M. Mozayyan; ali mohammad akhondali; A.R. Massah Bavani; F. Radmanesh
Abstract
Introduction: Due to the effects of climate change on water resources and hydrology, Changes in low flow as an important part of the water cycle, is of interest to researchers, water managers and users in various fields. Changes in characteristics of low flows affected by climate change may have important ...
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Introduction: Due to the effects of climate change on water resources and hydrology, Changes in low flow as an important part of the water cycle, is of interest to researchers, water managers and users in various fields. Changes in characteristics of low flows affected by climate change may have important effects on various aspects of socioeconomic , environmental, water resources and governmental planning. There are several indices to assess the low flows. The used low flow indices in this research for assessing climate change impacts, is include the extracted indices from flow duration curve (Q70, Q90 and Q95), due to the importance of these indices in understanding and assessing the status of river flow in dry seasons that was investigated in Tang Panj Sezar basin in the west of Iran.
Materials and methods: In this paper, the Tang Panj Sezar basin with an area of 9410 km2 was divided into 6 smaller sub catchments and the changes of low flow indices were studied in each of the sub catchments. In order to consider the effects of climate change on low flow, scenarios of temperature and precipitation using 10 atmospheric general circulation models (to investigate the uncertainty of GCMs) for both the baseline (1971-2000) and future (2011-2040) under A2 emission scenario was prepared. These scenarios, due to large spatial scale need to downscaling. Therefore, LARS-WG stochastic weather generator model was used. In order to consider the effects of climate change on low flows in the future, a hydrologic model is required to simulate daily flow for 2011-2040. The IHACRES rainfall-runoff model was used for this purpose . After simulation of daily flow using IHACRES, with two time series of daily flow for the observation and future period in each of the sub catchment, the low flow indices were compared.
Results Discussion: According to results, across the whole year, the monthly temperature in the future period has increased while rainfall scenarios show different variations for different months, also within a month for different GCMs. Based on the results of low flow indices, in most cases, the three indices of Q70, Q90, and Q95 will show incremental changes in the future compared to the past. Also, the domain simulation by 10 GCMs for all three indices is maximum in Tang Panj Sezar and less for other sub catchments, which is related to better performance of IHACRES model in smaller sub catchments. In order to investigate the uncertainty of type changes in different indices in every sub catchment, changes in any of the indices were considered based on the median of GCMs. To achieve the correct type of changes in low flow indices, the amount of error in a simulation of the indices of IHACRES rainfall-runoff model should also be taken into consideration. Therefore, considering the error, the three indices Q70, Q90 and Q95 in all sub catchments (except for Tang Panj Sezar) will have the relative increase in the future period. The improvement of low flow state in the future period is related to the changes occurred in the state of climate scenarios. As the results indicated, most often, there is an increase in rainfall in dry seasons. Also, in different months of the wet season wet season, if the result of changes in quantity of rainfall is incremental, it can lead to an increase in river flow through groundwater recharge. On the other hand due to the limestone and karst forms in most of the basin area, water storage ability and increase the amount of river flow during low water season in this area is expected. The study on rainfall quantity in Tang Panj Sezar sub catchment also indicated that, there will be no significant increase or decrease in the quantity of rainfall in the dry season. Thus, it is expected that there will not be significant changes in low flow indices. In this sub catchment, changes in various low flow indices do not match perfectly, so more difficult to obtain reliable results. With regard to incremental changes of Q95, low flow index with less uncertainty, as well as improving indices of low flow in other sub-basins, it is possible to predict a relatively better state for low flow indices of Tang Panj Sezar in the future period.
Conclusion: Using temperature and rainfall scenarios to simulate river flow in the future, a relative increase of all three low flow indices Q70, Q90 and Q95 was predicted compared with the past period. Although all three of mentioned indices show the amount of low flow in the dry season, it is recommended that only two indices of Q90 and Q95 to assess the effects of climate change be considered. Q90 and Q95 indices are more suitable indices than Q70 for studying the effects of climate change on low flow state. These two indices indicate less quantity of flow in dry seasons; therefore, the changes of the two indices are more important in identifying the low flow state. However, there is less uncertainty in the estimation of the two Q90 and Q95 indices than Q70.
H. Sadeghi; ali mohammad akhondali; meisam haddad; M. Golabi
Abstract
Introduction: Accurate water demand modeling for the city is very important for forecasting and policies adoption related to water resources management. Thus, for future requirements of water estimation, forecasting and modeling, it is important to utilize models with little errors. Water has a special ...
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Introduction: Accurate water demand modeling for the city is very important for forecasting and policies adoption related to water resources management. Thus, for future requirements of water estimation, forecasting and modeling, it is important to utilize models with little errors. Water has a special place among the basic human needs, because it not hampers human life. The importance of the issue of water management in the extraction and consumption, it is necessary as a basic need. Municipal water applications is include a variety of water demand for domestic, public, industrial and commercial. Predicting the impact of urban water demand in better planning of water resources in arid and semiarid regions are faced with water restrictions.
Materials and Methods: One of the most important factors affecting the changing technological advances in production and demand functions, we must pay special attention to the layout pattern. Technology development is concerned not only technically, but also other aspects such as personal, non-economic factors (population, geographical and social factors) can be analyzed. Model examined in this study, a regression model is composed of a series of structural components over time allows changed invisible accidentally. Explanatory variables technology (both crystalline and amorphous) in a model according to which the material is said to be better, but because of the lack of measured variables over time can not be entered in the template. Model examined in this study, a regression model is composed of a series of structural component invisible accidentally changed over time allows. In this study, structural time series (STSM) and ARMA time series models have been used to model and estimate the water demand in Isfahan. Moreover, in order to find the efficient procedure, both models have been compared to each other. The desired data in this research include water consumption in Isfahan, water price and the monthly pay costs of water subscribers between 1388 and 1390. In structural time series model, the model was generated by entering the invisibility part of the process and development of a state-space model, as well as using maximum likelihood method and the Kalman-Filter algorithm.
