Sustainable development calls for the wise use of groundwater resources. Of particular concern is saline intrusion into productive agricultural land, which is contiguous with densely populated coastal settlements. To reverse saline intrusion in such coastal regions, information about the groundwater depth in terms of its spatio-temporal variability is essential. Using survey data from 2004 to 2007, the research revealed the temporal variation characteristics of groundwater depth in the Contemporary Yellow River Delta. It explored the temporal stability characteristics of groundwater depth by using the coefficient of variation, Spearman rank correlation coefficient, and average relative deviation and standard deviation, and confirmed that the representative point reflected the average groundwater depth of the study area. Results showed that spatial variation of the groundwater depth in the study area was medium, but the variation coefficient of groundwater depth showed the seasonal changes. The spatial variation coefficient was largest in the dry season; the other months were relatively stable. The groundwater depth in the study area had strong temporal stability. The correlation between the Spearman rank correlation coefficient and the time lags showed that the spatial pattern of groundwater depth in the study area was similar across two or three years but the similarity weakened beyond this period. The representative points of the whole area showed a good linear correlation, and were spatially concentrated. In different years or time periods, the representative points were not the same but belonged to the medium groundwater depth grade in the area. The study provides useful guidance for Yellow River irrigation, preventing saline intrusion and the restoration of saline-alkali soils. It offers a theoretical basis for identifying regional satellite groundwater depth monitoring points.

Land degradation is a major environmental problem internationally. Soil degradation is one of the key factors of land degradation, which is related to susceptibility to erosion, soil suitability, and soil characteristics especially at regional scale. It is important and meaningful to evaluate objectively land degradation at regional scale. The study is to present the classification approaches for land degradation by Degraded Soil Line Index (DSLI) and object-oriented method by determination of land degradation spectral response units (DSRU) compared to the spectral angle mapping (SAM) method using Hyperion image data for mapping land degradation. The method was tested in a study area located in Hengshan county in ShaanXi province, China, where is in the agriculture-pasture mixed area in Loess Plateau in China with complex physical geographical situation. The results showed that the three methods of SAM, DSLI and DSRU have the ability to map land degradation and degraded soil classes, and the performance of the methods of DSLI and SAM is different and DSLI is prior to SAM for land degradation mapping in the study area. Moreover, the results also showed that the object-oriented analysis method based on DSRU approach is valid for extraction of land degradation information and clearly shows the degraded land classes with an overall accuracy of 0.88 and Kappa coefficients of 0.86.

This paper analyzed land use change in Bashang area of Hebei province, with 1992 and 2002 TM (ETM). Based on GIS and statistical methods, the intensity, state index of land use change and transfer matrix were used to study spatio-temporal land use change in the region. The results showed that the area of arable land decreased greatly, also the area of wetland decreased. The other way round, the area of grassland, forest land and building land increased. As a whole, the intensity of forest land change was higher, but others were lower. From the transfer matrix, most of the arable land changed into grassland and forest land, some to building land. The grassland and forest land was mainly transferred from unused land, except for arable land. The building land mostly came from arable land. The wetland was used for grass and forest area. It was showed that the eco-environment degraded, and the land use change was an important driving force of eco-environment change in the study area. Unfeasible land use pattern and land reclamation by human beings resulted in soil loss and sandy land increase.