1043 
A SIMPLE METHOD FOR INFORMATION EXTRACTION 
OF FARM FIELD IN TARIM RIVER BASIN USING MODIS DATA 
Shudong Wang 3 ', Suhong Liu 3 ’*, Xiaohua Wang b , Jianxia Guo 3 , Yanmin Shuai 3 , Ni Hu 3 
State Key Laboratory of Remote Sensing Science; Beijing Key Laboratory for Remote Sensing of Environment and 
Digital Cities; Center for Remote Sensing and GIS, School of Geography; Beijing Normal University, 19 Xinjiekou 
Wai Street, Beijing, 100875, China-(wangsd @bnu.edu.cn 
b School of Economic and management, Hebei University of Engineering, 199 Guangming South Street, Handan, 
China,05 603 8-hdwxh@ 163 .com 
KEY WORDS: Tarim River Basin, MODIS Vegetation Index, Time Series, Farm Field 
ABSTRACT: 
High spatial resolution remote sensing data are expensive and hard to cover the whole basin at the same time in Tarim river basin, 
while, the low spatial resolution data, such as MODIS, which spatial resolution of first (red) and second (infrared) band are 250 m, 
may cover the whole basin in same day. In this paper, based on previous models and methods, we compared the remote sensing 
Vegetation index, NDVI, RVI and MSAVI (250m), which are thought most efficiently parameters and have been used widespread in 
arid and semiarid area. Analyzing changing rule of soil, sparse natural and farm field of underlying surface, we put forward a new 
method: calculating stand deviation using time series MODIS RVI data from April to October. Compared with extracting farm 
information method of previous classification method and principle component analysis method using time series MODIS data, the 
method is more efficient than others, and the accuracy exceed 80%, which verified by Landsat TM data and actual measurement by 
GPS. 
1. INTRODUCTION 
Water is the foundation of the composition, development, and 
stability of oasis ecosystems in arid areas [1]. It determines the 
evolution of the ecological environment, including the two 
contrary processes of oasis formation and development and of 
desertification, and it is the key ecological factor in arid areas 
[2]. It is widely recognized that human activities will affect 
water resources and hydrological processes. Located in the arid 
area of north-western China, Tarim River, about 1321 km long, 
is the longest continental river in the world. It is mainly fed by 
glacial/snow melt water, which accounts for 48.2% of the total 
water volume in the basin [1]. The ecological environment in 
the Tarim River Basin is extremely vulnerable. The 
contradiction between ecological protection and economic 
development is increasingly extrusive in the exploitation and 
utilization of water resources, and the sustainable development 
of the regional society and economy is seriously restricted [3-5]. 
Significant improvements have been made in regulating the 
main stream of the Tarim River for flood control and water 
supply mainly for agricultural purposes during the past several 
decades. These improvements have made a great contribution to 
the development of the economy in Tarim River Basin [2]. 
However, its negative influences such as deforestation, 
desertification, and increased soil salinity have also been 
considerable. Some eco-environmental problems including the 
serious degeneration of the natural vegetation that relies on 
groundwater for existence, the death of the herbs dominated by 
Phragmites the degeneration of Tamarix chinensis shrubbery 
and the Populus diversifolia forests in large areas, serious wind 
erosion and land desertification, as well as the seriously 
damaged ecosystems [6]. Both local and central governments 
have paid significant attention to the altered hydrological 
regime of Tarim River ecology. In an attempt to restore the 
ecological system, ecological water releases from Boston Lake 
through Daxihaizi Reservoir were carried out several times [7]. 
It was realized that these water releases were beneficial to the 
potential restoration of the ecosystem. 
But farm field water consumption is much larger than natural 
vegetation in same area, so flood control and water supply 
mainly for agricultural purposes during the past several decades, 
the ecosystem still is facing deterioration [2, 7]. When water 
supply for field isn’t enough, some field farm would be 
abandoned, new ecological problems appear again [5], So 
information extraction of farm field in Tarim River Basin is 
important to decision making of both local and central 
governments. 
Compared with methods of other investigation, application of 
remote sensing data is more efficient and timesaving. High 
spatial resolution remote sensing data, such as Landsat TM, are 
hard to cover the whole basin at the same time, and the low 
spatial resolution data, such as MODIS, which spatial resolution 
of first and second band are 250 m, may cover the whole basin 
everyday. In this paper, based on previous models and methods, 
we compared the remote sensing Vegetation index, NDVI, RVI 
and MSAVI (250m), which are most efficient parameters and 
are used widespread in arid and semiarid area, and selected 
NDVI and RVI as basic data of information extraction. 
2. SELECTION OF REMOTE SENSING VEGETATION 
INDEX 
Currently, the remote sensing Vegetation index, NDVI, RVI 
and MSAVI (250m), are most efficient parameters and are 
widespread used in arid and semiarid area. 
* Corresponding author. Suhong. Liu