Search for: watersheds
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    Estimation of 3-D pore network coordination number of rocks from watershed segmentation of a single 2-D image

    , Article Advances in Water Resources ; Volume 94 , 2016 , Pages 264-277 ; 03091708 (ISSN) Rabbani, A ; Ayatollahi, S ; Kharrat, R ; Dashti, N ; Sharif University of Technology
    Elsevier Ltd  2016
    In this study, we have utilized 3-D micro-tomography images of real and synthetic rocks to introduce two mathematical correlations which estimate the distribution parameters of 3-D coordination number using a single 2-D cross-sectional image. By applying a watershed segmentation algorithm, it is found that the distribution of 3-D coordination number is acceptably predictable by statistical analysis of the network extracted from 2-D images. In this study, we have utilized 25 volumetric images of rocks in order to propose two mathematical formulas. These formulas aim to approximate the average and standard deviation of coordination number in 3-D pore networks. Then, the formulas are applied... 

    Fertilizer, landscape features and climate regulate phosphorus retention and river export in diverse Midwestern watersheds

    , Article Biogeochemistry ; Volume 146, Issue 3 , 2019 , Pages 293-309 ; 01682563 (ISSN) Boardman, E ; Danesh Yazdi, M ; Foufoula Georgiou, E ; Dolph, C. L ; Finlay, J. C ; Sharif University of Technology
    Springer  2019
    Non-point source pollution of phosphorus (P) is a primary cause of eutrophication of aquatic ecosystems, and poses a persistent management challenge due to the dynamic and poorly understood processes controlling the transport and transformation of P at the watershed scale. We examined phosphorus inputs, retention, and riverine losses in 62 diverse watersheds that included a wide range of land cover and use (minimally disturbed to human dominated) and human P inputs in Minnesota, USA. Fertilizer inputs from row crop cultivation were the dominant source of P to agricultural watersheds. A large majority of P inputs was retained in watershed soils or removed in agricultural products. However,... 

    Obtaining the effect of sewage network on groundwater quality using MT3DMS code: Case study on Bojnourd plain

    , Article Groundwater for Sustainable Development ; Volume 11 , October , 2020 Kheirandish, M ; Rahimi, H ; Kamaliardakani, M ; Salim, R ; Sharif University of Technology
    Elsevier B. V  2020
    Groundwater contamination is a significant problem related strongly to both the protection of the environment and the need for water. In the present study, groundwater quality was investigated in the Bojnourd watershed. The Bojnourd watershed is located in the northeast of Iran, which covers 65.5 km2 of the North Khorasan province area. There are 11 extracting wells in the region. Annual water extraction from the alluvial aquifer in the area is used for agriculture, drinking, sanitary and industrial consumptions. In this research, groundwater quantity modeling, including calibration and verification by GMS software, had been performed. In the quality modeling stage, pollution contours for... 

    Application of the WEPP model to determine sources of run-off and sediment in a forested watershed

    , Article Hydrological Processes ; Volume 29, Issue 4 , 2015 , Pages 481-497 ; 08856087 (ISSN) Saghafian, B ; Meghdadi, A. R ; Sima, S ; Sharif University of Technology
    John Wiley and Sons Ltd  2015
    This study investigates critical run-off and sediment production sources in a forested Kasilian watershed located in northern Iran. The Water Erosion Prediction Project (WEPP) watershed model was set up to simulate the run-off and sediment yields. WEPP was calibrated and validated against measured rainfall-run-off-sediment data. Results showed that simulated run-off and sediment yields of the watershed were in agreement with the measured data for the calibration and validation periods. While low and medium values of run-off and sediment yields were adequately simulated by the WEPP model, high run-off and sediment yield values were underestimated. Performance of the model was evaluated as... 

    Watersheds are schramm-loewner evolution curves

    , Article Physical Review Letters ; Volume 109, Issue 21 , 2012 ; 00319007 (ISSN) Daryaei, E ; Araújo, N. A. M ; Schrenk, K. J ; Rouhani, S ; Herrmann, H. J ; Sharif University of Technology
    We show that in the continuum limit watersheds dividing drainage basins are Schramm-Loewner evolution (SLE) curves, being described by one single parameter κ. Several numerical evaluations are applied to ascertain this. All calculations are consistent with SLEκ, with κ=1.734±0.005, being the only known physical example of an SLE with κ<2. This lies outside the well-known duality conjecture, bringing up new questions regarding the existence and reversibility of dual models. Furthermore, it constitutes a strong indication for conformal invariance in random landscapes and suggests that watersheds likely correspond to a logarithmic conformal field theory with a central charge c-7/2  

