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Comparison of three remotely sensed drought indices for assessing the impact of drought on winter wheat yield

International Journal of Digital Earth 2020年第4期13卷 504-526页

作者： Jianxi Huang Wen Zhuo Ying Li Ran Huang Fernando Sedano Wei Su Jinwei Dong Liyan Tian Yanbo Huang Dehai Zhu Xiaodong Zhang College of Land Science and Technology China Agricultural UniversityBeijingPeople’s Republic of China Key Laboratory of Remote Sensing for Agri-Hazards Ministry of AgricultureBeijingPeople’s Republic of China CMA·Henan Key Laboratory of Agrometeorological Support and Applied Technique ZhengzhouPeople’s Republic of China Henan Institute of Meteorological Sciences ZhengzhouPeople’s Republic of China Department of Geographical Sciences University of MarylandCollege ParkMDUSA Key Laboratory of Land Surface Pattern and Simulation Institute of Geographic Sciences and Natural Resources ResearchChinese Academy of SciencesBeijingPeople’s Republic of China Department of Geography College of GeosciencesTexas A&M UniversityCollege StationTXUSA United States Department of Agriculture Agricultural Research ServiceCrop Production Systems Research UnitStonevilleMSUSA

Agricultural drought threatens food *** remote-sensing drought indices have been developed,but their different principles,assumptions and physical quantities make it necessary to compare their suitability for drought monitoring over large ***,we analyzed the performance of three typical remote sensing-based drought indices for monitoring agricultural drought in two major agricultural production regions in Shaanxi and Henan provinces,northern China(predominantly rain-fed and irrigated agriculture,respectively):vegetation health index(VHI),temperature vegetation dryness index(TVDI)and drought severity index(DSI).We compared the agreement between these indices and the standardized precipitation index(SPI),soil moisture,winter wheat yield and National Meteorological Drought Monitoring(NMDM)*** average,DSI outperformed the other indices,with stronger correlations with SPI and soil *** also corresponded better with soil moisture and NMDM *** jointing and grain-filling stages of winter wheat are more sensitive to water stress,indicating that winter wheat required more water during these ***,the correlations between the drought indices and SPI,soil moisture,and winter wheat yield were generally stronger in Shaanxi province than in Henan province,suggesting that remote-sensing drought indices provide more accurate predictions of the impacts of drought in predominantly rain-fed agricultural areas.

关键词： Agricultural drought remote sensing drought index winter wheat yield

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Spatiotemporal differentiation of changes in maize phenology in China from 1981 to 2010

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Journal of Geographical Sciences 2019年第3期29卷 351-362页

作者： LIU Yujie QIN Ya GE Quansheng Key Laboratory of Land Surface Pattern and Simulation Institute of Geographic Sciences and Natural Resources Research CAS University of Chinese Academy of Sciences College of Surveying and Mapping Science and Technology Xi'an University of Science and Technology

Spatio-temporal changes in the differentiation characteristics of eight consecutive phenological periods and their corresponding lengths were quantitatively analyzed based on long-term phenological observation data from 114 agro-meteorological stations in four maize growing zones in China. Results showed that average air temperature and growing degree-days (GDD) during maize growing seasons showed an increasing trend from 1981 to 2010, while precipitation and sunshine duration showed a decreasing trend. Maize phenology has significantly changed under climate change: spring maize phenology was mainly advanced, especially in northwest and southwest maize zones, while summer and spring-summer maize phenology was delayed. The delay trend observed for summer maize in the northwest maize zone was more pronounced than in the Huang-Huai spring-summer maize zone. Variations in maize phenology changed the corresponding growth stages length: the vegetative growth period (days from sowing date to tasseling date) was generally shortened in spring, summer, and spring-summer maize, although to different degrees, while the reproductive growth period (days from tasseling date to mature date) showed an extension trend. The entire growth period(days from sowing date to mature date) of spring maize was extended, but the entire growth periods of summer and spring-summer maize were shortened.

