Hasil untuk "Irrigation engineering. Reclamation of wasteland. Drainage"

یزدان محمدی, هوشنگ قمرنیا, مهدی جوزی

در این مطالعه به بررسی تأثیر سطوح مختلف کم‎آبیاری بر عملکرد و پارامترهای گیاهی محصول کینوا در گلخانه تحقیقاتی پردیس کشاورزی و منابع طبیعی دانشگاه رازی در دو سال زراعی 1397 و 1398 پرداخته شد. آزمایش در قالب طرح بلوک­های کامل تصادفی با پنج تکرار اجرا شد. تیمارهای اعمال‌شده شامل سطوح 40، 60، 80 و 100 (تیمار شاهد) درصد نیاز آبی محاسبه‌شده با تشت تبخیر کلاس A بود. نتایج نشان داد اثر کم‌آبیاری بر روی صفات ارتفاع بوته، عملکرد بیولوژیک، وزن هزاردانه، طول پدانکل، تعداد شاخه جانبی، وزن خشک ریشه و شاخص برداشت در سطح احتمال یک درصد معنی‌دار شد. هم‌چنین، نتایج نشان داد با افزایش درصد کم‌آبیاری، عملکرد دانه و عملکرد بیولوژیک کاهش می­یابند. برای سطوح آبیاری 100، 80، 60 و 40 درصد میانگین دو ساله عملکرد بیولوژیک به‌ترتیب 5/7445، 7316، 6410 و 5333 و عملکرد دانه 14/2068، 56/2026، 47/1987 و 45/18741 کیلوگرم بر هکتار شد. هم‌چنین کارایی مصرف آب براساس عملکرد بیولوژیک برای سطوح آبیاری مذکور به‌ترتیب 55/0، 67/0، 88/ و 23/1 و براساس عملکرد دانه 98/1، 43/2، 83/2 و 53/3 کیلوگرم بر مترمکعب به­دست آمد. نتایج کلی این پژوهش نشان داد که می‌توان با اجرای کم‌آبیاری به میزان 80 درصد نیاز آبی، بدون کاهش محسوس در عملکرد دانه و بیولوژیک و با افزایش معنی‌دار کارایی مصرف آب از این محصول به‌منظور کشت در مناطق خشک و نیمه‌خشک استفاده نمود.

DING Mingjing, TUO Yunfei, HE Xiahong et al.

【Objective】 Panax Notoginseng is a medicinal herb and primarily grown in Southern China. This paper investigates the impact of irrigation and fertilization on soil potassium and pH, as well as yield and quality of Panax Notoginseng. 【Method】 The experiment was conducted in Dalishu Village, Luxi County, located in the Honghe Hani and Yi Autonomous Prefecture, Yunnan Province. It consisted of four fertilizations by applying the 480 kg/hm2 of fertilizers at different ratios in the seedling, flowering, fruiting and root gain stages: 25%∶25%∶25%∶25%(F1), 25%∶30%∶20%∶25%(F2), 30%∶30%∶15%∶25%(F3), and 40%∶20%∶10%∶30%(F4). Each fertilization had three irrigation treatments: 200 m3/hm2(W1), 300 m3/hm2(W2) and 400 m3/hm2(W3). The control (CK) was F1 combined with 92 m3/hm2 of irrigation. In each treatment, we measured the changes in soil potassium content and pH. The technique for order preference by similarity to ideal solution (TOPSIS) was used to evaluate all treatments. 【Result】 ① When irrigation and fertilization were the same, soil pH decreased with soil depth and tended to stabilize as the crop grew. The soil pH showed little sensitive to fertilization. When irrigation was the same, the average soil pH was lower in the four treatments than in the CK. During the experimental period, pH of the 0-60 cm soil in different treatments varied from 4.80-8.66. W3F1, W2F4 and W2F3 gave the optimal soil pH for the crop to grow. ② Both total and available soil potassium decreased with increasing soil depth. As the crop grew, the total potassium in the 0-60 cm soil layer increased, while the available potassium decreased initially before increasing. With increasing irrigation amount, total soil potassium decreased, while the available potassium increased initially followed by a decline. Fertilization influenced the dynamics of total and available potassium. Irrespective of fertilization and irrigation, potassium uptake by roots in different growing stages was ranked as follows: fruiting period>flowering period>root weight gain period>seedling stage. Of all the treatments, W2F3 was optimal for soil potassium, with total and available potassium being 10.40 g/kg and 56.69 mg/kg, respectively. ③ Regardless of fertilization, with the increase in irrigation amount, the yield and partial factor productivity (PFP) of the crop increased first followed by a decline. The yield, water use efficiency and PFP varied with fertilization. TOPSIS analysis showed that the optimal irrigation was 300 m3/hm2 and the optimal fertilization was applying 144, 144, 72 kg/hm2 and 120 kg/hm2 of fertilizers in the seedling, flowering, fruiting and root weight gain stage, respectively. 【Conclusion】 Based on soil potassium, pH, as well as yield and quality of Panax Notoginseng, the optimal irrigation and fertilization for Panax Notoginseng production in the studied area were irrigating 300 m3/hm2 and applying 144, 144, 72 kg/hm2 and 120 kg/hm2 of fertilizers in the seedling, flowering, fruiting and root weight gain stage, respectively.

