Research Project on Land use Land cover Change in the Past Ten

Document Sample
Research Project on Land use Land cover Change in the Past Ten Powered By Docstoc
					Towards Digital Earth                                                                                                   1
  — Proceedings of the International Symposium on Digital Earth
Science Press 1999

         Research Activities on Land-use/Land-cover Change in the Past Ten Years
                             in China Using Space Technology

                                   Dafang Zhuang* Jiyuan Liu Mingliang Liu

                             Institute of Remote Sensing Applications, Chinese Academy of Sciences
                                            P.O. Box 9718, Beijing 100101, P. R. China
                                                 * Email:

ABSTRACT Land use/cover change, which in China is characterized by urbanization resulting in a decrease in arable
land in the east along with a large area of grassland being cultivated in the west, has been accelerated by rapid
economic development in the last ten years. All of the above changes will affect sustainable development in the next
century. The Chinese Academy of Sciences is conducting a study of land use/cover change over the last ten years based
on the integration of remote sensing and GIS technology to establish a multi-temporal database covering all of China.
   Fundamental data for land use/cover for the year 1996 has already been developed by the Chinese Academy of
Sciences. In order to reconstruct fundamental land use/cover data for the year 1986, a central data processing and
analyzing system and a regional data acquisition, processing and analyzing system have been established and are
joined together as a network.
   After the 1986 database is established, the comparative research on the reduction in arable land, urbanization,
desertification, changes in forest and grassland, and lake and wetland land use/cover change will be carried out. In
addition, a transect for a key regional comparative study was selected along the Yangzi river. The driving forces of these
changes also will be extracted. The result of this study will be not only make a contribution to global land use/cover
change research, but will also support decision making for sustainable national development.

1. Introduction                                                   can be transformed into spatial systems under the
Recent and future development of space-based                      support of spatial simulation models. Then a spatial
remote sensing technology has brought a                           information system integrated by societal, economic,
reformation to research work as well as formulating               environmental and land-use/land-cover change
suitable    policy    for   population,   resources,              data can be built up to reconstruct the
environment and development. Through real-time                    contemporary processes since the historical data
and periodic observations of a large area of the                  were produced, and to support the further quantified
earth’s environment and natural resources, the                    research work on the interaction process between
spatial    information    technology    plays    an               nature and human beings. In recent years, study on
indispensable role in surveying resources,                        global LUCC has become a core research project in
monitoring the environment, and estimating crop                   IGBP, HDP and WCRP . The purpose of the study
production areas. Especially with the need for                    is to carry out global LUCC research all over the
national and even global-level sustainable                        world to establish quantifiable models for LUCC
development, the sustainable management of land                   depending       on      the     terrestrial   surface
resources has been highlighted. Land use intensity,               temporal-spatial series of data, and to identify the
land use diversity and land cover are land quality                biophysical and social driving forces of the LUCC.
indicators for sustainable land management. To be                 Further, using dynamic theory, a predictive model
able to assess the indicators and then to judge the               for LUCC should be built in order to provide advice
implementation of sustainable strategies, we need                 to the governmental authorities in charge of land
to depend on the spatial technology that has special              use management.
characteristics to meet those needs. Nowadays                        It is now universally recognized that indisputably
spatial technology is an integrated methodology                   huge economic, social and cultural development
and technology, incorporating satellite technology,               has occurred in the past few years in China. All
remote sensing technology, and temporal-spatial                   Chinese people hope that the process will be a
GIS technology for retrieving and representing data               continuous one, or in scientific terms, a sustainable
sets. Studies of the physical characteristics of                  development. But in fact, in the past ten years due
earth’s surface and on-going processes of change                  to the single-minded enthusiasm for economic
have entered the quantification stage, with the                   development on the part of some regional
whole data acquisition accomplished with spatial                  authorities, many environmental problems have
technology. Historical point data and survey data                 occurred which could disrupt the sustainable

