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The soil and topography of Bangladesh are distinct from other countries. As a result, not all imported machine models work effectively here. Bangladesh needs to develop combine harvesters that are technically, environmentally, and economically viable. Thus, a research platform for locally acceptable combine harvesters was established by comparing the technoeconomic performance of three imported harvesters in haor districts. The Chinese (4LZ-0.6), Sifang (4LZ-1.5), and Zoomlion (4LZT-4.0ZD) models with a cutting width of 1000, 1500, and 2000 mm, respectively, were employed in this study. The harvesting capacity, fuel consumption, harvesting loss, minimum suitable plot area, ground pressure, business viability, transportation, and operator comfortless were considered to recommend a suitable machine. Based on the result, Zoomlion model whole feed combine harvester is excellent for harvesting in the haor area in the bigger sizes plot, while a head width of 1500mm for smaller plots. While a small combine's cost is incredibly low, farmers have refused to adopt the equipment since their businesses have failed because of its restricted harvesting capacity and high component failure rate. The machinery must be transportable in a conventional truck due to the remote road conditions (truck width 2000 mm). As a result, local roadways can accommodate whole feed combine harvesters with an 1800 mm width. In haor regions, 24 kNm-2 ground pressure and 300 mm ground clearance functioned effectively. The adjustment of the harvester machine is extremely subtle, resulting in strong vibrations in a single cylinder engine, causing parts to fail prematurely and the driver to be unable to operate the machine comfortably for extended periods of time. As a result, fourcylinder engines outperform one-cylinder engines in popularity. Access to machine components is critical, as is the presence of a grain tank for simple supply.

Haor areas are the most vulnerable areas in Bangladesh. Rice is the major food crops grown in the hoar areas despite natural threats during the harvesting period. The appropriate size of the mechanical harvester is one of the solutions to mitigate the natural calamities and labor shortage in the hoar regions. This paper examines the technical and financial performance of a small combine harvester with the aim of determining its market viability in Bangladesh's hoar areas. Based on the field test and economic assessment, data on field power, forward speed, fuel consumption, time allocation in harvesting, hire fee, and payback period of machine were determined. The study showed that the operation by width was 10% less than the operation by longitudinal. Plot length and area of the plot should be more than 25m and 400 m2, respectively, to operate the small combine harvester at full capacity. Harvesting speed ranged from 0.63-0.90 km hr-1, and actual field capacity ranged from 0.03-0.05 ha hr-1. Fuel consumption ranged from 25-32 L ha-1 due to slow cutting speed. The plant density was observed higher due to cultivating high yielding variety. The machine should be operated at a low speed, preferably walking speed, to avoid clogging in the conveying chain. The combine harvester has used 56% of the harvest time, and a remaining 44% for turning purposes and other inevitable uses. The small combine harvester recorded 1.12-1.40% loss of grain. However, grain damaged was not observed during harvesting. The small combine harvester becomes profitable for the investment cost of Tk 3,50,000 with a hiring rate of Tk 10,000 Tk ha-1 following 15 ha of harvesting area in a harvest capability of 0.04 ha hr-1. This machine is suitable for a small size of land where larger sizes of machines are inaccessible. This would offer small entrepreneur different choices of paddy harvesting mechanization to encourage future adoption of enhanced innovations.

Rice transplanting with a transplanter is a cost-effective process. Due to labor shortages during the peak time of rice transplanting, it is a promising technology in Bangladesh. However, the high-quality mat-type seedling is a prerequisite factor for mechanical transplanting. The experiments were conducted at three different locations (Gazipur, Tangail, and Rangpur) during the dry season (Boro)/2019-20 to determine the best seeding density for high-quality mat-type seedlings to be prepared for mechanical rice transplanters. The effects of seeding rate on seedling quality such as survival rate, seedling strength, stem thickness of newly released boro rice varieties BRRI dhan86, BRRI dhan89, and BRRI dhan92 were studied using four seeding rates (130, 140, 150, 160 g/tray). Results revealed that BRRI dhan92 showed quick seedling emergence compared to BRRI dhan89 and BRRI dhan86. Seedling mortality was found the lowest BRRI dhan92 while the highest in BRRI dhan86. 25 - 30 days old seedling was found suitable for mechanical transplanting in terms of seedling mortality. Seedling height increased with the increase in seed density. BRRI dhan92 showed the highest stem thickness followed by BRRI dhan89 and BRRI dhan86 with seed rate 150 - 160 g per tray. The suitable seeding rate (150 - 160 g/tray) for the studied varieties was found better for raising mat-type seedlings suitable for mechanical transplanting, which could coordinate the production of larger population growth and higher harvest index to achieve high grain yield.

