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Management & Engineering Based on TM Images
Management & Engineering 06 (2012) 1838-5745 Contents lists available at SEI Management & Engineering Journal Homepage: www.seiofbluemountain.com Dynamic Monitoring of Land Use/Cover in the Qufu City Based on TM Images Weihua JIA College of Geography and Tourism, Qufu Normal University, 273165, P.R.China KEYWORDS ABSTRACT Qufu city, Land use/cover, Dynamic monitoring, TM images Qufu city is the hometown of Confucius. It is located in the southwest of Shandong Province. And its area is 895.93 square kilometers. The annual equal temperature is 13.3 degree and annual amount of precipitation is 666.3 mm. In this paper, the land use/cover change (LUCC) in the Qufu City is researched using two sets of Landsat images acquired in 1987 and 2005. The land use information in the study area is derived with the supervised classification, and the causes resulting in LUCC are analyzed. The research shows that the areas of urban and rural building land expand by reducing the area of farmland and the areas of the woodland and water are sharply increased. The economy development and the city development are the macroscopically driving forces of the land use/cover change. The sharp population growth and rapid development of primary industry are the direct reasons that reduce the area of farmland. While the increasing water area is greatly related to the building of Ni Mountain Reservoir. © ST. PLUM-BLOSSOM PRESS PTY LTD 1 Introduction With the research and development of global change, land development and the coming land cover change are considered as important parts of global environmental change. International Geosphere - Biosphere Programme (IGBP) and International Human Dimensions Programme (IHDP) jointly proposed “Land Use and Cover Change” (LUCC) research projects in 1955, making land use changes the frontier and hot issues of the current global change research[4]. In China as the huge population base, relatively limited farmland resources, and the urgent development of economy and improvement of living standards and other special situation. Remote sensing image has been widely used in the extraction of land cover information. This article analyzes the basic characteristics and disciplines of the land use/cover change in Qufu city based on Landsat TM image. 2 Research Area and the Data Sources 2.1 General situation of research area Corresponding author. E-mail address: [email protected] English edition copyright © ST. PLUM-BLOSSOM PRESS PTY LTD DOI: 10. 5503/J. ME. 2012. 06. 007 33 Located in the southwest of Shandong Province, Qufu city has the latitude ranging from 35°29'N to 34°49'N and longitude from 116°51'E to 117°13'E. It has warm continental monsoon climate which has four distinct seasons and abundant rainfall with the annual (1965-1990) average temperature of 13.6℃ and the annual precipitation 666.3mm. 135km south of Jinan, 45km southwest from Jining, the east next to Sishui and north to Ningyang while the west to Yanzhou and south to Zoucheng, Qufu has an total area of 895.93 square kilometers with the largest vertical north-south distance of 35.8 kilometers and east-west distance of 5km. Meanwhile, as one of 24 historical cultural cities in China, Qufu is the homeland of Confucius, the famous ancient educator and thinker. Being famous in the world for its rich underground cultural relics and magnificent buildings on the ground, Qufu is a tourist attraction aspired by Chinese and foreign visitors [6]. 2.2 Data sources The data sources used in this study include: Landsat TM images of Jining accessed on September 19th, 1987 and May 31st, 2005, the administrative vector map of Jining, the recent land use map of Qufu and the related statistical yearbooks and social economic statistic data. 3 Research Method and Data Process 3.1 Land categorized system First of all, the approximate land use types are defined by the unsupervised classification of the remote sensing images of Qufu in 1987 and 2005. Then, 5 categories come out considering the classification standards in the National “Land Use Survey Technical Specification” as well as the actual situation of the area. They are residential and industrial land, woodland, farmland, water and unused land. 3.2 Selection of research method Currently, measurements of land use/cover change based on satellite remote sensing are mainly post-classification comparison and object spectrum direct comparison. Due to some factors such as atmospheric conditions, solar altitude angle, soil moisture and phenology in different times have direct impacts on spectral images, spectrum direct comparison must be strictly spectral standardized, yet standardization is in immaturity. Post-classification comparison does not require rigorous radiation normalization, but high classify precision of single scene image. Because the accumulation of classification errors in different times will affect the ultimate accuracy of the information of land use/cover changes, it is critical to succeed of this method that classification accuracy of single scene image be improved [1]. Based on the dynamic monitoring experiment in small area, taking the long time span of the remote sensing data into account, this article apply the post-classification comparison to measure the land use/cover change. It firstly extracts land use information in 1987 and 2005 using supervised classification, then on this basis it calculates land use transition matrix and then analyzes land use change. The study proceeds in accordance with the remote sensing image processing, land use information extraction, analysis of land use change. 