WaDI (water delivery for irrigation): A simulation tool to address strategic interaction of water demand and supply in irrigation schemes

The WaDI (water delivery for irrigation) model deals with the relations between the collective water supply and the demand within irrigated schemes. It is based on a separate modelling of the water supply and demand, including (i) a simplified representation of the hydraulic structure, characteristics and organizational parameters of the scheme, (ii) an assessment of the water demand of farms based on their total irrigated area, cropping pattern and irrigation practices, (iii) a farm typology, (iv) a confrontation between water demand and supply at each node of the scheme from pumping plants to tertiary canals, and (v) calculation of response factors between supply and demand during the peak demand period. “What-if” scenarios are simulated in order to enhance the stakeholders’ capacity to plan strategic decisions such as water delivery allocation rules or infrastructure investments. WaDI was implemented on two Brazilian schemes. It allowed broadening the stakeholders’ limited representation of collective water supply and demand into a more comprehensive understanding of these relations. The approach however showed some limits, along with the difficulty of assessing the real impact on the stakeholders’ capacity for strategic planning.     

Approaches to modular model development

One of the main goals of the International Consortium for Agricultural Systems Applications (ICASA) is to advance the development and application of compatible and complementary models, data and other systems analysis tools. To help reach that goal, it will adopt and recommend modular approaches that facilitate more systematic model development, documentation, maintenance, and sharing. In this paper, we present criteria and guidelines for modules that will enable them to be plugged into existing models to replace an existing component or to add a new one with minimal changes. This will make it possible to accept contributions from a wide group of modellers with specialities in different disciplines. Two approaches to modular model development have emerged from different research groups in ICASA. One approach was developed by extending the programming methods used in the Fortran Simulation Environment developed in The Netherlands. This method is being used in revisions of some of the Decision Support Systems for Agrotechnology Transfer crop models. A simple example of this approach is given in which a plant growth module is linked with a soil water balance module to create a crop model that simulates growth and yield for a uniform area. The second approach has been evolving within the Agricultural Production Systems Research Unit group in Australia. This approach, implemented in software called Agricultural Production Systems Simulator, consists of plug-in/pull-out modules and an infrastructure for inter-module communication. The two approaches have important similarities, but also differ in implementation details. In both cases, avoiding reliance on any particular programming language has been an important design criterion. By comparing features of both approaches, we have started to develop a set of recommendations for module design that will lead to a ‘toolkit’ of modules that can be shared throughout the ICASA network.     

A European irrigation map for spatially distributed agricultural modelling

We present a pan-European irrigation map based on regional European statistics, a European land use map and a global irrigation map. The map provides spatial information on the distribution of irrigated areas per crop type which allows determining irrigated areas at the level of spatial modelling units. The map is a requirement for a European scale assessment of the impacts of irrigated agriculture on water resources based on spatially distributed modelling of crop growth and water balance. The irrigation map was compiled in a two step procedure. First, irrigated areas were distributed to potentially irrigated crops at a regional level (European statistical regions NUTS3), combining Farm Structure Survey (FSS) data on irrigated area, crop-specific irrigated area for crops whenever available, and total crop area. Second, crop-specific irrigated area was distributed within each statistical region based on the crop distribution given in our land use map. A global map of irrigated areas with a 5′ resolution was used to further constrain the distribution within each NUTS3 based on the density of irrigated areas. The constrained distribution of irrigated areas as taken from statistics to a high resolution dataset enables us to estimate irrigated areas for various spatial entities, including administrative, natural and artificial units, providing a reasonable input scenario for large-scale distributed modelling applications. The dataset bridges a gap between global datasets and detailed regional data on the distribution of irrigated areas and provides information for various assessments and modelling applications.     

某装备吊装装置运动学及动力学分析研究

利用虚拟样机技术进行开发是产品现代设计方法之一,其重点是建立开发系统的计算机虚拟样机模型。利用机械系统动力学仿真软件ADAMS(Automatic Dynamic Analysis of Mechanical Systems),建立和测试了某装备吊装装置的虚拟样机,仿真分析了该机械系统的运动学性能和动力学性能,计算出整个机构运动过程中各构件的各种力和载荷参数,为吊装装置在各种姿态下的有限元分析提供了受力数据。     

Flexible delivery schedules to improve farm irrigation and reduce pressure on groundwater: a case study in southern Italy

