Hamzehali Alizadeh; Abdolmajid Liaghat; Taymour Sohrabi molayouef
Abstract
Introduction: Agricultural activity in Varamin plain has been faced with many challenges in recent years, due to vicinity to Tehran the capital of Iran (competition for Latian dam reservoir), and competition with Tehran south network in allocation of Mamlou dam reservoir and treated wastewater of south ...
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Introduction: Agricultural activity in Varamin plain has been faced with many challenges in recent years, due to vicinity to Tehran the capital of Iran (competition for Latian dam reservoir), and competition with Tehran south network in allocation of Mamlou dam reservoir and treated wastewater of south wastewater treatment plant. Mamlou and Latian dam reservoirs, due to increase of population and industry sectors, allocated to urban utilization of Tehran. Based on national policy, the treated wastewater should be replaced with Latian dam reservoir water to supply water demand of agricultural sector. High volume transmission of wastewater to Varamin plain, will be have economical, environmental, and social effects. Several factors effect on wastewater management and success of utilization plans and any change in these factors may have various feedbacks on the other elements of wastewater use system. Hence, development of a model with capability of simulation of all factors, aspects and interactions that affect wastewater utilization is very necessary. The main objective of present study was development of water integrated model to study long-term effects of irrigation with Tehran treated wastewater, using system dynamics modeling (SD) approach.
Materials and Methods: Varamin Plain is one of the most important agricultural production centers of the country due to nearness to the large consumer market of Tehran and having fertile soil and knowledge of agriculture. The total agricultural irrigated land in Varamin Plain is 53486 hectares containing 17274 hectares of barley, 16926 hectares of wheat, 3866 hectares of tomato, 3521 hectares of vegetables, 3556 hectares of alfalfa, 2518 hectares of silage maize, 1771 hectares of melon, 1642 hectares of cotton, 1121 hectares of cucumber and 1291 hectares of other crops. In 2006 the irrigation requirement of the crop pattern was about 690 MCM and the actual agriculture water consumption was about 620 MCM (supplying 90 percent of the demand), 368 MCM of which was supplied through groundwater and 252 MCM was supplied by surface water. In recent years supplying water from Latyan Dam to the agriculture in Varamin Plain due to water supply of Tehran and the recent droughts has been reduced to lower than half (the average 68.8 MCM). On the other hand, shortage of surface water resources has caused an additional pressure to the groundwater resources of the Plain. Excessive groundwater withdrawal and use of brackish reused waters in the southern parts of the plain has caused the quality loss in groundwater resources, so that groundwater salinity has increased about 0.5 dS/m from the year 2000 to 2011. Obviously, by continuing the present situation, in less than two decades the groundwater resources in Varamin will be either quite destroyed or unable to be used due to inappropriate quality. Another source of surface water is allocated to the Varamin Plain is treated wastewater produced from Tehran Wastewater Treatment Plant. Utilizing the phases 1 to 4 of this treatment plant, about 80 MCM (2.5 up to 4 m3/s) of wastewater is annually transferred to Varamin Plain. According to the projections, it is assumed that wastewater will be used in near future as the most important water resource to Varamin Plain. In this study, SD was applied as the system analysis method for the Varamin wastewater management. The spatial boundary of the SD model for Varamin model was the whole Varamin area, which is 1584 km2. The historical review period was from 2001 to 2011, the simulated period was from 2011 to 2036, and the simulation time interval was one year. The most important scenarios evaluated consisted of four wastewater allocation scenarios [(i) keeping the excising condition, (ii) complete allocation of Latian dam reservoir water to Tehran domestic use, allocation of 200 MCM treated wastewater during growing season to agricultural sector and 40 MCM to artificial aquifer recharge during non-growing season starting year 2016, (iii) similar to scenario number two w/o artificial aquifer recharge and (iv) similar to scenario number two plus allocating 50 MCM starting year 2021]. Mass flow or convection method by considering surface adsorption of solute was used to survey movement and adsorption of elements in soil. Adsorption isotherms delineated and determined by field and experimental measurement.
Results and Discussion: The result indicated that if raw wastewater be used till 2031, Cadmium and Copeer concentration will be outstanding and will have harmful effects on farmer’s health. Utilization of treated wastewater will be safe and will have not harmful effects on farmer’s health by heavy metals, to about 150 future years. Also, simulating result showed that Nitrate concentration in groundwater will exceed from allowable limitation for potable water in all scenarios to 2031. Application of scenarios (iv) and (iii) lead to the lowest and the highest Nitrate concentration, respectively.