محمد جمالی, سید علیرضا گوهری, غزل اخوان صراف

پدیده تغییر اقلیم باعث تغییر در شدت و فراوانی پدیده‌های حدی به‌ویژه بارش‌های حدی شده است. تحلیل مکانی و زمانی روند بارش حدی به‌منظور افزایش انعطاف پذیری سیستم­های اجتماعی-اکولوژیکی و زیرساخت­های آن­ها تحت تغییر اقلیمی بسیار مهم است. این مطالعه به بررسی تغییرات مکانی-زمانی ویژگی‌های بارش همزمان با تغییر دما می­پردازد. برای این منظور، آزمون ناپارامتری اسپیرمن برای ارزیابی روند در سه شاخص بارش (بیشینه بارش سه و شش ساعته و مجموع بارش سالانه) و دو شاخص درجه حرارت (بیشینه و کمینه درجه حرارت سالانه) در 26 ایستگاه سینوپتیک واقع در گستره ایران استفاده شده است. در این پژوهش از آمار و اطلاعات 34 تا 70 ساله (از سال 1951 تا 2020) استفاده شد. روند داده‌ها در سطح معنی‌داری 95 درصد بررسی شد. نتایج نشان داد که بیشینه بارش سه و 24 ساعته در ایستگاه گرگان دارای روند مثبت است، اما شاخص مجموع بارش سالانه در این منطقه روندی منفی دارد، هم‌چنین بارش بیشینه سه و 24 ساعته در ایستگاه‌های اهواز، اصفهان و سمنان نیز دارای روند افزایشی معنی­دار بوده و این مناطق مستعد وقوع سیلاب هستند. هم‌چنین نتایج نشان داد که افزایش بارش بیشینه سه و 24 ساعته در دماهای بالاتر در تعداد محدودی از ایستگاه‌ها منجر به افزایش در بارش سالانه می‌شود و اکثر ایستگاه‌ها کاهش بارش را با افزایش دما نشان می‌دهند. هم‌چنین، بیشینه دما در همه ایستگاه‌ها (به‌جز شهرکرد و بیرجند) دارای تغییرات افزایشی است که نشان‌دهنده گرم‌شدن هوا در تابستان است.

HAO Ruichao, WANG Qibao, WANG Chen et al.

