Papers by ALIREZA PILPAYEH
World applied sciences journal, 2010
Inappropriate distribution of precipitation measurement stations has increased the use of gridded... more Inappropriate distribution of precipitation measurement stations has increased the use of gridded precipitation datasets consisting of satellite. reanalysis and ground-based datasets .Accurate measurement and estimation of precipitation amounts and events is very important. With the increasing development of satellite technologies in recent decades. access to high spatio-temporal resolution of precipitation data has been provided in many parts of the world. Given that these precipitation datasets cannot be used without initial assessment due to uncertainties in estimating cloud and precipitation thickness. The purpose of this study was to evaluate CMORPH. PERSIANN and PERSIANN-CDR precipitation datasets based on statistical indices such as contingency table indices at Dare-roud basin which is located in Ardabil province. Results show that CMORPH product performs better in estimating basin precipitation in most of the stations with RMSE index less than 3 mm and CC index higher than 0.7. Also in terms of the contingency table indices. The CMORPH performs better in most of the indices (except Bias) than other products. So it is recommended to correct its bias and use this precipitation product in future studies in Dare-Roud basin.
Revista INGENIERÍA UC, 2019
Soil wetting profile is one of the most important parameters in soil physics that influence on cr... more Soil wetting profile is one of the most important parameters in soil physics that influence on crops growth. The aim of this study is estimating of soil wetting profile in 1 m depth of soil surface under saturated and unsaturated infiltration process. The study has been conducted in loamy soil of Gonbad research station, Hamadan, Iran. Field infiltration experiments were carried out in four tensions including, 0 cm H O (using double 2 ring infiltrometer), 6, 9 and 15 cm H O (using tension infiltrometer), five slopes including 0-, 10-, 20-, 30-and 40 2 degree of slope and in 3 replications. Water contents in various soil depth measured using a TDR instrument in different times. Totally 60 water infiltration were carried out. Soil wetting profile extracted using measured data and numerical simulation using Hydrus 2D code. Results indicated that before beginning of infiltration volumetric water content at near the soil surface is less than that of deep soil depth, but after beginning of infiltration volumetric water content at near the soil surface is more than that of deep soil depth. With increase in slope gradient water content values decreased in same soil depth. In low tension moisture distribution were more extended than that of high tension. In all tension treatments relative error and root mean square error between simulated and measured data were calculated less than 3.22% and 0.032 respectively. Therefore inverse numerical simulation has acceptable consistency with measured data.
The purpose of this study was to investigate hydraulic and structural variations resulted from se... more The purpose of this study was to investigate hydraulic and structural variations resulted from sectional changes of soil to concrete canals. In the study of hydraulic regime of water transport canals, other components of flow can be obtained if cross-section and velocity of flow are known and it is possible to analyze water surface profile. Hydraulic calculations are not manually possible or require spending a lot of time and cost. In this study, HEC-RAS model was used for hydraulic and structural simulation in Moghan canal, located in the northwest of Iran. This software has been developed by U.S. Army Engineering Center as a hydraulic analysis system. According to field observations and experience, roughness coefficients were estimated for soil to concrete sections. Hydraulic structures of canal path such as water level control structures, flow control structures and bridges were also simulated in the model. This study demonstrated that, in soil and concrete canals, roughness coefficients were one of the effective parameters on the water surface profile and lead to hydraulic drop of the flow. Also, consecutive hydraulic structures in soil-concrete canal path can create a new water surface profile.
Advances in Water Resources, 2001
Although models are now routinely used for addressing environmental problems, both in research an... more Although models are now routinely used for addressing environmental problems, both in research and management applications, the problem of obtaining the required parameters remains a major challenge. An attractive procedure for obtaining model parameters in recent years has been through inverse modeling. This approach involves obtaining easily measurable variables (model output), and using this information to estimate a set of unknown model parameters. Inverse procedures usually require optimization of an objective function. In this study we emulate the behavior of a colony of ants to achieve this optimization. The method uses the fact that ants are capable of ®nding the shortest path from a food source to their nest by depositing a trail of pheromone during their walk. Results obtained with the ant colony parameter optimization method are very promising; in eight dierent applications we were able to estimate the`true' parameters to within a few percent. One such study is reported in this paper plus an application to estimating hydraulic parameters in a lysimeter experiment. Despite the encouraging results obtained thus far, further improvements could still be made in the parameterization of the ant colony optimization for application to estimation of unsaturated¯ow and transport parameters.