3.3 Data processing 3.3.1 Image registration To begin with, change the map projection of TM image of Jining in 2005 into WGS84, then use quadratic polynomials and bilinear interpolation to do the geometric correction of the images. By means of reselecting 15 ground control points to be tested, the error is within one pixel and the re-sampling of image output is 30 meters. Then it does matching processing of the TM image in 1987 according to the corrected image in 2005, unifying projection and pixel size. The RMS error is less than one pixel after reselecting the points, which meets the requirements of further analysis. The image of Qufu city is cut based on the well-geometric correction image using the administrative vector map of Jining by software ERDAS. 3.3.2 Image enhancement processing Due to the stability of the satellites, atmospheric conditions, solar altitude angle, soil moisture and phenology, all of which have direct impacts on spectral images,directly extracting information from the remote sensing images is difficult. Therefore, it is necessary to do image enhancement processing in order to extract information easily. Take color composite by selecting the best band combinations for example, the result of color composite of band 5,band 3 and band 1 standing for RGB is better in the test. 3.3.3 Classification of RS image and extraction of land use information Unsupervised classification is a natural classification depending on the distribution of spectrum characteristics of remote sensing images. The classification results only distinct different categories, not knowing the certain types of the property, which is achieved by analyzing the various spectral response curve afterwards. Compared with unsupervised classification, supervised classification has some advantages, but its results often have mistakes, leading to low classification accuracy. Therefore, measures should be taken before classification in order to improve the accuracy of supervised classification when extracting land use information. Measures taken before image classification mainly aimed at training area, because the supervised classification accuracy is closely related to the choice of training areas [3]. Therefore, classification module should be defined before supervised classification combined with 34 spectral information of remote sensing images. Initial definition of the classification module may be very different from the actual situation, which requires redefinition of the module until it is consistent with the actual situation of the land use. Small polygons will inevitably appear in the supervised classification when using this classification module. The analysis function of GIS such as Clump, Sieve, and Eliminate in ERDAS can complete the processing of these small polygons. The ultimate result after processing is shown in Figure 1. Fig.1 Distribution of land use types in the Qufu region (left: 1987; right: 2005) 3.3.4 Accuracy analysis With reference to the surface data of the same period, it calculates the classification confusion matrix and kappa coefficients by selecting randomly a number of samples of the area. Kappa coefficients through accuracy test on the final land use results map are 0.75 (in 1987) and 0.78 (in 2005). This shows that the results of both single scene images are ideal, so it can be further analyzed to extract dynamic information of land use/cover change. 3.3.5 Analysis of LUCC characteristics On the basis of information of land-use types in 1987 and 2005, this study obtains the land-use transfer matrix (Table 1) in the study area during this period, using the method of algebraic operation of the map. Tab.1 Matrix of the change of land use in the Qufu region during the period from 1987 to 2005 /ha Residential and industrial land Woodland Unused land Farmland Water Total Proportion Residential and industrial land Woodland Unused land Farmland Water Total Proportion 5401.53 3051.99 355.05 531.36 263.79 9603.72 0.12 1804.68 14560.9 2379.96 7341.84 583.11 26670.49 0.33 735.48 2530.08 184.32 10656.09 0.13 3951.54 10841.9 331.74 32738.07 0.41 2808.09 1698.39 107.91 7349.4 0.09 2640.42 16593.8 34.83 27142.25 0.34 252.36 1136.25 665.55 2901.06 0.04 10387.89 32800.42 1324.35 0.13 0.40 0.02 As can be seen from Table 1, the land use is mainly on the great increases of structural adjustment, while a great decrease of farmland during 1987—2005 in Qufu, in which woodland increased 6067.58ha accounts for 22.8% of the total area of woodland in 1987, and water area which increased 1576.71ha is 119.1% times of waters in 1987, which is directly related to the construction of Ni Mountain Reservoir. Farmland which decreased 5658.17ha accounts for 17% of the area of farmland in 1987. The decreasing of farmland ca n not be ignored in the process of local development. Therefore, we should protect the limited farmland resources strengthening the construction of basic farmland to achieve regional sustainable development. Residential and industrial land which increased 1052.37ha accounts for 11% of the total area in 1987. Combined with the land use in 1987 and 2005 and land-use transfer matrix, it is easily drawn that the increase of residential and industrial land was mainly achieved through the occupation of a lot of farmland. A total of 2530.08ha farmland changes into residential and industrial land, representing 46.4% of total conversion of residential and 35 industrial land. Area of unused land reduces 3038.49ha, showing that unused land is well developed. From the mutual transformation of different land use patterns, farmland mainly changes into woodland and urban construction land, with the conversion area of 10841.9ha and 2530.08ha respectively. Farmland and woodland transform mutually in spatial land use, about 7341.84ha of woodland being developed into farmland and 10841.9ha farmland being converted to woodland. Unused land is developed primarily for the cultivated farmland and woodland, 2640.42ha and 3951.54ha respectively. Part of the waters is the occupied with the residential and industrial land and woodland. The main ways of increase of farmland in this period are developing the unused land and occupying a large number of woodland. Increase of woodland is mainly returning farmland to forest as well as developing unused land. Residential and industrial land enlarges its area mainly through occupation of a large number of farmland and woodland. Besides 4541.31ha land changes into unused land, showing a certain degree of degradation. 