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Feedbacks between vegetation restoration and local precipitation over the Loess Plateau in China

Science China Earth Sciences 2021年第6期64卷 920-931页

作者： Baoqing ZHANG Lei TIAN Xining ZHAO pute wu Key Laboratory of Western China’s Environmental Systems(Ministry of Education) College of Earth and Environmental SciencesLanzhou UniversityLanzhou730000China Institute of Green Development for the Yellow River Drainage Basin Lanzhou UniversityLanzhou730000China Institute of Soil and Water Conservation Northwest A&F UniversityYangling712100China

The implementation of large-scale vegetation restoration over the Chinese Loess Plateau has achieved clear improvements in vegetation fraction,as evidenced by large areas of slopes and plains being restored to grassland or ***,such large-scale vegetation restoration has altered land-atmosphere exchanges of water and energy,as the land surface characteristics have *** variations could affect regional climate,especially local *** evaluating this feedback is an important scientific question in *** study constructs a coupled land-atmosphere model incorporating vegetation dynamics,and analyzes the spatio-temporal changes of different land use types and land surface parameters over the Loess *** considering the impacts of vegetation restoration on the water-energy cycle and on land-atmosphere interactions,we quantified the feedback effect of vegetation restoration on local precipitation across the Loess Plateau,and discussed the important underlying *** achieve a quantitative evaluation,we designed two simulation experiments,comprising a real scenario with vegetation restoration and a hypothetical scenario without vegetation *** enabled a comparison and analysis of the net impact of vegetation restoration on local *** results show that vegetation restoration had a positive effect on local precipitation over the Loess *** show that precipitation on the Loess Plateau increased significantly,at a rate of 7.84 mm yr^(-2),from 2000 to *** simulations show that the contribution of large-scale vegetation restoration to the precipitation increase was about 37.4%,while external atmospheric circulation changes beyond the Loess Plateau contributed the other 62.6%.The average annual precipitation under the vegetation restoration scenario over the Loess Plateau was 12.4%higher than that under the scenario without vegetation *** above research re

关键词： Coupled land-atmosphere modeling Vegetation restoration Water balance Hydrometeorology Ecohydrology

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Model of soybean NDVI change based on time series

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International Journal of Agricultural and Biological Engineering 2014年第5期7卷 64-70页

作者： Zhang Zhitao Yubin Lan wu pute Han Wenting College of Water Resources and Architectural Engineering Northwest A&F UniversityYangling 712100China Aerial Application Technology USDA-ARS-SPARC-AATRUCollege StationTX 77845USA Institute of Water Saving Agriculture in Arid Area of China Northwest A&F UniversityYangling 712100China

Normalized Difference Vegetation Index(NDVI)has been found to have good correlations with many physical properties of soybean *** to the factors of air temperature,humidity,solar radiation,soil moisture,etc.,NDVI of soybean varies dynamically in a *** establishment of the soybean NDVI prediction model at different times in a day can effectively modify this *** soybean NDVI values are continuously monitored in hours during soybean seeding,flowering&podding and maturating stages by way of Green *** show that the trend of NDVI change every day in the three stages is taken on as a reverse *** NDVI value reaches to the maximum at 8 am or 9 am and decreases to its minimum at 2 pm before a moderate rise.A model for intraday and long-term NDVI change for soybean is *** test of the model with independent data indicates that the precision meets the demands,with the root mean square error(RMSE)of each day being 3.95,5.45 and 2.86 for the seeding stage,the bean podding stage and the maturation period,*** prediction RMSEs of the soybean NDVI model for soybeans of the three stages for the fifth day are 5.75,2.65 and 5.51,respectively and the prediction RMSEs for the sixth day are 9.74,2.82 and 14.04,respectively according to the data from the first four days.

关键词： model NDVI monitoring time time series atmospheric radiation soybean

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Effects of alfalfa coverage on runoff,erosion and hydraulic characteristics of overland flow on loess slope plots

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Frontiers of Environmental Science & Engineering 2011年第1期5卷 76-83页

作者： Shufang wu pute wu Hao FENG G.P.Merkley College of Water Resources and Architectural Engineering China Academy of Water-saving Agriculture on Arid RegionsNorthwest A&F UniversityYangling 712100China State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau Institute of Soil and Water ConservationChinese Academy of SciencesYangling 712100China Biological and Irrigation Engineering Department Utah State UniversityLoganUT 84116USA

