| Cultivated land is one of the most important resources for humans.In resent years,the remote sensing.Satellite remote sensing technology is widely used for widespread crop yield estimation, crop condition monitoring, etc. Remote sensing has become a way that is fast and effective to survey cultivated land resources. Cultivated land resource is limited and population is expanding .So we are under the pressure. It is realistic significance to have a scientific judgment simply and fast on karst region of cultivated land use status and provide timely information services for relevant decision-making departments .Zuojiang river basin is located in southwest China. It is karst area in southern zone with complex topography and typical karst ecological environment. The karst spread large area. The droughts and floods occur frequently. Destroying forest, opening up wasteland on steep hill slopes, serious soil erosion, have serious impacts on the agricultural production and hinder the sustainable development of cultivated land use. This paper select the Zuojiang river basin as studied area,?combined with Landsat thematic mapper remote sensing 30m×30m image data and MODIS 250m×250m enhanced vegetation index data.?Relying on GIS related technologies as research methods, TM image data is selected as studied original data.?After projection transformation and geometric correction, we can get cultivated land use data by the means of people– machine interactive interpretation and create cultivated land use database. Furthermore, it analyzes the cultivated land use status. It gets MODIS image data years from 2001~2007 and removes invalid value data. This paper explores the ways to estimate cultivated land resource by using remote sensing data. Using the Best Index Slope Extraction (BISE) method and Savitzky_Golay (S-G) filter, it removes cloud pollution and reduces the noise for the image .In addition. It reconstructs EVI time-series data on study region and get Satisfied image.?By using two times differencing algorithm, this paper extracted the numbers of peaks of time series of EVI profile and the numbers cultivated land grid. And then, it get the multiple cropping index of the study region. Moreover, it made overlay analysis with images of peaks from MODIS and the actual land use map from TM to obtain cultivated land use efficiency in Zuojiang river basin. Results show that:(1) The result of TM remote sensing image illustrated that Zuojiang river basin haves farmland with total area 458023.74 hectares. Therein, paddy field accounted for 234600.11 hectares and dry land accounted for 223421.03 hectares. In cultivated land use types, 113 (paddy in plain) and 123 (upland in plain) of farmland area proportion is the largest, which sum accounted for total farmland area proportion greater than 65%.The total cultivated land area accounted for the total river basin area 22.72%. The statistic cultivated land landscape features index show that the average plaques area is reducing shape index and fractal dimension is becoming smaller, landscape fragmentation index is becoming greater than before. The change of cultivated landscape features most due to human interference.(2) The result of study area multiple cropping index shows that distribution of Zuojiang river basin is lower in central region, second in the northwestern ,higher in the northern and eastern in the year 2001.However, the multiple cropping index improved in the year 2007. The multiple cropping index between 180 to 190 concentrated in the south. The area that multiple cropping index was more than 200 was larger than the year 2001.It is very different from the year 2001 that the area where multiple cropping index from 180 to 190 in the year 2001, was improved more than 200 in the year 2007.The area where the multiple cropping index below 180 decreased. With official statistics and sample data, it verify that remote sensing data and the method of multiple cropping index extraction was feasible. It is effective method to estimate the multiple cropping index.(3) Cultivated land use efficiency evaluation results indicate that the paddy field use efficiency and the dry land use efficiency decrease in generally from the year 2001 to 2007. In plain area, which elevation is lower, the paddy field use efficiency higher than the upland use efficiency. The paddy field was planted a wide range of crops for plenty of water or storing water more easy. The use efficiency of paddy field lower than the dry land when there is higher elevation. The overall situation appeared that the dry land in mountainous area had the highest use efficiency, dry land in the hilly higher, dry land in the plain lowest between the types of dry land. The dry land use efficiency increase with the elevation rising. However, the use efficiency has no obvious change with the elevation between the types of paddy field. It analyzed the cultivated land use efficiency factors with method of principal component analysis. The result illustrate that cultivated land use efficiency is mainly influenced by population, economy and irrigation works. |
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