Zhao Wenji

Using RS and GIS to monitoring Beijing wetland resources evolution

In Beijing, Wetlands have been playing a crucial role in conserving municipal freshwater and retaining biodiversity. The classification system of Beijing wetland has been set up. The interpretation keys of six main wetland types in Beijing, including River, Reservoir, City Lake, Artificial Canal, Pound and Paddy Field, were built up using TM/ETM+ multi-spectral pseudo-color composition images as the data source. The modern information technology such as RS, GIS and GPS is combined with field investigation for further analysis to obtain the historical change information of wetland area, water quality and landscape pattern, The wetland soil and plant distribution maps in different large scale were sketched, and their attribute databases including hydrology, soil and plant were built up also. From which, its trend of evolution and some driving factors are analyzed successfully. This study indicates that not only have wetland areas been reduced by half, but also their ecological environments have been degraded because of rapid economic development and population increase. Suggestions based on this research are made to reconstruct the ecological environment of the wetlands and return them to their previous state.

Research of the display question in the 3D pipeline management information system

Good visual effect and visualization of topological relation of pipeline are characteristics of 3D pipeline management information system. So display of 3D pipeline is one of the key issues to research in the design and development course of 3D pipeline management information system. This article researches how to display 3D pipeline with good effect and at high speed using coordinate transformation and clip plane in OpenGL. The result we realize has good effect and multi-level-details characteristics.

A design method for building a multi-scale navigation electronic map

The functions of successive display and intelligent zoom among objects at different scales have not been developed in existing multi-scale navigation electronic map software system. So, taken the multi-scale and multi-media characteristics into consideration, this paper discusses the design and development strategies of multi-scale navigation electronic map. The total structure is built from the view of software engineer, and the key techniques based on interpolation method are proposed in details for intelligent zoom of multi-scale road map. At last, a case in point is given to build a convenient and visual spatial information services platform for route design, route guide and route display.

Texture Analysis and its Application for Single-Band SAR Thematic Information Extraction

In this paper single-band and single-polarization Radarsat-1 SAR image is used to evaluate image classification with textural analysis. Firstly, the statistic information of sample were analyzed using semivariogram to determine the optimum parameters for textural extraction; Then four textures such as Homogeneity, Mean, Angle Second Moment and Entropy had been calculated based on GLCM, and the image data were processed using Support Vector Machine classification. The results show that the water and settlement areas are extracted accurately with accuracy 99.34% and 82.54%, and the SVM method has better extension ability for SAR image classification; Assisting with textural information, the image classification based on SVM has a obvious enhancement to original SAR, especially for some complex objects such as settlement areas(about increasing accuracy 18%).

A study on optical and SAR data fusion for extracting flooded area

This article proposes a method of fusing the optical data before the flood and SAR (synthetic aperture radar) data during the flood. The main goal of this study is to evaluate the capability of data fusion to combine the information from Landsat ETM image with Radarsat SAR image for water body and flooded area extraction. The Landsat ETM data will basically provide the information of landform and background information which includes the normal water extent. The Radarsat SAR data however was taken during flood will provide information mainly on water body extent and flooded area. In the result image, flooded area was significantly enhanced. We can distinguish the flooded area and normal water area easily.

Thematic Information Extraction from IKONOS Imagery based on Object and Various Features

As to high-resolution remote sensing imagery classification based on object-orientated methodology, the precision is related to feature configuration and classification algorithm. In this paper, the IKONOS multi-spectral image is selected as sample data, and segmentated into many image objects. Firstly, the supervising classification is applied to extract land cover thematic information, based on nearest distance and SVM methods respectively, and the total classification accuracy is analysed and compared with each other. Follow the feature space is changed into different dimensionality, and the relation between feature configuration and classification accuracy is discussed respectively with nearest distance and SVM methods. The results show that the SVM classifier can well relax the relationship between image classification and representative feature configuration, and improved the insufficiency of nearest distance methodology during nonlinearity classification processing.