This study was conducted on an irrigated area of southern Italy to analyze the current operation of a large-scale irrigation delivery system and the effects of the operation procedures on crop irrigation management and aquifer salinity increase. The area is characterized by relatively high levels of groundwater salinity in the summer that are probably due to intensive groundwater pumping by farmers during periods of peak irrigation demand, with the resulting seawater intrusion. Two alternative delivery schedules, namely the rotation delivery schedule and the flexible delivery schedule, referred to as RDS and FDS, respectively, were simulated using a soil-water balance model under different combinations of crop, soil and climatic conditions. The first set of simulations concerned the farm irrigation management constrained by the rotational delivery used by the local water management organization. The second scenario simulated the farm irrigation schedule most commonly used by growers in the area for maximizing crop yields. Based on crop irrigation management under RDS and FDS, two alternative operational scenarios were also developed at the scheme level and then compared for evaluation. Winter and summer salinity maps of the aquifer were developed by interpolating salinity measurements of the groundwater samples collected during the 2006 irrigation season. From these maps, a close relationship can be inferred among delivery schedule, aquifer exploitation and salinity increase, which justifies the need for implementing FDS that might reduce the groundwater demand for irrigation.     

Combining remote sensing-simulation modeling and genetic algorithm optimization to explore water management options in irrigated agriculture

We present an innovative approach to explore water management options in irrigated agriculture considering the constraints of water availability and the heterogeneity of irrigation system properties. The method is two-folds: (i) system characterization using a stochastic data assimilation procedure where the irrigation system properties and operational management practices are estimated using remote sensing (RS) data; and (ii) water management optimization where we explored water management options under various levels of water availability. We set up a soil–water–atmosphere–plant model (SWAP) in a deterministic–stochastic mode for regional modeling. The distributed data, e.g. sowing dates, irrigation practices, soil properties, depth to groundwater and water quality, required as inputs for the regional modeling were estimated by minimizing the residuals between the distributions of field-scale evapotranspiration (ET) simulated by the regional application of SWAP, and by surface energy balance algorithm for land (SEBAL) using two Landsat7 ETM+ images. The derived distributed data were used as inputs in exploring water management options. Genetic algorithm was used in data assimilation and water management optimizations. The case study was conducted in Bata minor (lateral canal), Kaithal, Haryana, India during 2000–2001 rabi (dry) season. Our results showed that under limited water condition, regional wheat yield could improve further if water and crop management practices are considered simultaneously and not independently. Adjusting sowing dates and their distribution in the irrigated area could improve the regional yield, which also complements the practice of deficit irrigation when water availability is largely a constraint. This result was also found in agreement with the scenario that water is non-limited with the exception that the farmers have more degrees of freedom in their agricultural activities. An improvement of the regional yield to 8.5% is expected under the current scenario.     

Management of water consumption in agriculture A model for the economic optimisation of water use: application to a sub-humid area

This paper present a set of solutions for new irrigation transformation in a sub-humid area such as Salvatierra (Alava, Spain). The research is based on the choice of crop rotation (cultivated species and its degree of participation) being able to economically optimise the use of available water for irrigation. Hence, we will be able in helping make decisions to plan, from origin, the transformation of a dry area into an irrigated area. To do this, a model of economic use of water has been used in an area with climatic features very similar to a large part of Europe, representing an interesting scenario compared to the places where the model had not been applied. Crops taking part in this rotation to optimise use of water are mainly vegetables, with high water needs, that coexist together with crops for dryland farming even in conditions of lack of water. Crops for dryland farming allow an interesting diversification of activity as well as an average resource assignment to the farms that make possible to cultivate many farms at a time, which obviously implies socio-economic benefits for the achievements in the zone.     

基于新陈代谢GM（1,1）-Markov链模型的有效灌溉面积预测

采用新陈代谢GM（1,1）模型对全国有效灌溉面积的动态变化进行初次拟合和预测,并根据有效灌溉面积时间序列波动的随机性,利用Markov链模型对新陈代谢GM（1,1）模型的残差进行修正,以概率形式确定出未来全国有效灌溉面积的动态变化区间,并依此模型预测未来10年全国有效灌溉面积的发展趋势。结果表明,该模型预测结果准确可靠...     

