模糊随机优选模型在区域水环境承载力评价中的应用

基于水环境一社会经济系统的随机不确定性特征，建立了一种适用于指标信息不确定的区域水环境承载力评价模糊随机优选模型。在该模型中，考虑到随机因素的影响，将不确定性指标的属性值划分为若干状态，每个状态都与一定的发生概率相对应。在此基础上，依据模糊理论构造以待评样本加权距优距离的二次方与加权距劣距离二次方之和为最小的目标函数，由此求得样本优属度值。根据样本优属度大小，对区域水环境承载力状况或变化趋势进行分析。实例研究表明，对具有随机不确定性特征的区域水环境承载力评价，所建模型具有很好的适用性。     

An inexact two-stage water management model for planning agricultural irrigation under uncertainty

In this study, an inexact two-stage water management (ITWM) model is developed for planning agricultural irrigation in the Zhangweinan River Basin, China. The ITWM model is derived from the incorporation of interval-parameter programming (IPP) within a two-stage stochastic programming (TSP) framework. It can reflect not only uncertainties expressed as probability distributions but also interval numbers. Moreover, it can provide an effective linkage between conflicting economic benefits and the associated penalties attributed to the violation of the predefined policies. Four decision scenarios associated with different water-resources management policies are examined. Targeted incomes, recourse costs, and net system benefits under different scenarios are analyzed, which indicates that different policies for agricultural irrigation targets correspond to different water shortages and surplus, and thus lead to varied system benefit and system-failure risk. The results are valuable for supporting the adjustment or justification of the existing irrigation patterns and identify a desired water-allocation plan for agricultural irrigation under uncertainty.     

灌区用水优化模型参数全局敏感性分析与不确定性优化

灌区水资源优化配置中存在众多不确定性因素，而考虑不确定性因素的优化模型往往存在结构复杂、不确定性参数考虑有限、计算精度和效率较低等问题。本文将LH-OAT（Latin hypercube-One factor at a time）方法与灌区用水优化模型耦合，构建了灌区用水优化模型参数敏感性分析与不确定性优化方法，并以黑河流域中游典型灌区为案例研究区，对模型中6类共25个不确定性参数进行了全局敏感性分析。计算获得了模型中25个不确定性参数的敏感度排序，并从中筛选出10个高敏感性参数，以高敏感性参数作为优化模型不确定性参数输入，获得了不确定性下的灌区用水优化结果。案例分析表明，该方法有效筛选出优化模型中高敏感的关键参数，综合考虑了不确定性参数对模型优化结果的影响，大大减少了模型不确定性参数的表征数量，降低了模型复杂性，有效提高了模型计算效率，可为灌区水资源优化配置问题提供方法参考。     

基于水权的金沟河流域农业水资源优化配置

为了实现金沟河流域枯水期农业水资源的合理配置,以农业水权分配的公平、效率、可持续性原则为目标,建立金沟河流域农业水权分配指标体系,以该指标体系为模型,利用模糊优选理论对模型进行了求解,通过计算与现状相比,流域11个用水单位农业水资源得到了较为公平、有效的配置。     

The effect of water supply uncertainty on farmers’ choice of crop portfolio

This paper analyzes the effect of water supply uncertainty on farmers’ choice of crop portfolio. The paper presents an innovative model to estimate the value of uncertainty of water supply, and then tests the model using data from Israel. The modeling results provide support to the hypothesis that uncertainty induces farmers to prefer crops whose growth requires less agricultural capital accumulation, despite their lower profitability (agricultural capital referring to trees and other plants which take a significant period of time to mature). This is due to the risk that in a given year water supply will fall below a certain minimal level, thereby causing loss of all accumulated capital. The paper also examines a government intervention policy for mitigating uncertainty: use of reclaimed wastewater in crop irrigation as a supplement for freshwater supply. The costs associated with constructing the required wastewater reclamation and supply facilities are compared to the benefits of additional farm income earned through a more certain on-farm water supply. It is shown that under certain conditions implementation of this policy is indeed economically worthwhile.     

Fuzzy multi-objective linear programming applying to crop area planning

Crop area planning plays significant role in agricultural water management. During the planning, because of ambiguous or uncertain information caused by the vagueness of decision makers’ subjective preference or the uncertainty of objective information, conventional multi-objective linear programming (MOLP) model is not suitable for such decision-making in such fuzzy environment. In this study, we proposed the fuzzy multi-objective linear programming (FMOLP) model with triangular fuzzy numbers and transformed the FMOLP model and its corresponding fuzzy goal programming (FGP) problem to crisp ones which can be solved by the conventional programming methods. The FMOLP model was applied to crop area planning of Liang Zhou region, Gansu province of northwest China, and then the optimal cropping patterns under different water-saving levels and satisfaction grades for water resources availability of the decision makers (DM) were obtained. Compared to the MOLP model, the FMOLP model itself expresses the fuzzy information effectively, and its solutions can represent the DMs satisfactory degree of the subjective preference and propose alternative solutions for better decision support when applied in the crop area planning.     