    A multispectral image segmentation method using size-weighted fuzzy clustering and membership connectedness

    , Article IEEE Geoscience and Remote Sensing Letters ; Volume 7, Issue 3 , March , 2010 , Pages 520-524 ; 1545598X (ISSN) Hasanzadeh, M ; Kasaei, S ; Sharif University of Technology
    Clustering-based image segmentation is a well-known multispectral image segmentation method. However, as it inherently does not account for the spatial relation among image pixels, it often results in inhomogeneous segmented regions. The recently proposed membership-connectedness (MC)-based segmentation method considers the local and global spatial relations besides the fuzzy clustering stage to improve segmentation accuracy. However, the inherent spatial and intraclass redundancies in multispectral images might decrease the accuracy and efficiency of the method. This letter addresses these two problems and proposes a segmentation method that is based on the MC method, watershed transform,... 

    Phosphorus transport in intensively managed watersheds

    , Article Water Resources Research ; Volume 55, Issue 11 , 2019 , Pages 9148-9172 ; 00431397 (ISSN) Dolph, C. L ; Boardman, E ; Danesh Yazdi, M ; Finlay, J. C ; Hansen, A. T ; Baker, A. C ; Dalzell, B ; Sharif University of Technology]
    Blackwell Publishing Ltd  2019
    Understanding controls of P movement through watersheds are essential for improved landscape management in intensively managed regions. Here, we analyze observational data from 104 gaged river sites and 176 nongaged river sites within agriculturally dominated watersheds of Minnesota, USA, to understand the role of landscape features, land use practices, climate variability, and biogeochemical processes in total, dissolved and particulate P dynamics at daily to annual scales. Our analyses demonstrate that factors mediating P concentration-discharge relationships varied greatly across watersheds and included near-channel sediment sources, lake and wetland interception, assimilation by algal P,... 

    The impact of pavement permeability on time of concentration in a small urban watershed with a semi-arid climate

    , Article Water Resources Management ; Volume 34, Issue 9 , 2020 , Pages 2969-2988 Ghazi Zadeh Hashemi, M. S ; Tajrishy, M ; Jalilvand, E ; Sharif University of Technology
    Springer  2020
    Despite the popularity of the permeable pavements in urban areas in recent years, a few empirical equations have been developed to estimate the time of concentration (Tc) on pervious surfaces, and almost none of them is evaluated over the permeable pavements. In this paper, we aim to investigate the effect of low impact development (LID) on Tc and develop a new equation for estimating overland flow Tc compatible with both permeable and impermeable pavements in small urban watersheds with a semi-arid climate. An experimental model was devised to determine the new equation. Synthetic rainfall (22–40 mm.h−1) was applied to a rectangular shaped (6 m × 1 m) test watershed with an adjustable... 

    Modeling of point and non-point source pollution of nitrate with SWAT in the Jajrood river watershed, Iran

    , Article International Agricultural Engineering Journal ; Volume 19, Issue 2 , 2010 , Pages 23-31 ; 08582114 (ISSN) Jamshidi, M ; Tajrishy, M ; Maghrebi, M ; Sharif University of Technology
    The Latian dam reservoir is one of the most important drinking water sources for Tehran, Iran. Nitrate is a major water quality problem in this reservoir. The Jajrood River, the most important water source for the reservoir, discharges large amounts of nutrients to it every year including high levels of nitrate, a pollutant of particular concern. This study presents the results obtained from simulating different point source and nonpoint source impacts on the fate and transport of nitrate in the 470 km2 Jajrood watershed using the Soil and Water Assessment Tool (SWAT) model version 2000 (SWAT2000). The SWAT model was calibrated and validated over an extended time period (1997-2005) for this... 

    The power of environmental observatories for advancing multidisciplinary research, outreach, and decision support: the case of the minnesota river basin

    , Article Water Resources Research ; Volume 55, Issue 4 , 2019 , Pages 3576-3592 ; 00431397 (ISSN) Gran, K. B ; Dolph, C ; Baker, A ; Bevis, M ; Cho, S. J ; Czuba, J. A ; Dalzell, B ; Danesh Yazdi, M ; Hansen, A. T ; Kelly, S ; Lang, Z ; Schwenk, J ; Belmont, P ; Finlay, J. C ; Kumar, P ; Rabotyagov, S ; Roehrig, G ; Wilcock, P ; Foufoula Georgiou, E ; Sharif University of Technology
    Blackwell Publishing Ltd  2019
    Observatory-scale data collection efforts allow unprecedented opportunities for integrative, multidisciplinary investigations in large, complex watersheds, which can affect management decisions and policy. Through the National Science Foundation-funded REACH (REsilience under Accelerated CHange) project, in collaboration with the Intensively Managed Landscapes-Critical Zone Observatory, we have collected a series of multidisciplinary data sets throughout the Minnesota River Basin in south-central Minnesota, USA, a 43,400-km2 tributary to the Upper Mississippi River. Postglacial incision within the Minnesota River valley created an erosional landscape highly responsive to hydrologic change,... 

