黄河流域粮食生产水足迹及虚拟水流动影响评价EI北大核心CSCD

为分析黄河流域粮食生产用水的可持续性,引入水足迹和虚拟水相关理论方法,对研究区主要粮食生产水足迹及粮食贸易伴生的虚拟水流动格局进行了量化解析,并对未来粮食生产水足迹进行了预估。结果表明:2011—2016年,全流域粮食生产总水足迹和单位水足迹分别由460亿m^(3)和1.20 m^(3)/kg降为402 m^(3)和0.93 m^(3)/kg,均呈下降趋势;从粮食贸易伴生的虚拟水流动特点来看,流域全口径粮食虚拟水从2011年的110.7亿m^(3)减小到2016年的50.3亿m^(3),呈输入态势;除稻谷之外的粮食虚拟水由82.6亿m^(3)增加到193.4亿m^(3),呈输出态势;在流域不同气候情景下,2035年粮食生产总水足迹为481.9亿~518.7亿m^(3),其中绿水足迹增幅达20%,而蓝水足迹增长不显著;未来流域内粮食输出量的增加会进一步加剧本地农业生产的用水矛盾,但粮食灌溉总用水量的增速可能放缓。     

辽宁省春玉米生产水足迹的时空变化研究

为降低农业生产活动中农作物对水资源的高消耗,提高用水效率,借助辽宁省1987—2018年19个气象站点逐日气象数据及春玉米产量数据,全面计算绿水足迹、蓝水足迹及灰水足迹的真实消耗。结果表明：（1）辽宁省春玉米生产水足迹自2002年起变化幅度不明显,多年平均值是1424.21 m³/t,其中绿水足迹占54%,灰水足迹占27%,蓝水足迹占19%。（2）从绿水足迹看,辽宁省春玉米绿水足迹每年以6.28 m³/t速率减少,空间分布上2002年绿水足迹高值区主要集中在东部地区;2010年辽宁省整体绿水足迹较高。（3）从蓝水足迹看,每年以1.06 m³/t的速率增长;2002年辽宁春玉米蓝水足迹高值区主要分布在环渤海、宽甸及其周围地区;2010年,辽宁省大部分地区蓝水足迹较低。（4）灰水足迹整体以每年14.03 m³/t的速率降低,主要与农作物产量及氮肥施用量相关。     

An Evaluation of China’s Water Footprint

The water footprint is an indicator of freshwater consumption that looks not only at direct water consumption of a consumer or producer, also at the indirect water consumption. The water footprint can be regarded as a comprehensive indicator of freshwater resources appropriation, next to the traditional and restricted measure of water withdrawal. Based on the concept and calculating method of water footprint, this paper estimates the water footprint of China in 2007. The result shows that the total water footprint of China is 856.34 × 10⁹ m³ and the per capita water footprint is 648.11 m³/year. The spatial difference of per capita water footprint is obvious among all provinces of China. Generally, the more developed cities, the southern and coastal provinces have a higher per capita water footprint, lower water footprint intensity and higher efficiency of water consumption, while the North West China has lower water utilization efficiency. China is one of the thirteen water scarce countries in the world and spatial distribution of water resources is non-uniform. In addition to the virtual water trade, government should apply advanced technology and best available management practices, improve the efficiency of water use, reduce virtual water content per unit product, and continue nation-wide readjustment of industrial structure to guarantee an efficient use of limited water resources.     

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.     

Crop Water Productivity of Irrigated Teff in a Water Stressed Region

In water stressed regions such as the Central Rift Valley of Ethiopia, increasing Crop Water Productivity (CWP) is imperative for sustainable food and water security. This paper presents CWP of Teff (Eragrostic Tef), a staple food in Ethiopia and an important export crop. Field experiments were conducted under irrigated agriculture during the dry seasons in the periods: 1) November 2010 to March 2011; and 2) December 2011 to April, 2012 at Melkassa Agricultural Research Centre in Ethiopia. Teff crop was irrigated at sixteen different water application depths ranging from 100 to 25 % of the optimum Crop Water Evapotranspiration (ETc.) during the four growing stages, the initial, development, mid season and late season. The effect of seeding rates of 25 kg/ha and 10 kg/ha on lodging and yield of the crop was also determined. The main results were: 1) At 25 % deficit irrigation applied for the whole growth period, Teff CWP was the highest at 1.16 and 1.08 kg/m³ respectively for the seeding rates of 25 kg/ha and 10 kg/ha; 2) the CWP slightly decreased to 1.12 and 1.07 kg/m³ when the 25 % deficit was applied during the late season stage; 3) the crop yield response factor (K_y) of 1.09 and 1.19 was obtained for seeding rates of 25 kg/ha and 10 kg/ha respectively; the equivalent biomass response factor (K_y) was less at 0.88 and 0.96 respectively.     