冯家山水库供水持续性评价

结合可持续发展理念与风险分析的理论和方法,选取可靠性、弹性、脆弱性、均方差及最大缺水率等5个性能指标为持续性指标,以冯家山水库为研究对象,针对生活、工业、生态环境、农业灌溉等水库用水户,合理选取性能指标构建持续性指标,对其持续性进行了评价;并用这4个用水户作为用水群的组成构建群持续性指标对水库供水持续性进行了评价.冯家山水库供水持续性评价结果表明,在现状情形下,水库供水持续性为35%,持续性较低;尤其农业灌溉供水持续性仅为29%.减少农业灌溉对水库需水要求的30%时,生活、工业、生态环境、农业灌溉用水户的可靠性及持续性都得到提高,此时,农业灌溉供水持续性为40%,水库供水持续性为45%,水库供水持续性得到提高.可在灌区采取一定的节水措施,以减少农业灌溉对水库的需水,提高农业灌溉用水户的持续性和水库供水持续性,降低缺水风险,促进水库的可持续发展.     

Position of the Australian horticultural industry with respect to the use of reclaimed water

Australia is the driest inhabited continent on earth, and pressure on its water resources is already high and increasing. Environmental, social, and economic drivers are forcing horticultural industries in Australia to reassess their use of freshwater resources. Reclaimed water is potentially a major resource for the horticultural industry. In general, however, there has been some apprehension towards using reclaimed water for irrigation, owing primarily to uncertainties related to agricultural sustainability and human health. Here, we consider the current standing of the Australian horticultural industry in terms of its preparedness to use reclaimed water for irrigation. We address issues related to policy, economics, market access, pragmatic directives (such as state and federal guidelines), environmental impact, agronomic sustainability, and public health. From these appraisals, we have attempted to summarise the major impediments to the use of reclaimed water by the Australian horticultural industry. These are: insufficient knowledge of impacts on market access; commitment to provide continuity of quality and supply to markets; implications of substitution of alternative water sources on security of supply; insufficient knowledge of food safety issues; inadequate understanding of consumer perceptions; and uncertainty about pricing of reclaimed water.     

Optimal decision schemes for agricultural water quality management planning with imprecise objective

Agricultural activities are the main sources of water pollution to surface water and groundwater in rural areas. Extensive soil disturbance and application of fertilizer and manure in agriculture cause nonpoint source losses of soil and nutrients such as nitrogen and phosphorus. How to generate preferred decision schemes for agricultural activities that cause such nonpoint source water pollution is a critical issue for the decision makers. In this study, an inexact agricultural water quality management (IAWQM) model is developed and applied to a case study to generate optimal decision schemes for integrated water quality management within an agricultural system. The model is based on a hybrid fuzzy possibilistic robust programming approach, which improves upon the existing fuzzy possibilistic programming and fuzzy robust programming methods by allowing fuzzy information in the model's objective and constraints to be directly communicated into the optimization processes and resulting solutions. Optimal decision schemes for agricultural activities can be generated, including cropping area, manure/fertilizer applied, and livestock husbandry size, where implications of water quality/quantity restrictions for achieving regional economic development objectives are studied. The results of the case study indicate that useful information can be obtained through the proposed IAWQM model for providing feasible decision schemes, which reflect tradeoffs between economic and environmental considerations. The decision variables are useful for the decision makers to justify and/or adjust the decision schemes for agricultural activities through incorporation of their implicit knowledge on water quality management.     

基于模糊几何加权模型的灌区水资源优化配置

针对农业水资源优化配置中多目标赋权的不确定性问题,以黑龙江省绰尔屯灌区为研究区域,构建了基于模糊几何加权法的灌区水资源优化配置模型,把多目标规划问题转化为单目标非线性问题,得到了不同权重下不同生育期的灌区水资源最佳配置方案,并通过灌区综合能力评价体系进行比选.结果表明:通过与线性多目标模糊规划模型的对比,模糊几何加权模型可以根据实际情况对不同目标的权重进行调整,得出该条件下的灌区水资源最佳配置方案;当灌水量权重为0.3和经济权重为0.7时为最优方案,水稻产值为8 245万元,分蘖期、拔节期、抽穗期、乳熟期的灌水量分别为1 154.56万、779.12万、539.45万、336.57万m³.验证了模糊几何加权法在灌区水资源优化配置的可行性应用,为灌区农业水资源高效利用提供参考方案和决策支持.     

