Finally, the extensive quarrying and crushing activities without any safety measure lead to breaking the environmental sustainability as well as workers and nearby dwellers were exposed to several respiratory diseases.