Revista INGENIERÍA UC, 2019
In recent years, various studies have been conducted on optimization of hydro and thermal power p... more In recent years, various studies have been conducted on optimization of hydro and thermal power plants; however, due to the complexity of this problem, optimal operation of power systems consisting of hydro-thermal power plants with multi-purpose reservoirs, which is mostly resulting from their uncertain, non-convex, non-linear and dynamic nature, numerous simplifications and approximations have been applied in modeling these systems in order to provide the possibility of their analysis using mathematical methods. But, the result of these simplifications and approximations is distancing of the obtained models from practical operational realities of the system which limits application of their results. With progress of computational technology and advent of effective algorithms, more practical aspects of the system's real productivity can be used in optimization models. Considering the importance of this issue in the present work, a new method was presented for simultaneous long...
World applied sciences journal, 2011
Journal of Soil and Water Resources Conservation, Jul 22, 2020
Inappropriate distribution of precipitation measurement stations has increased the use of gridded... more Inappropriate distribution of precipitation measurement stations has increased the use of gridded precipitation datasets consisting of satellite. reanalysis and ground-based datasets .Accurate measurement and estimation of precipitation amounts and events is very important. With the increasing development of satellite technologies in recent decades. access to high spatio-temporal resolution of precipitation data has been provided in many parts of the world. Given that these precipitation datasets cannot be used without initial assessment due to uncertainties in estimating cloud and precipitation thickness. The purpose of this study was to evaluate CMORPH. PERSIANN and PERSIANN-CDR precipitation datasets based on statistical indices such as contingency table indices at Dare-roud basin which is located in Ardabil province. Results show that CMORPH product performs better in estimating basin precipitation in most of the stations with RMSE index less than 3 mm and CC index higher than 0.7. Also in terms of the contingency table indices. The CMORPH performs better in most of the indices (except Bias) than other products. So it is recommended to correct its bias and use this precipitation product in future studies in Dare-Roud basin.
World applied sciences journal, 2010
In recent years, various studies have been conducted on optimization of hydro and thermal power p... more In recent years, various studies have been conducted on optimization of hydro and thermal power plants; however, due to the complexity of this problem, optimal operation of power systems consisting of hydro-thermal power plants with multipurpose reservoirs, which is mostly resulting from their uncertain, non-convex, non-linear and dynamic nature, numerous simplifications and approximations have been applied in modeling these systems in order to provide the possibility of their analysis using mathematical methods. But, the result of these simplifications and approximations is distancing of the obtained models from practical operational realities of the system which limits application of their results. With progress of computational technology and advent of effective algorithms, more practical aspects of the system's real productivity can be used in optimization models. Considering the importance of this issue in the present work, a new method was presented for simultaneous long-t...
The purpose of this study is hydrodynamic simulations of the water control gates in the water tra... more The purpose of this study is hydrodynamic simulations of the water control gates in the water transport channels. Hydrodynamic simulations give a proper understanding of how performance and optimize utilization of the gates controlling the water level. Non-linear equations governing the open channel flows due to changes in water flow rate and other parameters of complexity is important. Four different sluice gates simulate the water surface level using HEC-RAS in Moghan main channel. This channel is the main transition channel in the northwestern of Iran and its resources is Aras river in Iran. Aras river originated from Turkey. Hec-Ras model is produced by US Army for analyzing river system. This model could simulate steady and unsteady open channel flow. Model results was assumed and compared with the observed data in real channel. Calibration and verification of data was derived to plot the water surface level of gradually varied flow in different discharges to provide operationa...