关键词： maize phenology climate change spatio-temporal differentiation China

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Advancing sustainable agricultural: A novel framework for mapping annual 30-m resolution national-level irrigated croplands

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International Journal of Applied Earth Observation and Geoinformation 2025年 140卷

作者： Du, Enyu Chen, Fang Jia, Huicong Dong, Jinwei Wang, Lei Chen, Yu Key Laboratory of Digital Earth Science Aerospace Information Research Institute Chinese Academy of Sciences Beijing 100094 China International Research Center of Big Data for Sustainable Development Goals Beijing 100094 China University of Chinese Academy of Sciences Beijing 100049 China Key Laboratory of Land Surface Pattern and Simulation Institute of Geographic Sciences and Natural Resources Research Chinese Academy of Sciences Beijing 100101 China

With regard to climate change and population growth, irrigated croplands need to be accurately delineated for sustainable water resource management. Owing to the lack of extensive training samples and the limitations of coarse spatiotemporal resolution data in complex agricultural regions, China's irrigated croplands are difficult to map with a unified spatiotemporal framework. This study presents an innovative method for mapping irrigated and rainfed croplands in mainland China with a local adaptive random forest classifier on the Google Earth Engine platform. Based on the dynamic threshold extraction of multiple peak vegetation index values and a rigorous multi-dataset integration strategy, the annual sample sets of irrigated and rainfed croplands are generated automatically. After constructing 147 multi-feature variables sensitive to irrigation activities, China's annual irrigated croplands dataset (CAICD) is developed, with 30-m spatial resolution for the 1990–2022 period. The results show the following:(1) CAICD has higher accuracy and a more realistic spatial distribution of irrigated croplands compared with existing datasets, with an average overall accuracy of 0.80. (2) The most sensitive classification features for irrigation signals are spectral indices and original bands, with regional differences influenced by climate characteristics (precipitation and evapotranspiration) and terrain features. (3) Over the past three decades, China's irrigated croplands have expanded overall and Xinjiang has exhibited the most significant increase and the highest growth rate of irrigated area in mainland China, with an annual expansion of 103 thousand hectares. The results exhibit significant implications for the balance between food security and water resource security, providing valuable insights and contributions for future global monitoring of irrigated croplands. © 2025 The Author(s)

关键词： Automatic sampling China Irrigation Random forest Spatiotemporal patterns

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The impact of global cropland changes on terrestrial ecosystem services value, 1992–2015

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Journal of Geographical Sciences 2019年第3期29卷 323-333页

作者： LI Yuanyuan TAN Minghong HAO Haiguang Key Laboratory of Land Surface Pattern and Simulation Institute of Geographic Sciences and Natural Resources Research CAS International College University of Chinese Academy of Sciences State Key Laboratory of Environmental Criteria and Risk Assessment Chinese Research Academy of Environmental Sciences

From 1992 to 2015, ecological environment has been threatened by the changes of cropland around the world. In order to evaluate the impact of cropland changes on ecosystem, we calculated the response of terrestrial ecosystem service values (TESVs) variation to cropland conversion based on land-use data from European Space Agency (ESA). The results showed that cropland changes were responsible for an absolute loss of $166.82 billion, equivalent to 1.17% of global TESVs in 1992. Among the different regions, the impact of cropland changes on TESVs was significant in South America and Africa but not obvious in Oceania, Asia and Europe. Cropland expansion from tropical forest was the main reason for decreases in TESVs globally, especially in South America, Africa and Asia. The effect of wetland converted to cropland was notable in North America and Europe while grassland converted to cropland played an important role in Oceania, Africa and Asia. In Europe, the force of urban expansion cannot be ignored as well. The conversion of cropland to tropical or temperate forest partly compensated for the loss of TESVs globally, especially in Asia.

关键词： terrestrial ecosystem services values (TESVs) cropland conversion global

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Investigating the spatially heterogeneous relationships between climate factors and NDVI in China during 1982 to 2013

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Journal of Geographical Sciences 2019年第10期29卷 1597-1609页

作者： GAO Jiangbo JIAO Kewei WU Shaohong Key Laboratory of Land Surface Pattern and Simulation Institute of Geographic Sciences and Natural Resources Research CASBeijing 100101 China Key Laboratory of Forest Ecology and Management Institute of Applied Ecology CASShenyang 110016China University of Chinese Academy of Sciences Beijing 100049 China