【Objective】 Frequent droughts have significantly impacted agricultural productivity and ecological health of the Loess Plateau. This study investigates the characteristics and driving factors of dry-wet evolution in the region. 【Method】 The analysis was based on meteorological data, including temperature, precipitation, relative humidity, sunshine hours, and wind speed, measured from 1961 to 2020 at 71 weather stations across the Loess Plateau. The changes in wet and dry spells and their underlying determinants were analyzed using standardized precipitation evapotranspiration index (SPEI), Mann Kendall test, and run length theory. 【Result】 Temporally, temperature showed a significant increase, while wind speed, relative humidity and sunshine hours showed significant decreases from 1961 to 2020. In contrast, precipitation showed a weak decrease, while ET0 (reference crop evapotranspiration) exhibited a first increase followed by a decrease during this period. Spatially, the Northwest saw increased precipitation and decreased ET0. Conversely, the Northeast experienced declines in both precipitation and ET0. From 1999 onward, the SPEI showed an initial decrease followed by an increase. The Southeast experienced high drought frequency but with shorter durations and lower severity, extreme drought events in which were rare. In contrast, the Northwest had fewer but more severe and prolonged droughts. Rising temperatures, increasing precipitation and decreasing ET0 were the primary drivers of dry-wet alterations. ET0 had a stronger influence on dryness and wetness patterns than precipitation. The correlation between the mid-latitude westerly belt, sunspot activity, and SPEI was weak, indicating limited influence of large-scale atmospheric and solar factors. 【Conclusion】 The Loess Plateau showed a warm-drying trend from 1961 to 1999, followed by a warm-wetting trend thereafter. These findings improve our understanding of hydrological changes and help develop mitigating strategies for managing drought and water resources in the region.

Candelaria N. Tejada-Tovar, María M. Rocha-Caicedo, Isabel C. Paz-Astudillo

Contamination of water bodies by heavy metals is a continuously growing environmental issue. High concentrations of mercury (Hg) in river waters are a recognized environmental problem, because it is one of the most toxic heavy metal ions as it causes damage to the central nervous system. Its negative impact has led to the development of different methods for the treatment of effluents contaminated with Hg(II). The aim of this article is to evaluate the use of coffee ( Coffea arabica) residues as adsorbent of Mercury in an aqueous solution. Four kinetic models, including intraparticle diffusion, pseudo-first-order, pseudo-second-order, and Elovich kinetic models were applied to explore the internal mechanism of mercury adsorption. Results indicate that the pseudo-first-order and pseudo-second-order models could accurately describe the adsorption process. It means that chemical adsorption play an important role in the adsorption of mercury by activated carbon. Meanwhile, the external mass transfer process is more effective in controlling the activated carbon mercury adsorption according to the fitting result of the pseudo-first-order model. The fitting to Langmuir’s model suggested that the material surface is energetically homogeneous. The technique of contaminated biomass encapsulation proved to be safe for short-term disposal when metal recovery is not desired.

QIU Xinqiang, YANG Haochen, ZHANG Yushun et al.

Due to the increased imbalance between water supply and water demand since the 1980s, especially the increase in agricultural water usage, China has undergone four stages in reforming agricultural water price since 2006: initial stage, in-depth pilot stage, comprehensive promotion stage, and policy classification stage. The focus of policy has also shifted from so-called “extensive” to “intensive”. From 2016 to 2020, over 28.7 million hectares of farmlands across the country have been reformed in the country. The comprehensive reform of agricultural water price is a systematic project, and this paper aims to explore a comprehensive, practical, and operational initial water rights accounting and distribution scheme for agriculture at county scale. The scheme can provide guidance for smooth implementation of the comprehensive reform of agricultural water price. We first provide a brief introduction to the current situation of the comprehensive reform of agricultural water price in China and then identify the key tasks in its implementation. An accounting method for the initial water rights of county agriculture is proposed based on the existing rigid constraint system of water resources. The initial agricultural water rights at the county level are allocated according to the priority-order of irrigation areas-beneficiary village groups-townships (and water users). Taking Huangchuan County as an example, the agricultural water rights of all irrigation areas in the county are allocated to the beneficiary villages and their subordinate towns. Completion of initial agricultural water right allocation in the county area is a priority as it not only helps to understand the base and reform process of the comprehensive reform of agricultural water price, but also facilitates follow-up reform work, such as the water-saving incentive mechanism. Our results can provide reference for comprehensive reform of agricultural water price in similar counties and regions and offer experience samples for the applied research of agricultural water right systems.

HU Mingyu, WANG Wen’e, HU Xiaotao et al.

