Bahram Gharabaghi

University of Guelph, XIA, Ontario, Canada

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Publications (42)54.05 Total impact

  • William R. Trenouth, Bahram Gharabaghi, Nandana Perera
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    ABSTRACT: Road authorities, who are charged with the task of maintaining safe, driveable road conditions during severe winter storm events are coming under increasing pressure to protect salt vulnerable areas (SVAs). For the purpose of modelling urban winter hydrology, the temperature index method was modified to incorporate ploughing and salting considerations and was calibrated using winter field data from two sites in Southern Ontario and validated using data collected from a section of Highway 401 - Canada’s busiest highway. The modified temperature index model (MTIM) accurately predicted salt-induced melt (R2 = 0.98 and 0.99, RMSE = 19.9 and 282.4 m3, CRM = -0.003 and 0.006 for calibration and validation sites respectively), and showed a demonstrable ability to calculate the Bare Pavement Regain Time (BPRT). The BPRT is a key factor on road safety and the basis for many winter maintenance performance standards for different classes of highways. Optimizing salt application rate scenarios can be achieved using the MTIM with only two meteorological forecast inputs for the storm event - readily available on-line through the Road Weather Information System (RWIS) - and can serve as a simple yet effective tool for winter road maintenance practitioners seeking to optimize salt application rates for a given storm event in salt vulnerable areas.
    Journal of Hydrology 05/2015; 524. DOI:10.1016/j.jhydrol.2015.03.004 · 2.69 Impact Factor
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    ABSTRACT: This study was carried out to investigate the effects of long-term cultivation and landscape position on organic carbon content and soil aggregation. Sampling sites were determined based upon land use at the end of 50 years soil use and management, cultivated/annual wheat cropping and grazed pasture, and landscape position in Chaharmahal-va-Bakhtiary province, southwest Iran. Soil samples were collected from the 0-5 cm and 5-15 cm depths in two adjacent fields that have the same slope and aspect. The soil was silty clay at the summit and footslope positions, and was a silty clay loam at the backslope. Wet-sieving analysis and aggregate-size fractionation methods were used to separate the samples into three aggregate fractions (i.e., 2-4.75, 0.25-2, and 0.053-0.25 mm). The treatments were arranged in a factorial design. Land use significantly affected the water-stable aggregate fractions, so that the wet soil stability of the macroaggregates (i.e., 2-4.75 mm) was higher in the pasture, whereas it was greater for the meso-aggregates (i.e., 0.25-2 mm) in the cultivated soils. Cultivation decreased both the wet-aggregate stability and percent of macroaggregates whereas long-term pasture enhanced aggregation. Soil organic carbon (SOC) content within aggregates and primary particles was also significantly influenced by landscape position, land use, and the depth of sampling. The SOC content was higher in clay than those in silt and sand contents. The SOC content decreased as depth increased in all fractions. In general, the highest and lowest wet-stable aggregates were observed on the footslope and backslope positions, respectively.
    Arid Land Research and Management 04/2015; DOI:10.1080/15324982.2015.1016244 · 0.56 Impact Factor
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    Ahmed M.A. Sattar, Bahram Gharabaghi
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    ABSTRACT: Longitudinal dispersion is the key hydrologic process that governs transport of pollutants in natural streams. It is critical for spill action centers to be able to predict the pollutant travel time and break-through curves accurately following accidental spills in urban streams. This study presents a novel gene expression model for longitudinal dispersion developed using 150 published data sets of geometric and hydraulic parameters in natural streams in the United States, Canada, Europe, and New Zealand. The training and testing of the model were accomplished using randomly-selected 67% (100 data sets) and 33% (50 data sets) of the data sets, respectively. Gene expression programming (GEP) is used to develop empirical relations between the longitudinal dispersion coefficient and various control variables, including the Froude number which reflects the effect of reach slope, aspect ratio, and the bed material roughness on the dispersion coefficient. Two GEP models have been developed, and the prediction uncertainties of the developed GEP models are quantified and compared with those of existing models, showing improved prediction accuracy in favor of GEP models. Finally, a parametric analysis is performed for further verification of the developed GEP models. The main reason for the higher accuracy of the GEP models compared to the existing regression models is that exponents of the key variables (aspect ratio and bed material roughness) are not constants but a function of the Froude number. The proposed relations are both simple and accurate and can be effectively used to predict the longitudinal dispersion coefficients in natural streams.