    Supported by key project of Chinese Academy of Sciences for Knowledge Innovation(KZCX1-Y-02)
2        Dafang Zhuang et al./Research on Land-use/Land-cover Change in Past Ten Years in China Using Space Technology

developmental foundation. LUCC can indicate land               3. Research Foci
quality and environmental change and provides                  This project focuses on the following aspects:
information about the result of the interaction
between human and natural driving forces. LUCC                 3.1. Constructing a TM Image Database and
also can cause regional and even global climate                Landuse Maps in Mid-90’s.
change through changing the energy exchange                       (a) The Chinese Academy of Sciences (CAS) has
substance cycle within terrestrial ecosystems. In              completed the construction of a TM image database
addition, because the Chinese government is                    covering the whole country with images dating from
making great efforts to manage its land resources in           the years 1995 to 1996. The images have been
a sustainable way, LUCC data for the recent past               rectified and registered to a consistent projection
and the regional driving forces should be applied by           system with the same parameters, which will also
the government through the use of spatial                      be used to construct the image database from the
technology. Under the above circumstances, the                 TM images dating from the mid-1980s.
Chinese Academy of Sciences is carrying out a                     (b) Also the CAS has made a digital land-use
study of the land use/cover change over the past               map at the scale of 100,000, including an
ten years based on the integration of remote                   ecology/environmental       background      spatial
sensing and Geographic Information System                      database . These databases will provide
technology to establish a multi-temporal database              fundamental data for reconstructing the historical
covering all of China. A brief description of the              situation.
project will be presented in this paper, including
what the objectives are and how the objectives and             3.2. Reconstructing the Land Use Distribution in the
purposes can be reached.                                       Mid-80’s;
                                                                  (a) Constructing the image database covering all
2. Objectives                                                  of the country in the mid-1980s.
   (1) With the anxious need by the Chinese                       Since the development of remote sensing
government for a variety of data sets covering the             techniques since the 1960s, especially with the
whole country, a fundamental land-use/cover digital            launch of Landsat series satellites by the USA in
temporal-spatial database, which can reconstruct               1972 and the widespread use of those images, the
the history of land-use/land-cover change during               application of remote sensing has proved to be very
the past decade in China, should be built through              successful in the development of national economic
integrated application of spatial information                  indicators. The success of trial applications of
technology.                                                    remote sensing in China in 1979 has lead to the
   (2) LUCC mechanisms should be studied under                 development of widespread aspects of the
the impact of environmental dynamics and human                 implementation of remote sensing. Ground stations
activity. Research should be done on the                       in China were built in the mid-1980s, and they have
interactions between land use and terrestrial                  received and distributed a large amount of
biophysical processes and to further identify current          multi-temporal and multi-sensor remote sensing
LUCC trends so that future land-use/cover changes              image data. At the same time, with help from some
can be foreseen and rigorous decision support can              other related research projects, many other types of
be provided for sustainable land use management.               multi-temporal      remotely-sensed   image     data
Supervision of the implementation should also be               covering various regions have been collected,
provided;                                                      which reinforce the data sourced from the satellite
   (3) Keeping pace with significant international             ground stations.
research projects on global environmental changes,                Mining and managing the various existing aerial
the LUCC research project in China should focus                and satellite remotely-sensed data obtained since
on some key research subjects with high                        the 1980s has an indispensable role for
compatibility      with       the       International          understanding the national land resources and
Geosphere-Biosphere      Programme        and     the          environmental situations as of the mid-80s. On the
International Human Dimension Program on Global                basis of the image databases for the mid-90s, the
Environmental Change.        For    instance,     the          national database for the mid-80s will also be
contemporary process in global environmental                   created to meet the project needs and to further
change, their formation mechanisms, the driving                provide the data foundation for an even longer
forces of LUCC, and a temporal-spatial                         temporal series of land-use/cover change research.
imitation/forecast model should be emphasized in                  (b) Representing the national land-use spatial
the project.                                                   distribution in the mid-80s.
                                                                  The research project plans to reconstruct the
         Dafang Zhuang et al./Research on Land-use/Land-cover Change in Past Ten Years in China Using Space Technology   3

