اثر ارتفاع آب آبیاری بر نفوذ تجمعی در شرایط اراضی شالیزاری (مطالعه موردی: خاک‌های دشت فومنات استان گیلان)

نویسندگان

چکیده

نفوذ آب در خاک،‏ از حساس‌ترین پارامترهای هیدرولیکی مؤثر بر آبیاری سطحی است که به دلیل تأثیر‌پذیری از عوامل متعدد خاک و شیوه آبیاری،‏ پیچیدگی زیادی دارد. بررسی اثر ارتفاع آب آبیاری بر نفوذ تجمعی و لحاظ کردن این پارامتر در مدل‌های نفوذ،‏ منجر به کارآیی بهتر این مدل‌ها در شرایط کاربری مختلف می‌شود. هدف در پژوهش حاضر،‏ بررسی تأثیر ارتفاع‌های مختلف آب روی سطح خاک در فرآیند نفوذ،‏ در برخی کلاس‌های بافتی خاک بخشی از دشت فومنات در استان گیلان در نظر گرفته شد. بدین منظور 17 نمونه از خاک منطقه‌ی مورد مطالعه برداشت شد. آزمایش‌های نفوذ برای سه تیمار ارتفاع آب 3،‏ 5 و 7 سانتی‌متر در سه تکرار به صورت فاکتوریل در قالب طرح تصادفی و در مدل فیزیکی که برای این منظور ساخته شده بود،‏ انجام شد. برای ارزیابی نتایج،‏ تجزیه واریانس و مقایسه میانگین‌ها به روش توکی در سطح 5 درصد صورت گرفت. مقایسه تیمار ارتفاع آب در 17 نمونه خاک،‏ نشان داد که این تیمار اثر قابل توجهی را در مقدار نفوذ تجمعی چهار نمونه شامل بافت‌های Silty Clay Loam و Silty Clay داشت. بررسی سه تیمار زمان نفوذ تجمعی 30،‏ 360 و 600 دقیقه نشان داد که در 14 نمونه از خاک‌ها بین نفوذ تجمعی در زمان 30 دقیقه با زمان‌های 360 و 600 اختلاف معنی‌داری (05‎/0p

کلیدواژه‌ها


عنوان مقاله [English]

Evaluation of the irrigation water effect on cumulative infiltration under paddy field condition (Case study: Foumanat plain soils of Guilan)

نویسندگان [English]

  • Dr Maryam Navabian
  • Amir Shahriary
  • Dr. Mehdi Esmaeili Varaki
  • Dr. Mohamad Reza Khaledian
چکیده [English]

Infiltration is one the most sensitive hydraulic parameters that has more effect on the efficiency of water, especially in surface irrigation design and management. The fact that infiltration is affected by several factors of soil and irrigation method makes it a complex parameter. Evaluating the impacts of irrigation water head on cumulative infiltration and using this parameter in infiltration models will lead to better performance of the models which are widely used in different conditions. So far, many studies have been conducted, in the field of infiltration. Forman et al (2006) investigated the effect of water height on parameters of Kostiakov soil infiltration equation in the soils with Sandy loam, loam and Silt showed that the parameters k and a had the most variability in sandy loam soil texture. However, the parameter k, in the Silty soil texture, showed little variation due to water height changes. Valyntzas et al (2009) studied the effect of water height as an upstream boundary condition on the parameters of Kostiakov equation in Sandy Clay Loam soil texture and showed that by modifying the infiltration coefficient based on water height, the simulation results of infiltration by HYDRUS improved. The purpose of this study was to investigate the effect of different water heights on the infiltration process, in some soil texture in Foumanat plain in Guilan province. In this way, 17 soil samples that had more than 15% Clay and less than 30% Sand were gathered. Infiltration tests were carried out with three replications in a completely randomized design, in a physical model. The factors included soil texture with 17 levels: the height of water with three levels (3, 5 and 7 centimeters) and three levels of the time. The results also showed that height of water on the soil surface had more impact on Loam soil texture than Clay soil texture. Infiltration testing time was 600 minutes and cumulative infiltration values were calculated in 30, 360 and 600 minutes. The physical model includes a water tank, manometer for reading the water level, reservoir water for fixing water level on the surface of soil and polyethylene cylinder with an internal diameter of 15.23 cm and a height of 35 cm, as a soil box. To maintain the soil water level, a float was used. Analysis of variance hypotheses for normal distribution was done. After passing normal distribution test, Analysis of variance and the comparison of averages were done by Tukey’s method at 5% level using SAS software. Results showed that treatment of water height had a significant effect on cumulative infiltration of the four soil samples in Silty Clay and Loam Silty Clay soil textures. Although, the results of statistical tests showed no significant effect between water height treatments (3, 5 and 7 cm) in 13 soil samples, the difference between the amount of infiltrated water in the samples should be considered due to the critical situation of water resources and necessity of increasing in irrigation efficiency. Comparison of the difference percentage of cumulative infiltration in different soil textures showed that, apart from the 3 cm water height treatment, in the two other water height treatments, Clay Loam, Silty Clay Loam, Silty loam and Silty Clay soil textures had the highest percentage of difference between the two time periods, respectively. On the others in estimating of cumulative infiltration, Clay Loam texture has more sensitivity to the cumulative time of infiltration. The difference of cumulative infiltration between treatments 3 and 5 cm was more than the other two treatments (5 and 7 cm), despite the equal difference of 2 cm in the water height. The reason for this result could be explained by reducing the influence of gravity due to increasing the height of water on the soil surface. Investigating the three infiltration time treatments (30, 360 and 600 minutes) showed that in 14 soil samples, there were significant differences between cumulative infiltration in 30 min with infiltration time in 360 and 600 minutes (p < 0.05). The difference was greater in Clay Loam soil. In all soil samples, except the soil sample number 15, steep slope of infiltration curve was similarly. Study of soil particles distribution showed that the percentage of sand in the soil sample number 15 was the least among the other soil samples, which could explain the higher slope of infiltration curve

کلیدواژه‌ها [English]

  • Surface irrigation.-Infiltration duration-Clay soil-Irrigation water depth-Cumulative infiltration-