农业干旱卫星遥感监测与预测研究进展

干旱是影响农业生产的主要气候因素.传统的农业干旱监测主要是基于气象和水文数据,虽然能提供监测点上较为精确的干旱监测结果,但是在监测面上的农业干旱时,仍存在一定的局限.遥感技术的快速发展,尤其是目前在轨的卫星传感器感测的电磁波段涵盖了可见光、近红外、热红外和微波等波段,为区域尺度农业干旱监测提供了新的手段.充分利用卫星遥...     

Retrieval of irrigated and rainfed crop data using a general maximum entropy approach

This paper presents a method to separate harvested area and yield for irrigated crops from rainfed crops in a region, given gross harvested area and yield, and climatic, agronomic and economic data for crops. The method is based on the principle of general maximum entropy, which combines incomplete data, empirical knowledge and a priori information to derive desired information. The model is applied to three large basins with aggregated climatic and agricultural conditions, and to five counties in Texas and California. The modeled results and assessed values in these study areas are compared. While the dependability of model outputs relies on empirical knowledge and judicious parameter estimation, the model remains reliable even for the significant level of uncertainty produced by subjectively predetermined major parameters. The model can be applied to retriving historical data for irrigated and rainfed crops; it can also be used for irrigated and rainfed agriculture planning based on climatic and technological projections. Moreover, the model provides other useful information, including water allocation by crop, water use efficiency and the impact of other agricultural inputs.     

水稻水肥耦合效应研究

研究寒地黑土区水稻水肥耦合效应对产量的影响规律,运用二次饱和D-416最优设计方案,以施氮量、施钾量、施磷量、分蘖末期土壤含水率占土壤饱和含水率的百分比为设计因子,以产量为目标因子,编制四因素二次饱和D-416设计表,结合基于实数编码的遗传算法与BP神经网络强大的函数拟合、寻优功能,以设计表中四因素为输入层,产量为输出层,建立基于RAGA-BP神经网络模型,并对该模型进行预测和优选。结果表明,当产量最高时水肥耦合的最优方案施氮量为1.01g/盆、施钾量为0.63g/盆、施磷量为0.46g/盆、分蘖末期土壤含水率占饱和含水率的75.2%,此时得到的产量为74.78g/盆,与模型预测的最优个体适应度值73.55g/盆误差仅为1.68%,说明该模型能较好的反映出水肥投入量与产量之间的复杂关系,对指导农业生产实践具有一定的意义。     

The meaning of agricultural sustainability: Evidence from a conjoint choice survey

Because of its complex, multi-dimensional nature, agricultural sustainability is most often assessed using numerous indicators, which make aggregate comparisons among different production systems difficult. In this paper we propose a methodology that could be beneficial in aggregate sustainability assessment. We apply the method of conjoint analysis to select economic, social, and ecological attributes that are perceived as important for agricultural sustainability by different stakeholders and to assess their relative impact on the overall sustainability measure. Our method presents a flexible framework which could be adopted for a variety of specific applications and allows drawing comparisons among various stakeholder groups based on how they perceive agricultural sustainability.     

A mathematical model for simulating water balances in cropped sandy soil with conventional flood irrigation applied

In this paper, a model that integrates various complex model components for the purposes of water balance modeling throughout crop development in arid inland region under the conventional flood irrigation practiced is presented. These components are modules for calculating dynamic soil water content based Richard's equation, potential and actual evapotranspiration, and crop root water uptake. Soil water content in the active root zone and soil evaporation simulation obtained from the model were test using field data in 2003. The low values of MARE and high values of R² and PE in the active root zone of soil profile as well as daily soil evaporation indicated that the soil water balance simulation model presented in the paper can be used with reliable accuracy to simulate the components of water balance in cropped sandy soil under the conventional flood irrigation condition in arid inland regions. The model simulation on components of water balance using observed field data in 2004 indicated that large quantities – about 43% of irrigation water (amounting to 840 mm) – were consumed by deep percolation, only small (less than 41%) proportions of irrigation water used by the plants for transpiration. The current irrigation scheme is characterized by the unreasonable agricultural water management with the waste of water in the irrigational system in this region. The impact of irrigation scheduling on water balance presented in this paper showed that the reasonable irrigation scheme with more frequent irrigation and less amounts is more suitable for the irrigation of spring wheat in Heihe River basin, northwest China. Therefore, to establish a decision-making system for agricultural irrigation scheme and to utilize the limited water resources in this region have become an urgent problem that needs to be solved.     

