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Xu Z.-X.,Beijing Normal University | Li J.-Y.,China Institute of Land Surveying and Planning
Shuikexue Jinzhan/Advances in Water Science | Year: 2010

The paper reviews and summaries the state-of-the-art, major progresses, and future perspectives in hydrological sciences. The study reveals that the societal need is the fundamental driving force and the advance in science and technology is the source for the development of hydrological sciences. In hydrological sciences, land surface hydrological processes should be investigated, as well as the water and energy exchanges among the atmosphere, land surface and groundwater. Physical processes of water transfer and movement should be investigated, as well as the chemical processes of different chemical compositions dissolved in the water. The study, in particular, the need for including the biological processes in hydrological cycle and water movement should be strengthened towards ecohydrology. At present, both ecohydrology and impact of climate change are very active in hydrological sciences under the changing environment. The theory of hydrological sciences should be further improved and developed. The socio-economic benefits of hydrological services should be enriched and strengthened in the future. Hydrological science could thus play an active role to support socio-economic development. Copyright.


Zuo D.-P.,Beijing Normal University | Xu Z.-X.,Beijing Normal University | Li J.-Y.,China Institute of Land Surveying and Planning | Liu Z.-F.,Beijing Normal University | Liu Z.-F.,CAS Institute of Geographical Sciences and Natural Resources Research
Shuikexue Jinzhan/Advances in Water Science | Year: 2011

The parameters in the temperature-based Hargreaves method for the estimation of potential evapotranspiration (ETP) are calibrated by the FAO Penman-Monteith method and daily data during the period 1959-2008 at 20 meteorological stations in the Weihe River basin. To study the impact of climate change on potential evapotranspiration, the projected daily maximum and minimum air temperature (Tmax/Tmin) of HadCM3 GCM under A2 and B2 scenarios are first downscaled onto local meteorological stations using the statistical downscaling model (SDSM). Using the calibrated Hargreaves method, the future ETP, Tmax and Tmin time series under A2 and B2 scenarios can then be calculated. The spatiotemporal characteristics of these series are analyzed. Results show that the calibrated Hargreaves method reproduces well the observed potential evapotranspiration at each of the 20 meteorological stations; upward trends in daily Tmax and Tmin and annual ETP could be significant compared to that of the baseline period 1961-1990 under both scenarios; the increase in meteorological variables would be greater under A2 than B2; over different regions of the Wei River basin, the annual ETP could be gradually increasing for the three future periods, the 2010-2039, the 2040-2069 and the 2070-2099; and the greatest increase of ETP could be expected in the south bank of the basin, while the lowest increase might be found in the north bank.


Wu R.,Hohai University | He X.,Hohai University | Wang J.,China Institute of Land Surveying and Planning
Gaojishu Tongxin/Chinese High Technology Letters | Year: 2015

The study was conducted to assess the fusion of the ZY-3 satellite's multi-spectral (MS) images and panchromatic (PAN) images from the angles of coastal wetland classification comparison and quantitative analysis. Four MS-PAN fusion methods of generalized intensity-hue saturation (GIHS) transformation, à trous wavelet transformation (AWT), nonsub sampled Contourlet transformation (NSCT) and NSCT-GIHS (NSCT-GIHS combination) were used to achieve the fusion of ZY-3 images, and spectral information indices as well as spatial information indices were utilized to quantitatively assess the quality of the fusion products. The assessment results showed that the fusion quality of the NSCTGIHS was superior to that of other three fusion methods from the spectral and spatial fidelity view. Meanwhile, an object-based classification approach was developed for coastal wetland mapping. The classification results demonstrated that NSCTGIHS based image obtained the highest overall accuracy and Kappa coefficient, 96% and 0.9425. It was obvious that wetland classification result was consistent with quantitative assessment. ©, 2015, Inst. of Scientific and Technical Information of China. All right reserved.


Wu R.,Hohai University | He X.,Hohai University | Wang J.,China Institute of Land Surveying and Planning
Journal of Applied Remote Sensing | Year: 2015

The new launched ZiYuan-3 (ZY-3) satellite with multispectral (MS) bands and a panchromatic (PAN) band has presented a new opportunity to assess image fusion methods for coastal wetland mapping. This study focuses on image fusion quality assessment through both quantitative spectral and spatial quality analysis and object-oriented classification comparison. Various methods for pan-sharpening ZY-3 MS and PAN bands are tested, including generalized intensity-hue-saturation transform (GIHS), à trous wavelet transform (AWT), nonsubsampled contourlet transform (NSCT), and a combination of NSCT with GIHS (NSCT-GIHS). Spectral fidelity and spatial preservation of fused bands are compared with the original MS bands as reference, and spatial information injections of fused bands are compared with the resampled PAN band as reference. The fusion results demonstrate that, on average, the NSCT-GIHS method has the best performance on spectral fidelity and spatial preservation as well as spatial information injection. The near-infrared (NIR) band has the best spatial information injection in terms of entropy and cross-entropy indices, whereas the NIR band has the best spatial preservation in terms of entropy and structure similarity indices. The classification results show that NSCT-GIHS method also obtains the highest overall accuracy (96%) and Kappa coefficient (0.9425); this is in agreement with the quantitative analysis. © 2015 Society of Photo-Optical Instrumentation Engineers.


