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Effect of Organic Matter Amendment on Hydraulic and Pore Characteristics of a Clay Loam Soil

Open Journal of Soil Science 2012年第4期2卷 372-381页

作者： moniruzzaman khan eusufzai Katsumi Fujii Faculty of Agriculture Iwate University Morioka Japan Faculty of Agriculture Iwate University Morioka Japan

The objective of this study was to examine the effect of compost, rice straw and sawdust amendment on hydraulic and pore characteristics of a clay loam soil. Amendments were applied at an application rate of0.2 m3/m3 (apparent soil volume) in three rectangular plots each comprising an area of3.0 m2. Water retention characteristics were measured by hanging water column and centrifuge method. Hydraulic conductivity was measured by disc permeameter at -15.0, -6.0, -3.0 and0 cmof water pressure heads. Volumetric water content increased in all amended soils, compared with the control. Unsaturated hydraulic conductivity was almost identical for straw and sawdust at all pressure heads, although that for compost amended soils were much higher. Field saturated hydraulic conductivity (Kfs) was higher in organic matter amended soils as were number of macropores (14.7% - 29.2%). Contribution of each pore class to the total saturated flux was evaluated from the hydraulic conductivity and water retention measurement. A new alternative weighed factor (We) was proposed to estimate the actual contribution of macro- and mesopores to the total saturated water flux. The Wg was found to be more representative for calculating pores contribution to saturated water flux than that of hydraulic conductivity measurement. Although there is only a small fraction of the total porosity, amendment increased effective macro- and meso-porosity (qe). Pores in the amended soils were hydraulically active and water movement was dominated by gravity. Collectively, our results demonstrated that organic matter generated as agricultural by-product could effectively be used to improve soil

关键词： Organic Matter Hydraulic Conductivity Volumetric Water Content Saturated Water Flux Porosity

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Impacts of Dredging on Fluvial Geomorphology in the Jamuna River, Bangladesh

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Journal of Geoscience and Environment Protection 2021年第6期9卷 1-20页

作者： Md Mosiur Rahman Md Sazadul Hasan moniruzzaman khan eusufzai Md Munsur Rahman Institute of Water Modelling (IWM) Dhaka Bangladesh Department of Civil Engineering Stamford University Bangladesh Dhaka Bangladesh River Research Institute (RRI) Faridpur Bangladesh Institute of Water and Flood Management (IWFM) Bangladesh University of Engineering and Technology Dhaka Bangla-desh

Jamuna, a major braided river in Bangladesh, has an enormous hydrological impact on the surrounding areas and streams. Erosion and sedimentation in the Jamuna river cause a large flow fluctuation and floods round the year. Bangladesh Water Development Board has initiated a pilot capital dredging project in the Jamuna river in 2011-2012, aiming to guide the flow to reduce the risk of failure of the city area and right guide bundh of the Jamuna Bridge. This study explores the long-term role of dredging on river morphology us-ing erosion-sedimentation numerical modeling approaches. Primary data were employed in numerical models to estimate the erosion-sedimentation and compared outputs with the real-time cross-sectional variation at selected sections along the reach during 2012-2013. The analysis suggested that the rate of sedimentation is higher (60% to 80%), where the dredging alignment crosses through the existing sandbar/char. Moreover, a cross-section com-parison revealed that the channel near Sirajganj Hardpoint shifted towards the left (east) bank, and the channel within the study area developed very fast along the right (west) bank. However, satellite image analysis revealed that the major bankline shifting occurred from 2000 to 2010 and the channel shifting was observed from 2014 to 2018 along the reach, mostly, after the construction of some river training works. The variation of the channel per-sistence (40% - 100%) selected part of the study area in the channel inci-dence map, indicating the rapid dynamic behavior of the river morphology. This study showed a good agreement of measured data and simplified em-pirical relationships to predict the long-term morphodynamic behavior of the braided Jamuna river.

关键词： Sediment Transport Erosion Dredging Satellite Image River Morphology

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