Dongting Lake is the second largest freshwater lake in China, and its water surface area varied very significantly during last decade. Remote sensing technology has more advantages in macro monitoring of lake water surface area than the traditional methods. In the paper, an integrated threshold method of water body extraction based on MODIS data is given, which synthesizes several factors, including vegetation index—NDVI, spectrum characters of water body, cloud and shadow, and the SRTM digital elevation information. With this method and 356 scenes MODIS 8-Day composite (MOD09Q1) image, water surface area of Dongting Lake was dynamically monitored from 2000 to 2009. The result shows that during 1 year, the water area variation in Dongting Lake area had a typical seasonal (monsoon) behavior, and during last decade, the water area decreased gradually and obviously. Based on variation monitoring, yearly max-submersion time index has been suggested to analyze flood hazard in study area. With the support of ArcGIS software, authors estimated the yearly submersion time of the Dongting Lake for each year separately and average submersion time from 2000 to 2009. The result shows 67.46% of study area is being with high flood hazard.

Aiming to solve the weakness of defining the boundary of the construction land expansion within the current land use general planning,this paper tries to develop a method based on the spatial analysis technology of geographical information system(GIS).After quantitatively calculating the total amount of construction land within the boundary of construction land expansion through mathematical models,fully using the powerful spatial analysis ability of GIS,and comprehensively taking into account the sensitiveness of environment and the feasibility of construction land in different regions,this paper develops a"bottom-up"method to visually and quantitatively define the boundary of the construction land expansion.The result of research shows that the defined elastic boundary of construction land basically accords with the urban structure that planned in the Urban Planning of Beijing 2004-2020,i.e.,the so-called pattern of"two axis,two belts,and poly-centers",which thus reveals accuracy of the newly developed method in this paper.The conclusion of the study shows that the method is reliable and can be applied widely.Furthermore,if the developed method is ameliorated by combining the natural boundaries such as landform,rivers,and the artificial boundaries such as traffic and greenbelts,it will obviously improve the scientificity in defining the boundary of construction land expansion in the current land use general planning.

Satellite-borne microwave remote sensing is one of the important technology tools for flood disaster monitoring.Up to now,the advanced synthetic aperture radar,ASAR instrument on board the ENVISAT satellite is one of the most powerful radar systems.So in this paper,in accordance with the characteristic that the water body has relatively low backscattering coefficient on ASAR images,two scenes ENVISAT/ASAR APP-1P imageries during the low water season and high water season in 2007 were taken as the test examples in Dongting Lake region,and the common algorithm in image segmentation-threshold methods were applied to the water body extraction from the above ENVISAT/ASAR imageries.The experiment results show that comparing with the double-peak threshold method and traditional Otsu threshold method,the precision of water body extraction based on a modified Otsu threshold method is the highest,which comprehensively considers both variances of inter/inner classes.In addition,through the experiment results it also shows that after solving the issue of threshold by the modified Otsu method,the automatic level of water body extraction from ASAR data and the application of ASAR data to flood disaster monitoring under the wet or cloudy weather conditions are greatly promoted.

Dynamic spatial models are useful tools to understand the urbanization process and support urban planning and management policies. Macro-scale contributing factors to urban expansion including population and capital are not fully integrated in many current cellular automata (CA)-based urban expansion models. We present a new urban expansion dynamic (UED) model that incorporates a potential model into a CA model in order to effectively capture the urban expansion process. The implementation of the UED model in Beijing, China demonstrated its ability to trace past urban development and to predict future expansion. The advantage of the UED model lies in its feature to link the individual cell evolution, overall urban pattern and spatial interaction of total population and capital at different scales.

How to effectively and reasonably assess the ecological risk of the natural/semi-natural landscapes under the fast urbanization process is helpful to optimize the urban land use pattern and to reduce and keep away the urban environment venture.So,in this paper,firstly based on the Landsat TM/ETM+ data in 1991,1997,2000 and 2004 and combining with the geographic information system(GIS) and landscape analysis techniques,the landscape pattern changes in Beijing region from 1991 to 2004 were measured.Then through quantifying the influences from four factors of inner stability,neighborhood stability,external accessibilities and external pressure within every natural/semi-natural landscape cell,a multi-factor evaluating model for the spatial ecological risk of landscape was constructed.And finally using the model the spatial ecological risk level of natural/semi-natural landscapes in Beijing region was assessed in the process of fast urban expansion from 1991 to 2004.The research showed that:(1)With the rapid urbanization process,the primary characteristic of the landscape changes in Beijing region was the persistent increase of factitious building landscape and the substantial decrease of cropland landscape from 1991 to 2004.The proportion of factitious building landscape cells increased from 5.58% in 1991 to 12.72% in 2004,and that of cropland landscape cells decreased from 33.14% in 1991 to 22.19% in 2004,with approximately an average annual reduction rate of 1%.In the meantime,there also was a durative increasing for the woodland landscape.(2)The landscape ecological risk level of the natural/semi-natural landscapes in the study area put up an ascending tendency during 1991 to 2004.For the natural/semi-natural landscapes in mountain regions,the landscape ecological risk level was better than that in plain areas,and the impact of the rapid urbanization process on the landscape ecological risk level of mountain regions was comparatively faint.(3)There also existed some differences among all the natural/semi-natural landscape styles in the study area.The landscape ecological risk level of forest landscape was the lowermost,and the mixed landscape was the topmost,namely the effect of the fast urbanization process to the fixed landscape was most obvious.(4)The newly increased landscape cells of construction land from 1991 to 2004 in Beijing region were primarily from the landscapes of cultivated land and mixed styles,and the total amount from the two landscape styles was more than 95%.Especially to the mixed landscape,the percentage was the highest and exceeded 60%.