Wang J.,China Institute of Land Surveying and Planning | Wang J.,Hong Kong Polytechnic University | Chen Y.,Hong Kong Polytechnic University | He T.,China Institute of Land Surveying and Planning | And 2 more authors.
International Journal of Applied Earth Observation and Geoinformation | Year: 2010

Land type is the base of land change analysis or landscape analysis. Land type classification is often based on land resources survey. Updating land type is generally difficult, mainly due to the lack of appropriate information. Hence, it is of importance to develop a method for land type classification using remote sensing images. The study was to propose the geographic image cognition (GEOIC) approach for land type classification. The approach was realized by the segmentation of land units, using Hyperion image, geographic information, vegetation, soil, DEM, and geosciences knowledge. It is the extension of the methodologies of object-based image analysis. Results showed that the GEOIC approach is an integrated approach with objectification cognition on remote sensing images and multi-source information using geo-knowledge. The GEOIC approach included three aspects: spatial feature perception, spatial object cognition and spatial pattern cognition. The use of the GEOIC approach in land type classification was tested in a study area in the agriculture-pasture mixed region of Loess Plateau in China. Results of land type classification at different scale levels showed that the overall accuracy ranged from 72.4% to 88.3%, with an average about 80%. The accuracy of classification at similar pixel level was relatively low, with an overall accuracy of 73.1% and Kappa coefficients of 0.69. The classification at scale level of 100 was effective for mapping land types with an overall accuracy of 88.3% and Kappa coefficients of 0.86. The classification accuracy through the segmentation of land units at an appropriate scale level was higher than that for pixel to pixel methods. This study concluded that the GEOIC approach on land type classification is significant and appears potential for land type classification aiming to land assessment and planning. © 2009 Elsevier B.V.


Wang J.,China Institute of Land Surveying and Planning | Wang J.,Hong Kong Polytechnic University | He T.,China Institute of Land Surveying and Planning | Lv C.,China Institute of Land Surveying and Planning | And 2 more authors.
International Journal of Applied Earth Observation and Geoinformation | Year: 2010

Soil degradation is the core of land degradation. The lost of organic material is a signature of the quality degradation and productivity decline of soils. Therefore, it is of importance to develop a relatively rapid and economic method for mapping soil organic matter (SOM) at regional scale using remote sensing images. The study was to investigate the upscaling method of estimation model for mapping SOM using hyperspectral remote sensing images and multi-source data through segmentation of land degradation spectral response units (DSRUs). The estimation model of SOM based on DSRUs was developed to map SOM using Hyperion images of Hengshan County in the northern Shaanxi Province of China. Results showed that the DSRU estimation model, based on the relationship between the SOM content and features of spectral and regional variables of DSRUs, was valid to estimate the content of SOM. The determinative coefficient (R 2) of the model increased from 0.562 at the scale level of 25, to 0.721 at the scale level of 50, and to 0.722 at the scale level of 100. The environmental variables of elevation, slope and vegetation index (MCARI) were included in the DSRU models, making it advantageous over the in situ models. The mapping content of SOM based on DSRU estimation model using Hyperion image agreed with that by the field survey and by the Kridge interpolation. Our research concluded that the DSRU model provides a relatively rapid, cost-effective, and accurate way to map the content of SOM for the land management of large area. © 2010 Elsevier B.V..


Wang J.,China Institute of Land Surveying and Planning | Wang J.,Hong Kong Polytechnic University | Chen Y.,Hong Kong Polytechnic University | Shao X.,China Institute of Land Surveying and Planning | And 2 more authors.
Land Use Policy | Year: 2012