    Journal of Hydrology 03/2015; 524. DOI:10.1016/j.jhydrol.2015.03.016 · 2.69 Impact Factor
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    ABSTRACT: In this study we investigated the transport of nalidixic acid-resistant Escherichia coli (E. coli NAR) and bromide (Br¯) through two soils, a sandy loam (SL) and clay loam (CL). Soils were repacked in columns (45 cm length × 22 cm diameter) and subjected to physical (freeze/thaw, and wet/dry cycles) and biological (by earthworms, Eisenia fetida) weathering for 12 months. Saturated flow conditions were maintained using a tension infiltrometer. Tests were carried out at either 5 or 20 °C. After steady-state flow conditions were established, a suspension containing E. coli NAR and Br¯ was sprayed onto the surface of soil columns. Leachate was sampled at three depths, 15, 30 and 45 cm. Time to maximum concentration (Cmax) of E. coli NAR was greater for SL at all depths. Both tracers had rapid breakthrough curves (BTCs) shortly after the suspension injection followed by prolonged tailing indicating the presence of preferential pathways and thus soil heterogeneity regenerated after the induced physical and biological weathering. About 40% of the E. coli NAR and 79% of the Br¯ leached through the entire 45 cm soil columns during the experiments. Leaching with cold water (5 °C) led to lower hydraulic conductivity and flow rate and consequently enhanced bacterial filtration for both soils. Very low values for the detachment coefficient for E. coli NAR at 5 °C suggest an irreversible process of bacterial attachment in heterogeneous soils. BTCs were well described by the mobile-immobile model (MIM) in HYDRUS-1D. Soil texture/structure and temperature had a significant effect on the model’s fitted parameters.
    Journal of Hydrology 03/2015; 522. DOI:10.1016/j.jhydrol.2015.01.003 · 2.69 Impact Factor
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    ABSTRACT: Sediment discharge is one of the main water quality concerns in integrated watershed management. A proper identification of sediment sources is therefore important to the success of watershed conservation programs. Since water quality monitoring data collected at the mouth of the watershed alone are typically not sufficient for identifying key sediment sources distributed in the watershed, hydrologic models can be applied to prioritize Best Management Practices (BMPs) implementation for sediment control in a watershed. In this paper, the Soil and Water Assessment Tool (SWAT) is applied to the South Tobacco Creek (STC) watershed in Canada to identify sediment sources and to estimate the spatial distribution of sediment yield from both upland and channel erosion processes. The model is calibrated and validated against observed flow and sediment data measured at fourteen edge-of-field and mainstream stations based on 20 years of land management data. Modeling results show that approximately 60 and 40 % of the sediment discharge at the mouth of the watershed are originated from channel erosion and upland erosion respectively. A high spatial and temporal variation of sediment yield is found in the watershed depending on climate, topography, land use, and soil conditions. These findings will be helpful for understanding the runoff and erosion processes and evaluating the cost-effectiveness of soil and water conservation programs at a watershed scale.
