Farzin Parchami-Araghi; seyed majid mirlatifi; Shoja Ghorbani Dashtaki; Majid Vazifehdoust; Adnan Sadeghi-Lari
Abstract
Introduction: In order to provide more realistic representation of processes governing the water and energy balances as well as water quality and plant physiological processes, weather data are needed at finer timescales than currently are available at most regions. In this study, a physically based ...
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Introduction: In order to provide more realistic representation of processes governing the water and energy balances as well as water quality and plant physiological processes, weather data are needed at finer timescales than currently are available at most regions. In this study, a physically based framework was developed to disaggregate daily weather data needed for estimation of subdaily reference evapotranspiration, including air temperature, wind speed, dew point, actual vapour pressure, relative humidity, and solar radiation. In this paper, the results of performance comparison of the utilized disaggregation approaches are presented.
Materials and Methods: In developed framework, missing daily weather data are filled by implementation of a search-optimization algorithm. Meanwhile, disaggregation models can be calibrated using Unified Particle Swarm Optimization (UPSO) algorithm. Daily and subdaily solar radiation is estimated, using a general physically based model proposed by Yang et al. (YNG model). Long-term daily and three-hourly weather data obtained from Abadan (59 years) and Ahvaz (50 years) synoptic weather stations were used to evaluate the performance of the developed framework. In order to evaluate the accuracy of the different disaggregation models, the mean error (ME), mean absolute error (MAE), root mean square error (RMSE), and Pearson correlation coefficient (r), and model efficiency coefficient (EF) statistics were calculated. Different contributions to the overall mean square error was decomposed, using a regression-based method.
Results and Discussion: The results indicated that compared to the WAVE I, WAVE II, WCALC, ERBS, and ESRA models, the calibrated TM model had the best performance to disaggregate daily air temperature with a EF of 0.9775 to 0.9924. Compared to air temperature disaggregation models with an arbitrary value for the time of maximum and minimum air temperature, the models in which the above mentioned times are described as a function of sunrise and/or sunset had better performance in describing the diurnal variations of the air temperature. HUM III model (based on cosinusoidal disaggregation of daily actual vapour pressure) had the best performance to disaggregate daily dew point, actual vapour pressure, and relative humidity with an EF of 0.7266 to 0.8896. In addition, subdaily wind speeds were predicted with an EF of 0.3357 to 0.6300. The results showed high agreement between daily and sum-of-subdaily solar radiation (with an EF of 0.9801 to 0.9729). The use of the WAVE II and HUM II (based on linear disaggregation of relative humidity) models can be recommended for the regions with no subdaily weather data needed for calibration of the weather data disaggregation models. The results indicate the need for calibration of Green and Kozek model for disaggregation of the daily wind speed at different regions.
M. Shafiei; B. Ghahraman; B. Saghafian; K. Davary; M. Vazifedust
Abstract
Uncertainty analysis is a useful tool to evaluate soil water simulations in order to get more information about the models output. These information provide more confidence for decision making processes. In this study, SWAP model is applied for soil water balance simulations in two fields which are planted ...
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Uncertainty analysis is a useful tool to evaluate soil water simulations in order to get more information about the models output. These information provide more confidence for decision making processes. In this study, SWAP model is applied for soil water balance simulations in two fields which are planted by wheat and maize in an arid region. First the amount of uncertainty is estimated and compared for soil moisture simulation by using Generalized Likelihood Uncertainty Estimation (GLUE) in the two fields. Then based on the computed parameter uncertainty, the effect of uncertainty in soil moisture simulation is evaluated on soil water balance components. Results indicated that in arid regions with irrigated agricultural fields, prediction of actual evapotranspiration is relatively precise and the coefficient of variation for the two fields are less than 4%. Moreover, the prediction of deep percolation for the two fields are influenced by the uncertain hydraulic conductivity and showed lower precision according to the actual evapotranspiration.
maysam majidi; a. Alizade; m. vazifedoust; a. faridhosseini
Abstract
Introduction: Water when harvested is commonly stored in dams, but approximately up to half of it may be lost due to evaporation leading to a huge waste of our resources. Estimating evaporation from lakes and reservoirs is not a simple task as there are a number of factors that can affect the evaporation ...
