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Land use and land cover (LULC) change detection and its subsequent impact on hydrology are of significant importance in the field of urban planning and the sustainable management of water and land resources. The primary objective of this research work is to illustrate LULC map in a specific study area, which encompasses approximately 316.7 km² in the Noakhali region. Additionally, this study tries to examine the enduring impacts of LULC changes on surface runoff within the specified area. In order to achieve this goal, the analysis of LULC change trends in the region was conducted using Landsat OLI/TM data from 2000 to 2020. The analysis focused on five distinct classes: built-up land, vacant land, farmland, vegetation, and waterbodies. The research employs the Soil Conservation Service Curve Number (SCS-CN) model to evaluate the influence of LULC changes on surface runoff. Notably, the findings indicate a substantial increase in built-up areas from 1.05% in 2000 to 11.21% in 2020. This urban expansion is strongly correlated with a notable rise in surface runoff, as evidenced by a high correlation coefficient (R² = 0.98) between urban expansion and modelled runoff depth. The observed increase in impervious urban areas contributes to a 2.65% rise in average runoff from 2000 to 2020, equivalent to an 8.96 mm increment in average runoff. The study underscores the profound implications for managing urban storm floods and designing urban areas, especially in rapidly expanding cities globally, with a focus on developing nations. The insights gained offer valuable information for informed decision-making in sustainable urban development and water resource management, not only in the Noakhali region but also beyond. [ABSTRACT FROM AUTHOR]

In Rayer Bazaar, different industries like tannery, plastic, textile, battery recycling industry etc. are increasing rapidly without considering the environmental issues and deterioration. Since chromium (Cr) pollution of this area has been widely investigated due to the presence of tannery industries, this study was focused on examining other environmental factors. Field visits and analytical results of semi-quantitative and quantitative analysis as well as three dimensional excitation emission matrix spectroscopy (3DEEM) of water, soil and vegetative tissues indicated that, the area is highly polluted in term of different environmental parameters and metal content. The extremely high lead (Pb) content of the soil (1171.7 mg/kg in summer, 2157.1 mg/kg in winter) and blackish materials of vegetative tissues (6585.6 mg/kg in summer, 1974.1 mg/kg in winter) indicates excessive lead deposition of this area that makes it a lead polluted hotspot. One of the possible sources of the extremely high lead concentration is adjacent battery recycling industry and/or other industries surrounding this area. So it is urgent to take necessary steps to find out immediate options for possible mitigation.

Textile effluents are highly colored for synthetic dyes, cause significant water pollution due to high pH, TDS, EC, BOD, and COD content, and are harmful to aquatic species. Among different treatment processes, biological treatment process is considered as a promising approach. In this investigation, a mixed aerobic bacterial consortium was used for the treatment of wastewater. In addition, the fenton process with a normal sand filter was used for treatment and compared with the biological method. The mean values of BOD, COD, TDS, EC, DO, and pH in the raw wastewater indicated that the effluent was highly contaminated according to Bangladesh standard (ECR, 1997). Both the biological treatment process and fenton process separately showed promising removal of pollution load. The aerobic mixed bacterial consortium reduced TDS (66.67%), EC (60%), BOD (91.67%), and COD (85.45%) and fenton process reduced TDS (74.71%), EC (55.11%), BOD (88.33%), and COD (83.63%) compared to the raw effluent bacterial consortium simultaneously degraded dyes and decolorized the wastewater from dark deep green to transparent. Color removal for the mixed aerobic bacterial process after 72 hours of aeration was 58.57% and for the fenton process with a normal sand filter was 80%. BOD and COD removal percentages for aerobic mixed bacterial consortium showed higher removal efficiency than the fenton process with a normal sand filter. Though 92 hours of aeration showed the maximum satisfactory result, aeration time could be reduced to 72 hours which also satisfied the Bangladeshi standard (ECR, 1997). [ABSTRACT FROM AUTHOR]

Noakhali Pourashava is an important municipality in southern Bangladesh, faces severe waterlogging problems every year during the monsoon period. The present study aimed to investigate the major causes of waterlogging and its negative effects on life, from the viewpoint of people residing in different areas of Noakhali Pourashava, various government, non-government, development organizations as well as various stakeholders including experts. It has been found that Noakhali Pourashava experienced waterlogging during peak monsoon season in ward no. 1, 2, 4, 5, and 8. Most of the inhabitants/respondents of the Noakhali Pourashava claimed that lack of drainage facility; excessive rainfall; inadequate, low capacity and conventional drainage system; natural siltation; improper waste management; absence of proper inlets and outlets; and blockage and encroachment of existing drainage are responsible for waterlogging. It has ascertained that the water logging becomes a burden for the inhabitants of the Pourashava and creating adverse effects on livelihood, society, infrastructure, economy and environment. Other notable adverse effects of waterlogging are disruption of traffic movement and normal life, structures and infrastructure damage and loss of income potentials with a lot of sufferings. The stagnant water acts as a breeding site for the vectors of various diseases and becomes a health hazard to people residing in the waterlogged area. The current study suggests that close coordination among Pourashava authorities, local government agencies and a strong collaboration between public and private sectors as well as local people participation are essential for solving the waterlogging problem effectively and sustainably. [ABSTRACT FROM AUTHOR]

Arsenic is a well-known natural environmental contaminant distributed in food, water, air, and soil. The developmental toxicity of arsenic exposure is a significant concern in large parts of the world. Unlike acute toxic exposure, the classical dose–response relationship is not adequate for estimating the possible impact of chronic low-level arsenic exposure. The real-life risk and impact assessments require the consideration of the co-exposure to multiple toxins, individual genetic and nutritional predisposition, and the particularly vulnerable stages of the neurodevelopment. This context shifts the assessment model away from the 'one-exposure-for-one-health-effect.' We underscore the need for a comprehensive risk assessment that takes into account all relevant determinants. We aim to elaborate a model that can serve as a basis for an understanding of complex interacting factors in a long-lasting and ongoing low-level arsenic exposure, to identify, protect, and support the children at risk. [ABSTRACT FROM AUTHOR]