    Water Resources Management 01/2015; DOI:10.1007/s11269-014-0729-5 · 2.46 Impact Factor
  • Journal of Water Resource and Protection 01/2015; 07(01):14-40. DOI:10.4236/jwarp.2015.71002
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    ABSTRACT: Windblown dust simulations are one of the most uncertain types of atmospheric transport models. This study presents an integrated PM10 emission, transport and deposition model which has been validated using monitored data. This model characterizes the atmospheric phosphorus load focusing on the major local sources within the Lake Simcoe airshed including paved and unpaved roads, agricultural sources, construction sites and aggregate mining sources. This new approach substantially reduces uncertainty by providing improved estimates of the friction velocities than those developed previously. Modeling improvements were also made by generating and validating an hourly windfield using detailed meteorology, topography and land use data for the study area. The model was used to estimate dust emissions generated in the airshed and to simulate the long-range transport and deposition of PM10 to Lake Simcoe. The deposition results from the model were verified against observed bulk collector phosphorus concentration data for both wet and dry deposition. Bulk collector data from stations situated outside the airshed in a remote, undeveloped area were also compared to determine the background contribution from distant sources.
    Atmospheric Environment 10/2014; 96:380-392. DOI:10.1016/j.atmosenv.2014.07.060 · 3.06 Impact Factor
  • A.R. Betts, B. Gharabaghi, E.A. McBean
    Journal of Hydrology 09/2014; 517:877-888. DOI:10.1016/j.jhydrol.2014.06.005 · 2.69 Impact Factor
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    ABSTRACT: The aim of this study was to survey long-term changes in phosphorus (P) fractions in soils in different land uses. Sequential extraction had been used to determine soil P fractionation on the basis of land-use change, i.e. native forest to vineyard and wetland to both alfalfa and wheat at the end of 30 and 20 years, respectively. The highest values of labile-P (L-P) fractions in surface soil layers were observed in the cultivated land. The calcium-bound P was the most affected fraction by land-use change with the lowest amount in the vineyard and the highest amount in the alfalfa land. Conversion of forest to vineyards causes P in the soils to be more vulnerable to transmission; thus, the least amount of total P (T-P) in vineyard may be attributed to the removal of sediment and sediment bond P from runoff in response to land-use changes. Average L-P in alfalfa land was two times more than that in vineyard. Results showed that 44.5% of T-P in native land was stored in surface layer; besides, the portion of the arable surface horizon in T-P sequestration was 33%.
    Archives of Agronomy and Soil Science 08/2014; 61(6):1-13. DOI:10.1080/03650340.2014.954106 · 0.52 Impact Factor
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    ABSTRACT: Cultivating native lands may alter soil phosphorus (P) distribution and availability. The present study aimed to determine the distribution of P in soil aggregates for different long-term land management practices. The partitioned P in labile (L), Fe/Al-bound, Ca-bound, organic pools, and total P in four aggregate size fractions were determined for five land uses (forest, vineyard after 30 years, wetland, alfalfa, and wheat cultivated soil after 20 years). Both native land uses (forest and wetland) were distinguished by high and low amounts of large macro- and micro-aggregates, respectively, compared with disturbed soils (vineyard, alfalfa, and wheat soils). Labile P in large macro-aggregates were higher in native land use when compared with the other land uses, which led to increasing lability of P and accelerated water pollution. Soils under native conditions sequestered more Ca-bound P in large macro-aggregates than the soils in disturbed conditions. Conversion of native lands to agricultural land caused enhanced organic P storage in aggregates smaller than the 2 mm from 31.0 to 54.3 %. Soils under forest had 30 % total P more than the vineyard for the aggregates >2 mm after 30 years land use change. However, the amount of P in smaller (<2 mm) sized aggregates was increased by 29 % for the vineyard when compared with the forest. The P storage as bound Ca particles for the large macro-aggregates had negative correlation with the micro-aggregates.