有效、合理地评估快速城市化过程中自然/半自然景观的生态风险,对于优化城市土地利用格局、降低和防范城市生态环境风险,非常必要。论文在利用遥感和G IS技术测量北京1991～2004年景观变化的基础上,建立了一个多因素景观空间生态风险评价模型,并以此对北京地区1991～2004年快速城市扩展过程中的自然/半自然景观的空间生态风险水平进行了评估分析。具体结论为：①伴随着快速城市化过程,1991～2004年北京景观变化的主要特征为人工建筑景观持续增加以及耕地景观大量减少;同时,山区林地景观增加也比较明显。②研究区自然/半自然景观的生态风险水平总体表现出上升的趋势。其中,山区自然景观空间生态风险水平要明显低于平原区,受区域快速城市化过程影响相对较小。③研究区各种自然/半自然景观类型间生态风险水平也存在一定的不同。其中,森林景观的生态风险最低,而混合景观的生态风险最高,受区域快速城市化过程的影响最为明显。④研究区新增建设用地景观单元主要来源于耕地和混合两种景观类型,其中混合景观所占比重最高。

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Since current administrative unit-based urban land area statistical data in China lack enough spatial information, the urbanization process research at large scale cannot be effectively supported. Based on the current administrative unit-based urban land area statistical data in China, a new approach to quickly and cheaply derive urban land information from the non-radiance-calibrated Defense Meteorological Satellite Program/ Operational Linescan System (DMSP/OLS) nighttime light imagery is presented in this paper. With the new approach, the urban pattern information in China in 1992, 1996 and 1998 was derived with the urbanization processes in China in the 1990s restored by using the non-radiance-calibrated DMSP/OLS nighttime imagery. The accuracy assessment based on the statistical data showed that the relative error between the derived total urban land area and the statistical data at national scale was less than 2% in 1992, and less than 1% in 1996 and 1998, and the maximum relative error at province scale do not exceed 10% with most of the provinces less than 3%. In addition, the urban patterns derived from the high-resolution Landsat TM imagery were compared with those from the DMSP/OLS data. The results showed that the urban pattern characteristics derived from DMSP/OLS were basically coincident with those from TM imagery with the total accuracy of about 80%. Thus it can be seen that our restored urbanization process in China in the 1990s by using the non-radiance DMSP/OLS night-time imagery can be accepted and can represent the actual urban development in China at that time on the whole.

中国大陆目前以行政单元为基础的城镇用地面积统计数据缺乏足够的空间信息, 难以满足大尺度城市化空间格局和变化过程研究的需要. 文中首先提出了一种以现有统计数据为基础, 借助DMSP/OLS夜间灯光遥感数据, 快速恢复和提取中国大陆城镇用地空间信息, 弥补现有统计资料不足的新方法. 进而以该方法为基础, 利用 1992, 1996和1998年的3期DMSP/OLS夜间灯光数据, 重建了中国大陆20世纪90年代的城市化空间过程. 利用统计数据对该方法提取结果的面积总量评估表明, 二者在全中国大陆尺度上的面积相对误差在1992年小于2%, 1996年和1998年则均小于1%, 在省级尺度, 相对误差最大的省份也没有超过10%, 大部分省份的相对误差小于3%. 同时利用高分辨率Landsat TM数据对该方法提取结果的城市空间格局特征分析也表明, 利用DMSP/OLS 提取的城市格局特征与Landsat TM提取的城市格局特征基本上是吻合的, 两者的相似程度在80%左右. 这说明利用该方法重建的中国大陆20世纪90年代城市空间过程, 基本上可以反映当时中国大陆城市发展的实际状况, 具有一定的可信性, 可以在一定程度上为中国大陆宏观城市空间格局和变化过程研究提供帮助.