Economic analysis of navel orange cv. ‘Lane late’ grown on two different drought-tolerant rootstocks under deficit irrigation in South-eastern Spain

During a three-year period, we evaluated the profitability of a deficit-irrigation (DI) treatment in mature ‘Lane late’ navel orange (Citrus sinensis (L.) Osb.) trees grafted on two different drought-tolerant rootstocks, ‘Cleopatra’ mandarin (Citrus reshni Hort. ex Tanaka) and ‘Carrizo’ citrange (C. sinensis (L.) Osb. × Poncirus trifoliata L. Raf.). The irrigation strategies for each rootstock were a control treatment, irrigated at 100% crop evapotranspiration (ETc) during the entire season, and a DI, irrigated at 100% ETc except during phase I (fruit set) and phase III (fruit maturation) of fruit growth, when complete irrigation cut-off was applied. The main difference found was between rootstocks, orchards of ‘Carrizo’ being 39% more profitable than those of ‘Cleopatra’ due to the greater yield and fruit size and higher price (0.02 € kg⁻¹) for trees on ‘Carrizo’. The application of the DI treatment increased the profit for ‘Carrizo’ since the decrease in pruning costs was greater than the reduction of incomes. The profit of ‘Cleopatra’ under DI decreased due to yield reduction. The variable and fixed operating costs during the growth cycle were decreased by the DI treatment, with a reduction of fertiliser (40%), water applied (30%) and electricity consumed (30%) compared with the control. In addition, in ‘Carrizo’, DI decreased the pruning (16%), machinery (11%) and phytosanitary products (9%) costs as a result of the reduction of the canopy growth. From these results, we conclude that, with similar crop management, orchards of ‘Lane late’ navel orange on ‘Carrizo’ rootstock were more profitable than those on ‘Cleopatra’ under deficit-irrigation conditions.     

Adapting to intersectoral transfers in the Zhanghe Irrigation System, China: Part I. In-system storage characteristics

The Zhanghe Irrigation System (ZIS), in Central China, has drawn attention internationally because it managed to sustain its rice production in the face of a dramatic reallocation of water to cities, industries and hydropower uses. Ponds, the small reservoirs ubiquitous in the area, are hypothesized to have been instrumental in this. Ponds are recharged by a combination of return flows from irrigation and runoff from catchment areas within the irrigated perimeter. They provide a flexible, local source of irrigation water to farmers. This paper assesses the storage capacity and some key hydrological properties of ponds in a major canal command within ZIS. Using remote sensing data (Landsat and IKONOS) and an area–volume relationship based on a field survey, we obtained an overall pond storage capacity of 96 mm (per unit irrigated area). A comparative analysis between 1978 and 2001 reveals that part of this capacity results from a very significant development of ponds (particularly in the smaller range of sizes) in the time interval, probably as a response to rapidly declining canal supplies. We developed a high-resolution digital elevation model from 1:10,000 topographic maps to support a GIS-based hydrological analysis. Pond catchments were delineated and found to extensively overlap, forming hydrological cascades of up to 15 units. In a 76-km² area within the irrigation system, we found an average of close to five ‘connected’ ponds downstream of each irrigated pixel. This high level of connectivity provides opportunities for multiple reuses of water as it flows along toposequences. A fundamental implication is that field ‘losses’ such as seepage and percolation do not necessarily represent losses at a larger scale. Such scale effects need to be adequately taken into account to avoid making wrong assumptions about water-saving interventions in irrigation.     

A rule-based method for the development of crop management systems applied to grain sorghum in south-western France

A generic approach is proposed for the development and testing of crop management systems in contrasting situations of water availability. Ecophysiological knowledge, expertise, regional references and simulation models are combined to devise management strategies adapted to production targets and constraints. The next stage consists of converting these crop management strategies into logical and consistent sets of decision rules. Each rule describes the reasoning which is used to apply a technical decision by taking account of observed or simulated environmental conditions or predicted agronomic risks.

This approach was applied to design crop management systems for grain sorghum (Sorghum bicolor L. Moench.) in south-western France. For spring-sown crops, management (sowing date, plant density, varietal choice, N fertilizer rate and timing) was based on water availability, both for economic and environmental reasons. Specific sets of decision rules were written for irrigated and rainfed conditions. The establishment of rules was based on agronomic principles (e.g. for plant density) or on the application of a simulation model (e.g. for sowing date, variety). N fertilization and irrigation were applied using combined N and water dynamic models.

A novel methodology combining crop diagnosis, analytical trials and crop simulation was developed to evaluate the management systems. An irrigated and a rainfed rule-based management system were compared near Toulouse (S.W. France) from 1995 to 2002. The profitability of rainfed low-input management was confirmed for sorghum in spite of high yields under irrigation (up to 10 t ha⁻¹). The adaptation of sorghum management in rainfed conditions was mainly achieved through early maturing cultivars and by reducing N applications by 65%.     