Dynamic monitor and analysis of Beijing wetland resource on the basis of RS and GIS

Supported by RS and GIS technology, combining the former achievements in scientific research and lots of field investigations, we used IRS image of 2000 and Landsat-TM images of 1984, 1989, 1992, 1996, 1998, 2002 and 2004 as information source, then, with the help of GIS and RS software, interpreted the images and built up Beijing wetland resource and ecological environment information system. On the basis of it, we can dynamic monitor wetland resource and wetland change trend of Beijing region in the past twenty years, including the wetland type, area and distribution; wetland biodiversity; wetland exploitation, etc. After all of these, analyze the actual state of wetland resource and the dynamic change of wetland in Beijing region. Keyword--GIS, RS, Beijing wetland resource, dynamic monitor

Research on water environmental quality evaluation and characteristics analysis of TongHui River

This study evaluated water quality of TongHui River in Beijing based on the fuzzy mathematics comprehensive evaluation model and the spatial cluster analysis, according to the measured data, seven evaluation parameters were chosen: dissolved oxygen, total nitrogen (TN), total carbon(TC), chemical oxygen demand (COD), ammonia nitrogen, nitrate nitrogen and total phosphorus (TP). The fuzzy comprehensive evaluation results show that: water quality of sample point 15, 8, 9 (GaoBeiDian sewage treatment plant), 19 and 5 is good, water quality of sampling 10, 11 (sewage outfalls), 1, 2, and 3 (south channel) is bad. Because of GaoBeiDian reclaimed water supply place, water quality of sampling 8 and 9 is improving; TN and TP were reduced by 30% and 9.7%. But the whole river water quality still lower than the national fifth kinds of water quality. Hierarchical clustering analysis results show that: the distribution of TongHui River is obviously spatial, water conditions can be divided into three groups: A class represents mild pollution is mainly distributed in DaWangLu, YongAnLi, etc, near which factories, printers, water pollution and central business district (CBD),water quality is general. Class B represents moderate pollution, it located downstream of C kind, Contaminated influence of polluted water, water quality is poorer; C kind is dirtiest for pollutant discharges. Results of evaluation and hierarchical analysis provides scientific basis for water pollution management and control.

Estimation of vegetation net primary productivity of Beijing Yeyahu wetland based on remote sensing

Wetlands play more important role in people daily lives and are specifically valuable to people as places for educational activities and recreational. It also can provide wetland functions like storage of water, transformation of nutrients, and growth of living matter for its surrounding ecosystems. Given their great ecological and conservation values of the wetland system the work of wetlands protection becomes increasingly important. Beijing, capital of China, used to be a richly endowed region with abundant wetlands. But with the highly development of social-economy, these fragile ecosystems had become imperiled due to rapid urbanization and industrialization.Yeyahu wetland is an artificial wetland which located in the northwest of Beijing city. It is one suitable place for educational activities and recreation for local people and can also provides other functions like water storage, transformation of nutrients, growth of living matter for surrounding ecosystems. But with the highly development of social-economy, this fragile ecosystem had become imperiled due to rapid urbanization and industrialization. For further protection of the valuable wetland resources, the value of major function as its capabilities of providing habitant for field animal was evaluated. In this paper, Landsat TM Images were geometrically corrected and other geo-data like DEM and climate data of Beijing area were collected. The field survey was also conducted and six plant percentage cover sampled in 1×1m quadrate evenly located in the study area. Assumed that the dry weight of the fully growth plant in August can highly represent the net primary productivity of the Yeyahu wetland in 2008. The estimation model of vegetation net primary production based on remote sensing data and climatic data was build to estimate the NPP in 2008 of Yeyahu wetland.

Remote sensing applications: Ecological environment effect analysis of Widgeon Lake Wetland change in Beijing region

Using Landsat TM and ETM+ images from 1984 to 2004, this paper analyzed the hydrology, soil, plant condition of the Widgeon Lake Wetland in Beijing. And the results are as follows: Salinized area had increased every year and reached to a head in 2004. Due to the soil salinization, the marsh vegetation species changed to the mesophytic, xeromorphic and salt tolerable ones. Along with the continuously shrinking of water area, wetland dominated the low coverage. The cold-humid effect of wetland had been impaired for the breakage of wetland environment in recent years. The decrease amount of regional daily evapotranspiration proved that the climate was drying and warming. The regional ecological negative effects were closely connected with the decrease of wetland resources. We should bring forward corresponding effective protection and utilization measures and give the scientific basis for the restoration of wetland resources.