System Dynamic Model for Crop Production,Water Footprint,and Virtual Water Nexus

Intended for comprehensive assessment of water usage in agricultural for food production and to address its future, it is essential to scrutinize the dynamic behavior of crop production and its water footprint and virtual water trade. Through the current research a System Dynamic model that can be applied to estimate crop production, water footprint, and virtual water nexus was developed. The system could be applied to explore how water footprint of crop production and consumption change under proposed planned scenarios which differ from each other in terms of main drivers of change. The drivers of change include population, per capita crop consumption, crop trade patterns, crop yield, and climate change impact. The system is developed to be applied at the country level. A case study from Egypt was analyzed applying the developed system. Where, water footprint of wheat production (green, blue, and grey water), consumption (internal, import and export), and its virtual water balance for years 2010 to 2050 were analyzed under proposed planned scenarios. These proposed planned scenarios were varying in wheat trade pattern strategies and impact of climate change on wheat water consumption and its yield.     

松嫩平原区粮食生产与水资源需求分析

松嫩平原在黑龙江省经济、农业和粮食生产中占有重要地位,但水资源短缺和连年发生的干旱对农业发展构成威胁。选择对农业发展有较大影响的农业用水供需关系,以粮食生产能力和农业水土平衡为前提,摸清松嫩平原农业水资源的现状以及未来的变化趋势及开发利用中存在的问题,根据水资源开发潜力经济社会发展情况研究确定农业合理用水指标,提出合理开发利用水资源的对策措施。     

Water conservation through trade: the case of Kenya

This study quantifies and maps the water footprint of Kenya from both production and consumption perspectives and estimates the country’s virtual water export and import. Kenya’s virtual water export related to trade in agricultural products was 4.1 km³/y; its virtual water import was 4.0 km³/y. The average export earning per unit of water consumed or polluted in producing agricultural export products was USD 0.25/m³, while the average expenditure on imported commodities per unit of virtual water imported was USD 0.10/m³. In addition to increasing water productivity in crop production, Kenya can mitigate its water scarcity by increasing imports of water-intensive products such as cereals and exports of high-value products such as cut flowers, vegetables, spices and tea.     

北京市农业节水与作物种植结构调整

从农业供水资源对作物种植结构的影响、作物种植结构对农业用水量和农业水资源供需平衡的影响,以及作物种植结构对农业节水灌溉方式的要求和对灌溉效益的影响等几方面研究探讨了农业节水与作物种植结构这种既相互制约,又相互促进的关系,并就北京市作物种植结构调整和今后农业节水灌溉工程建设提出几点建议.     

Rapid assessment of the water–energy–food–climate nexus in six selected basins of North Africa and West Asia undergoing transitions and scarcity threats

Existing strategies for management of water scarcity in the Middle East and North Africa negotiate a complex system of trade-offs between water, energy, and food production. The effects of rural households' green water management practices on basin-level water, energy, food and carbon stocks and flows are sketched qualitatively in six basin agro-ecosystems. The case for increased strategic support for green agricultural water management practices appears stronger when weighed from the nexus perspective, rather than purely from the point of view of water balance and food production. Trade-offs under critical transitions affecting agricultural water use are explored, and the scope for quantitative monitoring is discussed.     

On the rationalization of water management for food production

This paper, the second of two (the first published in Water Resources Management 3, 1989), sets out to specify the ways and means of defining a water management strategy for food production as an ordered set of principles and measures designed to exploit and/or operate the system of irrigated agriculture in the optimum manner in order to achieve the predetermined objectives and maximum economic results. To this end, alternatives with regard to project size, irrigation method, mode of operation, cropping pattern and calendar should be evaluated by means of simulating irrigation system operation and agricultural performance. The optimum scenario is selected by analyzing the balance of water resources and irrigation needs as well as by comparing the expected relative crop yield and the guaranteed rate of target yield achievement of different scenarios. Irrigation and crop production regines are then defined for the selected scenario, taking into account the expected water availability and/or scarcity. Furthermore, short- and medium-term measures, designed to optimize the operation of the system and its agricultural performance, are outlined. Finally, the paper identifies the aim of long-term measures as the stabilization of the system's overall performance, balancing the effects of expected population growth (especially in developing countries) and ensuring the positive biogeochemical development of the land.     

