Temporal Variability of Water Footprint for Maize Production: The Case of Beijing from 1978 to 2008

The water footprint (WF) of crop production is a comprehensive indicator that can reflect water consumption types, quantities and environmental impacts during the crop growth period. This study assesses interannual variability of green, blue and grey WFs of maize production in Beijing from 1978 to 2008. Results indicate that: (1) The multi-year average WF of maize was 1,031 m³ ton^?1 which was 56 % green, 25 % blue, and 19 % grey; (2) the climate experienced a warm-dry period in Beijing during the period from 1978 to 2008, and this lead to the increase of crop water requirement and irrigation water requirement for maize with trends of 0.52 mm a^?1 and 2.86 mm a^?1, respectively; (3) under the combined effects of climate change and agricultural inputs, the total WF and green WF presented decreasing trends. The blue and grey WFs had clear increasing trends; (4) statistical analysis revealed that interannual variability of green and blue WFs were caused by both climatic factors (effective precipitation) and non-climatic (agricultural inputs) factors. The grey WF was mainly associated with non-climatic factors, such as chemical fertilizers consumption.     

Water footprints and irrigated agricultural sustainability: the case of Chile

This paper estimates the agricultural production water footprint (WF) of Chile, assessing green, blue and grey WFs of the main agricultural products for the main productive regions, taking into account climatic and soil differences. Chile’s agricultural production blue WF is geographically concentrated in the lower portion of the Northern Dry Pacific and Central Chile area, which present less water availability. Thus, irrigated agricultural production in Chile, a semiarid country, is characterized by high water stress. In this scenario, public policies are required to incentivize better water management in order to reduce water vulnerability while boosting development.     

Irrigation water requirement models of some major crops

A case study of the Mahanadi-Kathjori-Devi delta of Orissa, India was undertaken for the formulation of irrigation water requirement models of some major crops. Principal crops such as paddy (both during the Kharif and Rabi Seasons), sugarcane, jute, chilly, mustard, groundnuts, etc., which are mostly grown in the delta, were taken into account for the present study. Effective rainfall and irrigation water requirements are the two basic parameters of the developed models. The models help in predicting irrigation water requirements for different crops once the values of effective rainfalls are ascertained. This irrigation water requirement, estimated by models so developed, includes water requirements for consumptive use only and when any other water used for special requirements such as leaching, seed bed preparation, etc., is added to it, the total irrigation water requirement is determined. The models so developed can be used for the same crops grown in other areas having the same hydrometeorological characteristics.     

Irrigation

This paper provides an overview of the main features of irrigation in Japan, and the issues it raises, rather than an exhaustive survey of the subject. The authors’ remarks concentrate on irrigation for rice cultivation, since irrigation for non‐paddy crops is not widely developed and claims a very minor share of the country's water resources. The main components of the water requirements of rice irrigation are identified, and then the composition and functions of farmers’ irrigation associations, or more correctly ‘land improvement districts’, are described.     

Drivers of groundwater utilization in water-limited rice production systems in Nepal

ABSTRACT

Most rice farmers in Nepal’s Terai region do not fully utilize irrigation during breaks in monsoon rainfall. This leads to yield losses despite abundant groundwater resources and ongoing expansion of diesel pumps and tubewell infrastructure. We investigate this puzzle by characterizing delay factors governing tubewell irrigation across wealth and precipitation gradients. After the decision to irrigate, different factors delay irrigation by roughly one week. While more sustainable and inexpensive energy for pumping may eventually catalyze transformative change, we identify near-term interventions that may increase rice farmers’ resilience to water stress in smallholder-dominated farming communities based on prevailing types of irrigation infrastructure.     

Considerations on methodological challenges for water footprint calculations

We have investigated how different approaches for water footprint (WF) calculations lead to different results, taking sugar beet production and sugar refining as examples. To a large extent, results obtained from any WF calculation are reflective of the method used and the assumptions made. Real irrigation data for 59 European sugar beet growing areas showed inadequate estimation of irrigation water when a widely used simple approach was used. The method resulted in an overestimation of blue water and an underestimation of green water usage. Dependent on the chosen (available) water quality standard, the final grey WF can differ up to a factor of 10 and more. We conclude that further development and standardisation of the WF is needed to reach comparable and reliable results. A special focus should be on standardisation of the grey WF methodology based on receiving water quality standards.     