Climate change is a major driver of vegetation activity, and thus their complex processes become a frontier and difficulty in global change research. To understand this relationship between climate change and vegetation activity, the spatial distribution and dynamic characteristics of the response of NDVI to climate change were investigated by the geographically weighted regression(GWR) model during 1982 to 2013 in China. This model was run based on the combined datasets of satellite vegetation index(NDVI) and climate observation(temperature and moisture) from meteorological stations nationwide. The results showed that the spatial non-stationary relationship between NDVI and surface temperature has appeared in China: the significant negative temperature-vegetation relationship was located in Northeast, Northwest and Southeast China, while the positive correlation was more concentrated from southwest to northeast. By comparing the normalized regression coefficients from GWR model for different climate factors, it presented the regions with moisture dominants for NDVI were in North China and the Tibetan Plateau, and the areas of temperature dominants were distributed in East, Central and Southwest China, where the annual mean maximum temperature accounted for the largest areas. In addition, regression coefficients from GWR model between NDVI dynamics and climate variability indicated that the higher warming rate could result in the weakened vegetation activity through some mechanisms such as enhanced drought, while the moisture variability could mediate the hydrothermal conditions for the variation of vegetation activity. When the increasing rate of photosynthesis exceeded that of respiration, the positive correlation between vegetation dynamics and climate variability was reflected. However, the continuous and dynamic process of vegetation activity response to climate change will be determined by spatially heterogeneous conditions in climate change and vegetation cov

关键词： NDVI climate change spatial heterogeneity GWR China

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Large-Scale Single Tree Information Extraction of Oil Palm in Malaysia Based on Sub-Meter Visible Light Satellite Images

SSRN

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SSRN 2024年

作者： Zhang, Sen Li, Nan Cui, Yaoping Dong, Jinwei Yu, Le Ran, Lishan Chen, Ziyue Niu, Jiqiang Yan, Wei Kanniah, Kasturi Devi Xiao, Xiangming Zhang, Yongguang Key Laboratory of Geospatial Technology for the Middle and Lower Yellow River Regions Henan University Ministry of Education Kaifeng475004 China College of Geography and Environmental Science Henan University Kaifeng475004 China Jiangsu Center for Collaborative Innovation in Geographical Information Resource Development and Application International Institute for Earth System Sciences Nanjing University Nanjing210023 China Key Laboratory of Land Surface Pattern and Simulation Institute of Geographic Sciences and Natural Resources Research Chinese Academy of Sciences Beijing100101 China Department of Earth System Science Ministry of Education Key Laboratory for Earth System Modeling Institute for Global Change Studies Tsinghua University Beijing100084 China Department of Geography The University of Hong Kong Pokfulam999077 Hong Kong State Key Laboratory of Earth Surface Processes and Resource Ecology College of Global Change and Earth System Science Beijing Normal University Beijing100875 China College of Geographic Sciences Xinyang Normal University Xinyang464000 China Department of Geoinformation Faculty of Built Environment & Surveying Universiti Teknologi Malaysia Johor Bahru81310 Malaysia Department of Microbiology and Plant Biology Center for Spatial Analysis University of Oklahoma NormanOK73019 United States College of Environment and Planning Faculty of Geoinformation and Real Estate

The distribution of specific tree species and single tree information can shift down the research scale of geography and ecology, bridging research from regional to local scales. However, efficiently and finely extracting the spatial distribution and single tree information for a tree species regionally has always been a challenge due to the constraints of data and algorithms. With sub-meter visible light satellite images (RGB bands) in 2021 to 2022, we constructed a novel method for extracting the spatial distribution and single tree information of oil palm across Malaysia, namely the Single Tree Extraction Method - Oil Palm (STEM-OP). We developed a graphic morphological algorithm based on gradient difference window detection to extract the spatial distribution of oil palms. Then, we proposed an algorithm of double ring sliding detection algorithm to identify the canopy texture features of single oil palm. Finally, an adaptive iterative erosion algorithm was employed to separate overlapping and adjacent canopies into single trees. The overall accuracy of both the spatial distribution and number of single oil palm extracted by STEM-OP exceeded 90%. Our study revealed that the total area of oil palm in Malaysia was 5.25 million hectares, with a total of 572.6 million trees and an average planting density of 109 palms per hectare. The STEM-OP addresses the computational inefficiencies of methods with training samples and limitations of satellite image bands. For the first time, our study extracts the refined spatial distribution of oil palm and obtains the planting density and single tree position on a national scale. All of these are of great value to the formulation of oil palm development policies and ecological protection measures. © 2024, The Authors. All rights reserved.