【Objective】 Flow measurement through sluice gates in U-Shaped channels depends on a range of factors. We experimentally measured the characteristics of flow through the gates under different designs and working conditions, and then derived a formula using these data to estimate flow rates based on hydraulic characteristics of the gate and channel, as well as the working conditions. 【Method】 The experiments were conducted by controlling the flow rates from 10 to 50 L/s. The critical ratio of orifice flow to weir flow, as well as the flow capacity were analyzed utilizing hydraulic parameters, including water surface line, Froude number, and water head loss across the gate. These parameters were used in the orifice flow formula to calculate the flow rate. 【Result】 The critical ratio of orifice flow to weir flow was close to 1, the Froude number was uniformly distributed along the flow path, and the average relative head loss across the gate was 7%. Compared to the measured data, the error of the derived formula was less than 3.5%. 【Conclusion】 The sluice gate for the U-Shaped channel works well, and water head loss across it is minor. The derived formula for calculating flow rate is accurate. These results are helpful for designing U-shaped channels in irrigation areas and calculating flow rates through them.

سیده مریم افضلی, جواد خوشحال دستجردی, عزیز تراهی

یکی از مسائل مهم کنونی بشر تولید مواد غذایی بیشتر برای جمعیت رو به رشد جهان است. اقلیم هر منطقه اهمیت بسزایی در بخش کشاورزی و میزان تولیدات آن دارد. کشور ایران یکی از کشورهای خرماخیز جهان است که از نظر تولید و صادرات خرما در جهان، رتبه دوم را دارا می‌باشد. این گیاه دارای ۲۰۰ جنس و ۴۰۰۰ گونه است که هر کدام توانایی تطبیق با منطقه‌ای از مناطق خشک را دارد و می‌تواند در محل مناسب خود بیشترین تولید و بازده اقتصادی را داشته باشد. با توجه به پدیده‌ی گرمایش جهانی و چالش‌های پیش‌آمده ناشی از آن، برنامه‌ریزان در تلاش هستند با آگاهی از شرایط اقلیمی کنونی و آتی و انتخاب گیاهان پایا با عمر طولانی‌تر حداکثر بازدهی اقتصادی را از هر منطقه به دست آورند. لذا یکی از بهترین مدل‌ها جهت شناخت رویشگاه‌های بالقوه کشت، مدل حداکثر آنتروپی است. در تحقیق حاضر، مدل CCSM4 با سناریوهای RCP2.6، RCP4.5، RCP6.0 و RCP8.5 برای پیش‌نگری و استعدادیابی مناطق مختلف کشور برای دو رقم خرمای حلاوی و گنطار انتخاب و مورد استفاده قرار گرفته است. نتایج نشان داد که پراکنش و سطح زیر کشت ارقام خرمای گنطار و حلاوی متفاوت است و در دوره‌های آتی سطح مطلوب کشت رقم گنطار کاهش و سطح مطلوب کشت رقم حلاوی افزایش خواهد یافت. آزمون جک‌نایف نشان داد که این مدل در پیش‌بینی قلمرو مطلوب کشت بر اساس معیار سطح زیر نمودار (4AUC) موفق بوده است (بالاتر از ۹۰/۰).

