Land Use Classification And Safety Level Evaluation Based On Mixed Classification

Recently, due to the natural disaster and human disturbance, the ecological environment in Sanjiangyuan declined. This situation has seriously limited not only the local economic development, but also the ecological environmental security of the middle and low reaches of Sanjiangyuan watershed. The sustainable development and protection place the fundamental roles in the safeguard task in this area, which is essential and pressing. On top of this, Satellite imagery is the major data source for regional to global land cover maps. However, land cover mapping of large areas with medium-resolution imagery is costly and often constrained by the lack of good training and validation data so that the accuracy mostly cannot be qualified.Based on the hybrid classification for Landsat series satellite data, this thesis categorized the data, we can utilize the advantages of different methods and finally acquire the land use thematic map of 2010 and 2013 in Sanjingyuan. According to the output information, the geo-statistics and landscape analysis has been applied to the whole area and also 7 ecological core areas, where we continue to test the land eco-security level assessment.(1) The hybrid classification derived all advantages from both supervised and unsupervised classification can avoid the inconvenience to acquire training and validation data of large area and also keep high accuracy. The chain classification involved with SVM is very promising by using the overlap areas between two Landsat images. The across track accuracy is from 93.93% to 96.72% while the along track accuracy is from 96.24-97%, which in total accuracy is 91.75% for the hybrid classification.(2) There is no significance in landscape level for the land use in Sanjingyuan from 2010 to 2013 but the vegetation and bare land for some small areas. The grassland declined by 8302.56km2 and the forest declined by 1279.27 km2 while the bare land increased by 9016.53km2. The agricultural land and urban area expanded separately with 339.59km2 and 15,05 km2. The water resource is modified with 157.61 km2 increase in open water and 53.10 km2 in glacial snow area. The patches decreased for grassland. And the dominance level is medium, which presented in low level heterogeneity and yet high level fragmentation.(3) Based of the geologic factor including elevation, slope and aspect and soil background factor including erosion and pH value and water environmental factor and existing land use factor, we evaluate and assess the land security among 7 ecological core area in Sanjiangyuan. Finally,5 levels was classified:(1) non-sensitive area (2) low-sensitive area (3) medium-sensitive area (4) high sensitive area (5) extreme-sensitive area.