Land surface temperature (LST) is a basic determinant of the global thermal behavior of the Earth surface. LST is a vital consideration for the appraisal of gradual thermal change for urban areas to examine the strength of the thermal intensity of the surface of urban heat island (SUHI) and to see how hot the surface of the Earth would be in a particular location. In this respect, the most developed urban city like Dhaka Metropolitan Area (DMA), Bangladesh is considered for estimation of LST, and Normalized Difference Vegetation Index (NDVI) changes trend in more developed and growing developing areas. The focus of this study is to find out the critical hotspot zones for further instantaneous analysis between these two types of areas. The trends of long-term spatial and temporal LST and NDVI are estimated applying Landsat images-Landsat 5-TM and Landsat OLI_TIRS-8 for the period of 1988 to 2018 for DMA and for developed and growing developing areas during the summer season like for the month of March. The supervised classification was used to estimate the land cover categories and to generate the LST trends maps of the different percentiles of LSTs over time using the emissivity and effective at sensor brightness temperature. The study found the change in land cover patterns by different LST groups based on 50th, 75th, and 90th percentile where the maximum LST for the whole DMA went up by 2.48°C, 1.01°C, and 3.76°C for the months of March, April, and May, respectively for the period of 1988 to 2018. The highest difference in LST was found for the most recently developed area. The moderate change of LST increased in the built-up areas where LST was found more sensitive to climate change than the growing developed areas. The vegetation coverage area decreased by 6.74% in the growing, developing areas compared to the developed areas from 1988 to 2018. The findings of the study might be helpful for urban planners and researchers to take up appropriate measures to mitigate the thermal effect on urban environment.

Flood havoc during 2019 in the Sangu River basin caused widespread damage to residents, crops, roads, and communications in parts of hills in Bangladesh. Developing flood hazard maps can play an essential step in risks management. For this purpose, this study assessed 12 hydro‐geomorphological factors, namely, topographic wetness index, elevation, slope, extreme rainfall, land‐use and land‐cover, soil type, lithology, curvature, drainage density, aspect, height above the nearest drainage, and distance from streams. Maps prepared by individual application of the Analytical Hierarchy Process (AHP) and Analytical Network Process (ANP) exhibit validation scores ranging from 0.77 to 0.79. It is found that the ANP‐based model under 1‐day maximum rainfall denotes a reliable hazard map presenting comparable accuracy to the field results. The hazard map under 100‐year return periods shows that a total of 0.71 million population living downstream is prone to “very high” flood because of its lowland morphology, mild slope, and high drainage density. Alarmingly, 39% of roads, 43% of farming lands, and 25% of education buildings are observed to lie in the highest flood‐prone area. Details on subdistrict level exposures have the potential to serve the decision‐makers and planners in site selection for flood management strategies and setting priorities for remedial measures.

Most catchments in tropical regions are ungauged and data deficient, complicating the simulation of water quantity and quality. Yet, developing and testing hydrological models in data-poor regions ...

