Y. Khoshkhoo; parviz irannejad; ali khalili; Hassan Rahimi; A. Liaghat; P. Erik Jansson
Abstract
In this research calibration and uncertainty analysis of COUP model with focus on soil temperature simulation for 3-hours time scale have been performed for Hamedan synoptic station. The Generalized Likelihood Uncertainty Estimation (GLUE) was used for this object. In order to simulate the soil temperature, ...
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In this research calibration and uncertainty analysis of COUP model with focus on soil temperature simulation for 3-hours time scale have been performed for Hamedan synoptic station. The Generalized Likelihood Uncertainty Estimation (GLUE) was used for this object. In order to simulate the soil temperature, 22 parameters were chosen and by using the Monte Carlo stochastic sampling method from the uncertainty space of the parameters, 25000 scenarios were produced and model simulations were implemented. For separate behavioral and non-behavioral simulations, 3 criteria including Nash-Sutcliff, Mean Bias Error, and Root Mean Square Error were considered and acceptable thresholds for each criterion were defined. With applying the acceptable thresholds, 253 behavioral simulations were detected and used for calibration and uncertainty analysis of the model. Based on posterior parameter distributions some parameters were recognized as sensitive parameters. The median of behavioral simulations was considered for model calibration and the uncertainty analysis of the model was performed based on 90% confidence levels of behavioral simulation errors. The results showed that calibration of the model has considerably improved the performance of the model in comparison to default parameter values. In addition, the uncertainty analysis showed that the uncertainty of parameters has been considerably decreased in most cases with application of the GLUE method. Other differences between simulated and observed values were attributed to other sources of model uncertainty.
J. Rahimi; A. Khalili; J. Bazrafshan
Abstract
The estimation of effective rainfall is an important technique for exploiting the rainwater resource, planning for irrigation in irrigated agriculture, and determining changes in dryland wheat products for country's macroeconomic management. In this research, a two-layer soil-water balance model based ...
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The estimation of effective rainfall is an important technique for exploiting the rainwater resource, planning for irrigation in irrigated agriculture, and determining changes in dryland wheat products for country's macroeconomic management. In this research, a two-layer soil-water balance model based on a new approach has been formulated to estimate the effective rainfall in dryland wheat crop. In this model, it is assumed that, in addition to the soil moisture retained on root zone on before day, also that part of water saved between the previous and current root-zone development add to the effective rainfall at current day. Greater ability of current approach to determine changes in wheat yields, which can be justified by changes in effective rainfall, confirms superiority of the current approach. Besides that, In order to estimate the effective rainfall in dryland wheat crop by this approach, daily climatic records during statistical period (1999-2000 till 2008-2009) from 12 meteorological stations of Fars province were collected. Results indicated that among the studied stations the amount of mean annual effective rainfall in dryland wheat crop changes from 296.4 (mm) in Doroodzan dam station to 112.6 (mm) in Abadeh station. Also, it is assumed that production of dryland wheat crop at north and northwest of Fars province is more success than other parts, due to satisfactory supply of effective rainfall.
Kh. Ghorbani; A. Khalili; S.K. Alavinezhad; Gh. Nakhaezadeh
Abstract
Abstract
Precipitation is an important variable which is used in definition of drought. Based on precipitation amounts, some indices are devised for drought monitoring including, the Standardized Precipitation Index (SPI) and the Standard Index of Annual Precipitation (SIAP). Each of these Drought indices ...
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Abstract
Precipitation is an important variable which is used in definition of drought. Based on precipitation amounts, some indices are devised for drought monitoring including, the Standardized Precipitation Index (SPI) and the Standard Index of Annual Precipitation (SIAP). Each of these Drought indices are classified into some classes so that each class descripts a given severity of drought. Investigation of simultaneously occurrence situation for two drought indices can be an appropriate measure to evaluate the agreement of indices. Association Rules in DATA MINING is used to find rules and patterns in database. In this paper, two drought indices, SPI and SIAP, were computed at 11 meteorological stations belong to Ministry of Energy in Kermanshah province. Then, based on Association Rules, simultaneously occurrence situation of drought severity classes for both indices were determined in seasonally, half yearly and yearly time scales. Results showed that there is not any good agreement between most of drought category from these indices (less than 50 percent) and Shows different behavior of drought.
Keywords: Data Mining, Drought, Association Rules, Kermanshah
B. Bakhtiari; A. Khalili; A. Liaghat; M.J. Khangani
Abstract
Abstract
In recent years, automatic weather stations have been widely used for recording meteorological data in different time scales. Therefore the accurate estimation of ETo by combination equations can be evaluated using these set of short time scales data. Daily ETo can also be calculated by summation ...
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Abstract
In recent years, automatic weather stations have been widely used for recording meteorological data in different time scales. Therefore the accurate estimation of ETo by combination equations can be evaluated using these set of short time scales data. Daily ETo can also be calculated by summation of hourly ETo values. The purpose of this study is to compare the ETo values estimated by hourly and daily data. Totally, 7270 hourly meteorological data obtained from the automated weather reference station where placed in Shahid Bahonar university of Kerman, Iran during April to December 2005 and January to March 2006. The Penman-Monteith equations proposed by the Food and Agriculture Organization (FAO-56) and American Society of Civil Engineers (ASCE) were used for hourly and daily (24 hours) ETo estimation. The paired t- student test was used for comparison of estimated ETo values by two methods (daily and hourly summation) in each month. The results of this study showed significant differences between ETo values estimated by daily and hourly summation data in both equations at 5 percent level. The hourly summation method overestimated ETo values from 5.8 to 44.6 percent in different months using FAO-56 Penman-Monteith equation and from 7.4 to 47.6 percent using ASCE Penman-Monteith equation. The regression coefficients of correlation equations between the daily and hourly summation method in both combination models were strongly significant.
Keywords: Reference evapotranspiration, Hourly time scale, FAO-56 Penman-Monteith, ASCE Penman-Monteith