The Low Flow Assessment of Padma River in Bangladesh

Low flow or Environmental Flow (EF) assessment is vital to ensure the river and ecosystem remain healthy. Both natural and human interventions might alter a river. Therefore, this study presents EF requirements of the famous Hilsa breeding center in the Padma River, Bangladesh, by applying the Hydrologic Engineering Centers River Analysis System (HEC-RAS) for discharge and water surface levels simulations at different stations. The frequency analysis of 20 years of historical data, spanning 2000-2019, used the Log-Pearson Type III (LP-III) distribution method, while the one-dimensional unsteady flow simulation was performed for the last 10 years (i.e., 2012-2019). Subsequently, the HEC-RAS simulated water level values reasonably correlated with the field observations at four stations, namely Baruria Transit, Mawa, Tarpasha, Sureswar, with Coefficient of determination R2=0.86, 0.83, 0.92, and 0.74, alongside simulated minimum water surface levels of 1.57 m, 0.37 m, 0.30 m, and 0.27 m, respectively. Also, the Baruria Transit and Mawa had simulated flows that reasonably correlated with the field observations at R2=0.70 and 0.61, with a simulated minimum flow of 3849.51 m3/s and 3789.14 m3/s, respectively. The minimum flow according to the frequency analysis was 4017 m3/s, 3685 m3/s, 3449 m3/s, 3229 m3/s, and 3113 m3/s at Baruria Transit and 3304 m3/s, 2781 m3/s, 2438 m3/s, 2141 m3/s, 1992 m3/s at Mawa station in 5, 10, 20, 50 and 100 years return periods, respectively. This study overlooked to report the ongoing investigations into the water quality issues. Thus, this study is expected to guide the required EF quantity towards a healthy Hilsha fish habitat and surface water source for drinking purposes in this studied river. The stated method is also applicable to other similar rivers around the world.

A Study on the Flux of Total Suspended Matter in the Padma River in Bangladesh Based on Remote-Sensing Data

The flux of total suspended matter (TSM), FTSM, output by several large rivers in Asia, has been in decline due to human activities. As the estuary of the Ganges–Brahmaputra River, the Padma River transports a significant amount of suspended matter (SM) to the Bay of Bengal each year. In this study, the TSM concentration (CTSM) and FTSM in the Padma River in the period 1991–2019 were calculated based on the data acquired by the Landsat series satellites and an empirical TSM algorithm model for large, high-turbidity rivers. The results showed that the maximum and minimum FTSM values (318 ± 62 and 73 ± 29 mt, respectively) in the Padma River occurred in 2011 and 2015, respectively. On average, FTSM in the Padma River decreased at an annual rate of 3.3 mt (p < 0.01). The impact of human activities on CTSM contributed more significantly to the changes in FTSM (R = 0.76) than natural factors (R = 0.44). Due to a lack of water conservancy facilities within the river basin, changes in the water and soil retention capacity due to the changes in vegetation coverage were an important human factor (R = −0.79).

Fish culture in net cages improves the livelihood of Charland population: a case study from Padma (Ganga) River, Munshiganj, Bangladesh

Char dwellers are considered poorer than the mainland population. A constant threat of riverbank failure, flooding, and seasonal cyclone, combined with lack of physical infrastructures, and employment opportunities in the Chars, makes a vulnerable, difficult, and fragile life. The aim of the present work was an initiative to improve the livelihood of Char dwellers through fish culture in the net cages. A focus group survey was conducted on Char dwellers to know about the livelihood conditions. Quantitative and qualitative analysis of plankton was performed to know the productivity of the Padma River. In the study area, there was an average of 5 household members in each family of the Charland dwellers, and the average sex ratio of males and females was 56.67% and 43.33%, respectively. The age group of below 15 to 60 years and their religion ratio of Muslim and Hindu was 45% and 55%. The total number of identified genera of phytoplankton was 41, and the total number of zooplankton genera was 20 in the Padma River. Tilapia (Oreochromis niloticus) was cultured in the net cages providing three different feeds i.e. natural feed, kitchen waste (leftover rice), and rice bran. The final weights of the experimental tilapia were 314.8 ± 24.3 g after 5 months of feeding natural food, 321.4 ± 22.8 g after 5 months of feeding natural food with kitchen waste, and 324.8 ± 29.5 g after 5 months of feeding natural food with rice bran. Considering the plankton populations and water quality parameters, the Padma River near the Charland of Munshiganj was productive for fish farming. We found the results of Genetically Improved Farmed Tilapia (GIFT) farming in net cages near the river of Char, which were almost the same (has no significant difference among the diets) by providing low-cost supplementary feed and without supplementary feed. Therefore, the result indicates that Char dwellers can culture fishes in net cages to have the fish in their daily meals and can earn extra income from selling the fish to improve their livelihood. Moreover, applied research and interdisciplinary adaptive policy framework are requisite for the Charland livelihoods sustainability in the Padma River, Munshiganj, Bangladesh. Asian J. Med. Biol. Res. 2021, 7 (2), 174-181

Two important bridges protected from earthquake by extremely big sliding pendulum isolators

<p>The Padma Bridge is a multipurpose road-rail bridge across the Padma River currently under construction in Bangladesh and is one of the most important projects in the whole south east Asia with a total length of 6150 m. The maximum design vertical load reaches 98725 kN.</p><p>The Holtekamp Bridge is a steel road bridge with 2 main spans of 150 m and 2 lateral spans of 75 for a total length of 450 m. The bridge is isolated by use of sliding pendulum isolators having a maximum vertical load capacity at ULS of 54915 kN.</p><p>In both cases the isolators are double sliding surface type but with a different approach about the central articulation. The paper aims to put in evidence the difference in behaviour of the 2 types of pendulum, analysing both the theoretical approach and the test results with a special focus over the adopted solution for perform the test on a device which exceed the capacity of aby existing laboratory.</p>