农田水利投资促进粮食综合生产能力的机理和冲击程度分析——基于黑龙江省历史数据的计量分析

农田水利是粮食产出的一个重要投资方面。为了更具体地分析农田水利投资对提高粮食综合生产能力的促进机理和影响程度,利用黑龙江省历史数据建立了VAR模型,对农田水利投资进行了实证分析。结果表明:水利建设投资对粮食综合生产能力具有显著的正向冲击影响;这种影响主要是通过降低水旱等自然灾害和调节粮食作物结构来实现的;这种影响具有时滞性,主要在3～6a的时间段内比较有效。为此,提出了加大主产区水利建设支持力度、改变投资方式和资金管理模式、因地制宜、分类重点投资等对策。     

Integrated water and food analysis at the global and basin level. An application of WATERSIM

Several recent studies warn that under ‘Business-as-Usual’ a water crisis is impending, suggesting that appropriate actions need to be taken on the water supply and demand side. While many measures to alleviate water scarcity are within the water sector, it is increasingly recognized that many drivers, policies and institutions outside the water sector have large and real implications on how water is being allocated and used. Important drivers for water use include population and income growth, urbanization, trade and other macroeconomic policies, environmental regulations and climate policy. While some of these processes and trends, especially those at global level, may prove difficult to influence directly, it is important to understand their linkages with water issues to analyze the relative impact of various policies in the agricultural and water sectors on water and food security. The strong linkages between economic trends, agricultural policies and water use call for an integrated and multidisciplinary modelling approach. The WATERSIM model, developed by the International Water Management Institute (IWMI) is a suitable tool to explore the impacts of water and food related policies on global and regional water demand and supply, food production and the environment. This paper introduces the WATERSIM model and, using some preliminary results, illustrates the importance of global economic trends on food and water outcomes.     

基于作物耗水定额控制的灌溉管理模型

海河流域水资源供需矛盾突出,其中农业灌溉所占用水量和耗水量比例最大,而其水分利用效率相对偏低,因此节水潜力较大,为合理调控区域灌溉用水,本文将田间试验观测为基础的灌溉节水理论和方法与遥感数据反演区域耗水(ET)的点面优势相结合,提出了基于作物耗水定额管理的农业灌溉管理模型,通过控制区域上的作物耗水量分布,促进区域灌溉水资源的合理调配和利用,实现资源性节水。模型主要功能包括遥感反演数据统计分析、区域耗水目标分解、作物ET定额分配、种植结构调整、节水潜力分析以及净灌溉需水量估算。可实现从区域综合耗水控制目标向主要作物ET定额的分解,并转化为灌溉用水管理中可控制的灌溉定额,通过逐年设置主要作物的ET控制定额和种植结构情景方案,分析区域的节水潜力,消除奢侈耗水,实现不同水文年和耗水控制阶段目标下的灌溉定额管理,为区域灌溉水管理提供技术支持。     

水塘系统对农业流域水资源调控的定量化研究

本文以一个典型农业小流域为对象，定量化研究水塘系统对流域因作物需水引起的水资源短缺的调控功能。结果表明，六岔河流域的水塘系统蓄水容量6.72万m3，在不同水文年均能有效地调控流域水资源的时空分布，满足作物生长需求。六岔河流域的多数降雨径流被水塘系统截留，减少流域径流输出；在连续流过程中，流域径流峰值急剧降低。水塘系统能够截留日降雨强度为144mm降雨产生径流的90%，径流峰值大大降低。由此说明水塘系统是雨水资源可持续利用的一种有效方法。     

江苏省主要农作物的生产水足迹研究

运用水足迹的理论和方法对江苏省播种面积最大的6种农作物在2000-2010年间的水足迹进行计算,并分析各农作物生产水足迹的特点以及灰水足迹对水环境的不利影响。结果表明:6种农作物生产消耗的蓝水和绿水量总体上呈现下降趋势,江苏省农业生产的用水效率在逐年提高。6种农作物的绿水足迹占比为61.88%~88.17%,绿水在当地农作物生产中占有重要的地位;江苏省6种主要农作物中,水稻和小麦生产的水足迹之和占比为84.15%;单位质量棉花生产水足迹最大,其产生的灰水足迹也最大;单位质量小麦生产的水足迹是稻谷的近两倍,单位质量小麦生产产生的灰水足迹也明显大于水稻。     