    The Watershed Model and Schramm-loewner Evolution

    , Ph.D. Dissertation Sharif University of Technology Daryaei, Ebrahim (Author) ; Rouhani, Shahin (Supervisor)
    Schramm Loewner evolution (SLE) is a one-parameter family of random simple curves in the complex plane introduced by Schramm in 1999 which is believed to describe the scaling limit of a variety of domain interfaces at criticality. This thesis is concerned with statistical properties of watersheds dividing drainage basins. The fractal dimension of this model is 1.22 which is consistent with the known fractal dimension for several important models such as Invasion percolation and minimum spanning trees (MST). We present numerical evidences that in the scaling limit this model are SLE curves with =1.73, being the only known physical example of an
    SLE with <2. This lies outside the... 

    Modelling Point and non Point Source of Nitrate with SWAT in the Jajrood River Watershed

    , M.Sc. Thesis Sharif University of Technology Jamshidi, Mahdi (Author) ; Tajrishy, Masoud (Supervisor)
    To investigate boiling heat transfer characteristics of nanofluids, transient quenching¬ experiments of a high temperature silver sphere in water-based nanofluids with Ag and TiO2 nanoparticles were performed. A silver sphere of 10 mm in diameter at the initial temperature of 700o C was quenched in the nanofluids at the temperature of 90o C. The results showed considerable reduction in the quenching ability of nanofluids compared to that of pure water. The presence of nanoparticles in water caused film boiling mode to vanish at lower temperatures depending on the mixture concentration. Computed heat transfer rates in nanofluids were lower than those in pure water. In the quenching... 

    Estimating the Time of Concentration in Small Urban Watersheds (Case Study: Tehran)

    , M.Sc. Thesis Sharif University of Technology Ghazizadeh Hashemi, Sedigheh Alsadat (Author) ; Tajrishy, Masoud (Supervisor)
    Hydrologic analysis in order to design the collection and transmission structures of urban runoff require some time parameters as input that the accuracy of these analysis is directly sensitive to the accuracy of these parameters. Among these parameters, the time of concentration is the most frequently utilized time parameter and numerous equations for estimating the time of concentration in urban watersheds have been proposed. The purpose of this study is to propose some equations to estimate the time of concentration of overland flow in small urban watersheds with pattern similar to arid and semiarid regions and investigate the effect of using LIDs on reducing the surface runoff.... 

    Climate change and hydropower in Iran's Karkheh River Basin

    , Article World Environmental and Water Resources Congress 2012: Crossing Boundaries, Proceedings of the 2012 Congress ; 2012 , Pages 3341-3349 ; 9780784412312 (ISBN) Abrishamchi, A ; Jamali, S ; Madani, K ; Hadian, S ; Sharif University of Technology
    ASCE  2012
    The Karkheh River Basin is one of the Iranian river basins with a high potential for hydropower production. While Iran is actively constructing large dams in the Basin for hydropower production, climate change is putting the future status of hydropower production in the Basin in question. Using MODSIM, sensitivity of the Basin to climate change is investigated by estimating stream flow changes and the resulting impacts on hydropower production for different climate change scenarios. Results indicate considerable reductions in annual and seasonal hydropower production due to the expected dry climatic conditions under the existing operation rules. Findings highlight the necessity for revision... 

    Performance evaluation of water resources systems using system dynamics approach: Application to the Aras River Basin, Iran

    , Article World Environmental and Water Resources Congress 2012: Crossing Boundaries, Proceedings of the 2012 Congress ; 2012 , Pages 2367-2377 ; 9780784412312 (ISBN) Jood, M. S ; Abrishamchi, A ; Sharif University of Technology
    ASCE  2012
    System Dynamics approach is a powerful tool in water resources systems simulation for evaluating proposed plans and policies in development projects. In Aras River basin, existing water resources do not suffice increasing demand in the near future, thus construction of new reservoirs is under study. In this study, system dynamics approach is used to simulate the water resources system of Darehrood sub basin located in eastern part of Aras River basin. Performance indices are used to evaluate the alternative plans and policies.. Reliability, resiliency and vulnerability, the three performance indices used in study, are estimated using maximum value and mean value estimators mentioned in the... 