An evaluation of the interactions between vegetation,overland and soil erosion can provide valuable insight for the conservation of soil and *** experiment was conducted to study water infiltration,runoff generation process,rate of sediment erosion,and hydrodynamic characteristics of overland flow from a sloping hillside with different draw-off discharges from alfalfa and control plots with 20°*** effect of alfalfa on runoff and sediment transport reduction was quantitatively *** was discussed for its ability to reduce the overland flow scouring force or change the runoff *** to the bare-soil plots,alfalfa plots generated a 1.77 times increase in infiltration ***,the down-slope water infiltration rate for the bare soil plots was higher than in the up-slope,while the opposite was found in the alfalfa *** addition,alfalfa had a significant effect on runoff and sediment *** comparison to the control,the runoff coefficient and sediment transportation rate decreased by 28.3%and 78.4%in the grass slope,*** runoff generated from the alfalfa and bare-soil plots had similar trends with an initial increase and subsequent leveling to a steady-state *** transport of sediment reduced with time as a consequence of the depletion of loose surface *** maximum sediment concentration was recorded within the first few minutes of each *** alfalfa plots had subcritical flow while the baresoil plots had supercritical flow,which indicate that the capability of the alfalfa slope for resisting soil erosion and sediment movement was greater than for bare soil ***,the flow resistance coefficient and roughness coefficient for the alfalfa plots were both higher than for the bare-soil plots,which indicate that overland flow in alfalfa plots had retarded and was blocked,and the flow energy along the runoff path had gradually ***,the ability to erode and transport sediment had de

关键词： alfalfa soil erosion runoff and sedimentation soil water infiltration overland flow hydrodynamic characteristics

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Dry/wet climate zoning and delimitation of arid areas of Northwest China based on a data-driven fashion

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Journal of Arid Land 2014年第3期6卷 287-299页

作者： QingLing GENG pute wu QingFeng ZHANG XiNing ZHAO YuBao WANG Institute of Soil and Water Conservation Chinese Academy of Sciences and Ministry of Water Resources Institute of Water Saving Agriculture in Arid Regions of China Northwest A&F University National Engineering Research Center for Water Saving Irrigation at Yangling Northwest A&F University

The division of arid areas is important in water and land resources management, planning and for a long-term agricultural, economic and social planning. Northwest China （NW） dominates the main arid areas in China. There is thus a need to adopt adequate concepts relative to the scope of arid areas of NW China and identify its climate types and characteristics. In this study, we analyzed climatic data over the last 30 years （1981-2010） from 191 stations in three provinces and three autonomous regions of NW China. The factor-cluster analysis technique （FC）, an objective and automated method was employed to classify the dry/wet climate zones. The traditional methods with predefined thresholds were adopted for providing a comparison with FC. The results showed that the wet/dry climate zones by FC were mainly distributed along mountains, rivers and desert borders. Climate-division boundaries relied heavily on the major terrain features surrounding the grouped stations. It also showed that the climate was dry in the plain sandy areas but relatively wet in the high mountain areas. FC method can reflect the climate characteristics more fully in NW China with varied and complicated topography, and outperform the tradi- tional climate classifications. Arid areas of NW China were defined as four climate types, including five resultant classes in FC classifications. The Qinling and Da Hinggan Mountains were two important boundaries, besides main administrative boundaries. The results also indicated that there are some differences between two traditional clas- sifications. The precipitation moved and fluctuated to an extent, which confirmed that climate change played an important role in the dry/wet climate zoning, and the boundaries of dry/wet climate zones might change and migrate with time. This paper is expected to provide a more in-depth understanding on the climate characteristics in arid areas of NW China, and then contribute to formulate reasonable water and land manageme

关键词： arid areas classifications climate zoning factor-cluster analysis

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Spatiotemporal variation in water footprint of grain production in China

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Frontiers of Agricultural Science and Engineering 2015年第2期2卷 186-193页

作者： pute wu Yubao WANG Xining ZHAO Shikun SUN Jiming JIN Institute of Water Saving Agriculture in Arid Regions of China Northwest A&F UniversityYangling 712100China Institute of Soil and Water Conservation Chinese Academy of Sciences and Ministry of Water ResourcesYangling 712100China National Engineering Research Center for Water Saving Irrigation at Yangling Yangling 712100China College of Water Resources and Architectural Engineering Northwest A&F UniversityYangling 712100China

Water shortage has become a significant constraint to grain production in China.A more holistic approach is needed to understand the links between grain production and water *** footprint provides a framework to assess water utilization in agriculture *** paper analyzes the spatiotemporal variation in water footprint of grain production(WFGP)in China from 1951 to *** results show that,jointly motivated by the improvement of agricultural production and water use efficiency,WFGP in all areas showed a decreasing *** average WFGP has decreased from 3.38 to 1.31 m^(3)·kg^(–1).Due to regional differences in agricultural production and water use efficiency,spatial distribution of WFGP varies significantly and its pattern has changed through ***,WFGP may show significant differences within areas of similar climatic conditions and agricultural practices,indicating that there is a strong need to improve the management of water use *** analysis revealed that regional differences in grain yield are the main cause for variations in spatiotemporal ***,the scope for further increases in grain yield is limited,and thus,the future goal of reducing WFGP is to decrease the water use per unit area.