historical    land-use/cover   and    environmental            development of natural resources and environment,
situations as of the mid-80s with the application of           which can be used as a way to achieve the
remotely sensed images and spatial technology.                 sustainability of regional economic development
   Since     1980s,     the continuous economic                and ultimately to realize the concordant and further
development in China has had more and more                     development of the national economy.
impact on the land resources and environment both                 The establishment of “national environment and
in quantity and in extent. The usage style of land             resource database and information system”
resources and resource structure has been                      provides not only the data resource for comparison
changed very seriously. As a result, resource                  and analysis of the spatial characteristics of land
shortages and ecological environmental crises have             use, but also the technique and methodology is
received broad attention from all around the world,            needed in such kinds of studies. In addition, it is the
and these situations can hinder China’s sustainable            premise for improving quality analysis. On the basis
development        strategies. Understanding      the          of the comprehensive and systematic study of
changing conditions of national land resources in              time-serial data covering the mainland of China, this
recent years, we can create the data foundation to             project will explore the temporal-spatial dynamics of
preserve and explore the land resources effectively            national resources and environment as well as their
in a sustainable way and put forward decision                  characteristics in different regions.
support for preserving and reforming the                          Examples are:
environmental conditions to realize regional                      (a) The regularity and regional characteristics of
sustainable development in the future.                            land use.
   Remote sensing technology is an important                      (b) Land use spatial structure and its regional
pathway to acquire spatial and temporal series of                 differences.
data. The land-use situation, with spatial and                    (c) Land use intensity properties and their
temporal characteristics, is a direct indicator of                regional differences.
human activity on the land conjoined with the                     (d) Quantitative descriptions of the characteristics
natural impact on it. The remotely-sensed data that               of land use change processes in the past ten
were received by the ground stations in China since               years by use of the new concept of “land use
their construction have became a most important                   change degree” and forecasting the change
information source for reconstructing the history of              tendencies in land use patterns, land use
the land-use/cover situation.                                     structure and land use intensity.
   Depending on the abundance of remotely sensed                  Research emphasizes the following aspects:
data and the integrated technology of remote                      (a). Changes in urbanization and basic farmland
sensing and Geographic Information Systems, the                   resource dynamics.
project will reconstruct the land use history in                  (b). Forest resource dynamics.
mid-80s        with     man-machine     interactional             (c). Lake dynamics.
interpretation within an overall digital working                  (d). Desertification dynamics in semi-arid and arid
environment. Comparing the land use situation in                  areas.
the mid-80s with that of the mid-90s, the modern               Analysis and tendency forecasts in land use change
change process and the change trends on land                   characteristics will be performed in six zones:
resources and ecological environment can be                       1) Northeast China.
derived in order to provide useful information on                 2) North China.
forecasts and decision advice.                                    3) Northwest China.
                                                                  4) Southwest China.
3.3. Research on Regional Characteristic of Land                  5) Central China.
use Dynamics in the Past Ten Years;                               6) East China.
As a large country, China exhibits great differences
in   natural resources and            social-economic          3.4. LUCC Contemporary Processes and the
development. Obvious regional characteristics also             Driving Forces in Typical Research Zones;
exist in land use patterns, land use structure and             In the past ten years, while the economic zone
land use intensity. The purpose of spatial                     along the Yangzi River has achieved big progress in
comparison and analysis in land use and land use               economic development, environment problems
change in different areas is to get a full understand          have also occurred. The project selected this zone
about land use spatial information and the spatial             as case study area because of its unique
characteristics of land use change, and thus to                characteristics with multiple land use categories,
assure the validity and effectiveness of making                different economic development levels, and
decisions. It will also be helpful for the sustainable         different landscapes. Through the case study, we
4        Dafang Zhuang et al./Research on Land-use/Land-cover Change in Past Ten Years in China Using Space Technology

