The relationship between the shear strength and water retention curve of unsaturated sand at different hydraulic phases

Acta Geotechnica - This technical paper focuses on evaluating the shear strength of unsaturated sand at drying, wetting and alternate drying–wetting cycles, as well as the correlation between...     

Morphometric Analysis and Hydrological Inference for Water Resource Management in Atrai-Sib River Basin,NW Bangladesh Using Remote Sensing and GIS Technique

Demand for irrigation water increases day by day along with meteorological vagaries and extension of irrigated area in the drought-prone Barind area of Bangladesh. This increasing stress on water resource is gradually making the area water scare. The study is aimed at studying the morphometric parameters of the Atrai-Sib river basin in the Barind area and on their relevance in water resource management based on satellite images and SRTM DEM. Computation and delineation of linear and areal aspects of the river basin and its morphometric components reveals that stream order ranges from first to eighth order showing dendritic drainage pattern. The basin represents homogeneity of soil texture; possibility of flash flood after heavy rainfall with low discharge of runoff; and is not largely affected by structural disturbance. Moderate drainage density of the river basin area indicates semipermeable soil lithology with moderate vegetation. Mean bifurcation ratio of the basin is calculated as 3.92 and elongation ratio 0.75, which indicate elongated shape of the river basin with low to moderate relief bounded in the east and west by ‘moderate to steep’ sloping land area. It reveals a flatter peak of runoff flow for longer duration and gravity flow of water. The gentle but undulating slope of the basin represents ‘excellent’ category for groundwater management as the site is favorable for infiltration due to maximum time of runoff water percolation. The east facing slopes of the basin show higher moisture content and higher vegetation than the west-facing slope. The land use pattern of the area shows that major part (95.29%) comes under the cultivated land which will support future river basin development and management. Results obtained from the study would be useful in categorization of river basins for future water resource development and management, and selection of suitable sites for water conservation structures such as check dam, percolation tank, artificial recharge of groundwater through MAR technique etc.     

Metamorphic P–T evolution of the Gotsu blueschists from the Suo metamorphic belt in SW Japan: Implications for tectonic correlation with the Heilongjiang Complex,NE China

Mineralogy and Petrology - In the Gotsu area of the c. 200 Ma high-P/T Suo metamorphic belt in the Inner Zone of southwest Japan, blueschists occur as lenses or layers within pelitic...     

Hydrochemistry in coastal aquifer of southwest Bangladesh: origin of salinity

In the coastal region of Bangladesh, groundwater is mainly used for domestic and agricultural purposes, but salinization of many groundwater resources limits its suitability for human consumption and practical application. This paper reports the results of a study that has mapped the salinity distribution in different aquifer layers up to a depth of 300 m in a region bordering the Bay of Bengal based on the main hydrochemistry and has investigated the origin of the salinity using Cl/Br ratios of the samples. The subsurface consists of a sequence of deltaic sediments with an alternation of more sandy and clayey sections in which several aquifer layers can be recognized. The main hydrochemistry shows different main water types in the different aquifers, indicating varying stages of freshening or salinization processes. The most freshwater, soft NaHCO₃-type water with Cl concentrations mostly below 100 mg/l, is found in the deepest aquifer at 200–300 m below ground level (b.g.l.), in which the fresh/saltwater interface is pushed far to the south. Salinity is a main problem in the shallow aquifer systems, where Cl concentrations rise to nearly 8000 mg/l and the groundwater is mostly brackish NaCl water. Investigation of the Cl/Br ratios has shown that the source of the salinity in the deep aquifer is mixing with old connate seawater and that the saline waters in the more shallow aquifers do not originate from old connate water or direct seawater intrusion, but are derived from the dissolution of evaporite salts. These must have been formed in a tidal flat under influence of a strong seasonal precipitation pattern. Long dry seasons with high evaporation rates have evaporated seawater from inundated gullies and depressions, leading to salt precipitation, while subsequent heavy monsoon rains have dissolved the formed salts, and the solution has infiltrated in the subsoil, recharging groundwater.     