ادیب روشنی, مهدی حمیدی

تغییرات اقلیمی بر تمامی فرآیندهای محیط‌زیستی و جامعه تأثیرگذار است. در این مطالعه سه مدل ACCESS-CM2، HadGEM3-GC31-LL و NESM3 از مجموعه مدل‌های برونداد اقلیمی سری ششم (CMIP6) صحت‌سنجی شده و از مناسب‌ترین مدل (ACCESS-CM2) با استفاده از جدیدترین سناریوهای انتشار که به اسم خط سیر اجتماعی-اقتصادی (SSP) نام گذاری شده است، به شبیه‌سازی پارامترهای آب و هوایی ایستگاه ساری پرداخته شد. برای ریزمقیاس سازی از مدل LARS-WG6 استفاده شد و دو سناریو انتشار SSP2-4.5 و SSP5-8.5‌، برای دو دوره زمانی (2060-2041) و (2100-2081) بکار گرفته شد. در ادامه از آزمون‌های آماری F-test، t-student، Kolomogrov-Smirnov، ضریب تعیین (R2 ) و ریشه میانگین مربعات خطا (RMSE)، جهت صحت‌سنجی مدل LARS-WG بهره گرفته شد و نتایج حاصل از صحت‌سنجی نشان از کارایی مناسب مدل دارد. همچنین با بکار بردن آزمون من-کندال و شیب سن روند پارامترهای مشاهداتی اقلیمی مشخص شد. نتایج به طور کلی نشان داد که میانگین تغییرات دما از 16/1 تا 09/4 درجه سانتی‌گراد افزایش خواهد یافت و میانگین مقدار بارش سالانه نیز در حدود 24 درصد تا 36 درصد افزایش می‌یابد. نتایج آزمون شیب سن برای دمای حداکثر و حداقل نشان دهنده صعودی بودن روند این پارامتر دارد و برای بارش روند مذکور نزولی است. تغییرات بلند مدت آب و هوایی یکی از عناصر تاثیر گذار بر منابع آب‌های زیرزمینی و سطحی می‌باشد، که ضروری است برای حفظ زیست‌بوم و سازگاری انسان با تغییر اقلیم، توسعه استراتژی‌های مدیریتی مناسب برای آینده در نظر گرفته شود.

LIU Chang, QI Wei, WANG Ce et al.

【Objective】 Swelling and shrinkage are important process reshaping soil structure. It is impacted by many factors, and the objective of this paper is to investigate how fertilization impacts this process. 【Method】 We used a silty loam in the experiment. The soil was fertilized using different inorganic N and K fertilizers at concentrations ranging from 1 g/L to 3 g/L. The emergence and development of the shrinkage during and following multiple wetting-drying cycles were measured in each treatment. 【Result】 ① The shrinkage in the transverse and longitudinal directions both decreased asymptotically with the increase in the number of drying-wetting cycles. Adding inorganic fertilizer reduced the shrinkage in both transverse and longitudinal directions, and the reduction became more significant as the wetting-dying cycles increased. ② The VG-Peng model can fit the effects of the fertilization on soil shrinkage, and the shrinkages in each treatment can be classified into four types: structural shrinkage, proportional shrinkage, residual shrinkage and zero shrinkage. Increasing drying-wetting cycles increased the structural shrinkage at the expense of proportional shrinkage and residual shrinkage. The addition of the inorganic fertilizers reduced the void ratio of the soil in the shrunk region. ③ Soil shrinkage experienced three stages: complete longitudinal shrinkage, longitudinal-dominant shrinkage, and transverse-dominant shrinkage, with the anisotropy of the shrinkages decreasing after several drying-wetting cycles. 【Conclusion】 Applying inorganic fertilizers reduced soil shrinkage due to wetting-drying cycles, and the inorganic fertilizers accumulated after multiple wetting-drying cycles due to the decline in soil shrinkage.

WU Xiangyun, WANG Dong, CAI Xiao et al.

【Objective】Rainfalls in the growth season of summer maize in most areas in northern China are insufficient to meet its demand, and supplementary irrigation is thus required. The purpose of this paper is to investigate the efficacy of different hose-micro-sprinkler irrigation amounts at improving yield and water use efficiency of the maize. 【Method】The experiment was conducted in 2018—2019 at a field, with the four irrigation amounts determined by topping up the soil water in depth of 0~10 (W10), 0~20 (W20), 0~30 (W30) and 0~40 (W40) cm to the field capacity at sowing, beginning of jointing and tasseling stages, respectively. The traditional border irrigation was taken as the control (CK). During the experiment, we measured plant growth, yield components, evapotranspiration and water use efficiency (WUE) of the crops in each treatment. 【Result】With the increase in soil depth used to determine the irrigation amount, the plant height, leaf area index (LAI), aboveground dry biomass and grain yield either increased monotonically or concavely. After the soil reference depth exceeded 20 cm, the efficacy of increasing irrigation at improving crop growth declined. Among all treatments, W20 gave the highest value for all four measured indicators. Irrigation amount impacted both evapotranspiration and WUE at significant level, with the evapotranspiration increasing while the WUE decreasing with irrigation amount. No significant difference in grain yield we found between W20, CK and W40 treatments, and compared to the CK and W40, W20 reduced irrigation amount and water consumption by 47.33%~54.73% and 9.86%~13.85% respectively, with its WUE increasing at significant level by 11.48%~19.26%. 【Conclusion】Considering irrigation amount, grain yield, evapotranspiration and WUE, our results suggested that topping up soil water in the depth of 0~20 cm by the hose-micro-sprinkling irrigation to the field capacity at sowing, beginning of the jointing and tasseling stages respectively, was most effective.

