地下水埋深对棉花灌溉制度的影响

针对黑龙港流域地下水位总体趋势持续下降的现象,结合沧州市南皮县棉田的原位试验,采用HYDRUS 1D模型进行数值模拟,分析不同地下水埋深条件下,地下水对棉花根系层的补给作用对灌溉制度的影响。结果表明,当全生育期地下水平均埋深为1.5、2m时,地下水对棉花根系层的补给量相当于实验棉田0.5~1.5倍的灌水定额。由此制定3种(1.5、2、3m)地下水埋深条件下不同降水水平年的棉田灌溉制度:播前灌之后,50%水平年不再灌溉;75%水平年当地下水平均埋深为3m时,灌一次花铃水;85%水平年在地下水平均埋深为2、3m时,各灌一次花铃水。地下水补给作用对棉花根系层土壤含水率存在着不可忽视的影响,特别是当地下水埋深不超过2m时制定棉田的灌溉制度应充分考虑地下水的补给作用。     

发展山园瓯柑节水喷灌机械配套节本增效技术

随着我国综合国力的稳步发展,城乡人民的生活水平也不断提高,发展瓯柑种植面积和提高产量,改善瓯柑品质,是人们物质生活的需要,也是我国新形势下农业产业结构调整的发展趋势,并带动山区农民共同致富,利国又利民。本文就温州地区发展山园瓯柑节水喷灌机械配套节本增效技术进行叙述,对于推广应用具有重要的现实意义。     

Effect of soil matric potential on tomato yield and water use under drip irrigation condition

Field experiment was carried out to investigate the effect of soil matric potential (SMP) on tomato yield, evapotranspiration (ET), water use efficiency (WUE) and irrigation water use efficiency (IWUE) under drip irrigation condition in North China Plain. The experiment included five treatments, which controlled SMP at 0.2 m depth immediately under drip emitter higher than −10 (S1), −20 (S2), −30 (S3), −40 (S4) and −50 kPa (S5), respectively, after tomato plant establishment. The results showed that different SMP affected irrigation amount and tomato ET. Irrigation amount decreased from 185 mm (S1) to 83.6 mm (S5) in 2004, and from 165 mm (S1) to 109 mm (S5) in 2005, respectively. The ET decreased from 270 mm (S1) to 202 mm (S5) in both years. However, it was found that SMP did not affect the tomato yield significantly, for the range of SMP investigated. Both WUE and IWUE increased as SMP decreased. The maximum WUE (253 and 217 kg/ha mm) and IWUE (620 and 406 kg/ha mm) were for S5 in 2 years, whereas the minimum WUE (178 and 155 kg/ha mm) and IWUE 261 and 259 kg/ha mm) were for S1 in 2004 and 2005. Based on the above results, therefore, it is recommended that if the tomatoes are well irrigated (SMP is higher than −20 kPa) during establishment, controlling SMP higher than −50 kPa at 0.2 m depth immediately under drip emitter can be used as an indicator for drip irrigation scheduling during following period of tomato growth in North China Plain.     

An evaluation of the Porac River irrigation system

An irrigation water management research programme was implemented by Hydraulics Research in collaboration with the National Irrigation Administration of the Philippines on the Porac Area of Porac Gumain Rivers Irrigation System. The objectives of the study are to monitor the response of the main canal network to changes in water availability and assess its capability to deliver crop water requirements to sub-areas jointly managed by National Irrigation Administration staff and existing Irrigator Associations. This paper presents an analysis of the response of the main system to the varying irrigation demands, and assesses the conjunctive use of groundwater with surface water and the potential of computer models to assist management with the preparation of the annual irrigation schedules.     