Economic analysis of drought risk: An application for irrigated agriculture in Spain

This paper describes a two-part methodology for managing the risk posed by water supply variability to irrigated agriculture. First, an econometric model is used to explain the variation in the production value of irrigated agriculture. The explanatory variables include an index of irrigation water availability (surface storage levels), a price index representative of the crops grown in each geographical unit, and a time variable. The model corrects for autocorrelation and it is applied to 16 representative Spanish provinces in terms of irrigated agriculture. In the second part, the fitted models are used for the economic evaluation of drought risk. Inflow variability in the hydrological system servicing each province is used to perform ex-ante evaluations of economic output for the upcoming irrigation season. The model's error and the probability distribution functions (PDFs) of the reservoirs’ storage variations are used to generate Monte Carlo (Latin Hypercube) simulations of agricultural output 7 and 3 months prior to the irrigation season. The results of these simulations illustrate the different risk profiles of each management unit, which depend on farm productivity and on the probability distribution function of water inflow to reservoirs. The potential for ex-ante drought impact assessments is demonstrated. By complementing hydrological models, this method can assist water managers and decision makers in managing reservoirs.     

Application of a simulation software to the analysis of a peasant farming system

A simulation software, GRANJAS was utilized to analyze a Chilean peasant farming system. The purpose of this simulation experiment was to test the impact of the technological innovations being proposed to the peasant family within the context of a Farming Systems Research and Development (FSRD) project.The use of GRANJAS allowed the timely detection of erroneous assumptions concerning the feasibility of solving the present labor shortages in the peasant farm while at the same time intensifying the use of the available irrigated land. It also permitted the comparison of two general options for the development of this particular farming system: development based on the intensification of the crop subsystem, or development based on the intensification of both crop and livestock production.It is concluded that GRANJAS, if properly combined with other analytical tools and techniques, can be a useful and cost efficient instrument for the design of development proposals for peasant farming systems such as the one analyzed in this paper.     

The impact of water and agriculture policy scenarios on irrigated farming systems in Italy: An analysis based on farm level multi-attribute linear programming models

The objective of this paper is to evaluate the impacts of agriculture and water policy scenarios on the sustainability of selected irrigated farming systems in Italy, in the context of the forthcoming implementation of the directive EC 60/2000. Directive EC 60/2000 (Water Framework Directive) is intended to represent the reference norm regulating water use throughout Europe. Five main scenarios were developed reflecting aspects of agricultural policy, markets and technologies: Agenda 2000, world market, global sustainability, provincial agriculture and local community. These were combined with two water price levels, representing stylised scenarios for water policy. The effects of the scenarios on irrigated systems were simulated using multi-attribute linear programming models representing the reactions of the farms to external variables defined by each scenario. The output of the models consists of economic, social and environmental indicators aimed at quantifying the impact of the scenarios on different aspects of sustainability relevant for irrigated farming systems. Five Italian irrigated farming systems were considered: cereal, rice, fruit, vegetables and citrus. The results show the diversity of irrigated systems and the different effects that water pricing policy may produce depending on the agricultural policy, market and technological scenarios. They also highlight a clear trade-off between socio-economic sustainability and environmental (water, nitrogen, pesticide) sustainability. Water pricing will have, in most cases, less impact than agricultural markets and policy scenarios, though it appears to be an effective instrument for water regulation in the least intensive irrigated systems considered. This emphasises the need for a differentiated application of the Water Framework Directive at the local level as well as a more careful balance of water conservation, agricultural policy and rural development objectives.     

Estimation of a production function for wheat under saline conditions

Salinity is a major problem for irrigated agriculture in many parts of the world. Farmers face economic questions such as optimal water applications for given irrigation water quality, reuse of drainage water, reduction in income from using drainage saline waters and rate of mixing good quality water. Crop yield response to water quality and quantity is required to answer these questions. Therefore, this paper is concerned with estimating a set of production functions relating wheat yield to initial soil salinity and water quantity and quality. Crop-water production functions are estimated from experimental data from wheat crop at Sampla village in Rohtak district of Haryana (India).     