Bilateral virtual water trade in agricultural products: a case study of Germany and China

Most studies in the field of virtual water trade concentrate either on the global, national or sub-national level, or on the water footprint of individual products. This article assesses the virtual water trade in agricultural products between Germany and China during the period 2008–2010. Germany exported 192 million m³ of virtual water to China and imported 801 million m³ from China. Through the bilateral trade, Germany saved 69.8 million m³ water, while China had a net water loss of 469.4 million m³. Thus, the global water loss amounts to 399.6 million m³.     

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。     

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%     

Groundwater Use for Irrigation and its Productivity: Status and Opportunities for Crop Intensification for Food Security in Bangladesh

Bangladesh has a large and growing population that will demand more food and place greater pressure on resources. Dry season irrigated Boro rice production is important for national food security. Dry season irrigation mainly uses groundwater, but the extent of its use is not well known. We assessed groundwater use and water productivity of Boro in the northwest region of Bangladesh using remote sensing based energy balance modelling, crop classification and secondary statistics. The energy balance modelling shows a large spatial variation in the actual evapotranspiration (ET_a) from about 325 to 470 mm, with an overall spatial average of 365 mm during dry season. The estimated values of ET_a correspond well with independent values from field and regional scale soil and water balance modelling results. From spatial estimates of ET_a and effective rainfall, we computed regional net groundwater use for Boro production in 2009 as 2.4 km³. Groundwater is being used unsustainably in some areas, and a spatial time series (1990 to 2010) of pre- and post-monsoon groundwater depth changes in the northwest region of Bangladesh suggests that, with the current level of groundwater use, falling groundwater levels may pose a long term threat to the sustainability of irrigated agriculture in much of the region. Boro water productivity varies from 0.95 to 1.35 kg/m³, allowing the identification of high performing “bright” and low performing “hot” spots and the development of strategies to reduce crop yield/productivity gaps and ensure future food security.     

Resolving Trans-jurisdictional Water Conflicts by the Nash Bargaining Method: A Case Study in Zhangweinan Canal Basin in North China

Trans-jurisdictional conflict in both water quantity and quality is a general concern in large river basins. In this paper, the relative utility function combined with the asymmetric Nash bargaining method was established to analyze the trans-jurisdictional conflict between water quantity and water quality in the Zhangweinan Canal Basin in China. The basin was divided into four conflict stakeholders, namely, Shanxi, Hebei, Henan, and Shandong Provinces, based on administrative unit. The water usage and pollutant discharge scheme for multiple stakeholders was optimized using the established model to satisfy the environmental flow and water quality objectives at the identified conflict sections. The results indicated that the total water consumption was reduced from 4.38?×?10⁹?m³ in 2007 to 1.97?×?10⁹?m³, and that the allowable COD and NH₃-N discharged into the river was less than 3.8?×?10⁴?t and 4.3?×?10³?t, respectively. About 81.1 % of COD and 76.1 % of NH₃-N should be further reduced compared with the values in 2007.     

Effectiveness of Rainwater Harvesting in Runoff Volume Reduction in a Planned Industrial Park,China

It is urgent to effectively mitigate flood disasters in humid mountainous areas in southeastern China for the increasing flood risk under urbanization and industrialization. In this study, a rural district with an area of 13.39 km² that planning to build an industrial park covering an area of 7.98 km² in Changting was selected to estimate the potential of collectable rainwater and the extent to which runoff volume can potentially be mitigated by rainwater harvesting. In addition, the optimum cistern capacity of a rainwater harvesting system in the planned industrial park was evaluated using daily water balance simulation and cost-efficiency analysis. The results showed that rainwater harvesting in the planned industrial park has great potential. The annually collectable rainwater is approximately 9.8?×?10⁶ m³ and the optimum cistern capacity is determined to be 0.9?×?10⁶ m³. With the optimum cistern capacity, the annual rainwater usage rate is 0.99, showing neither financial savings nor deficits. Rainwater harvesting can reduce 100 % of runoff volume in the cases of critical rainfall storm (50 mm) and annual average maximum daily rainfall (111.2 mm), and 58 % of runoff volume in the case of maximum daily rainfall (233.6 mm), respectively. All surface runoff can be collected and stored in the cisterns when rainfall amount is less than 135.5 mm in a rainstorm event.     

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.     