关键词： water footprint grain production grain security water scarcity water-saving

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Measuring and modeling two-dimensional irrigation infiltration under film-mulched furrows

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Research in Cold and Arid Regions 2016年第5期8卷 419-431页

作者： YongYong Zhang pute wu XiNing Zhao WenZhi Zhao Linze Inland River Basin Research Station Key Laboratory of Eco-hydrology of Inland River Basin Northwest Institute of Eco-Environment and Resources Chinese Academy of Sciences Institute of Water Saving Agriculture in Arid Regions of China Northwest A & F University

Furrow irrigation with film-mulched agricultural beds is being promoted in the arid region of northwest China because it improves water utilization. Two-dimensional infiltration patterns under film-mulched furrows can provide guidelines and criteria for irrigation design and operation. Our objective was to investigate soil water dynamics during ponding irrigation infiltration of mulched furrows in a cross-sectional ridge-furrow configuration, using laboratory experiments and mathematical simulations. Six experimental treatments, with two soil types （silt loam and sandy loam）, were investigated to monitor the wetting patterns and soil water distribution in a cuboid soil chamber. Irrigation of mulched furrows clearly increased water lateral infiltration on ridge shoulders and ridges, due to enhancement of capillary driving force. Increases to both initial soil water content （SWC） and irrigation water level resulted in increased wetted soil volume. Empirical regression equations accurately estimated the wetted lateral distance （Rl） and downward distance （Rd） with elapsed time in a variably wetted soil medium. Optimization of model parameters followed by the Inverse approach resulted in satisfactory agreement between observed and predicted cumulative infiltration and SWC. On the basis of model calibration, HYDRUS-2D model can accurately simulate two-dimensional soil water dynamics under irrigation of mulched furrows. There were significant differences in wetting patterns between unmulched and mulched furrow irrigation using HYDRUS-2D simulation. The Rd under the mulched furrows was 32.14% less than the unmulched furrows. Therefore, film-mulched furrows are recommended in a furrow irrigation system.

关键词： soil water distribution wetting pattern film-mulched furrows furrow irrigation HYDRUS-2D model

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Newly-simplified method for hydrauli design of micro-irrigation laterals based on emission uniformity

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排灌机械工程学报 2015年第8期33卷 691-700页

作者： Ju Xueliang wu pute Paul R.Weckler Zhu Delan Zhang Lin Institute of Soil and Water Conservation Northwest A&F University Institute of Water Saving Agriculture in Arid Areas of China Northwest A&F University Department of Biosystems and Agricultural Engineering Oklahoma State University College of Water Resources and Architectural Engineering Northwest A&F University

An analytical approach was developed to design a single uniformly sloping lateral in the micro-irrigation *** uniformity was used as the water application uniformity *** relations based on the energy-gradient-line approach were revamped to account for the spatial variance of emitter outflow and the emitter connections local energy *** pressure head grade line profiles were distinguished:uphill,horizontal,gentle downhill and steep *** expressions of emission uniformity by hydraulic variation for each pressure profile were developed based on the design variables:length and diameter of lateral,emitter spacing,emitter flow equation parameters,equivalent length characterizing local losses and ground *** design conditions for selecting emitter type,the number of emitters per plant and designing the diameter of the uphill and steep downhill laterals were also *** nonlinear equations for determining lateral diameter and lateral length were solved iteratively by using the built-in root-finding function of(Tools>Goal Seek…)in the calculation spreadsheet of Microsoft *** procedures also provide the options to fix the design lateral diameter with the commercial standard size or fix the design lateral length based on the field *** operating inlet pressure and maximum amplitude of the pressure head throughout the lateral could also be determined easily by the *** numerical applications with various slope combinations indicate that the proposed analytical approach produces results close to the accurate stepwise numerical *** comparison with Keller method,the proposed approach could produce more appropriate designs.