Conclusion: In this model a systems system dynamics approach was applied to understand how various factors related to operation of wastewater and water sustainability interrelate. The developed model is capable to simulation of all factors, aspects and interactions that affect wastewater utilization. Result of this study demonstrated that SD is a useful decision support tool for sustainable wastewater management. By considering severe water shortage problems in the study area, and safe utilization of treated wastewater, treated wastewater transmission of Tehran plant to Varamin Plain can help to solve water shortage problems. Increase of treated wastewater allocation lead to decrease of raw sewage and hereby decreasing hygienic harmful effects.
F. Abbasi; A. Liaghat; H. A. Alizadeh; Y. Abbasi; A. Mohseni
Abstract
چکیده
در این تحقیق، به منظور مطالعه و بررسی اثرات کودآبیاری بر تلفات نیترات از طریق رواناب سطحی در آبیاری جویچه ای و همچنین ارزیابی یک مدل ریاضی کودآبیاری، 12 آزمایش ...
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چکیده
در این تحقیق، به منظور مطالعه و بررسی اثرات کودآبیاری بر تلفات نیترات از طریق رواناب سطحی در آبیاری جویچه ای و همچنین ارزیابی یک مدل ریاضی کودآبیاری، 12 آزمایش در دو سال زراعی 1387 و 1388در مقیاس بزرگ و در حضور گیاه ذرت روی جویچه های انتها باز در یک خاک لومی انجام شد. تعداد جویچه های هر آزمایش 5 عدد، طول جویچه ها 165 متر، فاصله بین جویچه ها 75 سانتی متر و شیب عمومی مزرعه 006/0 متر بر متر بود. کود مصرفی مورد نیاز مطابق توصیه کودی از منبع کود اوره و طی چهار تقسیم مساوی (قبل از کاشت، مرحله هفت برگی، مرحله ساقه رفتن و مرحله سنبله زدن) اضافه گردید. دبی جویچه ها با استفاده از فلوم WSC و غلظت نیترات خروجی از روش طیف سنجی اندازه گیری شد. از داده های سال اول برای تعیین بهترین زمان تزریق کود با هدف دستیابی به کمترین درصد تلفات نیترات استفاده شد. در سال دوم، تزریق کود فقط در زمان بهینه شده بر اساس نتایج سال اول انجام گرفت. نتایج نشان داد که بهترین زمان تزریق کود به سیستم آبیاری جویچه ای 20 دقیقه انتهایی آبیاری می باشد. تلفات نیترات از طریق رواناب سطحی در سال اول بسته به زمان تزریق کود بین 7/5 تا 0/42 و در سال دوم با اعمال مدت زمان تزریق بهینه بین 4/1 تا 3/12درصد متغیر بود. همچنین، نتایج نشان داد که مدل کودآبیاری مورد استفاده در این تحقیق قابلیت برآورد تلفات نیترات از طریق رواناب سطحی را دارد. ضریب تبیین (R2) بین مقادیر اندازه گیری و شبیه سازی شده تلفات آب در دو سال زراعی به طور متوسط 85/0 و برای تلفات کود به طور متوسط 80/0 بود.
واژه های کلیدی: کودآبیاری، تلفات نیترات، مدل ریاضی کودآبیاری، آبیاری جویچه ای
H.A. Alizadeh; A. Liaghat; F. Abbasi
Abstract
Abstract
Water and nitrogen are the main limiting factors affecting agricultural production in arid and semiarid regions. Therefore, improving the efficiency of these factors is very important. The method of fertilizer application is affecting water and fertilizer use efficiency. The objective of this ...
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Abstract
Water and nitrogen are the main limiting factors affecting agricultural production in arid and semiarid regions. Therefore, improving the efficiency of these factors is very important. The method of fertilizer application is affecting water and fertilizer use efficiency. The objective of this study was to investigate the effect of furrow fertigation on fertilizer use efficiency (FUE), water use efficiency (WUE), and corn yield. A field experiment was carried out in furrows which have 165m length and 0.006 (m/m) slope in Karaj. The corn Hybrid 370 double-cross was planted on June 2008. A factorial design based on randomized complete block design with 4 replicates. Four levels (0, 60, 80 and 100%) of the recommended fertilizer value and four levels (60, 80, 100, and 120%) of the irrigation water requirement were applied. These 16 treatments were compared with traditional fertilizer application method. Fertilizer treatments were accomplished in four critical stages of the growth (before cultivation, in seven leaves stage, shooting stage and Flowering stage) for fertigation treatments and two stages (before cultivation and seven leaves stage) for the traditional method. Results showed that effects of levels of different water and fertilizer on yield component were significant. Water use efficiency (WUE) was significantly affected by nitrogen rate. On the other hand, water treatments significantly affected fertilizer use efficiency. Increasing fertilizer increased water use efficiency. Increasing water levels to 100% of ETC resulted in increasing fertilizer use efficiency. Highest yield was obtained from the full irrigation treatments (W100%). Albeit the difference among W120%, W100% and W80% was not significant (P=0.05), because W100% was always higher than W120%, treatment of W80% recommends as optimum water level for arid and semi arid region. The maximum and minimum WUE was 2.24 and 0.66 (kg/m3) in W80%N100% and W100%N60%, and The maximum and minimum FUE was 29.85 and 8.52 (kg/kg) in W100%N100% and traditional method, respectively.