A reservoir operational rule for irrigation in Japan

Operation of a reservoir for irrigation is more complicated and difficult than that for domestic water supply in Japan, owing to the fact that a requirement for irrigation takes various value depending upon effective rainfall on farmland, soil condition, and so on. Therefore, the reservoirs should be operated to correspond with demand, inflow, and unknown droughts occurring in the future. However, the reservoirs have been operated under operators' experiences without formal operational rules, because any effective theories or methods have been neither developed nor used in Japan at present.On operation of the reservoirs, there are two targets — promotion of effective release and restriction of release in preparation for droughts — conflicting with each other. It is useful to set up the operation with Required Storage for Drought Curve (RSDC) Method to achieve reasonable operation harmonizing those two targets. RSDC is composed with Target Line (TL) and Restrictive Release Lines (RRLs). TL is a target storage level to guarantee that storage will never empty until the end of the irrigation period under a certain probability. If actual storage remains above TL, effective release will be promoted. RRLs are storage levels pointing out the basis of restricting release. If actual storage falls below TL, release will be restrained in accordance with RRLs in order to get over uncertain droughts occurring in the future.In this paper, the theory of RSDC is described and the effectiveness of Rule Curve (RC) based on RSDC Method is illustrated by simulation on a single reservoir for irrigation.     

An economist's perspective on irrigation performance assessment: With examples from large scale irrigation in Morocco

This paper accepts that assessing the performance of irrigated agriculture is difficult because being multi-dimensional it requires a multi-disciplinary approach. Public irrigation schemes may have a number of often competing objectives and are assessed by interest groups with differing values and perspectives. A wide range of performance indicators are thus required. Some of these and the complex inter-relationships that may exist in the system are illustrated.     

The River Wadu role play — ten years experience

This paper describes a role playing planning exercise that has been used for training agriculturists, engineers and agricultural economists for more than ten years. It sets out the objectives and key features of the exercise and the experience that has been gained in its use. The exercise has been found to successfully test and integrate subject matter expertise acquired from formal teaching. It also highlights the multiple and often conflicting objectives of irrigation planning, and the need for full evaluation of alternatives and sound technical judgements under conditions of inadequate data and time pressure. The exercise is also successful in developing professional personal skills such as group working, interviewing and presentation, and is recommended as an effective training aid.     

Managing the water balance of The Fayoum Depression,Egypt

A study of the water balances of The Fayoum irrigated lands and Lake Qarun was made to investigate the management of the irrigation system and the efficiency of irrigation water use. The two water balances are strongly interrelated. The drainage flow to Lake Qarun and the water level of the Lake are in delicate balance. A rise in Lake level causes the inundation of adjacent land. Management of The Fayoum water balance assumes control over irrigation water flows, but this control has technical and organizational limitations. Also discussed is the influence of irrigation practices in The Fayoum on the water balance (e.g., the autumn flushing of fields and farmers' preference for not irrigating at night in winter). Notwithstanding a high overall efficiency, irrigation efficiency during the winter is low. The reasons for this are given, together with the constraints against improving system management. Improved uniformity of the division and application of irrigation water will enable a better technical control of flows and will result in better water management in The Fayoum. Abbreviations: FID — Fayoum Irrigation Department, 1 feddan (fe) — 0.4 ha, 1 mcm — 1 million cubic metres: an average annual flow of 3.17 m³/s gives 100 mcm, m³/fe.year — supplied volume (m³) per surface area (fe) per year: 1000 m³/fe.year equals 240 mm/year, MSL — Mean Sea Level     

A postscript: Macroeconomics and structural adjustment — the minimum for water sector specialists

The need for a grasp of macroeconomic concepts and methods for microeconomists and technical specialists is stressed. At this juncture policy failure is commonplace. Experience in using the World Bank Structural Adjustment in Lowinca as a training exercise is discussed.     

Water management for irrigation in Antiquity (Urartu 850 to 600 B.C.)

The kingdom of Urartu existed in Eastern Anatolia from about 850 B.C. to 600 B.C. Historical references and archaeological evidence indicate the considerable artistic and technical skill of the Urartian people. The supply of the kingdoms capital Tupa/Rusahinili with drinking and irrigation water is an outstanding example of a well-planned and excellently built historical inter-basin water management project. The system has been in operation for more than 2000 years and still serves, at least partly, its original purpose.