Coastal Flood Hazard Analysis for Bandar Anzali Coast Considering Joint Probability of Significant Events
M.
Olfateh
author
M.
Shafieefar
author
text
article
2013
per
Communities accommodated along shorelines have always been under devastating threats from thesea/ocean such as coastal flooding. Mitigation planning against such threads demands a wellunderstanding of the thread’s nature. In addition to the physical understanding, such planning isalways based on statistical representation of the thread generating events. Coastal hazard analysis isthe method of estimating such statistical representations based on the physics and time history of theevents and so, it is the preliminary step toward hazard mitigation planning. Methods that combinecontributing physical processes have weekly considered the dependence between the physicalprocesses. Using proper joint probability statistical methods, rational combinations of events can beestimated on the ground of their history. Copula functions are a group of functions that generate suchcombinations. Estimating the marginal distribution of the events, Copula functions represent the jointprobability of the events based on their historical joint occurrence. This method is used in this paper toderive the joint probability of storm surge and wave height for Bandar Anzali coasts. The ad-hocmethod of superimposing the significant events is also pursued for comparison. The marginaldistributions are chosen from GEV, Weibull, Gumble and Lognormal probability distributions. Themodel parameters are estimated using the Maximum Likelihood method, and the goodness of fit isevaluated using the Root Mean Square Error criterion. Deep water waves with return period of 20, 50and 100 years in addition to the joint probability results are transferred to the beach using the spectralcoefficient method. Considering wave setup and wave run up, the final inundation levels are estimatedand the inundated regions are plotted.
Journal of Hydraulics
Iranian Hydraulic Association
2345-4237
7
v.
4
no.
2013
1
18
http://jhyd.iha.ir/article_85352_fd08355c9f36b429bfe97330cd17a077.pdf
dx.doi.org/10.30482/jhyd.2013.85352
Hydraulics of Flow in Stilling Basins with Vertical Drops Using Grating and Netting Dissipators
Abdorreza
Kabiri-Samani
Associate Professor, Department of Civil Engineering, Isfahan University of Technology
author
E.
Bakhshian
author
text
article
2013
per
Abrupt change in the channel bed elevation in the hydraulic systems tends to create a severe flowkinematic energy. This excess energy results in different unfavorable phenomena includingtremendous forces on hydraulic structures, scouring and degrading the channel bed which results inthe destruction of the downstream structures. These phenomena would intensify while a number ofvertical drops constructed consecutively along the channel. The main goal of the present study is toexplore methods for increasing the energy dissipation efficiency of vertical drops by installing newtypes of dissipators, namely Grating and Netting drop-type dissipators based on theanalytical/experimental modeling. These types of dissipators could be established over the drop crestlooking like a bottom racks. In addition, the features of pressure distribution along the pool andreaction force over the pool floor were investigated. By assembling the above mentioned structuresover the stilling basins of vertical drops, the jet flow direction is changed and the degree of turbulenceincreases and as a result there is an increase in the head loss. The enhanced efficiency of the proposedstructures was quantified based on the experimental data obtained in this study. Both analytical andexperimental investigations were performed in the present study. Based on the model experimentationdata, empirical equations were presented to estimate the force acting on the basin floor. The proposedsemi-analytical model compared well with the experimental results. However, there are smalldiscrepancies between the analytical and experimental results of netting dissipators. This is partly dueto the flow high turbulence and complicated phenomena existed in the stilling basins of nettingdissipators. Also, the air bubble entrainment is another source of the difference between the two sets ofresults.
Journal of Hydraulics
Iranian Hydraulic Association
2345-4237
7
v.
4
no.
2013
19
36
http://jhyd.iha.ir/article_85353_2c26844e1ae1f87721d2efce11de624b.pdf
dx.doi.org/10.30482/jhyd.2013.85353
Uncertainty Analysis ofWater Surface Profile Computations in Rockfill Structures Using Fuzzy Probabilistic Method
A.
Yousefi
author
M.
Hosseini
نویسنده همکار
author
text
article
2013
per
Rockfill is one of the construction materials used in hydraulic structures. Water surface profilecomputations are required in the design and performance evaluation of many rockfill structures. Inwater surface profile computations in rockfill structures, some physical parameters cannot beaccurately measured and are uncertain. Uncertainty analysis can be used to estimate the uncertainty inthe output of a model due to uncertainty in its input parameters. In this study, uncertainty analysis ofwater surface profile computation in rockfill structures is conducted using a hybrid approach which isa fuzzy probabilistic method. This is done for Wilkins and Stephenson empirical equations and theresults are compared with those of a physical model. Results indicate that the Stephenson equationshows a better agreement with the experimental data. Also, if fuzzy parameters are estimated properly,the Stephenson equation shows less uncertainty.
Journal of Hydraulics
Iranian Hydraulic Association
2345-4237
7
v.
4
no.