Quantifying the Poorly Known Role of Groundwater in Agriculture: the Case of Cyprus

Agriculture in the Mediterranean region is constrained by limited water resources and in many countries irrigation demand exceeds the renewable water supply. This paper presents a comprehensive approach to (a) quantify the consumptive green (soil moisture provided by precipitation) and blue (irrigation) water use for crop production, (b) distinguish the contribution of groundwater to irrigation supply and (c) estimate groundwater over-abstraction. A spatiotemporally explicit soil water balance model, based on the FAO-56 dual crop coefficient approach, which includes the computation of evaporation losses of the different irrigation systems, was applied to the 5,760-km² area of the Republic of Cyprus for the agro-meteorological years 1995–2009. The model uses national agricultural statistics, community-level data from the agricultural census and daily data from 34 meteorological stations and 70 precipitation gauges. Groundwater over-abstraction is quantified per groundwater body, based on the sustainable abstraction rates specified in the Cyprus River Basin Management Plan, as prepared for the EU Water Framework Directive. It was found that, on average, total agricultural water use was 506 Mm³/year, of which 62 % is attributed to green water use and 38 % to blue water use. Groundwater contributed, on average, 81 % (151 Mm³/year) to blue water use and exceeded the recommended abstraction rates by 45 % (47 Mm³/year). Even though the irrigated area decreased by 18 % during the 2008 drought year, relative to the wettest year (2003), total blue water use decreased by only 1 %. The limited surface water supply during the driest year resulted in a 37 % increase in groundwater use, relative to the wettest year, and exceeded the sustainable abstraction rate by 53 % (55 Mm³/year). Overall, the model provides objective and quantitative outcomes that can potentially contribute to the improvement of water resource management in Mediterranean environments, in the light of climate change and expected policy reforms.     

Water Saving and Energy Reduction through Pressure Management in Urban Water Distribution Networks

Water shortages and climate change are worldwide issues. Reduction in water leakage in distribution networks as well as the associated energy saving and environmental impacts have recently received increased attention by scientists and water industries. Pressure management has been proposed as a cost-effective approach for reduction in water leakage. This study conducted a real-world water pressure regulation experiment to establish the pressure-leakage relationship in a district metering area (DMA) of the water distribution network in Beijing, China. Results showed that flow into the DMA was sensitive to inlet water pressure. A 5.6 m reduction in inlet pressure (from 38.8 m to 33.2 m) led to an 83 % reduction (12.1 l/s) in minimal night flow, which is a good approximator of leakage. These reductions resulted in 62,633 m³ of water saved every year for every km pipe, as well as associated savings of 1.1?×?10⁶ MJ of energy and 68 t of CO₂ equivalent greenhouse gas emissions. The results of this study provide decision makers with advice for reducing leakage in water distribution networks with associated energy and environmental benefits.     

Water footprints of nations: Water use by people as a function of their consumption pattern

The water footprint shows the extent of water use in relation to consumption of people. The water footprint of a country is defined as the volume of water needed for the production of the goods and services consumed by the inhabitants of the country. The internal water footprint is the volume of water used from domestic water resources; the external water footprint is the volume of water used in other countries to produce goods and services imported and consumed by the inhabitants of the country. The study calculates the water footprint for each nation of the world for the period 1997–2001. The USA appears to have an average water footprint of 2480,m³/cap/yr, while China has an average footprint of 700,m³/cap/yr. The global average water footprint is 1240,m³/cap/yr. The four major direct factors determining the water footprint of a country are: volume of consumption (related to the gross national income); consumption pattern (e.g. high versus low meat consumption); climate (growth conditions); and agricultural practice (water use efficiency).     

Water footprint of beef production on Texas High Plains pasture

ABSTRACT

Depletion of the Ogallala aquifer in the U.S. Great Plains demands information on water usage in forage-fed beef production. We compared a summer grazing system for beef steers consisting of warm-season grasses vs. grasses growing with lucerne (Medicago sativa L.). The water footprint averaged 39 and 26 m³ of water kg^?1 of beef liveweight gain, respectively, when water included rainfall, irrigation, and livestock drinking. Including lucerne reduced the water footprint of beef weight gain thanks to its ability to alleviate protein deficiency in the associated grasses, thus diminishing an important source of inefficiency in converting feed to meat.     