China has extremely scarce land resources compared to the world average. There is an urgent need for studies of the current situation and the trends in land-use change and assessment of the performance of land policies in China. Assessment of land-use change has long been hindered by a lack of accurate and reliable data. This paper uses the data obtained from the national land surveys of 1996 and land-use change surveys from 1997 to 2008, to analyze changes in land use and the policy dimension driving forces related to the changes, especially cultivated land, forestry land, grassland, as well as developed land. The aim of this analysis will be to derive the physical, social and economical driving forces of those changes to grasp the trends in land-use change and the effects of land policies and to formulate strategies for the protection and sustainable use of agricultural land. The results indicate that, although the overall change in land use was not large, cultivated land was significantly reduced and developed land rapidly increased. A great deal of high quality cultivated land was changed to developed land and low quality cultivated land generated from unused land, which has resulted in a serious threat to food supplies in China. Predictions using the methods of linear extrapolation and a BP neural network indicate that it is impossible to keep to a target of 0.12 billion hectares of cultivated land in the future under the mode of economic development used between 1996 and 2008. The results also indicate that the implementation of the laws and regulations about controlling the developed land and preserving cultivated land had significant effects on changes in land use, especially cultivated land and developed land. The results suggest that the changes in land use are closely related to economic fluctuation and the enaction and implementation of these land policies had a little time lag for cultivated land protection. There is a pressing need for China to use its limited land resources more efficiently and effectively by enacting or re-enforcing the laws and regulations on land resources protection and economic development, not only for its own growing population, but also the world. Therefore, we must formulate strategies for the protection and sustainable use of agricultural land. © 2011 Elsevier Ltd.


Wang J.,China Institute of Land Surveying and Planning | Wang J.,Hong Kong Polytechnic University | Liu A.,China Institute of Land Surveying and Planning | Li S.,Hong Kong Polytechnic University | Chen Y.,Hong Kong Polytechnic University
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2010

China's land resources are extremely scarce. There is a pressing need for building the technical system of land survey and monitoring for detail knowledge about the current situation of land use, land value and land property right of each piece of land in the whole country for land use and management. Many works of land survey and monitoring in China have been finished for providing references directly for the macro decision-making and making the national economic and social development planning. However, there were limits in integrity, systemization, and standardization, and some of works about survey and monitoring were carried out in the early period and their results were not updated in time. The purpose of the paper is to establish the framework of systemized technical system of land survey and monitoring for guidance of future national work of land survey and monitoring. The study was through comparing and analyzing the past and ongoing projects of land survey and monitoring. Results indicated that the technical system is constituted by 5 sub-systems. The system will integrate land survey and monitoring, land evaluation, and information sharing service into a whole. The regional arrangement of land survey and monitoring was proposed. Seven implementation regions of land survey and monitoring were divided, including the northeastern region, eastern coastal region, central region, southwestern region, northwestern region, Xinjiang Urgur region, and Qinghai-Tibetan region. The survey and monitoring objectives and contents in each region are different. The zoning is for guidance of the future project arrangement about national land survey and monitoring in China based on land resources background and economic development demands. © 2010 Copyright SPIE - The International Society for Optical Engineering.


Wang J.,China Institute of Land Surveying and Planning | Wang J.,Hong Kong Polytechnic University | Chen Y.,Hong Kong Polytechnic University | Liu A.,China Institute of Land Surveying and Planning | And 2 more authors.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2010

For the extraction of land degradation information we should use not only information on climate, soil, vegetation, physiognomy, land use and its productivities, but also the knowledge and methodologies of geosciences. It is of importance to study some conceptual issues about geographic image cognition (GEOIC) on studying land degradation. The study is to discuss some conceptual issues and the theoretical background of the approach of geographic image cognition (GEOIC) on studying land degradation for building its methodological framework. Some issues concerning the approach of GEOIC on studying land degradation, especially the factors of impacting human's visual cognition, were discussed. The results indicated that the GEOIC is the objectification cognition on remote sensing images and multi-source information using geo-knowledge. As an integrated approach, it is the extension of the methodology of OBIA. The key objective of the GEOIC on studying land degradation is to simulate the function and process of the visual interpretation by experts, and extract spatial features, spatial object and spatial pattern of land degradation under the cognition mode of feature-object-pattern from remote sensing images and multi-source information. The methodology of the GEOIC is realized through the segmentation of geo-objects or meaningful image objects using remote sensing information, geographic information, vegetation, soil, and other ancillary information with geosciences knowledge and intelligence. © 2010 Copyright SPIE - The International Society for Optical Engineering.


Liu A.,China Institute of Land Surveying and Planning | Zhao X.,China Institute of Land Surveying and Planning | Wang J.,China Institute of Land Surveying and Planning | He T.,China Institute of Land Surveying and Planning
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2013

Impervious surface is an important part of urban underlying surface, as well as an important monitoring index for city ecological system and environment changes. However, accurate impervious surface extraction is still a challenge. This paper uses the color, shape and overall heterogeneity features from the high spatial resolution remote sensing image to extract the impervious surface. An edge-based image segmentation algorithm is put forward to fuse heterogeneous objects which integrates edge features and multi-scale segmentation algorithm and uses the edge information to guide image objects generation. Results showed that this method can greatly improve the accuracy of image segmentation. Accuracy assessment indicated that the overall impervious surface classification accuracy and a Kappa coefficient yield 87% and 0.84, respectively. © 2013 SPIE.

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