中国主要粮食作物的生产水足迹量化及评价

明确作物消耗单位水量所提供的营养物质差异对于引导节水型膳食结构和农业种植规划具有重要意义,水足迹为进行上述分析提供了有效的指标。本文基于水足迹理论,在量化中国大陆主要粮食作物重量、能量和蛋白质水足迹的基础上,评价了各作物间及区域间三种水足迹的差异性,探讨了粮食作物消费结构调整对生产端水资源消耗产生的影响。结果显示:各作物生产水足迹差异显著并且具有明显的区域分布特征,东北地区、黄淮海地区作物重量水足迹均较低,表明上述地区的水分利用效率较高;5种粮食作物中,玉米和小麦具有较低的能量水足迹,而大豆具有较低的蛋白质水足迹,表明在耗水量相同的情况下,玉米和小麦较其他作物能提供更多的能量,大豆能提供更多的蛋白质;不同粮食作物消费结构下的农业用水差异显著,通过调整作物消费结构,可以达到显著的节水效果。本研究结果可为解决未来粮食生产水危机提供一个潜在途径。     

滴灌条件下脱毒马铃薯灌溉制度试验研究

马铃薯是干旱内陆河石羊河流域主要农作物之一。为了推广应用滴灌技术,对脱毒马铃薯夏波蒂进行了滴灌条件下灌溉制度试验研究,试验按土壤含水率(占田间持水量的百分数)不同设6个处理,处理Ⅰ、Ⅱ的土壤含水率下限为田间持水量的45%,上限分别为田间持水量75%、80%,灌水次数设定为4次;处理Ⅱ、Ⅴ的土壤含水率下限为田间持水量的55%,上限分别为75%、80%,灌水次数设定为5次;处理Ⅲ、Ⅵ的土壤含水率下限为田间持水量的65%,上限分别为田间持水量的75%、80%,灌水次数设定为6次。研究结果表明:适宜马铃薯生长发育的土壤含水率下限不应低于田间持水量的55%,上限在田间持水量的75%~80%为宜,灌水次数5~6次为宜,脱毒马铃薯夏波蒂生育期120 d,生育期灌溉定额控制在3 000 m~3/hm~2左右。     

灌溉水经济价值与粮棉作物种植布局

以我国十大区域灌溉需求指数为切入点,灌溉水经济价值为主要研究内容,在系统整编2000—2005年4种主要农产品成本收益资料的基础上,采用扣除非水成本法计算得出了十大区域4种主要作物灌溉水经济价值,研究了作物适应性种植的地域性特征和规律性,提出粮棉作物种植的优势地区、种植布局以及政策扶持和倾斜的品种,可为粮棉种植决策和维护国家粮食安全提供水资源方面的科学依据。     

试论灌溉水经济价值与粮棉作物种植布局

本文以我国十大区域灌溉需求指数为切入点,灌溉水经济价值为主要研究内容,在系统整编2000~2005年四种主要农产品成本收益资料的基础上,采用扣除非水成本法计算得出了十大区域四种主要作物灌溉水经济价值,揭示了作物适应性种植的地域性特征和规律性,提出粮棉作物种植的优势地区、种植布局以及政策扶持和倾斜的品种,为粮棉种植决策和维护国家粮食安全提供水资源方面的科学依据。     

徒骇马颊河流域不同尺度农业节水潜力

为了研究作物、田间、灌区和流域不同尺度之间的相互转化及尺度效应问题,针对水资源相对短缺的徒骇马颊河流域,采用水资源合理配置模型WACM作为分析手段,选择不同尺度的节水措施,设定节水方案,在考虑节水伴生的经济、社会、生态与环境效应的前提下,计算分析徒骇马颊河流域的农业节水潜力。计算结果表明,徒骇马颊河流域资源节水潜力为7.78亿m3,灌溉节水潜力13.00亿m3,作物和灌区尺度尚有一定的节水空间。     

甘肃中小型灌区节水改造的共性技术问题

甘肃省中小型灌区节水改造任务艰巨，在节水改造方向和技术路线、技术决策上存在一定的共性．包括以水资源承载能力确定灌区发展规模，根据作物要求分别确定灌溉标准等。因此，甘肃中小灌区节水技术改造有一些具有共性的需求，如灌区水循环的模拟和评价技术、渠道防冻胀技术、管道输水技术、非充分灌溉技术、耕地盐渍化控制技术和灌区分析评价技术。     

Water-saving strategies for irrigation agriculture in Saudi Arabia

Agriculture policy changes in Saudi Arabia are investigated by water footprint (WF) assessment. WF is calculated with the model SPARE:WATER for 3758 irrigated sites. The WF of agriculture areas (WF_area, km³ yr^?1) has decreased (–17%) since the year 2000 to 13.84 km³ yr^?1 (2011), which is mainly caused by the reduction of cropland by –33%. Nevertheless, water consumption per field has increased about 16%, which can be attributed to the cultivation of fodder crops (+12%). A scenario analysis revealed that a shifting cropping pattern towards less fodder crops reduces WF_area by –15%, and implementing improved irrigation technology leads to a combined reduction of up to 32%     

Tragedy? What tragedy? Swords of Damocles and common property irrigation

Discourse on common pool resources that are governed by common property regimes is commonly characterized by ‘tragedy’ and ‘threats’ to ‘community’ cooperation. This article questions the relevance of these notions in relation to changing rural reality in the hills of Nepal. Farmers individualize water tenure to overcome the shortcomings of common property regime irrigation for diversified crops. While cooperation in irrigation may decrease, new types of cooperation emerge that reflect a wider range of institutions suited to diversified and complex livelihood portfolios.     