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Introduction: Water when harvested is commonly stored in dams, but approximately up to half of it may be lost due to evaporation leading to a huge waste of our resources. Estimating evaporation from lakes and reservoirs is not a simple task as there are a number of factors that can affect the evaporation rate, notably the climate and physiography of the water body and its surroundings. Several methods are currently used to predict evaporation from meteorological data in open water reservoirs. Based on the accuracy and simplicity of the application, each of these methods has advantages and disadvantages. Although evaporation pan method is well known to have significant uncertainties both in magnitude and timing, it is extensively used in Iran because of its simplicity. Evaporation pan provides a measurement of the combined effect of temperature, humidity, wind speed and solar radiation on the evaporation. However, they may not be adequate for the reservoir operations/development and water accounting strategies for managing drinking water in arid and semi-arid conditions which require accurate evaporation estimates. However, there has not been a consensus on which methods were better to employ due to the lack of important long-term measured data such as temperature profile, radiation and heat fluxes in most lakes and reservoirs in Iran. Consequently, we initiated this research to find the best cost−effective evaporation method with possibly fewer data requirements in our study area, i.e. the Doosti dam reservoir which is located in a semi-arid region of Iran.
Materials and Methods: Our study site was the Doosti dam reservoir located between Iran and Turkmenistan borders, which was constructed by the Ministry of Water and Land Reclamation of the Republic of Turkmenistan and the Khorasan Razavi Regional Water Board of the Islamic Republic of Iran. Meteorological data including maximum and minimum air temperature and evaporation from class A pan were acquired from the Doosti Dam weather station. Relative humidity, wind speed, atmospheric pressure and precipitation were acquired from the Pol−Khatoon weather station. Dew point temperature and sunshine data were collected from the Sarakhs weather station. Lake area was estimated from hypsometric curve in relation to lake level data. Temperature measurements were often performed in 16−day periods or biweekly from September 2011 to September 2012. Temperature profile of the lake (required for lake evaporation estimation) was measured at different points of the reservoir using a portable multi−meter. The eighteen existing methods were compared and ranked based on Bowen ratio energy balance method (BREB).
Results and Discussion: The estimated annual evaporation values by all of the applied methods in this study, ranged from 21 to 113mcm (million cubic meters). BREB annual evaporation obtained value was equal to 69.86mcm and evaporation rate averaged 5.47mm d-1 during the study period. According to the results, there is a relatively large difference between the obtained evaporation values from the adopted methods. The sensitivity analysis of evaporation methods for some input parameters indicated that the Hamon method (Eq. 16) was the most sensitive to the input parameters followed by the Brutsaert−Stricker and BREB, and radiation−temperature methods (Makkink, Jensen−Haise and Stephen−Stewart) had the least sensitivity to input data. Besides, the air temperature, solar radiation (sunshine data), water surface temperature and wind speed data had the most effect on lake evaporation estimations, respectively. Finally, all evaporation estimation methods in this study have been ranked based on RMSD values. On a daily basis, the Jensen−Haise and the Makkink (solar radiation, temperature group), Penman (Combination group) and Hamon (temperature, day length group) methods had a relatively reasonable performance. As the results on a monthly scale, the Jensen−Haise and Makkink produced the most accurate evaporation estimations even by the limited measurements of the input data.
Conclusion: This study was carried out with the objective of estimating evaporation from the Doosti dam reservoir, and comparison and evaluation of conventional method to find the most accurate method(s) for limited data conditions. These examinations recognized the Jensen−Haise, Makkink, Hamon (Eq. 17), Penman and deBruin methods as the most consistent methods with the monthly rate of BREB evaporation estimates. The results showed that radiation−temperature methods (Jensen−Haise and Makkink) have appropriate accuracy especially on a monthly basis. Also deBruin, Penman (combination group), Hamon and Papadakis (temperature group) methods produced relatively accurate results. The results revealed that it is necessary to calibrate and adjust some evaporation estimation methods for the Doosti dam reservoir. According to the required input data, sensitivity and accuracy of these methods, it can be concluded that Jensen−Haise and Makkink were the most appropriate methods for estimating the lake evaporation in this region especially when measured data were not available.
F. Parchami Araghi; seyed majid mirlatifi; Sh. Ghorbani Dashtaki; M. Vazifehdoust; A. Sadeghi Lari
Abstract
Introduction: Subdaily estimates of reference evapotranspiration (ET o) are needed in many applications such as dynamic agro-hydrological modeling. However, in many regions, the lack of subdaily weather data availability has hampered the efforts to quantify the subdaily ET o. In the first presented paper, ...
