A. Liaghat; F. Abbasi
Abstract
Abstract
In this study, distribution uniformity of fertigation in different furrow irrigation regimes was evaluated. The experiments included injection of fertilizer during only the first half of the irrigation event (FH), injection in the second half (SH) and injection during the entire irrigation ...
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Abstract
In this study, distribution uniformity of fertigation in different furrow irrigation regimes was evaluated. The experiments included injection of fertilizer during only the first half of the irrigation event (FH), injection in the second half (SH) and injection during the entire irrigation (T) event. These options were conducted under free draining and blocked-end conditions with cutback method. The experiments were carried out in Golmakan Agricultural Research Station in 2006. Potassium nitrate was used in the experiments. Distribution uniformity of low half (DULH) and low quarter (DULQ) of water and fertilizer was calculated to evaluate different fertigation scenarios. The results showed that there is no significant difference among the distribution uniformities in the three application times (FH, SH, T). No significant difference was observed between distribution uniformity of free-draining and blocked-end experiments. The best case in blocked-end conditions was injection during the entire irrigation event preferably starting before completing advance phase. Because in this case, solute losses due to runoff from the outlet is zero and also distribution uniformity is somewhat higher whereas in free-draining conditions, fertilizer application during the first half of irrigation provides acceptable fertilizer uniformity and least losses due to runoff. The results also showed that fertilizer losses due to deep percolation in this method of fertilizer application (fertigation) would not be a threat in case of selecting proper irrigation parameters.
Key words: Furrow irrigation, Fertigation, Distribution uniformity, Mathematical model
M.R. Neyshabouri; M. Shorafa; A. Liaghat
Abstract
Abstract
Tillage properties at optimum moisture after irrigation or rainfall have a great influence on prevention of soil structure destruction. Soil sampling was carried out on spring of 1384 from Karaj and Varamin plains of Iran. The water content at inflection point of retention curve (θi) was used ...
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Abstract
Tillage properties at optimum moisture after irrigation or rainfall have a great influence on prevention of soil structure destruction. Soil sampling was carried out on spring of 1384 from Karaj and Varamin plains of Iran. The water content at inflection point of retention curve (θi) was used to determine the optimum water content for tillage. So, the soil moisture was measured in matric pressure heads 0, 1.5, 2.5, 5.5 kPa by hanging water column and in 10, 20, 30, 50, 100, 200, 300, 500, and 1000 kPa by pressure plate for 140 samples. The particle size distribution (clay, silt and sand) and bulk density data of soils with measured moisture contents in above suctions were input to RETC software and parameters of Van Genuchten equation (1980) and θi were determined for any samples. The results of this study showed that the range of θi was 0.17-0.77 and its mean was 0.52 cm3cm-3 in all 140 soil samples. Also there was a positive and significant correlation between θi and percentage of Clay, Calcium carbonate and saturated water content (P
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
A.R. Hasanoghli; A. Liaghat
Abstract
Abstract
Recharge of aquifers by using wastewater, is one of the important and applicable ways for reusing this valuable water resource, especially in arid and semi-arid regions. As the necessity of local practices for finding the proper management strategies and optimum use of recharge systems (conforming ...
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Abstract
Recharge of aquifers by using wastewater, is one of the important and applicable ways for reusing this valuable water resource, especially in arid and semi-arid regions. As the necessity of local practices for finding the proper management strategies and optimum use of recharge systems (conforming to climate, soil, etc.), a preliminary study was carried out. Three physical models were designed and made with a height of 2 m and diameter of 0.6 m. The models were filled with a soil of silty clay sand texture. Treated domestic wastewater of Ekbatan housing complex was used. Transfer of important pollutants indexed by BOD5, COD, nitrogen and phosphorous to shallow grounwaters were studied. Three management practices of wet-dry periods have been used: 1-permanent or long ponding (PP), 2- short period ponding and drying (SP) as 12 hours wetting and 12 hours free drainage, and 3- Moderate ponding (MP) and drying by means of wetting for one week and then drying for another week. The results showed that optimum BOD5, COD and nitrogen reduction occurred in the application of short period ponding management system (mean reduction percentage of 93.5%, 79.5% and 40.4%, respectively). The phosphorous reduction in all strategies was 65% - 75%. The efficiency of microbial indices removal (coliform and fecal coli.) from treated wastewater was high in all management systems. The amount of reduction in this case was between 97% to 99%.
Key words: Artificial recharge, Physical model, Treated domestic wastewater, fecal coliform
H. Ramezani; A. Liaghat; A.A. Naseri
Abstract
Abstract
Drainage water created from irrigation and drainage projects in south of Khuzestan province are saline and its disposal to rivers such as Karoon river is faced with certain constraints. One of drainage water disposal strategies is using evaporation ponds, in which the most important outlet ...
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Abstract
Drainage water created from irrigation and drainage projects in south of Khuzestan province are saline and its disposal to rivers such as Karoon river is faced with certain constraints. One of drainage water disposal strategies is using evaporation ponds, in which the most important outlet is evaporation. Evaporation rate of saline water of these ponds is lower than fresh water. In this study the evaporation rate of implicit ponds for drainage water control in Mirza Kuchak Khan Project was estimated by adjusting the saturation vapor pressure equation of saline water with regard to pure water and by using of Penman equation. Finally, using the evaporation and the annual drain water volume, the required area of evaporation ponds was determined. By evaporation of water from ponds the salinity of water increases. This increase of salinity continues until the salt saturation threshold is reached, and then salts precipitate. The most common salt in drainage water of Khuzestan province is NaCl which has a saturation threshold of 300 g/lit. The results showed that the average annual evaporation of water with 300 g/lit salt is 1903 mm. The drainage water volume produced from Mirza Kuchak Khan Project (12,000 ha area), requires evaporation ponds as big as 7740 ha. This study showed that disposal of the drainage water of sugarcane projects is impossible if only evaporation ponds are used, and therefore, other management options should be considered for reducing the volume and salinity of drainage water.
Key words: Evaporation ponds, Drainage water, Khuzestan, Salinity
H. Ebrahimian; A. Liaghat; M. Parsinejad; M. Akram
Abstract
Abstract
By evaluating the performance of the current drainage systems and exploration of their strengths and weaknesses a comprehensive perspective can be given to designers and organizers for optimum design and implementation of drainage systems for future plans. This study was conducted to evaluate ...
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Abstract
By evaluating the performance of the current drainage systems and exploration of their strengths and weaknesses a comprehensive perspective can be given to designers and organizers for optimum design and implementation of drainage systems for future plans. This study was conducted to evaluate the performance of subsurface drainage systems using rice husk as envelope in Behshahr, a coastal region in the northern part of Iran. For this purpose, eleven piezometers were installed between two subsurface drains designated as S3PD14 and S3PD15. Subsurface drainage system was monitored during rainfall seasons in 1383 and 1385. Parameters such as daily water table fluctuations and drain discharge rate were recorded. The overall conclusion was that subsurface drainage system performance was not satisfactory due to poor control of water table depth and low water discharge, which was mainly because of the drain envelope clogging. Therefore, the Hooghoudt’s equation should not be used for evaluation of design parameters, due to the fact that this equation is only valid for normal conditions (envelope without clogging).
Key words: Subsurface drainage, Rice husk envelope, Water table, Discharge rate, Behshahr, Iran