济南市部分农作物产品虚拟水含量的研究

基于虚拟水的理论,利用标准彭曼公式和Cropwat软件,对济南市2008年的部分农作物产品虚拟水含量进行了计算分析。结果表明:小麦的虚拟水净进口量为-77477.9×103m3,属于虚拟水出口型作物,稻谷、棉花、豆类和花生果的虚拟水净进口量都是正值,属于虚拟水进口型作物。但总的来说,虚拟水的出口大于进口,这直接危及到济南市的水资源安全。针对这一现状,提出了通过虚拟水贸易和调整农作物种植结构的途径来实现济南市水资源的安全和可持续利用发展。     

Water footprint for Korean rice products and virtual water trade in a water-energy-food nexus

ABSTRACT

One possible approach for addressing water and food insecurity involves food production, trade, and water used elsewhere. In this study, we introduce a water footprint for Korean rice products and focus on the impacts of localized cultivation and water supply systems on the water footprint. In addition, we discuss several studies on the application of water footprint and virtual water trade in water and food management in Korea. Finally, we suggest the role of water footprint and virtual water trade in sustainable resource management through a water-energy-food nexus approach.     

黄河流域作物生产与消费实体水-虚拟水耦合流动时空演变与驱动力分析

愈加有限的水资源是黄河流域生态保护和高质量发展面临的最主要矛盾和瓶颈。在部门用水竞争持续加剧的同时,内嵌在农产品中的虚拟水流动现象日趋频繁。本文以作物生产水足迹和虚拟水流动为表征参数,量化2000—2014年间黄河流域主要作物实体水-虚拟水耦合流动关键过程及其时空演变;从人口、社会经济、农业发展和居民消费4方面,运用扩展STIRPAT模型辨识其关键社会经济驱动因子。结果显示:黄河流域作物单产水平增加有效降低了作物单产水足迹,有效控制了作物生产总水足迹规模;随小麦、玉米和苹果等作物输出,流域作物虚拟水流动规模显著增加,2014年流域虚拟水总输出量占流域作物生产耗水的41%;人口和人均GDP对作物生产水足迹和虚拟水进出口量均起促进作用。     

虚拟水理论与方法的研究进展

虚拟水是当前研究的热点领域，是实体水资源概念在经济社会领域中的拓展。本文在对虚拟水相关概念和意义介绍的基础上，对国内外有关虚拟水问题的研究进展分虚拟水理论研究、虚拟水贸易与粮食安全、虚拟水战略、水生态足迹、虚拟水量化等5个方面进行了归纳和总结，最后探讨了未来虚拟水的研究方向，认为水资源概念的扩展、虚拟水的量化、以虚拟水概念理论制定相关政策、水生态足迹和虚拟水贸易平衡等5个方面是未来可以深入讨论的重点。     

京津冀地区主要农作物生产水足迹研究

利用京津冀地区(2个直辖市、11个地级市)气象及农业基础数据,采用彭曼公式与CROPWAT软件相结合的计算方法,分析了2014年京津冀地区主要农作物的生产水足迹。结果表明:小麦在整个生长期需水量主要以蓝水足迹为主,玉米在整个生长期主要以绿水足迹为主;2014年京津冀地区主要农作物总的生产水足迹为437.03×108m3,其中绿水足迹为137.71×108m3,蓝水足迹为176.03×108m3,灰水足迹为123.30×108m3;从京津冀地区主要农作物总的生产水足迹空间格局上来看,沧州、保定、邯郸和石家庄地区的主要农作物生产水足迹较大,是水资源调控的主要地区。     