can get the premier data material to construct and             image quality and consistency in sensor type,
rebuild the mutual effect between the LUCC and the             imaging dates and overall image characteristics,
driving forces from nature and from human beings.              and so data pre-processing requirements are
According to the landscape of Yangzi River, four               critical. The historiacal remotely sensed data for the
research districts are distinguished. They are:                middle of the 80s for China have just been acquired
   (a) Yangzi River delta.                                     from different remote sensing platforms and from
   (b) Middle Yangzi River plateau.                            different sensors. In other words, it is impossible to
   (c) Three Gorges Reservoir.                                 make the data sets of the two dates compatible
   (d) Yangzi River upper reach area.                          thoroughly over the large area of China. In addition,
                                                               the change detection results obtained in this way
4. Methodology                                                 contain much false information, in that the detected
Historical remotely sensed data is an important                changes are probably not true land use/cover
information source to reconstruct the history of               changes but are only due to different imaging dates.
land-use/land-cover. Since 70s, vast amounts of                   By comparison, the post-classification change
these valuable data have been received from the                detection process by overall man-machine
satellites and those data have been preserved as               interaction interpretation does not have the critical
digital image data or photos. Relaying on the                  requirement for image quality and precise
historical remotely sensed data and some other                 comparability. Further, this interpretation method
point data sources and survey data sets, the                   has very high accuracy due to the experts’
land-use/cover situation and other relevant                    integrated geo-scientific knowledge involved in the
terrestrial environmental conditions of the time can           classification process. Generally, a classification
be reconstructed through interpretation. Through               criterion should be pre-constructed before
comparing the historical condition with the recent             interpreting the images, so that consistency
one, the environmental change characteristics                  between the land-use/cover maps can be ensured.
during this period can be revealed. Assisted by                As an input to this project, the land-use maps at
spatially disaggregated socio-economic data, the               scale 1:100,000 for the year 1995 have been
environmental and human driving forces, and the                completed after about two years of work, and the
interacting process between them, can also be                  interpreting process on the image data for the
identified. According to the above idea, the experts           middle of the 80s is now getting underway. The
group of the LUCC research project brings forward              personnel in charge of this interpreting work are
a methodology to study the land-use/cover change               almost the same as for the mid-1990s data.
in the past ten years (1985 ~ 1995) almost covering            Therefore, the comparability between the two dates
the whole country. The methodology includes:                   of land use maps will be very high.
(1) Interpreting the historical remotely sensed data
sets of the year 1985 and the newly developed data             (2) Constructing data criterion and operationali-
sets of the year 1995 through overall man-machine              zing standardization in the tempo- spatial dyna-
interaction before the land-use/cover change                   mic database.
detecting operation.                                           In order to manage the multi-temporal series of data
   There are two main ways to detect the LUCC                  efficiently and ensure the consistency between the
using remotely sensed data imaged at different                 series of land use maps of multiple dates, data
dates from the remote sensing platforms. One is to             criterion, data operating standardization, and a
compare the two images directly using many digital             tempo-spatial database including data management
change-detection techniques, such as image overly,             and data maintenance, should be established.
image differencing, principal component analysis
and CVA (Change Vector Analyses) methods. The                  (3) Developing land-use/cover temporal-spatial
principle of this method is that the changes in                database system and metadata database.
radiance of the same pixel indicate that land                  Relaying on the two date series of national
use/cover type has changed during the period. The              agricultural land resources databases at the scale
other way is to interpret the images and then to               of 1:100,000, and with the consistent data and
produce the land use/cover maps of the two dates               metadata criterion support, the project will build up
separately before operating the change detection.              both an integrated temporal-spatial database and its
Advantages and disadvantages both exist in the                 metadata database.
two methods.
   With regard to the first method, although it needs          (4) Generating the land use temporal- spatial
less labor and has higher processing speed in                  thematic data sets.
detecting changes, it also has rigorous demands for            A dynamic database at the scale of 1: 100,000 with
         Dafang Zhuang et al./Research on Land-use/Land-cover Change in Past Ten Years in China Using Space Technology   5

different thematic subjects including farmland,                appeared before. However, by trial and error, we
urban area, forest and lakes for all of the country as         tackled these problems through developing
well as desertification dynamics in semi-arid and              expertise, and as a result plenty of experiments
arid region will be developed by overlaying the land           have been obtained. With the support from these
use data of two different periods (mid-80s and                 two periods of databases and these valuable
mid-90s). The contemporary land use/cover change               experiments, we can research on more time-slices
processes from the end of the 1950s along the                  of land use and cover history, reconstructing the
Yangzi River will be derived using spatial analysis            historical conditions and change processes, and
tools and the LUCC process database of different               understand the role of change in the terrestrial
case study areas will be derived by employing the              biosphere under the interactivities between humans
land use data of the two periods and other relevant            and nature.
5. Discussion                                                  [1] Land Use and Land Cover Change Science/research
This LUCC research project is supported by                        Plan. IGBP Report No.35, HDP Report No,7 Stockholm
Chinese government and so will serve the                          and Geneva, ISSN 0284-8015,1995
government at the national level directly. The                 [2] Liu Jiyuan, Macro-scale survey and dynamic study of
implementation plan has been brought into practice                natural resources and environment of China by remote
two years ago. During the former process, we                      sensing, Chinese Sciences & Technology Publish
confronted many new matters that had not                          house, ISBN 7-5046-2323-7, 1996