The increased human population and associated activities may create a risk in the ecological balance of Chattogram Hill Tracts (CHT), Bangladesh via contamination of soil with toxic heavy metals. Thus, the present study was conducted to assess the concentration of heavy metals (Lead, Cadmium, Copper, Zinc, Iron, Manganese, Chromium and Nickel) in forest soils of the CHT area by using an atomic absorption spectrometer. The degree of contamination of soil was evaluated by five indices: geo-accumulation index (I geo ), enrichment factor (EF), contamination factor (CF), pollution load index (PLI) and potential ecological risk index (PERI). According to these criteria, these soils can be classified as moderately contaminated with some metals. Furthermore, the identification of pollution sources based on principal component analysis and hierarchical cluster analysis have revealed that all analyzed metals are anthropogenic except Fe. Calculated hazard index>1 indicates the possibility of noncarcinogenic effect due to higher value of Fe. Carcinogenic risks through the ingestion, inhalation and dermal pathway for carcinogenic elements (Pb, Cd, Cr, and Ni) shows a non-significant risk (CR

International audience; In-situ cathodoluminescence (CL) spectroscopy is used to study point-defect formation in cerium dioxide (CeO$_2$) by high-energy electrons (400 keV-1,250 keV) at ∼100 K, 200 K, and 300 K in a high-voltage electron microscope (HVEM). Complementary CL spectra are also obtained for 20-keV electron excitation at ∼300 K in a scanning electron microscope (SEM). Experiments were carried out on a single crystal and polycrystalline sintered sample. The more prominent and broad emission band centered at a photon energy of ∼4.2 eV is ascribed to F+ centers (oxygen vacancies) produced by the high-energy electron irradiation. Two other weaker CL bands centered at ∼2.3–2.4 eV and 2.8–2.9 eV at 300 K are related to trivalent cerium ions, corresponding to 5d → 4f radiative transitions, regardless of electron energy. Similar spectra are recorded at 100 K and 200 K, yet with shifts and broadening of the latter emission bands. A maximum of all CL bands is found at ∼600 keV electron energy for the polycrystalline sample regardless of temperature, and for the single crystal at 300 K. In contrast, a continuous increase versus electron energy is observed for the 4.2-eV band of the single crystal at 100 K and 200 K above a threshold corresponding to the oxygen displacement energy. The dependence of CL intensities on the primary electron energy is analyzed on the basis of the interplay of the luminescence cross section and oxygen displacement cross section. The electron energy dependence of ionization cross sections is addressed by relying on secondary electron spectra computed with the PHITS code which is benchmarked against other computer codes such as PENELOPE, as implemented in Geant4. The F$^+$ center band intensity is strongly reduced in the polycrystalline sample with respect to the single crystal in the same irradiation conditions regardless of temperature due to grain boundaries.

Mosquito are small slender insect dreaded by humans with fragile wing measuring about 4-6mm...

Flood hazard is a global problem, but regions such as south Asia, where people's livelihoods are highly dependent on water resources, can be affected disproportionally. The 2017 monsoon flooding in the Ganges-Brahmaputra-Meghna (GBM) basin, with record river levels observed, resulted in ~1200 deaths, and dramatic loss of crops and infrastructure. The recent Paris Agreement called for research into impacts avoided by stabilizing climate at 1.5?C over 2?C global warming above pre-industrial conditions. Climate model scenarios representing these warming levels were combined with a high-resolution flood hazard model over the GBM region. The simulations of 1.5?C and 2?C warming indicate an increase in extreme precipitation and corresponding flood hazard over the GBM basin compared to the current climate. So, for example, even with global warming limited to 1.5?C, for extreme precipitation events such as the south Asian crisis in 2017 there is a detectable increase in the likelihood in flooding. The additional ~0.6?C warming needed to take us from current climate to 1.5?C highlights the changed flood risk even with low levels of warming. An analysis of other large river basins around the world also showed the majority will see increases in extreme precipitation, but the GBM, with a particularly vulnerable population, shows one of the largest increases.

