Benthic Nutrient Fluxes across Subtidal and Intertidal Habitats in Breton Sound in Response to River-Pulses of a Diversion in Mississippi River Delta

We measured benthic fluxes of dissolved nutrients in subtidal sediments and intertidal soils associated with river-pulse events from Mississippi River via the operation of a river diversion structure at Caernarvon, LA. Experiments measuring benthic fluxes in subtidal habitats were conducted during the early spring flood pulse (February and March) each year from 2002 to 2004, compared to benthic fluxes of intertidal habitats measured in February and March 2004. Nitrate (NO3−) uptake rates for subtidal sediments and intertidal soils depended on overlying water NO3− concentrations at near-, mid-, and far-field locations during river-pulse experiments when water temperatures were >13 °C (NO3− removal was limited below this temperature threshold). NO3− loading to upper Breton Sound was estimated for nine river-pulse events (January, February, and March in 2002, 2003, and 2004) and compared to NO3− removal estimated by the subtidal and intertidal habitats based on connectivity, area, and flux rates as a function of NO3− concentration and water temperature. Most NO3− removal was accomplished by intertidal habitats compared to subtidal habitats with the total NO3− reduction ranging from 8% to 31%, depending on water temperature and diversion discharge rates. River diversion operations have important ecosystem design considerations to reduce the negative effects of eutrophication in downstream coastal waters.

A Treatment Technology for Optimizing the Stress State of Railway Tunnel Bottom Structure

With the continuous increase of railway transportation volume, the aging problem of railway tunnel bottom structure is becoming more and more serious, which seriously threatens the safe operation of trains. Based on the cause analysis and field detection of the defects at the railway tunnel bottom structure, the “Anchor-Grouting-Drainage” treatment technology of the railway tunnel bottom structure is summarized. The research shows that (1) the technology is simple and can effectively repair the defects of railway tunnel bottom structure under the conditions of the narrow site, short time of maintenance skylight, strict requirements of track size variation, and no interference with the normal operation of the train, which has great significance and broad application prospect. (2) The drainage system of the existing railway tunnel bottom structure can be applied to the reconstruction of the railway tunnel bottom structure. The high-strength transverse diversion structure at the bottom of the tunnel has the advantages of strong bearing capacity, large drainage capacity, and corrosion resistance, which can provide a reference for the subsequent implementation of the reconstruction project at the railway tunnel bottom structure.

Control of oil spills in urban areas

The City of Toronto has experienced about 300 oil spills per year (Li 1997). Traditionally, the city recommends that businesses and industries practise pollution prevention and install on-site oil separators. Currently, the sizing criteria for these devices are not well defined and the draft code of practices for oil separators by the Canadian Petroleum Product Institute (1994) has not yet been approved by the Ministry of the Environment (Li 2000). Thus, the city is currently investigating the possibility of installing oil separators at spill prone sewer outfalls. The new application of oil separators at sewer outfalls requires that the devices be operable under high flow conditions and that their capacity should reflect the land use characteristics in the associated sewershed. This study has developed an innovative spill control device for the Humber Creek outfall and a Geographic Information System (GIS)-based analysis technique for urban oil spill management. First, a flow diversion structure was designed to capture the dry weather flow at the outfan and to transport the captured flow into an oil/water separator designed in accordance to the American Petroleum Institute's manual (1990). The designs of the flow diversion structure and the oil/water separator were evaluated by a physical model study using the National Water Research Institute's Hydraulics Laboratory at the Canada Centre for Inland Waters in Burlington, Ontario. Then, the GIS-based analysis technique was used to identify potential treatment options for spill-prone sewer outfall in the Town of Richmond Hill. It was found that (I) the spill event characteristics should be analyzed in order to develop design criteria for oil spill control systems; (2) the preliminary design of the oil spill control system at Humber Creek was different from the API's methodology; and (3) the physical model investigation confirmed the conveyance capacity of the diversion channel and the general behaviour of the tilted-plate separator. A database of oil spill records in the Greater Toronto Area from 1988 to 2000 were compiled and geo-referenced. By overlaying the spill characteristics and other GIS data layers, such as woodlots, wetlands and watercourses, spill prone areas were identified. In order to increase the accuracy of the analysis, the percentage of georeference oil spill locations should be increased.