Results and Discussion: Given the value of the test statistic ADF, with the exception of changing water use variables with a time difference of the steady rest. Superpopulation different modes of behavior were assessed based on the demand for water. Due to the likelihood ratio statistic is most suitable for the parameters, was diagnosed the steady-state level of randomness and the slope. Price and income elasticities of demand for water, respectively -0.81 and 0.85 shows that water demand is inelastic with respect to price and income and a lot of water is essential. Identify the nature of the request of one of the most important results in estimated water demand in the urban part of the state space time series structure and patterning methods, as an Alternative for variable is Technology preferences use. The model is estimated for the city's water demand time series model, respectively ARMA (3,1). Model performance metrics to compare the structural time series and time series ARMA, the result represents a structural time series model based on the fact that all the performance criteria in this study outperformed the ARMA model to forecast water city demand in the Isfahan.
Conclusion: Of a time series model structure to model ARMA in this research is to estimate the model and predict the number the less time is required, and also can be used for modeling of other variables (such as income and price) to this is helping to improve the models. Also, in ARMA time series the best model for data was selected according to the Schwarz Bayesian and Akaike criterion. Results indicate that the estimation of water demand using structural time series method is more efficient than when ARMA time series model is applied. Therefore, structural time series model can be used as an efficient tool for managers and planners in the Management Departmentsin order to forecast water demand. Used was for compare the performance of these two models of standard root mean square error (RMSE), mean absolute error (MAE) and mean absolute percentage error (MAPE).
mohammadreza golabi; ali mohammad akhondali
Abstract
During the last decades, urbanization expansion and industrial activities in large cities have led to remarkable changes in weather and local climate. Nowadays, analysis of meteorology data and also using them in programming the development of habitation centers are of importance and climate situation ...
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During the last decades, urbanization expansion and industrial activities in large cities have led to remarkable changes in weather and local climate. Nowadays, analysis of meteorology data and also using them in programming the development of habitation centers are of importance and climate situation affects people’s comfort. In fact, by recognition of city’s climate conditions in different months of the year and analysis of meteorology data, construction of climate comfort is possible. In this study, the monthly data of 4 climate factors (temperature average, minimum temperature, maximum temperature & relative humidity) from Aabadan’s meteorology station over 60 years (1330-1389) have been used. Using regression process, incongruity of data was evaluated and data’s homogeneity was studied by sequences’ examination. Then, using Mahani comfortable climate model, suitable months for convenience of human physiology in 6 ten-year periods were determined. Then, using Box–Jenkins models time series for 3 factors of climate, minimum temperature, maximum temperature and relative humidity is studied and the best model is fitted. Then, using suggested models, the next 10 years of any climate factor was predicted and the next years were studied from the viewpoint of comfortable climate using Mahani model. The results of this study indicated that based on Akaike criterion, the best Box–Jenkins model for minimum temperature is ARIMA (1,1,1)×(0,1,2)¹² model, for maximum temperature is ARIMA (0,1,2)× (0,1,1)¹² model and for relative humidity is ARIMA (1,1,1)×(0,1,1)¹² model. As for nightly comfortable climate, temperature has increased in Bahman, Esfand, Farvardin and Ordibehesht months. Temperature has decreased in Mordad, Shahrivar an Mehr months. As for daily convenience climate, temperature has increased in Dey, Bahman, Aazar and Esfand months, and temperature has decreased in Mehr month.
H. Seyyed Kaboli; A.M. AkhodAli; A.R. Masah Bavani; F. Radmanesh
Abstract
General Circulation Models (GCMs) have been identifiedas asuitable tool for studying climate change. Butthese models simulate climatic parametersinthe large-scale which has poor performance in the simulation of processes such asrain fall-run off. There fore, several of down scaling methods were developed. ...
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General Circulation Models (GCMs) have been identifiedas asuitable tool for studying climate change. Butthese models simulate climatic parametersinthe large-scale which has poor performance in the simulation of processes such asrain fall-run off. There fore, several of down scaling methods were developed. This researchis presented down scaling model based onk-nearest neighbor (K-NN) non-parametric method. The modelis used to simulate daily precipitation data in Ahvaz station for the next period (2015-2044) under climate change scenarios based on out puts of three General Circulation Models, including HADCM3, NCARPC Mand CSIROMK3.5. The results indicate that them odelhasa high capacity for down scaling data. It is predicted that the frequency of storm is increased with high intensity on future period in Ahvaz station while dry spells will be prolonged.
H. Seyed Kaboli; A.M. Akhondali
Abstract
Abstract
The aim of this study, is to evaluate the effect of loss methods application on run-off volume and hydrograph shape used by hydrologic models. In this research, four loss methods including constant loss (φ index), initial loss-loss rate, SCS and constant fraction approach were applied to be ...
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Abstract
The aim of this study, is to evaluate the effect of loss methods application on run-off volume and hydrograph shape used by hydrologic models. In this research, four loss methods including constant loss (φ index), initial loss-loss rate, SCS and constant fraction approach were applied to be evaluated. To do this, Clark Rainfall-Runoff model was applied for 24 storm events from kasilain basin. Then, the characteristics of calculated hydrographs were compared with the same characteristics of the same observed hydrographs. The result of statistical analysis showed that methods of SCS, initial loss-loss rate, constant loss (φ index) and constant fraction loss have relative advantage respectively to be used for the mentioned basin.
Key words: Loss methods, Kasilian, Flood Hydrograph, Clark