关键词： Morphology

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Climatic and Biotic Controls of Evapotranspiration Across Grassland Ecosystems on Tibetan Plateau

SSRN

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SSRN 2023年

作者： Peng, Siyuan Yang, Yue Luo, Dengnan Zeng, Xiang Liang, Minqi Tao, Long Zhang, Guangru Li, Pan Liao, Weijie Guo, Qun Cao, Ruochen Li, Yuzhe Zhang, Weirong Hu, Zhongmin School of Geography South China Normal University Shipai Campus Guangzhou510631 China Key Laboratory of Agro-Forestry Environmental Processes and Ecological Regulation School of Ecology and Environment Hainan University Haikou570228 China Center for Eco-Environment Restoration Engineering of Hainan Province Hainan University Haikou570228 China Facility of Geographical Science Beijing Normal University Beijing100875 China Zhuhai Branch of State Key Laboratory of Earth Surface Processes and Resource Ecology Beijing Normal University Zhuhai519087 China School of Atmospheric Sciences Guangdong Province Data Center of Terrestrial and Marine Ecosystems Carbon Cycle Sun Yat-sen University Guangdong Zhuhai510245 China Key Lab of Ecosystem Network Observation and Modeling Institute of Geographic Sciences and Natural Resources Research Chinese Academy of Sciences Beijing100101 China College of Resources and Environment University of Chinese Academy of Sciences Beijing101408 China International Institute for Earth System Sciences Jiangsu Center for Collaborative Innovation in Geographical Information Resource Development and Application Nanjing University Jiangsu210023 China Jiangsu Provincial Key Laboratory of Geographic Information Science and Technology Key Laboratory for Land Satellite Remote Sensing Applications of Ministry of Natural Resources School of Geography and Ocean Science Nanjing University Jiangsu210023 China Key Laboratory of Land Surface Pattern and Simulation Institute of Geographical Sciences and Natural Resources Research Chinese Academy of Sciences Beijing China

Accurately quantifying spatiotemporal variations in evapotranspiration (ET) and its components on Tibetan Plateau (TP) is crucial for understanding the regional water cycle and energy balance. However, the determinant of spatial variations in ET and its component processes in grassland ecosystems of TP remain unclear. In this study, we used 14 sites observation data and applied Shuttleworth-Wallace-Hu (SWH) model to investigate the spatial relationships between ET, its components, and influencing factors. Our results highlighted the good performance of SWH model. There were corresponding drops in ET on alpine meadow and on alpine steppe. And the ratio of ET and precipitation (ET/PPT) of most sites was less than 1 in alpine meadow. Furthermore, the ratio of transpiration (T) and ET (T/ET) in alpine meadow generally exceeded that in alpine steppe. PPT emerged as the primary driver of interannual spatial variations in ET, while LAI played a crucial role in regulating T/ET. Our results further demonstrated that in the grassland ecosystem of TP, as the aridity index increased, the ET gradually transitioned from being primarily influenced by water supply to energy demand. This transition occurred at an aridity index of 0.73 approximately. The results of this study imply that in the context of global warming, with aridity index in TP decreasing, the ET of more ecosystems will shift from energy-led to water-led. Such findings are of immense significance in enhancing our understanding of the intricate interactions of the water cycle between land and the atmosphere. © 2023, The Authors. All rights reserved.

关键词： Water supply

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Article a new method for wet-dry front treatment in outburst flood simulation

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Water (Switzerland) 2021年第2期13卷

作者： Liu, Dingzhu Tang, Jinbo Wang, Hao Cao, Yang Bazai, Nazir Ahmed Chen, Huayong Liu, Daochuan Key Laboratory of Mountain Hazards and Earth Surface Process Chinese Academy of Sciences Chengdu610041 China Institute of Mountain Hazards and Environment Chinese Academy of Sciences Chengdu610041 China University of Chinese Academy of Sciences Beijing100049 China Key Laboratory of Land Surface Pattern and Simulation Institute of Geographic Sciences and Natural Resources Research Chinese Academy of Sciences Beijing100101 China The Engineering & Technical College of Chengdu University of Technology Leshan614000 China Sichuan Highway Planning Survey Design and Research Institute Ltd Chengdu610041 China