This paper firstly derived urban information from Defense Meteorological Satellite Program/Operational Linescan System (DMSP/OLS) data in 1992, 1996 and 1998 with the support of statistical data, and then developed three basic urban models of polygon-urbanization, line-urbanization and point-urbanization in urban agglomerations from viewpoint of spatial analysis. The conclusions are as follows: (1) Urban patch numbers in the Bohai Rim increased from 1659 to 2053 with an annual average increase number of about 66. Meanwhile, the small urban patches accounted for a larger proportion in the region and the patch density increased fast. In addition, the urban barycenter of the region showed a moving trend toward northwest from 1992 to 1998. Urbanization in the Bohai Rim in the 1990s is fast and obvious. (2) Urbanization in the Bohai Rim can be reflected by three basic processes, i.e., the polygon-urbanization around the big cities, the line-urbanization around the transportation lines and the point-urbanization emerging in large areas. Of them, the polygon-urbanization has been in dominance. It is obviously within an effective range of 3–4 km surrounding the urban patches. The line-urbanization and point-urbanization in the region was relatively small, both of which showed an obvious increasing trend.

Modeling land use scenario changes and its potential impacts on the structure and function of the ecosystem in the typical regions are helpful to understanding the interactive mechanism between land use system and ecological system. A Land Use Scenario Dynamics (LUSD) model by the integration of System Dynamics (SD) model and Cellular Automata (CA) model is developed with land use scenario changes in northern China in the next 20 years simulated in this paper. The basic idea of LUSD model is to simulate the land use scenario demands by using SD model at first, then allocate the land use scenario patterns at the local scale with the considerations of land use suitability, inheritance ability and neighborhood effect by using CA model to satisfy the balance between land use scenario demands and supply. The application of LUSD model in northern China suggests that the model has the ability to reflect the complex behavior of land use system at different scales to some extent and is a useful tool for assessing the potential impacts of land use system on ecological system. In addition, the simulated results also indicate that obvious land use changes will take place in the farming-pastoral zone of northern China in the next 20 years with cultivated land and urban land being the most active land use types.

综合自上而下的系统动力学模型和自下而上的元胞自动机模型,从宏观用地总量需求和微观土地供给相平衡的角度,充分利用系统动力学模型在情景模拟和宏观驱动因素反映上的优势与元胞自动机模型在微观土地利用空间格局反映上的优势,发展了土地利用情景变化动力学LUSD (Land Use Scenarios Dynamics model)模型.利用该模型对中国北方13省未来20年土地利用变化的情景模拟结果表明,由于LUSD模型充分利用了系统动力学模型和元胞自动机模型的特点和优势,同时考虑了土地利用系统宏观驱动因素复杂性和微观格局演化复杂性的特征,因而提高了当前土地利用情景模型的可靠性,这将在一定程度上为理解土地利用系统的复杂驱动行为,评估脆弱生态区土地系统变化的潜在生态效应提供帮助.同时,LUSD模型的情景模拟结果也表明,农牧交错带地区是中国北方未来20年土地利用变化比较明显的地区,而耕地和城镇用地则是该区域内变化最为显著的两种用地类型.

Based on the long-term serial NOAA/NDVI dataset during 1983–1999 and SPOT/VGT dataset in 2001, the land use/cover change information in the 13 provinces of northern China was extracted based on the analysis of the cultivated landscape characteristics at first, then the effects of human activities on cultivated land process were explored by GIS and the driving forces of cultivated land change were investigated. The conclusions can be drawn as follows: (1) The constant increase of weak ecological function land as desert and cultivated land and the decrease of the ecological function land of forest and shrub were the main characteristics of the land use/cover change in the 13 provinces from 1983 to 1999, which showed the effects on the ecological adjustment function. However, such situations were changed to some extent in the 2000s because of the eco-construction policy of the government. (2) From 1983 to 2001, the Barycenter of cultivated land tended to move from northeast to southwest with the topography and transportation situations being the main influences on the cultivated land distribution. It is found that the cultivated land use intensity decreased noticably with the increase of distance from the main communication arteries. (3) The improvement of the people’s living standard is closely related with the cultivated land change. The structural adjustment in the agricultural land caused by economic development and the improvement of the people’s living standard is an important factor affecting the cultivated land change in northern China from 1983 to 2001.

Modelling scenarios of land use change and their impacts in typical regions are helpful to investigate the mechanism between land use and ecological systems and process the land use allocation under the ecological security. A system dynamics (SD) model with the aim to modelling scenarios of land use change and assessing ecological impact in northern China in the next 50 years is developed here. The accuracy assessment with the historic data from 1990 to 2001 indicated the SD model is robust. After the different “what-if” scenarios controlled by GDP, population, market, and technology advancement were built, the different scenarios of land use change in northern China from 2000 to 2050 were simulated with their ecological impact assessed. The result suggested that such factors as GDP, population, market and technology have a strong relationship with land use structural change in northern China. It also indicated that such measures as strict controlling of population increase, importing some food to keep the supply-demand balance in the region, and improving agricultural technology will be the guarantee of regional sustainable development with fast economic growth and the obvious land use structural improvement at the same time.