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Introduction: Subdaily estimates of reference evapotranspiration (ET o) are needed in many applications such as dynamic agro-hydrological modeling. However, in many regions, the lack of subdaily weather data availability has hampered the efforts to quantify the subdaily ET o. In the first presented paper, a physically based framework was developed to desegregate daily weather data needed for estimation of subdaily reference ET o, including air temperature, wind speed, dew point, actual vapour pressure, relative humidity, and solar radiation. The main purpose of this study was to estimate the subdaily ETo using disaggregated daily data derived from developed disaggregation framework in the first presented paper.
Materials and Methods: Subdaily ET o estimates were made, using ASCE and FAO-56 Penman–Monteith models (ASCE-PM and FAO56-PM, respectively) and subdaily weather data derived from the developed daily-to-subdaily weather data disaggregation framework. To this end, long-term daily weather data got from Abadan (59 years) and Ahvaz (50 years) synoptic weather stations were collected. Sensitivity analysis of Penman–Monteith model to the different meteorological variables (including, daily air temperature, wind speed at 2 m height, actual vapor pressure, and solar radiation) was carried out, using partial derivatives of Penman–Monteith equation. The capability of the two models for retrieving the daily ETo was evaluated, using root mean square error RMSE (mm), the mean error ME (mm), the mean absolute error ME (mm), Pearson correlation coefficient r (-), and Nash–Sutcliffe model efficiency coefficient EF (-). Different contributions to the overall error were decomposed using a regression-based method.
Results and Discussion: The results of the sensitivity analysis showed that the daily air temperature and the actual vapor pressure are the most significant meteorological variables, which affect the ETo estimates. In contrast, low sensitivity coefficients got for wind speed and the solar radiation. The similar patterns of ETo sensitivity coefficient to the air temperature ( ) and the air temperature (TA) showed that the extent of the seasonal variation of was mainly determined by the TA. Results showed a good agreement between daily and 24h sum of subdaily ETo derived from ASCE-PM (with an EF of 0.990 to 0.994) and FAO56-PM (with an EF of 0.992 to 0.995) models. The results showed a good generalization capability of the disaggregation models to estimate the subdaily ETo for the validation data set (Ahvaz). The 24h sum of subdaily ETo derived from both models underestimated and overestimated the daily ETo in calibration (Abadan) and validation (Ahvaz) data sets, respectively. In case of both models, the daily values of aerodynamic component of ETo were reproduced more efficiently, compared to radiation part. In case of the FAO56-PM model, the goodness of agreement between 24h sum of subdaily and daily values of aerodynamic part of the ETo showed a low sensitivity to variation of the time scale of weather data. With the increase of the time scale of the subdaily weather data, the ability of both models in retrieving the radiation component of the daily ETo was improved. Generally, there was no apparent relationship between the efficiency of the ASCE-PM and FAO56-PM models for retrieving the daily ETo and the time scale of weather data. Results showed that adoption of a smaller time step does not always leads to an improvement in the agreement between 24h sum of subdaily and daily values of ETo. For most of the studied subdaily time scales (1 to 360 min), the FAO56-PM model had better performance in retrieving the daily ETo, compared to the ASCE-PM model.
Conclusion: The results of this study showed that the developed disagregation framework was able to estimate the subdaily ET o. In this study, the promising results got in retrieving the daily ETo can be attributed mainly to the high sensitivity of ETo to the air temperature and actual vapor pressure (which were desegregated with a reasonable accuracy) and low sensitivity to the wind speed (which were desegregated with a low accuracy) and the solar radiation (which were disaggregated with a reasonable accuracy). The main reason for the absence of an apparent relationship apparent relationship between the efficiency of the ASCE-PM and FAO56-PM models for retrieving the daily ETo and the time scale of weather data can be attributed to adopted nighttime and daytime criteria in both models which is highly affected by time-scale of weather data and the estimated net long wave radiation.
F. Zadjanali Choubari; M. Navabian; M. Vazifehdust; M. Esmaeili Varaki
Abstract
Phosphorus is one of the main pollutants of agricultural surface drainage; that over standard doze of it cause eutrophication in surface water resource. This study investigates evaluation the ability of Semnan's zeolite, that modified by hexadecyltrimethylammonium, to removal phosphorus under flow conditions ...