When utilizing a finite volume method to predict outburst flood evolution in real geometry, the processing of wet-dry front and dry cells is an important step. In this paper, we propose a new approach to process wet-dry front and dry cells, including four steps: (1) estimating intercell properties;(2) modifying interface elevation;(3) calculating dry cell elevations by averaging intercell elevations;and (4) changing the value of the first term of slope limiter based on geometry in dry cells. The Harten, Lax, and van Leer with the contact wave restored (HLLC) scheme was implemented to calculate the flux. By combining the MUSCL (Monotone Upstream–centred Scheme for Conservation Laws)-Hancock method with the minmod slope limiter, we achieved second-order accuracy in space and time. This approach is able to keep the conservation property (C-property) and the mass conservation of complex bed geometry. The results of numerical tests in this study are consistent with experimental data, which verifies the effectiveness of the new approach. This method could be applied to acquire wetting and drying processes during flood evolution on structured meshes. Furthermore, a new settlement introduces few modification steps, so it could be easily applied to matrix calculations. The new method proposed in this study can facilitate the simulation of flood routing in real terrain. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.

关键词： Geometry

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AN IMPROVED ALGORITHM FOR TERRAIN RENDERING

AN IMPROVED ALGORITHM FOR TERRAIN RENDERING

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IEEE International Geoscience and Remote Sensing Symposium

作者： Wei Cao Lin Huang Yunfeng Hu Duanyang Xu Hongyan Ren Junxing Yang Key Laboratory of Land Surface Pattern and Simulation Chinese Academy of Sciences Beijing China

The real-time visualization of large-scale terrain is a very complex and challenging problem, as the increasing resolution of geometry and texture has greatly exceeded the rendering capabilities of the available hardware. This is an active research area, and has attracted the interest of researchers for decades. To solve this problem, LOD-based algorithms of various forms have been proposed. These aim to reduce the complexity of the geometry and decrease the number of triangles that must be rendered. In this paper we will mainly focus on LOD generation, data scheduling and terrain popping, and put forward a new approach for terrain rendering. To promote rendering efficiency, we will take advantage of the programmability of GPU and immigrate some algorithms from CPU to GPU.

关键词： Rendering (computer graphics) Indexes Graphics processing units Geometry Real-time systems Hardware Testing

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The spatial local accuracy of land cover datasets over the Qiangtang Plateau, High Asia

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Journal of Geographical Sciences 2019年第11期29卷 1841-1858页

作者： LIU Qionghuan ZHANG Yili LIU Linshan LI Lanhui QI Wei Key Laboratory of Land Surface Pattern and Simulation Institute of Geographic Sciences and Natural Resources ResearchCASBeijing 100101China University of Chinese Academy of Sciences Beijing 100049China CAS Center for Excellence in Tibetan Plateau Earth Sciences Beijing 100101China

We analyzed the spatial local accuracy of land cover (LC) datasets for the Qiangtang Plateau,High Asia,incorporating 923 field sampling points and seven LC compilations including the International Geosphere Biosphere Programme Data and Information System (IGBPDIS),Global land cover mapping at 30 m resolution (Globeland30),MODIS land Cover Type product (MCD12Q1),Climate Change Initiative land Cover (CCI-LC),Global land Cover 2000 (GLC2000),University of Maryland (UMD),and GlobCover 2009 (Glob- Cover).We initially compared resultant similarities and differences in both area and spatial patterns and analyzed inherent relationships with data *** then applied a geographically weighted regression (GWR) approach to predict local accuracy *** results of this study reveal that distinct differences,even inverse time series trends,in LC data between CCI-LC and MCD12Q1 were present between 2001 and 2015,with the exception of category areal discordance between the seven *** also show a series of evident discrepancies amongst the LC datasets sampled here in terms of spatial patterns,that is,high spatial congruence is mainly seen in the homogeneous southeastern region of the study area while a low degree of spatial congruence is widely distributed across heterogeneous northwestern and northeastern *** overall combined spatial accuracy of the seven LC datasets considered here is less than 70%,and the Globeland30 and CCI-LC datasets exhibit higher local accuracy than their counterparts,yielding maximum overall accuracy (OA) values of 77.39% and 61.43%,***,5.63% of this area is characterized by both high assessment and accuracy (HH) values,mainly located in central and eastern regions of the Qiangtang Plateau,while most low accuracy regions are found in northern,northeastern,and western regions.

关键词： land cover datasets spatial accuracy assessment remote sensing Qiangtang Plateau High Asia

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