基于Matlab地表滴灌土壤水分运动的数值模拟

滴灌条件下土壤水分运动规律是当前农业工程中重要研究领域。基于土壤水运动基本方程,结合作物根系吸水特点,建立了地表滴灌条件下土壤水分运动二维数学模型。应用Matlab软件,通过数值模拟方法,得出了Van Genuchten模型的参数值,推导了渗透参数拟合公式,进一步对地表滴灌土壤水分运动过程进行模拟。同时,利用Matlab强大的绘图功能对拟合曲线与实测数据进行了直观的比较。结果表明,所构建的数学模型对地表滴灌条件下的土壤水分运动变化具有较好的模拟效果。     

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.     

基于AHP和ArcGIS的北京市农业节水区划研究

在总结国内外学者农业节水分区先进经验的基础上,结合北京市农业生态节水发展实际,充分考虑自然条件、水资源状况、工程管理和社会经济状况等,构建涵盖干旱指数、地下水超采、土壤类型、节水灌溉率、农民人均收入在内的北京市农业节水分区指标体系,分析各指标空间分布规律,界定各指标的分级标准,并划定相应分区。采用层次分析法(AHP)对各指标分级赋值,利用ArcGIS软件中的叠加分析功能将图层按权重叠加,对分区重分类并相应赋值,将各影响因素的分值和权重相乘并求和得到最终的评分结果,按照评分结果将北京市划分为农业节水优先发展区、农业节水适宜发展区和农业节水鼓励发展区,根据分区结果提出相应工程节水及农艺节水措施。     

Institutional management regimes for pricing of irrigation water: the French model — lessons for India

In France, the River Basin Committees and Water Agencies are in-charge of managing water resources. However, many surface irrigation networks were initiated and operated by the Regional Companies and farmer syndicates exclusively for agricultural development in the southwest of the country. These are water institutions playing an active role in water management with an objective of cost recovery in order to improve the quality of irrigation services to the users. The implementation of various innovative institutional management approaches by these agencies have yielded a modest degree of success in addressing the crucial problems of the irrigation sector in terms of pricing water, cost recovery, financial viability and overall sustainability of the surface irrigation system. This study attempts to examine the relevance of the institutional management approaches of France to the Indian context. The institutional framework for setting the price of irrigation water is through negotiation between the management and the user representatives. The important lessons drawn based on the experiences of the French model include the granting of financial autonomy to the water institutions in order to recover operational and maintenance costs, participatory approaches of decentralised management, user involvement in the decision-making process, devolution of small-scale irrigation networks to the users for management and the promotion of effective and viable user associations with access to technical information relating to the use of irrigation technologies.     

Modeling wheat yield and crop water productivity in Iran: Implications of agricultural water management for wheat production

In most parts of Iran, water scarcity has been intensifying and posing a threat to the sustainability of agricultural production. Wheat is the dominant crop and the largest irrigation water user in Iran; hence, understanding of the crop yield-water relations in wheat across the country is essential for a sustainable production. Based on a previously calibrated hydrologic model, we modeled irrigated and rainfed wheat yield (Y) and consumptive water use (ET) with uncertainty analysis at a subbasin level in Iran. Simulated Y and ET were used to calculate crop water productivity (CWP). The model was then used to analyze the impact of several stated policies to improve the agricultural system in Iran. These included: increasing the quantity of cereal production through more efficient use of land and water resources, improving activities related to soil moisture conservation and retention, and optimizing fertilizer application. Our analysis of the ratio of water use to internal renewable water resources revealed that 23 out of 30 provinces were using more than 40% of their water resources for agriculture. Twelve provinces reached a ratio of 100% and even greater, indicating severe water scarcity and groundwater resource depletion. An analysis of Y-CWP relationship showed that one unit increase in rainfed wheat yield resulted in a lesser additional water requirement than irrigated wheat, leading to a larger improvement in CWP. The inference is that a better water management in rainfed wheat, where yield is currently small, will lead to a larger marginal return in the consumed water. An assessment of improvement in soil available water capacity (AWC) showed that 18 out of 30 provinces are more certain to save water while increasing AWC through proper soil management practices. As wheat self-sufficiency is a desired national objective, we estimated the water requirement of the year 2020 (keeping all factors except population constant) to fulfill the wheat demand. The results showed that 88% of the additional wheat production would need to be produced in the water scarce provinces. Therefore, a strategic planning in the national agricultural production and food trade to ensure sustainable water use is needed. This study lays the basis for a systematic analysis of the potentials for improving regional and national water use efficiency. The methodology used in this research, could be applied to other water scarce countries for policy impact analysis and the adoption of a sustainable agricultural strategy.