مهدی بهارشاهی, حسین خزیمه‌نژاد, ناصر نیک‌نیا et al.

در استان خراسان جنوبی کمبود آب از عوامل محدود کننده اصلی توسعه فعالیت‏‌های اقتصادی در دهه‌‏های آینده به‏‌شمار می‏‌رود. در این استان مانند سایر نقاط کشور هنوز استفاده مطلوب از آب به شکل یک فرهنگ جایگاه خاص خود را پیدا نکرده است؛ به همین جهت دستیابی به تعادل نسبی در زمینه عرضه و تقاضای آب یک اصل اساسی و ضروری است. این مهم جز با ایجاد یک نظام جامع در مدیریت آب و در نتیجه امنیت آبی میسر نمی‌باشد. به‏‌منظور پیشگیری از وقوع بحران‌های ناشی از عدم امنیت آبی، شناسایی تحولات سریع و روندهای معیوب در مدیریت کنونی آب و آن هم مبتنی بر واقعیت‏‌های اقلیمی، اجتماعی، اقتصادی و غیره در هر منطقه الزامی به نظر می‏رسد. در این راستا با ایجاد مجموعه‏ای از نشانگرها، وضعیت فعلی منابع آب در این استان پایش و ارزیابی شد. سپس با کمک تحلیل خاکستری که یک نوع روش رتبه‌بندی سلسله مراتبی است، دشت‌های استان از نظر امنیت آب رتبه‌بندی شد. نتایج تحلیل خاکستری نشان داد، بالاترین امتیاز سطح امنیت آبی در محدوده‌های ده‌سلم (0/524)، ده‌نو میغان (0/519) و چاهک موسویه (0/504) است. درجه امنیت آنها عمدتاً توسط توانایی آنها در کاهش مخاطرات کم‏آبی و کمیابی آب تفسیر می‌شود، هرچند که تا زمانی‏که خطر کم‏آبی و کمیابی وجود نداشته باشد، محدوده مطالعاتی امن نخواهد بود. محدوده مطالعاتی مهمی همچون دشت بیرجند (با امتیاز 0/462) وجود دارند که در حال حاضر دچار ناامنی آبی هستند. بیشترین سطح ناامنی آبی نیز در استان خراسان جنوبی، محدوده‏‌های در حال توسعه سرایان (0/268) و بشروئیه (0/363) دیده می‌‏شود.

علیرضا رادخواه, سهیل ایگدری, اسماعیل صادقی نژاد ماسوله

با توجه ‏به اینکه بخش قابل توجهی از آبزیان تجاری کشور در سیستم‌‏های مداربسته پرورش داده می‏‌شوند، ارزیابی و کنترل دقیق روی میزان کیفیت آب در این سیستم‌‏ها ضروری است. با توجه‏ به این مسئله، در پژوهش حاضر کارایی فیلتراسیون غشایی در تصفیه آب حاصل از سیستم‏های آبزی‏پروری مداربسته بررسی شد. در ابتدا اطلاعات کلی از فرآیند فیلتراسیون غشایی شامل انواع آن و مزایای آن‏ها ارائه شد و در ادامه، به اهمیت فیلتراسیون غشایی در حذف مواد آلاینده و تصفیه آب در سیستم‏‌های مداربسته آبزی‏‌پروری پرداخته شد. فیلتراسیون غشایی، طیف وسیعی از فرآیند فیلتراسیون شامل اسمز معکوس (RO)، نانوفیلتراسیون (NF)، اولترافیلتراسیون (UF) و میکروفیلتراسیون (MF) را شامل می‌‏شود. بررسی منابع به‏ دست آمده نشان داد مهم‌ترین مزایای روش فیلتراسیون غشایی کاهش هزینه‌‏های کلی تولید، انعطاف‌‏پذیری بالا و کیفیت بالای محصول می‌‏باشد. براساس مرور منابع، مواد جامد موجود در سیستم پرورش آبزیان از غذای مصرف‏ نشده و مدفوع تولید شده توسط ماهی حاصل می‌‏شود و می‏تواند عامل گسترش عوامل میکروبی و بیماری‏زا در محیط‌‏های آبی باشد. کاربرد روش‌‏های مختلف فیلتراسیون غشایی نشان داد این روش‌‏ها کارایی قابل توجهی در حذف ذرات ریز و مواد آلی از پساب‌‏های آبزی‌‏پروری دارند. از این‏رو، می‏‌توانند در جهت مدیریت پایدار ذخایر آبی و همچنین، تصفیه آب در این بخش استفاده شوند.