    Environmental Monitoring and Assessment 06/2014; 186(10). DOI:10.1007/s10661-014-3869-4 · 1.68 Impact Factor
  • Richard Harvey, Edward A. McBean, Bahram Gharabaghi
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    ABSTRACT: Effective management of aging water distribution infrastructure is essential for preserving the economic vitality of North American municipalities. Historical failures within Scarborough, Ontario, Canada, reveal a seasonal pattern to water main failures, with the majority of failures occurring during the very cold winter months. Extensive installation of cement mortar lining and cathodic protection have extended the life span of aging water mains and reduced escalating failure rates. Artificial neural networks are found to be capable of predicting the time to failure for individual pipes using a range of pipe-specific attributes, including diameter, length, soil type, construction year, and the number of previous failures. The developed models have correlation coefficients ranging from 0.70-0.82 on instances reserved for evaluating predictive performance and have utility on an asset-by-asset basis when planning water main inspection, maintenance, and rehabilitation. Simulated failure scenarios indicate a return to high failure rates if cement mortar lining and cathodic protection are not extended to all candidate pipes in the distribution system.
    Journal of Water Resources Planning and Management 04/2014; 140(4):425-434. DOI:10.1061/(ASCE)WR.1943-5452.0000354 · 1.76 Impact Factor
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    ABSTRACT: The combined effects of two soil textures and two types of crop management were investigated using lithium and bromide tracers transport under saturated flow conditions. Leaching tests were carried out through intact columns of two soils, a clay loam (CL) and sandy loam (SL), each cropped with either wheat (Triticum aestivam) (W) or alfalfa (Medicago sativa) (A) for 11 years. A saturated steady state flow condition was established using tap water prior to injecting a pulse of 0.005 M LiBr solution onto the surface of the soil columns. Breakthrough curves (BTCs) for leached Br− and Li+ in the soil columns (especially under alfalfa cultivation) exhibited an early arrival time and greater concentrations, indicating preferential flow effects. Relative 5% arrival times were 0.07, 0.11, 0.24 and 0.31 for CL-A, SL-A, CL-W, and SL-W, respectively; its smaller values confirmed the higher possibility of preferential flow under alfalfa than under wheat. The Br− concentration was higher than the Li+ concentration. With the exception of soils under alfalfa (CL-A and SL-A), the peak of the BTCs for Br− occurred earlier than that for Li+, by about 0.4 and 1.2 pore volumes for the CL-W and SL-W cases, respectively. Clay loam soil under alfalfa showed higher Br− and Li+ concentration levels when compared to sandy loam soil under alfalfa crop production. In the soils under alfalfa cultivation, structural cracks, root channels, and earthworm burrows were the cause of higher leached concentrations for both tracers when compared to the soil under wheat. Therefore, alfalfa-induced changes in soil structure lead to continuous macropores, a result of the decomposition of penetrating roots. Our results show that agricultural-management practices (i.e. the type of cropping) can play an important role in making groundwater vulnerable to leached solutes.
    Agriculture Ecosystems & Environment 04/2014; 188:221–228. DOI:10.1016/j.agee.2014.02.031 · 3.20 Impact Factor
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    ABSTRACT: In this study the least limiting water range (LLWR) and associated measurements (water content at field capacity, θFC, wilting point, θPWP, air filled porosity, θAFP, and mechanical resistance, θSMR) were tested on two soils of clay loam (CL) and sandy loam (SL), each under long-term cultivation with either wheat (Triticum aestivum L.) or alfalfa (Medicago sativa). Water content at field capacity (θFC) and wilting point (θPWP) decreased slightly with an increase in bulk density (Db) in clay loam soils under wheat and alfalfa, whereas in sandy loam soils under the same cultivation, both values of θFC and θPWP strongly increased by increments of Db. The variation of LLWR was negatively related to Db in clay loam soils under wheat and alfalfa cultivation. The LLWR