2013
37
52
http://jhyd.iha.ir/article_85354_4ae8565a35214526934f078c97e5138c.pdf
dx.doi.org/10.30482/jhyd.2013.85354
Sewer Layout Design in Flat Areas Using Growing Spanning Tree Method and Tabu Search Optimization
A.
Haghighi
Assistant Professor, Department of Civil Engineering, Shahid Chamran University of Ahvaz
author
A.E.
Bakhshipour
author
Sh.
Baig
author
text
article
2013
per
In order to optimize sewer networks layout in flat areas, this paper aims at introducing an optimizationmodel based on the growing spanning tree and Tabu search methods. In the beginning, an undirectedloop graph named as the base graph is prepared for the network at hand. For extracting a feasible treelikesewer layout from the base graph, one pipe from each loop must be cut. For this purpose, themethod of growing spanning tree from the graphs theory is adopted. Through this method, by defininga root (sewer system’s outlet), it is possible to develop a spanning tree from downstream to upstreamof the network. Herein, some modifications are added to the method to be used for sewer networks. Inflat areas, the number of possible trees exponentially increases with the network size. For finding theoptimum layout among too many alternatives, an objective function is defined in terms of sewerslength and discharge. The decision variables are the pipes to be cut for opening the base graph’s loopsplus the cut locations which can be either at the upstream or downstream of the chosen pipes. A Tabusearch optimization model is developed for solving the problem. The proposed scheme is then appliedagainst a hypothetical example and a part of Hendijan sewer network. The results manifest that themethod is computationally efficient, reliable and capable of solving large-scale problems.
Journal of Hydraulics
Iranian Hydraulic Association
2345-4237
7
v.
4
no.
2013
53
70
http://jhyd.iha.ir/article_85356_54bb1ce6b8df77fac7e4d22b122b36a8.pdf
dx.doi.org/10.30482/jhyd.2013.85356
Application of Least Square Methods in Pipe Network Analysis
N.
Moosavian
author
M.R.
Jaefarzadeh
عضو هیئت علمی دانشکده عمران دانشگاه فردوسی مشهد
author
text
article
2013
per
In this article, for the first time, the least square methods of Gauss-Newton (GN) and Levenberg-Marquardt (LM) are used for the solution of discharge Q-equations in water distribution networks. Theresults are compared with the Newton-Raphson method (NR) and global gradient algorithm, (GGA).The GGA is used in the current commercial softwares of Water Gems and Epanet. The Newtonianmethods are critically dependent on a suitable initial guess for achieving a desired accuracy tocompete with the GGA. To remove this defect, an algorithm is proposed by linearzing the head-lossfunctions. Thereby, the nonlinear energy equations are linearzed and the whole system is solved. Theresults are then used as an initial guess for the solution of linear-nonlinear system of discharge-energyequations. Using this algorithm, it is observed that the rate of convergence in the GN method is muchfaster than the GGA and its accuracy is higher.
Journal of Hydraulics
Iranian Hydraulic Association
2345-4237
7
v.
4
no.
2013
71
84
http://jhyd.iha.ir/article_85357_efbfe9020f2e57ec819cac6ee43a5ac0.pdf
dx.doi.org/10.30482/jhyd.2013.85357
Scour Profiles and Variation of Shear Stresses in Scour Holes Downstream of Adverse Stilling Basins
H.
Khalili Shayan
author
J.
Farhoudi
author
text
article
2013
per
This research is focused on local scour downstream of adverse stilling basins where the flow jet wasissuing from a submerged sluice gate. Totally, 233 tests were performed and 3262 scour profiles wererecorded in a wide range of Froude numbers, sediment grain sizes, tail-water depths, stilling basinlengths and bed slopes. The results showed that the scour holes are self-similar at any slopes. Apolynomial equation was derived to define the non-dimensional scour profiles at different slopes. In acertain condition of sediment grain Froude number, tail-water depth and length of basin, a change inthe slope of basin from 0 to 15.6%, caused a decrease of 15% in maximum depth of scour hole. Atheoretical approach was also derived to evaluate the bed shear stress, weight shear stress and shearstress at threshold state along the scour hole. It was found that the weight and bed shear stresses alongthe scour hole follow a time-dependent similar trend of variation. Finally, the geometry of basin wasinvestigated to examine its effects on the weight and bed shear stresses.
Journal of Hydraulics
Iranian Hydraulic Association
2345-4237
7
v.
4
no.
2013
85
99
http://jhyd.iha.ir/article_85358_bc5759a018f143fd092bc08a89c52ae1.pdf
dx.doi.org/10.30482/jhyd.2013.85358
English Abstract
text
article
2013
per
Journal of Hydraulics
Iranian Hydraulic Association
2345-4237
7
v.
4
no.
2013
103
108
http://jhyd.iha.ir/article_85359_c3cbbc2d447fb6d125d338da8b937245.pdf
dx.doi.org/10.30482/jhyd.2013.85359