CAO Xiujia, GU Jian, MA Ningning et al.

【Background】 Drought is the most common natural hazard occurring more frequently over the recent years, due to climate change, and could have calamitous impact on agriculture. In northeast China, damage caused by long-lasting and frequent droughts is especially severe and has been in increase over the past years. Forecasting drought occurrence in plant growth season is hence important to safeguard agricultural production. 【Objective】 This paper is to present and test a model for drought forecast in efforts to offer a guidance to water-saving irrigation for spring maize in the northeast of China. 【Method】 The Pearson correlation coefficient method was used to select the factors that impact the drought index most, based on daily meteorological data measured from 1965-2019 at Fumeng county in Fuxin City of Liaoning province. We then forecasted the crop water deficit index at different growth stages with the wavelet neural network model using the particle swarm optimization. 【Result】 The root mean square error (RMSE) of the drought forecasted by the model at sowing-seedling, seedling-joining, jointing-tasseling, tasseling-milking, and milking-maturity stages was 0.041 9, 0.017 4, 0.048 1, 0.029 7 and 0.042 1 respectively, and their associated determination coefficient was 0.840 2, 0.985 3, 0.899 0, 0.957 5 and 0.917 7 respectively. These were consistent with the ground-truth data, proving that the model is suitable for drought forecast in these areas. There were no or only mild droughts in the sowing-seedling stage, but moderate or even extreme drought may occur during the seedling-jointing stage. As the crop grew, the occurrence of severe drought became increasingly unlikely especially in the milking-maturity stage, although mild drought might still occur in the jointing-tasseling and tasseling-milking stages. 【Conclusion】 The spring maize in the studied area is most prone to drought during the seedling-jointing stage, and our results are of significance to precision irrigation, mitigating detrimental impact of droughts on agricultural production.

Yaser Mehri, Nader Abbasi

Development of irrigation and drainage networks is known as one of the most effective approaches for the optimal use of limited water resources (Abbasi., 2011). But many of the constructed networks suffer from different problems which raised from different reasons. Rahimi et al. (2011) categorized these reasons as; poor design, improper construction operation, low quality of construction materials, poor operation and maintenance, and geotechnical problems of the subgrade materials. Stilling basins are commonly used structures in order to dissipate the energy in downstream of chutes. In general, a hydraulic jump would be created at the end of the chute. The B-type hydraulic jump takes place on the positively inclined plane of a chute under particular conditions. In this condition, determination of the secondary depth and the length of the roller is essential for protecting the structures. Since there is no  proper analytical method to solve the momentum equation for the mentioned condition, using of different smart techniques such as artificial intelligence was considered recently. Caralo et al. (2011) developed different models for determination of the flow characteristics for B-type hydraulic jump. Dusan etal. 2012 presented a neo- Fuzzy system for predicting the weir coefficient.  Akib etal. (2014) predicted the scouring depth by using of neo- Fuzzy system. Azamathulla et al. (2012) developed a neo-fuzzy system for prediction of the sediment transport. In this research, the application of two intelligence methods including Neuro - Fuzzy Inference System and fuzzy inference system were investigated.