    Investigating sensitivity of flow parameters and uncertainty analysis of nutrient transport and dispersion model in shallow water. (Case study: Peer-bazar river and anzali wetland)

    , Article Desalination and Water Treatment ; Volume 174 , 2020 , Pages 204-214 Homami, M ; Mirbagheri, S. A ; Borghei, S. M ; Abbaspour, M ; Sharif University of Technology
    Desalination Publications  2020
    Accurate modeling of runoff in watersheds requires calibration and uncertainty analysis of effective flow parameters and identifying of their statistical characteristics based on inter-parameter relationships and model inputs. In this research, the transport and diffusion of pollution (nutrients) in the river were simulated through the two-dimensional finite-volume method using the shallow water equations. To numerically solve these equations, the governing equations were converted into linear equations. Uncertainty and sensitivity of the prepared pollution model were analyzed to achieve better results in estimating pollution concentrations in rivers within a reliable range. In this study,... 

    An automated simple algorithm for realistic pore network extraction from micro-tomography images

    , Article Journal of Petroleum Science and Engineering ; Vol. 123, issue , 2014 , pp. 164-171 ; ISSN: 09204105 Rabbani, A ; Jamshidi, S ; Salehi, S
    Using 3-D scanned data to analyze and extract pore network plays a vital role in investigation of porous media's characteristics. In this paper, a new simple method is developed to detect pores and throats for analyzing the connectivity and permeability of the network. This automated method utilizes some of the common and well-known image processing functions which are widely accessible by researchers and this has led to an easy algorithm implementation. In this method, after polishing and quality control of images, using city-block distance function and watershed segmentation algorithm, pores and throats are detected and 3-D network is produced. This method can also be applied on 2-D images... 

    A novel Markov random field model based on region adjacency graph for T1 magnetic resonance imaging brain segmentation

    , Article International Journal of Imaging Systems and Technology ; Volume 27, Issue 1 , 2017 , Pages 78-88 ; 08999457 (ISSN) Ahmadvand, A ; Yousefi, S ; Manzuri Shalmani, M. T ; Sharif University of Technology
    John Wiley and Sons Inc  2017
    Tissue segmentation in magnetic resonance brain scans is the most critical task in different aspects of brain analysis. Because manual segmentation of brain magnetic resonance imaging (MRI) images is a time-consuming and labor-intensive procedure, automatic image segmentation is widely used for this purpose. As Markov Random Field (MRF) model provides a powerful tool for segmentation of images with a high level of artifacts, it has been considered as a superior method. But because of the high computational cost of MRF, it is not appropriate for online processing. This article has proposed a novel method based on a proper combination of MRF model and watershed algorithm in order to alleviate... 

    Multispectral Fuzzy Image Segmentation

    , Ph.D. Dissertation Sharif University of Technology Hasanzadeh, Maryam (Author) ; Kasaei, Shohreh (Supervisor)
    Image segmentation is middle and an important task in image analysis and machine vision applications. The output images of imaging systems are often fuzzy because of noise, limitation in spatial and temporal resolution, blurring and intensity inhomogeneity in the objects. The goal of this thesis is exploring the fuzzy methods in multispectral image segmentation and proposing a new one to solve some of the recent difficulties and problems. The difficulties and problems such as simultaneous utilization of spatial and spectral information, necessity for dimension reduction, spatial and spectral and intra-cluster image information redundancy, existence of regions with widely varying size,... 

    Application and evaluation of RUSLE erosion model in JAJROOD watershed (ROODAK) with G.I.S

    , Article Proceedings of the 2nd IASTED International Conference on Environmental Management and Engineering, EME 2010, 15 July 2010 through 17 July 2010, Banff, AB ; July , 2010 , Pages 879-887 ; 9780889868526 (ISBN) Mirzai, M ; Sajadi, A ; Nazari, A ; Sharif University of Technology
    In this study amount of soil erosion in watershed of JAJROOD is estimated by use of the RULSE model with the help of GIS12. JAJROOD River is located in upstream of LATIAN Dam and is one of the most important water sources of Tehran. Also, this River has a big role in preventing the flood. modeling Results show that the amount of soil erosion is high due to high slope of the land, lack of plant coverage and the quality of soil and changing the land application, lead to increase in erosion potential. modeling Results have estimated the amount of erosion in this basin about 1,524,511 tons in a year. In order to evaluate Results and efficiency of the model, all of obtained results are compared...