4 Analysis of Driving Forces 4.1 Economy development and urbanization Since the reform and opening-up, China has taken economic construction as the center of the basic economic policy, making great changes on economic development strategies and economic system. With the rapid development of China's economy, prospects for national economic development are good. Especially the development of township enterprises becomes the main pillar of economic development, which promotes the increase of residential and industrial land by occupying large amount of farmland. There is 2530.08ha farmland in total converting to residential and industrial land. Qufu is a small city, where the contradiction between urban expansion and farmland protection is not very prominent but has been increasing. Therefore, in future urban development requires rational planning of urban spatial distribution to avoid occupation of farmland and develop unused land actively. 4.2 Population and economy development As the population growth increases the need of living area, large farmland surrounding the city is converted into urban construction land, leading the decrease of farmland area, which is represented obviously in the land use map of 1987 and 2005. Population growth demands for more farmland, which is lost due to urban expansion. Then more farmland is forced to be obtained by deforestation and in other ways, but deforestation can cause soil erosion and a series of environmental problems. Therefore, we should control the population, strengthen the protection of basic farmland, carry out afforestation and soil conservation, protect the local environment and take the path of sustainable development. 4.3 Government policy and social activities Land use/land cover change is a result of common impact of natural and human factors. In a very long period of time, changes of natural conditions such as changes of temperature, precipitation, and biological species and quantities will impact land use/land cover greatly, which is not obvious in a short period of time because changes of natural conditions isn’t significant. Thus, socio-economic activities become the main factors affecting land use/land cover change [5]. It is especially true for such a small city as Qufu that the land use policy and some major socio-economic activities will affect land use changes. The implement of reasonable urban planning and soil conservation policy will mollify the contradictions of economic development and farmland protection, making the land use legal and orderly. The construction of some projects will also affect the distribution of land, for the doubled area of water in 2005 compared with it was in 1987 is directly related to the construction of Ni Mountain Reservoir. Therefore, this area should be strengthened in the research of land use. 5 Conclusion and Discussion (1) Land use/cover change during the 18 years in Qufu shows that urban land extended by occupying a total area of 2530.08ha farmland which accounts for 11% of the total farmland in 1987. A substantial increase in woodland mainly comes from the occupation of farmland while the rest comes from unused land. The increase in the area of water itself is not large, but accounts for 119.1% of the water in 1987, primarily because of the construction of Ni Mountain Reservoir. Changes are very significant in non-urban land use structure, especially between the farmland and woodland, with 10842.9ha farmland converting into woodland, while 7341.84ha woodland into farmland. (2) Spatial pattern of land use: urban land concentrates in urban area of Qufu city either in 1987 or 2005, although little increase appears in other regions. Woodland as well as unused land mainly concentrates in the mountain areas in northern and southeastern. Farmland mainly concentrates in the flat plains area with good irrigation conditions, where Si River, Yihe River and other rivers flow across. (3) The land use/cover change in Qufu results from combined effect of different levels of driving forces. Human activity changes the overall pattern of land use, while policy guidance is the macro factor affecting land use change. Population growth and development of primary industry are the direct driving forces of the decreases of the farmland, and traffic conditions determine directly the scale 36 and direction of urban development. Land use change is a very complicated process which is influenced by a lot of natural and socio-economic factors interacting with each other. As the temporal-spatial scale changes, conversion and succession between the driving factors and background may arise. Therefore, the research of the land-use change and its driving forces is a complex and difficult task, with the occurrence mechanism of land use change to be further explored. References [1]. HE Chunyang, SHI Peijun, et al. A Study on Land Use/Cover Change in Beijing Area [J]. Geographical Research, 2001, 20 (6): 680-682 (in Chinese) [2]. ZHANG Hailong, JIANG Jianjun, ZHOU Jie, et al. Land Use/Cover Change in Xi’an Area Based Landsat TM [J]. Arid Zone Research, 2006, 23 (3): 428-431 (in Chinese) [3]. 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