Gądek Wiesław, Tokarczyk Tamara, Środula Arkadiusz

While determining theoretical flood hydrographs, different methods of their construction are used depending on the needs of the problem or the scope of the project. It should be remembered that these methods differ mainly with the principle of the waveform averaging, which may be done either according to the flow or time. The hydrographs may be divided into nonparametric (determining on the basis of registered floods) and parametric (using mathematical description of the flood course). One of the analytical methods is Strupczewski method which has two parameters: responsible for the waveform and specifies the base flow, the flow above which values of hydrograph are calculated. The functional description uses the Pearson type III density distribution.

B. Ababaei, H. Ramezani Etedali

Introduction: Water use and pollution have raised to a critical level in many compartments of the world. If humankind is to meet the challenges over the coming fifty years, the agricultural share of water use has to be substantially reduced. In this study, a modern yet simple approach has been proposed through the introduction concept ‘Water Footprint’ (WF). This concept can be used to study the connection between each product and the water allocation to produce that product. This research estimates the green, blue and gray WF of wheat in Iran. Also a new WF compartment (white) is used that is related about irrigation water loss. Materials and Methods: The national green (Effective precipitation), blue (Net irrigation requirement), gray (For diluting chemical fertilizers) and white (Irrigation water losses) water footprints (WF) of wheat production were estimated for fifteen major wheat producing provinces of Iran. Evapotranspiration, irrigation requirement, gross irrigation requirement and effective rainfall were got using the AGWAT model. Yields of irrigated and rain-fed lands of each province were got from Iran Agricultural-Jihad Ministry. Another compartment of the wheat production WF is related about the volume of water required to assimilate the fertilizers leached in runoff (gray WF). Moreover, a new concept of white water footprint was proposed here and represents irrigation water losses, which was neglected in the original calculation framework. Finally, the national WF compartments of wheat production were estimated by taking the average of each compartment over all the provinces weighted by the share of each province in total wheat production of the selected provinces. Results and Discussion: In 2006-2012, more than 67% of the national wheat production was irrigated and 32.3% were rain-fed, on average, while 37.9% of the total wheat-cultivated lands were irrigated and 62.1% was rain-fed from more than 6,568 -ha. The total national WF of wheat production for this period was estimated as 42,143 MCM/year, on average. Different compartments of wheat WF were estimated for 236 plains in fifteen selected provinces. For irrigated areas, the green WFs ranged from 499 to 1,023 m3/ton, the blue WFs from 521 to 1,402 m3/ton, the gray WFs from 337 to 822 m3/ton, and the white WFs from 701 to 2,301 m3/ton. The average total WF for irrigated areas among all the selected provinces is about 3,188 m3/ton, with almost equal shares of blue and green water. For rain-fed areas, the green WFs ranged from 1,282 to 4,166 m3/ton and the gray WFs from 100 to 740 m3/ton. The average total WF for rainfed areas is about 3,071 m3/ton with the share of green WF being nine times the gray WF. In irrigated areas, the percentages of green, blue, gray and white WFs are 23, 25, 17 and 35% of total WF, respectively in each province. The average total WF for irrigated areas is about 3,188 m3/ton with comparable shares of blue and green water. In irrigated areas, Fars, Khorasan and Khuzestan provinces have the largest of the total WF with 5,575, 5,028 and 4,123 MCM/year, respectively. In addition to large cultivated areas and high rates of potential evapotranspiration, high values of gray and white water is another reason for the high volume of total WF in these provinces. Conclusions: The results showed that the green WF related about wheat production in our country is about 2.3 times the blue WF. It confirmed the importance of green water in wheat production. Also the gray water footprint was assessed which is related about nitrogen application. Besides, the white water footprint was proposed here, which represents irrigation water losses. Results showed that the total water footprint in wheat production for the whole country is about 42,143 MCM/year on average over the period of 2006-2012. The ratios of green, blue, gray and white water were 41, 18, 16 and 25%, respectively. Different compartments of wheat WF were estimated for 236 plains over fifteen selected provinces. Total shares of gray and white water footprint were 41% of total wheat production water footprint. The average total WF for irrigated areas among all selected provinces is about 3,188 m3/ton, with almost equal shares of blue and green water. The authors admit that the accuracy of these results is subject to the quality of the input data.