Uncertainty of the Agricultural Grey Water Footprint Based on High Resolution Primary Data

The water footprint has been established as an indicator to assess water use by a product. However, the grey component of the water footprint (GWF) has received the least focus compared to the green and blue components. In developing countries, the GWF estimation is restricted by the availability of data concerning crop practices. The various biophysical and socioeconomic settings configure a system difficult to standardize even for small areas. The objective of this study was to assess the GWF uncertainty due to primary data for the main greenhouse tomato production from Colombia. The GWF for N and P fertilizers and pesticides were estimated based on detailed crop information collected from 2010 to 2013. The uncertainty was evaluated by fitting univariate theoretical distributions to the empirical distributions of the pollutants’ GWFs. Growers applied on average 419.2 and 201.9 kg ha^?1 of N and P fertilizers per cycle, respectively. The average rates of application for fungicides and insecticides were 11.8 and 3.5 kg ha^?1, respectively. The average GWF for N and P fertilizers and pesticides were 79, 6182.1 and 223.2 m³ t^?1, respectively. The empirical distributions of the GWF for N fertilizer and pesticides were fitted to a lognormal distribution while for P fertilizer the Weibull distribution showed the best fit. The pesticides GWF showed the highest coefficient of variation (615.3%), however the results for N and P fertilizers were also high with values of 79.8 and 74.1%, respectively. Additional to the methodological choices involved in the GWF estimation, the primary data is a relevant uncertainty source, which should be considered for systems operating under unstandardized practices. The decision making process to regulate the pollutants losses from the agroecosystem, based on environmental assessments such as the GWF, should consider all sources of uncertainty and address its implications in a quantitatively form.     

Assessment of Potable Water Savings in Office Buildings Considering Embodied Energy

The objective of this article is to assess the potential for potable water savings in office buildings located in Florianópolis, southern Brazil. The embodied energy of four alternatives to reduce potable water demand, i.e., rainwater harvesting, greywater reuse, dual-flush toilets and water-saving taps, was also assessed. The analyses took into account the potable water end-uses for ten buildings. The potential for potable water savings by using rainwater, as well as, the rainwater tank sizing were estimated using computer simulation. As for greywater reuse, it was considered that greywater from lavatory taps could be treated and reused to flush toilets. The potential for potable water savings by using water-saving plumbing fixtures was estimated by considering the replacement of toilets and taps. In order to estimate the embodied energy in the main components, each system was dimensioned and embodied energy indices were applied. The main result is that the potential for potable water savings by using dual-flush toilets ranges from 21.6 % to 57.4 %; by reusing greywater, it ranges from 6.8 % to 38.4 %; by using rainwater, it ranges from 6.1 % to 21.2 %; by using water-saving taps it ranges from 2.7 % to 15.4 %. However, by considering the embodied energy, the average for the ten buildings indicates that dual-flush toilets are the best choice as it is possible to obtain water savings of 5.50 m³/month per GJ of embodied energy, followed, respectively, by water-saving taps, greywater reuse and rainwater usage. The main conclusion is that the assessment of embodied energy should be considered when evaluating potable water savings in buildings as it helps to identify the best alternatives to save more water while causing less environmental impact.     

Towards Quantification of the Water Footprint of Paper: A First Estimate of its Consumptive Component

For a hardcopy of this article, printed in the Netherlands, an estimated 100 l of water have been used. Most of the water is required in the forestry stage, due to evapotranspiration (green and blue water). In addition, the water footprint during the industrial stage, as accounted for in this study, consists of evaporation from water obtained from ground water and surface water (blue water). In this study estimates are made of water requirements for producing paper using different types of wood and in different parts of the world. The water footprint of printing and writing paper is estimated to be between 300 and 2600 m³/t (~2-13 l for an A4 sheet). These estimates account for paper recovery rates in different countries. This study indicates that by using recovered paper for the production of paper the global average water footprint of paper is only 60% of what it would be if no recovered paper would be used at all. Further savings may be achieved by increasing the recovery percentages worldwide. In addition, the global water footprint of paper can be reduced by choosing production sites and wood types that are more water-efficient. The results of this study suggest that the use of recovered paper may be particularly effective in reducing water footprints. This study is a first step towards a better understanding of the significance of the water footprint of paper and the effect of using recovered paper.     

黑龙江省水足迹时空分布规律及空间均衡分析

利用水足迹理论,量化2000—2018年黑龙江省13个地级市的不同类型水足迹,分析其时空演变规律,并结合空间均衡分析研究了各地区水足迹的差异性。结果表明:2000—2018年黑龙江省总水足迹呈波动上升趋势,但灰水足迹一直下降,2018年人均灰水足迹为300.7m³;水足迹空间分布不均匀,水足迹富足和水足迹匮乏同时存在,整体上呈现出北低南高、东低西高的趋势;研究时段内,黑龙江省人均灰水足迹和人均水足迹的空间分布较为均匀,其总体空间均衡度超过0.6;水足迹强度、工业蓝水足迹和生态环境蓝水足迹的空间分布存在较大差异;水足迹的总体空间均衡度在逐渐上升,但最大值不超过0.6,区域分布仍有较大差异。