increased up to Db, equal to 1.56 Mg m−3 (when θFC = θ10kPa) and to 1.60 Mg m−3 (when θFC = θ33kPa) in sandy loam under alfalfa, and 1.42 Mg m−3 (both values of θFC) in sandy loam under wheat; LLWR then declined sharply with increasing Db. The highest value of LLWR was observed in the ranges of 0.034–0.167 cm3 cm−3 (when θFC = θ10kPa) and of 0.034–0.119 cm3 cm−3 (when θFC = θ33kPa) in clay loam under wheat. The lowest value of LLWR was observed in between 0.137 and 0.151 cm3 cm−3 (when θFC = θ10kPa) and between 0.087 and 0.111 cm3 cm−3 (when θFC = θ33kPa) in sandy loam under wheat. Linear regressions (Stepwise) showed that LLWR (when θFC = θ10kPa) was related to bulk density, clay, calcium carbonate (CaCO3) and organic carbon (OC) contents (r2 = 0.79). Considering θFC = θ33kPa, LLWR was related to bulk density, clay and OC contents (r2 = 0.48)
    Agricultural Water Management 04/2014; 136:34–41. DOI:10.1016/j.agwat.2014.01.007 · 2.33 Impact Factor
  • Bruce W. Kilgour, Bahram Gharabaghi, Nandana Perera
    Water Quality Research Journal of Canada 02/2014; 49(1):43. DOI:10.2166/wqrjc.2013.129 · 0.33 Impact Factor
  • Water Quality Research Journal of Canada 02/2014; 49(1):53. DOI:10.2166/wqrjc.2013.044 · 0.33 Impact Factor
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    ABSTRACT: Dye tracing field data were collected in small, steep streams in Ontario and used to calculate longitudinal dispersion coefficients for these headwater streams. A predictive equation for longitudinal dispersion coefficient is developed using combined data sets from 5 steeper head - water streams and 24 milder and larger rivers. The predictive equation relates the longitudinal dispersion coefficient to hydraulic and geometric parameters of the stream and has been developed using multiple regression analysis. The newly developed equation shows impressive accuracy of predictions for longitudinal dispersion coefficient (R2 = 0.86, RMSE = 25, Nash-Sutcliffe coefficient Ens = 0.86 and Index of Agreement D = 0.96) for both small, steep headwater streams as well as large, mild rivers. The Froude number has been introduced as a third key parameter to capture the effect of slope of the reach – in addition to the aspect ratio and bed material surface roughness – on the longitudinal dispersion coefficient. The pronounced improvement in the accuracy of the prediction is due to the addition of the Froude number to capture the effect of the slope of the reach on longitudinal dispersion coefficient. This article is protected by copyright. All rights reserved.
    Hydrological Processes 01/2014; 29(2). DOI:10.1002/hyp.10139 · 2.70 Impact Factor
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    ABSTRACT: The warming effect of the impervious surfaces in urban catchment areas and the cooling effect of underground storm sewer pipes on stormwater runoff temperature are assessed. Four urban residential catchment areas in the Cities of Guelph and Kitchener, Ontario, Canada were evaluated using a combination of runoff monitoring and modelling. The stormwater level and water temperature were monitored at 10 min interval at the inlet of the stormwater management ponds for three summers 2009, 2010 and 2011. The warming effect of the ponds is also studied, however discussed in detail in a separate paper. An artificial neural network (ANN) model for stormwater temperature was trained and validated using monitoring data. Stormwater runoff temperature was most sensitive to event mean temperature of the rainfall (EMTR) with a normalized sensitivity coefficient (Se) of 1.257. Subsequent levels of sensitivity corresponded to the longest sewer pipe length (LPL), maximum rainfall intensity (MI), percent impervious cover (IMP), rainfall depth (R), initial asphalt temperature (AspT), pipe network density (PND), and rainfall duration (D), respectively. Percent impervious cover of the catchment area (IMP) was the key parameter that represented the warming effect of the paved surfaces; sensitivity analysis showed IMP increase from 20% to 50% resulted in runoff temperature increase by 3 degrees C. The longest storm sewer pipe length (LPL) and the storm sewer pipe network density (PND) are the two key parameters that control the cooling effect of the underground sewer system; sensitivity analysis showed LPL increase from 345 to 966 m, resulted in runoff temperature drop by 2.5 degrees C.