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Phosphorus is one of the main pollutants of agricultural surface drainage; that over standard doze of it cause eutrophication in surface water resource. This study investigates evaluation the ability of Semnan's zeolite, that modified by hexadecyltrimethylammonium, to removal phosphorus under flow conditions in agricultural drainage. In this regard, after modifying natural zeolite, at first was absorption kinetics, adsorption isotherms, affecting of pH and temperature experiments on phosphorus removal conducted by modified zeolite in laboratory scale. The experiments were done in 3-5 mm size of zeolite for investigating effect of zeolite size on phosphorus removal. In order to assess the flow conditions on phosphorus removal physical model of agricultural drainage and the modified zeolite filter ponds were constructed in length of 2, 3 and 5 cm. The both discharge 0.05 and 0.1 lit/s were applied in drainage and changes of phosphorus concentrations were measured at various times after passing through the filter ponds. The sorption kinetic experiments showed maximum phosphorus removal by modified zeolite occurred in the first 2 hours. Moreover, percent phosphorus removal with increasing the pH from 3 to 8 decreased and increased from 8 to 12. Also percent removal with increasing temperature in the range of 17 to 30 °C decreased. The results showed Langmuir isotherm had good agreement for explan phosphorus removal by modified zeolite. The results of physical model showed that higher percent phosphorus removal occurred in higher discharge and lower length of filter pond due to more contact drain water with the modified zeolite.
M. Navabian; M. Aghajani; M. Vazifehdost; M. Rezaei
Abstract
Abstract
Rice is most important agricultural crop of Guilan province sensibility to salinity and alkalinity of water and soil. In recent years, using of toxicants and fertilizers in farmlands, constructing several dams upstream, entering agricultural, homemade and industrial sewage in to a river, and ...
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Abstract
Rice is most important agricultural crop of Guilan province sensibility to salinity and alkalinity of water and soil. In recent years, using of toxicants and fertilizers in farmlands, constructing several dams upstream, entering agricultural, homemade and industrial sewage in to a river, and drought have decreased gradually discharge of river and increased salinity of Sefidrud River as an irrigation source of Sefidrud irrigation network of Guilan province. This research tries to determine the optimal intermittent and depth of irrigating of rice in proportion to salinity of Sefidrud River using of optimization- simulation mechanisms as is the decrease in crop efficacy become minimum. To achieve this, an agro hydrological SWAP was used to simulate different stages of rice growing and an optimization model was used in a reasonable range of the intermittent rice irrigation period and depth with regard to different growth stages. Because some types of rice are affected by salinity, field experiments of Hashemi variety in Rasht in 1386 were used to calibrate the model. Optimal values of the intermittent irrigation regime in current salinity of the Sefidrud River (1.747 ds/m) included 8 days intermittent irrigation period and the depth of water for irrigating was 1, 3, 4 and 5 for vegetative, tiller, maturity and harvest stages respectively. The comparison of results of optimization- simulation model with field data in 1389 showed good efficiency of this model in irrigation optimization. In the field experiment 8 days intermittent period with irrigation 5 cm in depth was highest crop performance in 2 ds/m salinity.
Keywords: Rice, Intermittent irrigation management optimization, Sefidrud, Salinity, SWAP model
H. Zareabyaneh; E. Farokhi; M. Vazifeh Doost; Kh. Azhdari
Abstract
Abstract
Assessing moisture in the soil under cultivation of crops to achieve high performance and reduced water are necessary. Knowledge of the moisture distribution in the root zone, time consuming and costly field tests that simulation models, a suitable alternative in answer to issues of movement ...