Control of oil spills in urban areas

The City of Toronto has experienced about 300 oil spills per year (Li 1997). Traditionally, the city recommends that businesses and industries practise pollution prevention and install on-site oil separators. Currently, the sizing criteria for these devices are not well defined and the draft code of practices for oil separators by the Canadian Petroleum Product Institute (1994) has not yet been approved by the Ministry of the Environment (Li 2000). Thus, the city is currently investigating the possibility of installing oil separators at spill prone sewer outfalls. The new application of oil separators at sewer outfalls requires that the devices be operable under high flow conditions and that their capacity should reflect the land use characteristics in the associated sewershed. This study has developed an innovative spill control device for the Humber Creek outfall and a Geographic Information System (GIS)-based analysis technique for urban oil spill management. First, a flow diversion structure was designed to capture the dry weather flow at the outfan and to transport the captured flow into an oil/water separator designed in accordance to the American Petroleum Institute's manual (1990). The designs of the flow diversion structure and the oil/water separator were evaluated by a physical model study using the National Water Research Institute's Hydraulics Laboratory at the Canada Centre for Inland Waters in Burlington, Ontario. Then, the GIS-based analysis technique was used to identify potential treatment options for spill-prone sewer outfall in the Town of Richmond Hill. It was found that (I) the spill event characteristics should be analyzed in order to develop design criteria for oil spill control systems; (2) the preliminary design of the oil spill control system at Humber Creek was different from the API's methodology; and (3) the physical model investigation confirmed the conveyance capacity of the diversion channel and the general behaviour of the tilted-plate separator. A database of oil spill records in the Greater Toronto Area from 1988 to 2000 were compiled and geo-referenced. By overlaying the spill characteristics and other GIS data layers, such as woodlots, wetlands and watercourses, spill prone areas were identified. In order to increase the accuracy of the analysis, the percentage of georeference oil spill locations should be increased.

Recovery of Forest Soil Chemical Properties Following Soil Rehabilitation Treatments

Several rehabilitation treatments have been applied to mitigate runoff and sediment in machine trafficked areas following logging operations, while the knowledge on the consequence of these remediation techniques on the recovery of soil properties remains scarce. The objective of the study was to determine the effect of different rehabilitation treatments including sawdust mulch (SM), water diversion structure (WDS), untreated/bare trail (U), and undisturbed or control area (UND) on the recovery of soil chemical properties over a six-year period after machine-induced compaction occurred on three longitudinal trail gradients (10, 20, and 30 %).In each treatment, the following soil properties were measured: litter thickness, pH, EC, soil organic C, total N, and available P, K, Ca, and Mg. Five sampling plots (with 10 m length and 4 m width) were positioned in each trail gradient classes and three of these plots were randomly considered for soil sampling.The results demonstrate that litter thickness differed among the three treatments, with the highest amount present on the UND area and lowest on the U treatment. Meanwhile, the highest pH (6.75), EC (0.21 Ds m−1), N (0.27 %), available P (14.61 mg kg−1), available K (123.5 mg kg−1), available Ca (135.1 mg kg−1), and available Mg (42.1 mg kg−1) and the lowest C (1.21 %) and C/N ratio (7.83 %) were found on the SM with gradient of 10 % compared to other gradient classes on SM, WDS and, U treatments. The recovery value of litter depth, pH, EC, C, N, C/N ratio, and available nutrients (P, K, Ca, and Mg) were higher on the SM than the WDS at the gradient of 10 %, while significantly higher levels of these variables were measured under WDS installed on trail gradients of 30 % and 20 % when compared with the same gradients on SM. Results of the study revealed that soil chemical properties showed some evidence of recovery following SM and WDS rehabilitation treatments compared to U, although these properties did not fully recover within 6 years as compared to UND area.

Flow Over Side Weirs with Experimental & CFD Results

In irrigation, sewer systems and drainage engineering side weirs are used to as a hydraulic control structure from many decades. Labyrinth side weir is a side weir with increased crest length due to folding in plan view as it provides additional length for a given opening. As a flow diversion structure in irrigation, land drainage, urban sewage systems and in intake structures. Labyrinth side weirs can be used more efficiently than conventional side weirs. In this review paper some investigations of researchers with different parameter affecting coefficient of discharge and discharging capacity of side weirs are presented. In review it seems that different parameters are affecting on discharge of side weir has been considered in empirical equations given by researcher but few parameters are left for consideration. In this paper effect of additional parameters like side weir thickness and submergence condition is evaluated by CFD mo

Experimental and numerical studies for estimating coefficient of discharge of side compound weir

A sharp-crested side compound weir is a flow diversion structure provided on one or both side walls of a channel to divert water from the main channel. Compound sharp-crested weirs are widely used in irrigation, hydraulics, and environmental engineering. This article presents results of experimental and numerical studies conducted on sharp-crested side compound weirs in open channels. Owing to the complex mechanism of flow through a side compound weir it is difficult to establish a regression model to accurately predict the coefficient of discharge (Cd). In this study, an alternative approach to the conventional regression modelling in the form of artificial neural network (ANN) has been used to predict the values of Cd. A network architecture with trained values of connection weights and biases is recommended to predict Cd. The input to ANN model consists of grouped parameters pertaining to the ratio of weighted crest height to the length of the side compound weir ([Formula: see text]), the ratio of upstream depth to length of the side compound weir (Y1/L), and upstream Froude number (F1). The results of the ANN model applied herein were found to be superior to those obtained through regression modelling by previous researchers. The sensitivity analysis of the ANN model shows that [Formula: see text] is the most important parameter for the estimation of Cd; followed by Y1/L and F1.