    Journal of Hydrology 10/2013; 502:10-17. DOI:10.1016/j.jhydrol.2013.08.016 · 2.69 Impact Factor
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    ABSTRACT: Saturated hydraulic conductivity ( 𝐾 𝑠 ), among other soil hydraulic properties, is important and necessary in water and mass transport models and irrigation and drainage studies. Although this property can be measured directly, its measurement is difficult and very variable in space and time. Thus pedotransfer functions (PTFs) provide an alternative way to predict the 𝐾 𝑠 from easily available soil data. This study was done to predict the 𝐾 𝑠 in Khuzestan province, southwest Iran. Three Intelligence models including (radial basis function neural networks (RBFNN), multi layer perceptron neural networks (MLPNN)), adaptive neuro-fuzzy inference system (ANFIS) and multiple-linear regression (MLR) to predict the 𝐾 𝑠 were used. Input variable included sand, silt, and clay percents and bulk density. The total of 175 soil samples was divided into two groups as 130 for the training and 45 for the testing of PTFs. The results indicated that ANFIS and RBFNN are effective methods for 𝐾 𝑠 prediction and have better accuracy compared with the MLPNN and MLR models. The correlation between predicted and measured 𝐾 𝑠 values using ANFIS was better than artificial neural network (ANN). Mean square error values for ANFIS, ANN, and MLR were 0.005, 0.02, and 0.17, respectively, which shows that ANFIS model is a powerful tool and has better performance than ANN and MLR in prediction of 𝐾 𝑠 .
    06/2013; 2013. DOI:10.1155/2013/308159
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    ABSTRACT: After rapid urban expansion in Ontario, post-World War II, there followed a lengthy period of time where only minimal infrastructure maintenance occurred. Now, however, most of that infrastructure is approaching the end of its predicted life expectancy, and has started failing at an unprecedented rate. The combination of low maintenance and the increasing age of water distribution infrastructure has resulted in increasing rates of pipe failures. To assign priorities for repair/replacement, artificial neural network modelling is employed. Eight independent variables are employed, namely pipe length, diameter, age, break category, soil type, pipe material, the year of Cement Mortar Lining (if implemented), and the year of Cathodic Protection (if implemented), to determine the importance of different factors influencing the pipe failure rate. The results in application to the distribution system in Etobicoke, Ontario demonstrate that ANN models have very strong predictive capabilities (R2=0.94) when compared with the multiple linear regression method (R2=0.75) to assist rehabilitation planning.
    Canadian Water Resources Journal 03/2013; 38(1):24-33. DOI:10.1080/07011784.2013.774153 · 1.22 Impact Factor
  • Nandana Perera, Bahram Gharabaghi, Ken Howard
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    ABSTRACT: Chloride from road salt enters streams primarily through surface runoff and groundwater discharge. Monitoring of dry-weather flow chloride concentrations in the Highland Creek watershed of the eastern Greater Toronto Area indicates the presence of a previously unrecognised, dual porosity aquifer system whereby preferential flow associated with "urban karst" exerts a significant influence on baseflow chloride concentrations early in the year. A chloride mass balance undertaken annually over four successive salting seasons suggests that as much as 40% of the chloride applied as road salt enters the shallow aquifer resulting in a net accumulation of chloride and a gradual increase in mean baseflow chloride concentrations. Assuming current road salt application rates are continued, late summer baseflow chloride concentrations will reach around 505 mg/L, almost double present levels. Elevated chloride concentrations can affect the potability of water (the Canadian aesthetic drinking water quality guideline for chloride is 250 mg/L) and can also be toxic to aquatic organisms (CCME aquatic chronic toxicity guideline is 208 mg/L). Meeting these guidelines would require that the release of salt-laden runoff to the subsurface be reduced by over 50%.
    Journal of Hydrology 02/2013; 479:159–168. DOI:10.1016/j.jhydrol.2012.11.057 · 2.69 Impact Factor