Amelioration of calcareous sandy soil productivity via incorporation between biochar and some organic manures

Most arid and semi-arid soils, especially calcareous sandy soils, are widely distributed in the Middle East region; the deficiency in their content of many nutrients particularly phosphorus and organic matter limits crops production. This study aimed to assess the effects of adding biochar (B) with farmyard manure (FYM) and poultry manure (PM) on some soil properties, phosphorus (P) availability, and barley growth in calcareous sandy soil. The pot experiment includes the following treatments: Control, B, B?+?FYM (1:1), B?+?PM (1:1), B?+?FYM (2:1), B?+?PM (2:1), FYM?+?B (2:1), and PM?+?B (2:1). Biochar combined with FYM and PM enhanced the water holding capacity (WHC) and soil organic matter (SOM) content in calcareous sandy soil. Phosphorus availability was increased significantly by applying biochar mixed with farmyard manure and poultry manure at all treatments. Green biomass of barley improved because of adding biochar alone, poultry manure alone, and biochar co-applied with poultry manure at all mixing ratios. Biochar application caused significant increases in phosphorus use efficiency (PUE) by barley plants compared to all other treatments, except for the control. We recommend adding biochar either individually or mixed with poultry manure to improve the productivity of calcareous sandy soil.     

Experimental and Numerical Studies of Velocity and Turbulence Intensities for Mid-Channel Bar

Water Resources - Turbulent phenomenon in braided rivers is much more complex compared to the straight and meandering rivers. The turbulent flow structure at locations upstream and downstream of...     

Monitoring Heat Losses Using Landsat ETM + Thermal Infrared Data: a Case Study in Unzen Geothermal Field, Kyushu, Japan

The Unzen geothermal field, our study area, is situated in the Shimabara Peninsula of Kyushu Island in Japan and is an area of active fumaroles.. Our prime objectives were (1) to estimate radiative heat flux (RHF), (2) to calculate approximately the heat discharge rate (HDR) using the relationship of RHF with the total heat loss derived from two geothermal field studies, and (3) finally, to monitor RHF as well as HDR in our study area using seven sets of Landsat 7 ETM + images from 2000 to 2009. We used the normalized differential vegetation index (NDVI) method for spectral emissivity estimation, the mono-window algorithm for land surface temperature (LST), and the Stefan–Boltzmann equation analyzing those satellite TIR images for RHF. We estimated that the maximum RHF was about 251 W/m² in 2005 and minimum was about 27 W/m² in 2001. The highest total RHF was about 39.1 MW in 2005 and lowest was about 12 MW in 2001 in our study region. We discovered that the estimated RHF was about 15.7 % of HDR from our studies. We applied this percentage to estimate HDR in Unzen geothermal area. The monitoring results showed a single fold trend of HDR from 2000 to 2009 with highest about 252 MW in 2005 and lowest about 78 MW in 2001. In conclusion, TIR remote sensing is thought as the best option for monitoring heat losses from fumaroles with high efficiency and low cost.     

Sources and transports of organochlorine pesticides in the Nanshan underground river,China

Karst areas have much higher ecological vulnerability and are prone to be contaminated. Organochlorine pesticides (OCPs) were detected in waters and sediment from the two sites of the karst Nanshan underground river system, China, to understand the sources and transport of OCPs in the underground river systems. Obviously, seasonal variations were found both in the waters and the sediments. Detected OCPs ranged from 61 to 936 ng L^?1 in the groundwaters and 51–3,842.0 ng g^?1 in the underground sediments, respectively. OCPs in groundwaters were mixture of younger and older residues from commercial sources. The maximum OCPs in the sediments of the underground river were historically older residues from commercial sources. The sources of OCPs in the waters and sediments of the underground river indicated that the surface systems play an important role in OCPs transport and pollution in the underground river. Karst features were liable for the transport behavior.