水轮发电机组便携式实时数据分析

在水轮发电机组的振动监测中，为了能在数据采样实时观察数据波形并保存数据的同时，又可进行在线式的数据分析，研制了便携式实时振动监测系统。介绍了虚拟仪器开发平台LabWindows/CVI在水轮发电机组实时振动监测系统中的应用,讨论了该系统的硬件、软件体系、结构和功能。     

基于Landsat 8的节水改造背景下盐渍化土壤含盐量反演

为探明沈乌灌域节水改造后因渠道衬砌、引排水量减少引起的土壤含盐量时空分布特征及变化规律,采用区域土壤信息定点监测,结合经典统计学、空间插值以及机器学习建模反演等技术手段,利用Landsat 8卫星获取光谱数据,通过对实测土壤含盐量、光谱指数及波段反射率进行处理,运用Adaboost回归、BP神经网络回归、梯度提升树回归、KNN回归、决策树回归、随机森林回归方法构建了沈乌灌域土壤含盐量空间反演模型。采用最优反演模型对沈乌灌域土壤含盐量空间分布特征进行了遥感反演。结果表明： 通过全变量单一回归法筛选出相关系数大于0.55的9个光谱因子,使用SPSS PRO软件构建6种机器学习反演模型,对比6种反演模型精度,验证集决定系数R2由大到小依次为随机森林回归、梯度提升树回归、Adaboost回归、KNN回归、决策树回归、BP神经网络回归。其中随机森林回归模型的拟合精度最佳,训练集与验证集的决定系数R2分别为0.834和0.86,说明随机森林回归模型的反演效果较好。反演结果表明：节水改造后非盐渍土面积增加391.7km2,占灌域总面积的21%,中度盐渍土面积、重度盐渍土面积、盐土面积分别减少95.61、63.37、45.7km2,分别占灌域总面积的5%、3%、2%。综上所述,节水改造工程完成后,沈乌灌域土壤盐渍化程度减轻,作物生长安全区面积增加,但由于渠道衬砌以及引排水量减少,土壤盐分淋洗效果减弱,土壤盐分在灌域内部运移,整体土壤环境得到改善,局部地区出现盐分聚集。     

基于虚拟技术的车辆操纵稳定性评价系统

把虚拟样机技术与虚拟现实技术应用到车辆的操纵稳定性研究中，设计了车辆操纵稳定性虚拟试验研究平台，把车辆的建模、仿真分析、虚拟再现、评价集成在一起，并以车辆的单移线试验为例阐述了评价系统的实现。结果证明，配合虚拟仪表以及虚拟环境，虚拟试验突破了原有仿真曲线等评价的不足，通过立体视觉设备，人可以沉浸到环境中，以闭环的方式体验车辆的性能。     

Hydraulic-hydrological simulations of canal-command for irrigation water management

A modelling system that combines the hydraulic simulations of the canal and hydrological simulations of the irrigated command is introduced. It uses MIKE 11 and MIKE SHE, two well-established modelling systems, for the hydraulic and hydrological simulations respectively. In addition, it also has an irrigation scheduling module and a crop growth module. The modelling system is applied to the Mahanadi Reservoir Irrigation Scheme, a large irrigation project in Central India. The results show that presently a significant amount of water is wasted in the command during the monsoon season. It is demonstrated that the minimization of this wastage could lead to a substantial crop production in the subsequent dry season. Furthermore, the simulations illustrate the versatility of the modelling system for planning and analysing the various aspects of an irrigation project.     

Scheduling deficit irrigation of citrus trees with maximum daily trunk shrinkage

The feasibility of scheduling deficit irrigation using maximum daily trunk shrinkage (MDS) was evaluated during two consecutive seasons in a citrus orchard planted with mature ‘Clementina de Nules’ trees, in Valencia, Spain. Results showed that MDS in well irrigated trees varied largely according to the environmental conditions (higher correlation was obtained with global radiation), and therefore, the absolute values of MDS cannot be employed as the only variable to schedule irrigation. To avoid the effects of the climatic conditions we scheduled deficit irrigation using the MDS ratio, which is the MDS of any treatment related to the MDS of a control, well irrigated, treatment located in the same plot. We explored the feasibility of scheduling irrigation based on the MDS ratio in a deficit irrigated treatment, where water was applied as necessary, from July until mid October, in order to maintain the MDS values at 125% of that of the control treatment. Despite the large variability observed in the MDS measurements in both years no significant reduction in yield and fruit weight was observed in the deficit irrigated treatment compared with the control, allowing seasonal water saving between 18 and 12%.