关键词： micro-irrigation lateral slopes hydraulic design e

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Highlights of special issue on ‘Agriculture in Water-Limited Areas'

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Frontiers of Agricultural Science and Engineering 2017年第2期4卷 123-125页

作者： pute wu Institute of Water Saving Agriculture in Arid Areas of China Northwest A&F University

Agriculture in water-limited areas is an integral part of regional and global food ***,food production has increased dramatically in the arid and semiarid areas thanks to the advances in agronomy,genetics and *** technology,fertilizers and pesticides,and soil management have revolutionized agriculture in water-limited ***,water scarcity remains the greatest challenge for agriculture and usually is also the cause for other socioeconomic and environmental ***,water scarcity in an area often coexists with low water

关键词： in is Highlights of special issue on of that

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Dynamic remote monitoring system for plant root growth and water consumption

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International Journal of Agricultural and Biological Engineering 2013年第2期6卷 19-27页

作者： Han Wenting Ju Yutu wu pute Dang Gerong Nie Junfeng Su Ki Ooi Institute of Soil and Water Conservation Northwest A&F UniversityYanglingShaanxi 712100China College of Mechanical and Electronic Engineering Northwest A&F UniversityYanglingShaanxi 712100China Institute of Water Saving Agriculture in Arid Regions of China Northwest A&F UniversityYanglingShaanxi 712100China National ICT Australia Victoria Research Lab.Department of Electrical and Electronic EngineeringThe University of MelbourneParkvilleVIC 3010Australia

In order to improve the level of multi-functional and automatic observation of crop root system growth,a soil column monitoring system was designed to facilitate in situ dynamic monitoring of root growth and water *** system consists of 20 plastic tubular backfill soil columns,each with an inner diameter of 32 cm and height of 300 *** crops were planted at the top of the soil column with the surrounding leveled with the ground surface and the site is in a *** underground portion of the soil column contains small round windows on the tube through which root growth can be monitored,roots can be pruned and soil samples can be obtained.A multiport serial weighing system was designed and placed at the base of the soil *** electronic balances were connected to the personal computer through three CP-168U multiport serial cards and RS-232 serial *** host software was developed on the browser/server(Browser/Server),and data collection and remote data transmission and data sharing were implemented using the Java programming language and applying Internet data transmission technology and Web application *** tests showed a relatively good stability and real-time capability,and with accuracy up to 50 g and the evapotranspiration of each soil column was 0.25-0.65 kg per *** root-system observation system developed in this study surpassed the traditional method of root-digging sampling and thus provided an alternative that could be used to automatically monitor the root system growth status.

关键词： root system monitoring soil column real time weighing system root system growth

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坡面径流调控薄层水流水力学特性试验

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农业工程学报 2010年第3期26卷 14-19页

作者：吴淑芳吴普特原立峰西北农林科技大学旱区农业水土工程教育部重点实验室中科院水土保持研究所黄土高原土壤侵蚀与旱地农业国家重点实验室杨凌712100 中科院南京地理与湖泊研究所南京210008

为澄清复杂地表的水流运动过程、水流水力学参数受流量及地表状况的影响,该研究采用野外标准径流小区实地放水冲刷试验,研究了鱼鳞坑、苜蓿草地、秸秆覆盖不同径流调控措施的坡面薄层水流水动力学特性的变化规律,包括水流流速、水深、... 详细信息

为澄清复杂地表的水流运动过程、水流水力学参数受流量及地表状况的影响,该研究采用野外标准径流小区实地放水冲刷试验,研究了鱼鳞坑、苜蓿草地、秸秆覆盖不同径流调控措施的坡面薄层水流水动力学特性的变化规律,包括水流流速、水深、流态、阻力系数。研究结果表明:坡面薄层水流的平均流速与水深主要受流量控制,其二者之间呈现幂函数关系;地表状况与流量大小直接影响着坡面流态,对于裸地与鱼鳞坑坡面,流量较小时属于层流与缓流,在流量达到3.0m3/h时,属于过渡流、紊流和急流;而苜蓿草地、秸秆覆盖坡面均属于层流和缓流;并提出复杂坡面的阻力系数由颗粒阻力、形态阻力、波阻力叠加而成,其大小主要受地表状况影响;阻力系数与土壤侵蚀率呈现良好对数关系。总之,坡面采取径流调控措施后,其地表抗侵蚀力和泥沙搬运的能力明显强于裸地,径流流速明显降低,水流流态明显平缓,水流受阻力显著增加。研究结果对于揭示不同径流调控措施对坡面拦泥蓄水、减流减沙及侵蚀动力学机制有着重要的理论基础和实践指导意义。

关键词：土壤侵蚀水力学径流调控放水试验薄层水流

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