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Abstract
Assessing moisture in the soil under cultivation of crops to achieve high performance and reduced water are necessary. Knowledge of the moisture distribution in the root zone, time consuming and costly field tests that simulation models, a suitable alternative in answer to issues of movement and are water distribution. In this study assessment of soil moisture, to aid SWAP simulation model was and above model Empowerment compared with field results was assessed. SWAP model based on the information in a field irrigated onion, equipped with drip irrigation systems and soil hydraulic parameters obtained from model RETC, were performed. Moisture Information with harvest soil from emitter place and 10 cm of the layers 15-0, 30-15, 45-30 and 60-45 were obtained. Comparison of simulated moisture with observations moisture to a depth of 60 cm in the emitter place and 10 cm it, in the form of graphs and calculation criteria of Root Mean Squared Error (RMSE), Root Mean Squared error of normal (NRMSE) and mean absolute error (MAE) was performed. Values of RMS, RRMSE and MAE in the normal place dropper 0.001, 0.03 and 0.07 cm3cm-3 and in 10 cm were 0.08, 0.02 and 0.07 cm3cm-3, respectively. Low errors calculated from the model SWAP, shows good accuracy of the model simulated moisture distribution in the root zone. Operations irrigation through a drip irrigation system, with irrigation 48 hours was equivalent to performance kg/ha 14780 against 14134 kg/ha estimated by the model will follow. In total, the results indicate that the SWAP model is able to respond with a valid enough accuracy and precision in a relatively short time to provide. This model can be as effective and useful tool for evaluating and optimizing the distribution of moisture in the root-crop area, used.
Keywords: Moisture simulation, SWAP model, Drip irrigation, Onion farm
H. Noory; A.M. Liaghat; M. Parsinejad; M. Vazifedoust
Abstract
Abstract
In this study, evaluation of SWAP model in simulating crop yield, water and salt movement in soil were investigated in the wheat- fodder maize cultivated units. The research was conducted in the Voshmgir network, Golestan province. The crop yield, soil humidity and moisture data in different ...
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Abstract
In this study, evaluation of SWAP model in simulating crop yield, water and salt movement in soil were investigated in the wheat- fodder maize cultivated units. The research was conducted in the Voshmgir network, Golestan province. The crop yield, soil humidity and moisture data in different times of agriculture year of 2007-2008 were measured. The measured and simulated data were analyzed. The statistical comparison which was done base on the root mean square error (0.49 ton/ha), correlation coefficient (0.85) and modeling efficiency (0.84), for estimating the total crop dry matter of wheat and fodder maize showed that the estimated crop yield by SWAP agree well with observed values. Suitable values of statistical indexes obtained for estimating soil moisture and soil salinity by SWAP, indicated that considering suitable bottom boundary condition in SWAP which has important role on water and solute balance in soil, has affected on estimation of soil moisture and salinity considerably.
Keywords: Crop yield, Soil salinity, SWAP model, Water and salinity limitations
M. Vazifedoust; A. Alizadeh; Gh.A. Kamali; M. Feyzi
Abstract
Abstract
To explore the on-farm strategies which result in higher economic gains and water productivity (WP), a physically based agro-hydrological model, Soil Water Atmosphere Plant (SWAP), was calibrated and validated using intensive measured data at 8 selected farmer fields (wheat, fodder maize, sunflower ...
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Abstract
To explore the on-farm strategies which result in higher economic gains and water productivity (WP), a physically based agro-hydrological model, Soil Water Atmosphere Plant (SWAP), was calibrated and validated using intensive measured data at 8 selected farmer fields (wheat, fodder maize, sunflower and sugar beet) in the Borkhar district, Isfahan during the growing seasons of 2004-05. The WP values for the main crops were computed using the SWAP simulated water balance components i.e. transpiration (T), evapotranspiration (ET), irrigation (I), and the marketable yield (Y)M in terms of YM T -1, YM ET -1 and YM I -1. The average WP, expressed as YM T -1 (kg m-3) was 1.18 for wheat, 3.38 for fodder maize, 0.33 for sunflower and 1.72 for sugar beet. This indicated that fodder maize provided the highest economic benefit in the Borkhar irrigation district. Soil evaporation caused the average WP values, expressed as YM ET-1 (kg m-3), to be at least 11 to 27% lower than the average WP, expressed as YM T-1. Furthermore, due to percolation from root zone and stored moisture content in the root zone, the average WP values expressed as YM I-1 (kg m-3), had a 24 to 42 % reduction as compared with WP expressed as YM ET-1. Improved irrigation practices in terms of irrigation timing and amount, increased WP in terms of YM I-1 (kg m-3) by a factor of 1.5 for wheat and maize, 1.3 for sunflower and 1.1 for sugar beet.
Key words: Water productivity, Irrigation practices, Wheat, Fodder maize, Sunflower, Sugar beet