Salinization stands among the most prominent environmental hazards of the largest delta on Earth, the Bengal delta. It has significant impacts on the local societies and the economy. Using an unprecedented collection of in situ river salinity records over the Bengal delta, extending from the Hooghly estuary in the west to the Meghna estuary in the east, we report a sudden salinization of the central part of the delta that occurred in 2006–2007. This results in a sudden landward shift of the seasonal march of the salinity front by about 20 km, taking place in the pre-monsoon season. Such a regime shift was never reported before. We investigate the various drivers of this sudden change and identify three possible forcing factors: the decrease in Ganges freshwater discharge, the rise of sea level and the depletion of the groundwater level. These factors may act independently, or in concert. Given the threat of the ongoing climate change and its cohort of adverse effects expected in the course of the 21st century in the Bengal delta, our study contributes to set the observational basis for the development of the next generation of salinization modeling platforms.

Physicochemical parameters were studied for a period of two years from July 2012 to June 2014. The parameters namely air and water temperature were estimated using centigrade thermometer, transparency using secchi disc while pH, CO2, total hardness, total alkalinity, dissolved oxygen (DO) were estimated using HACH water test kit. The highest air and water temperature (31.52°C and 30.38°C) were recorded in September, 2013 whereas the lowest air and water temperature 21.04°C and 20.42°C were recorded in January, 2014. The pH of water was found to alkaline in nature (6.9 to 8.20). The maximum free CO2 value (7.81 mg/l) was recorded in February, 2014 and minimum (2.36 mg/l) in November, 2012.The value of total alkalinity was found to fluctuate from 51.9 mg/l in December 2012 to 90.68 mg/l in December 2013. Total hardness of lake water varied from 37.8 (August) to 47.3 (November) in 2012 and 55.17 (July) to 87.49 (February) in 2013-14 with regular trends in fluctuation. Mean secchi disc reading varied from 1.94±.57 m in 2012-13 and 2.02±0.40 m in 2013-14. Dissolved oxygen was found to vary from 6.10 (February) to 6.80 (November) during 2012, 3.90 (February) to 6.38 mg/l (July) during 2013 with a mean value of 6.4±1.51 and 5.74±0.68 mg/l. Water depth was found to fluctuate from 4.39 to 11.76 m with a mean value of 7.96± 2.56 m for one year study. The present research provides baseline information on changing trends of physicochemical parameters of Kaptai Lake which will facilitate sustainable management and conservation of this lake ecosystem.Res. Agric., Livest. Fish.2(2): 319-327, August 2015

Single presentation for all contributors from the REBuILD project Stakeholder Workshop, BRAC Inn, Dhaka, Bangladesh. 7th March 2017.

The detection of the spatio-temporal extent of inundation resulting from the floods in 2004 and 2007 in Bangladesh has been studied using time-series MODIS surface reflectance data. Flood inundation maps were developed from vegetation and land water surface indices derived using surface reflectance. The inundation map developed using MODIS data was compared with a corresponding RADARSAT image, where both images refer to the satellite-based remote-sensing data. The estimates show a strong correlation with the inundation area derived from the RADARSAT products (coefficient of determination of R 2 : 0.96). The paper shows that it is possible to study flood dynamics by assessing inundation and recession patterns and to perform flood assessments similar to the high-resolution (50m) microwave satellite, RADARSAT-based flood assessments using products derived from MODIS 500m imagery. MODIS has advantages over microwave satellite because it has a high observational frequency and these data are available free of cost. We have concluded that this is a useful method to assess the extent of the temporal floods in the People’s Republic of Bangladesh.

Remote sensing techniques are capable of identifying a particular crop as well as monitoring its growing stages, crop vigor, and biomass. Due to the increasing demand for food staples, potato cultivation in Bangladesh has increased substantially over the last decade. A study was carried out in the Munshiganj area, the main potato-producing district in Bangladesh, to assess the growth of potatoes by modeling its important life metrics. Normalized Difference Vegetation Index (NDVI) and Leaf Area Index (LAI) products were extracted from MODIS Surface Reflectance Eight-Day L3 Global 500 m data from November 25, 2005 to March 6, 2006. NDVI and LAI were extracted for 50 selected fields in the study area and used to construct potato phenological curves. Twenty-two life metrics were derived for potato from the phenological curves. The first 12 metrics are the basic life metrics of potato and the others are supplementary. Results showed a significant amplitude and distinct response period of these vegetation indic...