Key words: Fertigation, Fertilizer use efficiency, Productivity, Corn
H.A. Alizadeh; A. Liaghat; M. Noorimohamadeh
Abstract
چکیده
استفاده از کم آبیاری به منظور صرفه جویی در آب و همچنین اعمال حداقل ضریب آبشویی در طول فصل آبیاری و یا حتی در سراسر چندین فصل آبیاری باعث انباشته شدن املاح در منطقه ...
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چکیده
استفاده از کم آبیاری به منظور صرفه جویی در آب و همچنین اعمال حداقل ضریب آبشویی در طول فصل آبیاری و یا حتی در سراسر چندین فصل آبیاری باعث انباشته شدن املاح در منطقه ریشه میشود. طبیعتا وقتی از آبهای با کیفیت کم مثل پسابها و یا آبهای نامتعارف استفاده می کنیم وضع بدتر هم می شود. در چنین شرایطی گیاهان به طور همزمان تحت تأثیر تنش شوری و کم آبی قرار می گیرند. در زمینه چگونگی پاسخ گیاهان به تنش همزمان شوری و خشکی و سهم هر یک از آن ها در کاهش جذب آب مدل های ریاضی متعددی وجود دارد. مدل های جذب آب در شرایط تنش همزمان به سه دسته جمع پذیر، ضرب پذیر و مدل های مفهومی تقسیم بندی می شوند. از آنجایی که بیشترین مقدار آب مصرفی در مناطق خشک و نیمه خشک صرف تعرق می شود، کارآیی مدلهای شبیه سازی پیش بینی حرکت آب و املاح تا حد زیادی به توانایی آنها در پیش بینی تعرق بستگی دارد. در این مطالعه شش تابع کاهش جذب آب ماکروسکوپی وان گنوختن (جمع پذیر و ضرب پذیر)، دیرکسن و آگوستیجن، وان دام و همکاران، اسکگز و همکاران و همایی با استفاده از داده های گل خانه ای گوجه فرنگی مورد ارزیابی قرار گرفت. آزمایش در قالب طرح کاملاً تصادفی با هشت سطح شوری (75/0، 5/1، 5/2، 5/3، 5/4، 6، 8 و 10 دسیزیمنز بر متر) انجام شد. سطوح خشکی به صورت تغییرات پتانسیل ماتریک و در طول دور آبیاری اعمال می شد. نتایج نشان داد که در شرایط عدم وجود تنش شوری همه مدل ها برازش خوبی با داده های اندازه گیری شده داشتند. همچنین نتایج نشان داد در شوری های کم واکنش گیاهان به تنش همزمان شوری و خشکی جمع پذیر است در حالیکه در شوری های بالاتر از 5/3 دسیزیمنز بر متر مدل های ضرب پذیر برازش بهتری دارند. از میان مدل های ضرب پذیر مدل مفهومی همایی و مدل اسکگز و همکاران برازش بهتری دارند.
واژه های کلیدی: تنش شوری، تنش خشکی، تابع کاهش، گوجه فرنگی
H.A. Alizadeh; B. Nazari; A. Liaghat
Abstract
Abstract
Determining saturated hydraulic conductivity (Ks) is one of the important soil characteristics that its estimation is important in soil and water studies. There are several methods for estimating Ks in unsaturated conditions. These methods include the inversed-auger-hole method, the double-ring ...
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Abstract
Determining saturated hydraulic conductivity (Ks) is one of the important soil characteristics that its estimation is important in soil and water studies. There are several methods for estimating Ks in unsaturated conditions. These methods include the inversed-auger-hole method, the double-ring infiltrometer and the single-ring pressure infiltrometer. The measurement of Ks by these methods requires large volumes of water and long period of time. The Simplified Falling Head (SFH) technique is for rapid determination of Ks, using small volumes of water and easily transportable equipments. The SFH technique appears hopeful and suitable for detailed and repeated sampling, also, over large areas. In this study, Ks was measured by SFH method, double-ring and single-ring pressure infiltrometers for evaluating SFH method. Results showed that in a loam soil, the SFH method estimate higher values for Ks, compared with the double-ring and the single-ring pressure infiltrometers (respectively 9.6% and 18.5%). Statistical analysis of the results of above methods showed that there is no significant difference between Ks values (P