基于多源遥感数据和水量平衡原理的灌溉用水量分析

农业灌溉水量估算和区域农业用水的校核是用水统计、监管的难点。现行基于典型调查和定额推算的方法依赖统计人员经验,易受人为因素干扰,准确性难以控制;采用基于水量平衡的灌溉用水推算方法时,区域蓄水变量和耗水量等要素仅依靠传统地面监测条件难以获取。遥感技术能够解决水量平衡方程中区域蓄水变量和蒸散发的估算问题,可以提高水量平衡方法在计算灌溉用水中应用的可行性,但大多数遥感产品存在区域适用性和精度的问题,需要将多种产品结合,通过相互校验和组合控制误差;此外,遥感产品与水量平衡要素之间还存在一定程度的概念差异,需要进行匹配与转换。本文构建了一种基于多源遥感数据和水量平衡原理的灌溉用水分析方法,利用区域水量平衡方程检验多源遥感数据的一致性和可靠性,建立遥感数据与水量平衡要素的对应关系,选取合理的区域蒸散发数据,再利用田间水量平衡将总蒸散发分解为降水蒸散发和灌溉蒸散发,推算得到灌溉耗水量和灌溉用水量的合理范围。应用本文提出的方法进行山东省济南市2012—2015年灌溉用水分析,并与济南市水资源公报统计的农业用水进行对比,结果表明:在降水量接近多年平均的2012、2013、2015年,二者结果较为接近;在干旱的2014年,本文的分析结果与公报结果相差较大。结合同期农田作物长势、区域地下水位变化分析,认为该年份存在较大的灌溉用水,本文结果比较合理。本文方法可为校核区域灌溉用水统计数据的合理性提供技术支撑。     

浙江红壤区水分条件对冬小麦生长的动态耦合模拟

本文讨论了土壤水分运动与作物生长动态耦合模型的建立方法.经与试验结果比较，验证了土壤水分运动和作物生长动态耦合模型对冬小麦生长过程模拟的可靠性，分析了模型中有关作物旱害和渍害耦合参数的灵敏性.应用该模型对南方多雨地区冬小麦生长进行的分析。     

塔里木河流域基于作物水分生产函数的农业水价需求效应分析

基于不同作物(棉花、玉米、小麦)的水分生产函数,构建塔里木河流域农业水价的需求效应模型和水价需求弹性系数模型,并依据塔里木河流域的农业水价资料分析了塔里木河流域农业水价调整对塔里木河流域灌水量的节水效应。研究结果表明,塔里木河流域水价大幅调整是提高农业水价田间作物节水效应的重要经济手段;作物价格也是影响农业水价田间作物节水效应的重要因子之一;通过农业水价调整促进节水技术应用是提高农业水价田间作物节水效应的关键。     

Virtual Water in Global Food and Water Policy Making: Is There a Need for Rethinking?

The argument that economies that face acute water scarcity problems can and should meet their water demand for food through cereal imports from water-rich countries; and that virtual water trade can be used to achieve water securities has become dominant in global water discussions. Analysis of country level data on renewable freshwater availability and net virtual water trade of 146 nations across the world shows that a country's virtual water trade is not determined by its water situation. Some countries have the advantage of high “economic efficiency” in food production and have surplus water, but resort to food import, whereas some water scarce countries achieve high virtual water trade balances. Further analysis with a set of 131 countries showed that virtual water trade increased with increase in gross cropped area. This is because of two reasons: First, when access to arable land increases, the ability to utilize available blue water for irrigation increases. Second, increasing access to arable land improves the access to water held in the soil profile as “free good”, a factor not taken into account in assessing water availability. Hence, many of the humid, water-rich countries will not be in a position to produce surplus food and feed the water scarce nations; and virtual water often flows out of water-poor, land rich countries to land-poor water-rich countries. This means that “distribution of scarcity” and “global water use efficiency”, are goals that are difficult to achieve through virtual water trade in a practical sense. For a water-poor, but land rich country, virtual water import offer little scope as a sound water management strategy as what is often achieved through virtual water trade is improved “global land use efficiency”. The important policy inferences emerging from the analyses are two: First, assessing the food security challenges posed to nations in future purely from a water resource perspective provides a distorted view of the food security scenario. National policies on food security should take into account “access to arable land” apart from water availability. Second, analysis of water challenges posed by nations purely from the point of view of renewable water availability and aggregate demands will be dangerous. Access to water in the soil profile, which is determined by access to arable land, would be an important determinant of effective water availability.