山西省灌溉用水定额编制方法及其成果

根据水利部《编制灌溉用水定额》的大纲要求,结合山西省自然、地理、气候等情况,采用典型调研的方式,将山西省分为6个区,选取21个典型县为调查对象,以调查典型县现状灌溉用水定额为基础,以当地灌溉水可利用量为控制条件,采取自下而上、层层平衡的方法,制定了全省6个分区、7种主要作物的灌溉用水定额.经专家评审,认为该成果符合山西省的实际情况,对山西省节水灌溉事业的发展有重要指导作用.     

作物需水量与灌溉制度模拟

从作物需水量的基本概念出发，以水量平衡原理为基础，建立了模拟农田根层土壤水循环的计算机模型-ISAREG.这一模型具有多种功能，可模拟根层土壤水分变化，评价给定的灌溉制度，计算作物需水量和灌溉需水量，也可用以制订多种供水限制条件下的优化灌溉制度．用望都灌溉试验站的小麦、玉米、棉花3种作物两年的试验观测资料对上述模型进行了验证．     

Improving Water Reuse in Paddy Field Districts with Cascaded On-farm Ponds using Hydrologic Model Simulations

On-Farm Ponds (OFPs) are an important irrigation facility in rice-based irrigation systems. An OFP water reuse system in paddy field districts is composed of upstream commanded paddy fields, irrigation and drainage ditches, cascaded OFPs and downstream irrigated paddy fields. This study assesses the performance of an OFP water reuse system and explores potential water management strategies to enhance return flow reuse for rice production. A cascaded model including a modified two-tank module and a pond water balance module is developed to describe hydrologic characteristics of the water reuse system. Model calibration and validation show that the measured and simulated data are in a good agreement and the proposed model can be used to hydrologic analyses of OFP water reuse systems. The water reuse system has high water reuse efficiency as the return flow regulated by OFPs was reused several times from the upstream to downstream of the paddy fields. Return flow and actual reuse water increase with the maximum ponded depth of paddy fields. As the water level in a drainage ditch decreases, the available return flow increases and local water shortage can be alleviated. The supply-and-demand gap between seasons becomes more harmonized when the regulated water level in pond increases, resulting in a decrease in water shortage. The reuse of return flow is a quick-response water supply solution to meet the rice water demand during peak demand periods.     

黄河下游大型引黄灌区蒸散发长期变化特性

采用生态水文模型模拟黄河下游大型引黄灌区———位山灌区1984—2006年的水量平衡过程,分析蒸散发量的长期变化规律。结果表明:位山灌区多年平均蒸散发量为596mm,占降雨和灌溉总量的82%;小麦和玉米生长期内多年平均蒸散发量分别为284mm和314mm,分别占降雨和灌溉总量的99%和71%;降雨量的年际变异性较大,但受灌溉的影响蒸散发量的年际变异性较小,且无显著的时间变化趋势;作物主要生长期内蒸散发量的年际变化主要与潜在蒸发量有关;蒸散发量的季节变化主要受潜在蒸发量和作物生长过程的控制。     

南方季节性缺水灌区旱地节水灌溉技术设备适应性示范研究

南方季节性缺水灌区灌水次数少,建设一套节水灌溉系统加上运行维护管理费用经济效益往往难以体现,但若不建,干旱又造成作物减产甚至绝收.经过节水示范区建设研究认为,南方季节性缺水灌区适宜建立移动式的节水灌溉系统,适宜建设联合运用的小型水利工程及中低压喷灌、移动式机喷、大流道微喷等节水灌溉技术和灌水器.     

不同灌溉模式下太湖流域稻田土对氨氮的吸附特性

为了考察灌溉模式对稻田土吸附氨氮的影响,本文采集太湖流域不同灌溉模式下的稻田土,在室内开展氨氮的等温吸附试验。结果表明:氨氮在两种稻田土上的吸附动力学过程均可分为明显的快、慢两个阶段,且均以准二级吸附动力学方程的拟合结果最佳;控制灌溉模式下稻田土氨氮的理论平衡吸附量、试验平衡吸附量分别为454.5mg/kg和446.2mg/kg,均高于漫水灌溉模式。Freundlich方程对等温吸附数据的拟合结果最好。控制灌溉模式下稻田土的不均匀性、吸附氨氮的反应强度以及对氨氮的吸附容量均升高。