This paper summarizes our research on land use and cover changes in the critical areas named North Ningxia (Yinchuan Region), North Shaanxi (Yulin Prefecture/Mu Us) and Middle Tarim River in northwest China. The objectives of the study were to investigate the present land use situation and changes in the past decades and to understand causes of landuse changes. Multi-temporal Landsat TM and ETM+ images (plus an old Corona image for the Middle Tarim), countylevel
socioeconomic data and meteorological data were used for this task. The methods and procedures adopted in this work were image registration, atmospheric correction, tasseled cap transformation, indicator differencing, county-level change mapping, and multivariate regression modeling. The principal conclusions are as follows: (1) Not “advancing desert” was observed; however, signs of serious land degradation, e.g., vegetation degradation and soil salinization, have
apparently taken place in the past decades due to cultivation practices, land reclamation and grazing. Some of these changes can be traced back to land use policies. (2) Farmland extension is a remarkable rural environmental change in these sites and is associated with the increase in agricultural output. Taking up a small percentage of the total change, the urban extension is related to about 90% of the GDP growth and driven directly by the urban population and their socioeconomic activities. Some river courses have been narrowing, owing partly to climate variability but mainly to the overuse of water in agriculture.
This study is located in Tarim Basin southern part of Xinjiang Uygur Autonomous Region, China. Owing to the special landform of the basin, it has considered as one of the most representative region in arid and semi-arid lands in the globe. More and more scientists had paid attention to focus on its land-use and land-cover change. Expanding oases, soils salinization and dying poplar forest are the major changes in this region over the past forty years. Thus to investigate the reasonable causes and consequences for above three highlights, post-classification comparison change detection, which was considered as one of the most effective method among change detection techniques, was carried out between two satellite images of Landsat ETM in 2000 and Corona panchromatic in 1964. This paper is also concerned with the exact selection of experimental sites in critical region by individually designing several comparable areas for corresponding research purpose aimed at extract human-induced impacts from natural formed influence. In order to have a general understanding of this region, relative researches such as climate change as well as socioeconomic evolution was also discussed.
Since the construction of a harbour, Port de l'Amitie, an important importation gate for Nouakchott in 1987, the previous coast dynamic equilibrium had been destroyed and thus a significant littoral geomorphological change has occurred, which has produced a severe degradation of the littoral and urban environment. Our research is focused on this coastal environmental change monitoring and its potential evolution estimation by remote sensing techniques using multi-temporal SPOT images and Markov chain analysis. The objectives of this study are to understand coastline evolution particularities, measure geomorphological change rates, evaluate life-span of the harbour, produce useful data for the government to control the environment degradation and provide reference for the future similar coastal engineering. According to our research, the north beach of the harbour has extended by 0.92km<sup>2</sup> (91.6ha) from 1989 to 2001 and the accretion will probably reach its maximum limit in about 13.4 ± 0.5 years (in 2014-2015) and the harbour will arrive at the end of service. The south sandbar has been eroded by 1.34km<sup>2</sup> (134ha) and the coastline has landward retreated at the maximum by 362m. Another 0.91km<sup>2</sup> of land will be nibbled by seawater in the next 10 years. This erosion has caused several times inundation into the suburb and urban areas, provoking a deterioration of the urban environment.