The objective of this study was to determine suitable drought monitoring indexes using the approa... more The objective of this study was to determine suitable drought monitoring indexes using the approach of systematic simulation and evaluation of interactions between water resources and historical drought in a region and to develop a mixed method. One of the important and efficient tools in drought monitoring systems is monitoring indexes, which in the case of compatibility with the conditions of application environment has a considerable effect on monitoring, pre-warning and often predicting this phenomenon. This is only possible if the mentioned indexes are selected based on the need and conditions of the application location. In this research, the studied region was Ardabil province in north-west of Iran and the objective was to determine severity and range of drought in the region. Three indexes were utilized for monitoring drought: PNPI (Percent of Normal Precipitation Index), DPI (Deciles Precipitation Index) and SPI (Standardized Precipitation Index). Information of 10 stations...
2 Abstract: Soil wetting profile is one of the most important parameters in soil physics that inf... more 2 Abstract: Soil wetting profile is one of the most important parameters in soil physics that influence on crops growth. The aim of this study is estimating of soil wetting profile in 1 m depth of soil surface under saturated and unsaturated infiltration process. The study has been conducted in loamy soil of Gonbad research station, Hamadan, Iran. Field infiltration experiments were carried out in four tensions including, 0 cm H O (using double 2 ring infiltrometer), 6, 9 and 15 cm H O (using tension infiltrometer), five slopes including 0-, 10-, 20-, 30- and 40 2 degree of slope and in 3 replications. Water contents in various soil depth measured using a TDR instrument in different times. Totally 60 water infiltration were carried out. Soil wetting profile extracted using measured data and numerical simulation using Hydrus 2D code. Results indicated that before beginning of infiltration volumetric water content at near the soil surface is less than that of deep soil depth, but afte...
canals. In the study of hydraulic regime of water transport canals, other components of flow can ... more canals. In the study of hydraulic regime of water transport canals, other components of flow can be obtained if cross-section and velocity of flow are known and it is possible to analyze water surface profile. Hydraulic calculations are not manually possible or require spending a lot of time and cost. In this study, HEC-RAS model was used for hydraulic and structural simulation in Moghan canal, located in the northwest of Iran. This software has been developed by U.S. Army Engineering Center as a hydraulic analysis system.According to field observations and experience, roughness coefficients were estimated for soil to concrete sections. Hydraulic structures of canal path such as water level control structures, flow control structures and bridges were also simulated in the model. This study demonstrated that, in soil and concrete canals, roughness coefficients were one of the effective parameters on the water surface profile and lead to hydraulic drop of the flow. Also, consecutive h...
Greener Journal of Science, Engineering and Technological Research, 2013
Rivers are Consider as the most essential resources for preparing water to human beings and other... more Rivers are Consider as the most essential resources for preparing water to human beings and other living organisms and in some cases, this source may cause non recoverable damages. Prediction of river hydraulic characteristics in contrast to probable flooding for decreasing damages to urban area, in executing establishment, fields and other uses is very important. Allocating of flooding locations in cities is one of the basic data for controlling floods in a non structural manner. In this research determination of flooding locations of some part of urban Hir water shed (Hir Chai river) is done. Mathematical model which is used in this research is named HEC-RAS which has high potentiality in simulating river hydraulic regime, evaluating steady and unsteady floods, calculation of water level profile and finding relation with Geographical Information System (GIS). Geographical information system is a profitable science in systemic evaluation of different parameters and is considered as a Support factor in decision making. In this research its relation with mathematical model of HEC-RAS and HEC-GEORAS has been evaluated. Estimation of optimum return period and flood damages due to different return period has been done. The result of this research clearly shows the relationship between HEC-RAS and GIS, also the flood location in different return period has been determined.
Applied Water Science, 2016
It is of high importance to determine the flood discharge of different basins, in studies on wate... more It is of high importance to determine the flood discharge of different basins, in studies on water resources. However, it is necessary to use new models to determine flood hydrograph parameters. Therefore, it will be beneficial to conduct studies to calibrate the models, keeping in mind the local conditions of different regions. Therefore, this study was carried out to determine the peak flood discharge of a basin located in Southwest Iran, using the TR-20, TR55, and HEC-1 methods of the WMS model (watershed modeling system). The obtained results were compared with empirical values, as well as those of the soil conservation service (SCS) approach. Based on the results obtained, the TR55 method of the WMS model recorded the highest agreement with empirical values in Southwest Iran.
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Papers by ALIREZA PILPAYEH