Ren Chunying

A GIS-based Tupu analysis of dynamics of saline-alkali land in western Jilin Province

Based on Tupu theory, this paper studied the dynamic changes, conversion modes, expansion intensity and landscape attributes of the saline-alkali lands in Changling County, Zhenlai County and Da’an City of the western Jilin Province in 1980–2000 with the help of GIS. The results show that the saline-alkali land rather sharply increased in Da’an during 1995–2000; the main conversion processes in the three counties were from grassland to saline-alkali land and from saline-alkali land to grassland; and the typical shapes, spatial expansion speed and mode, and landscape attributes of the saline-alkali land were different in the three counties, which were closely related to local topography, predominant wind orientation, water resources distribution, etc. The corresponding spatial expansion mode was marginality in Changling, random in Zhenlai and more kernels in Da’an, respectively. Landscape attributes also responded to the spatial-temporal dynamic changes of the saline-alkali land and the landscape indices of Da’an fluctuated greatly. The frame of this research may provide fundamental reference for landscape analysis and give some suggestions for regional sustainable development.

Spatial Distribution Characteristics of Non-Point Source Pollution of Xingkai Lake Irrigation District Based on L-THIA Model

Agriculture has been identified as the largest contributor of non-point source (NPS) pollution of surface and ground water systems globally. Estimation of non-point source pollution under different land uses is an important task in non-point pollution control in China. Taking Mishan city in Xingkai lake irrigation district as the study area, with the help of GIS and RS technology, the long-term average pollution loads in Mishan city were estimated using the Long-Term Hydrologic Impact Assessment (L-THIA) model. The spatial distribution characteristics of the pollutants were analyzed, including total nitrogen, nitrate nitrogen, total phosphorus and suspended solids. Results indicated that the spatial distribution of the four non-point pollutants is quite identical. The total loads of four pollutants were different under different land use types, and the agricultural land had the most important impact on non-point pollution in the study area. Forests and grassland contributed more to the retention of the pollutants in this area. The result of this research showed that L-THIA model is available for the spatial distribution of non-point pollution and it can provide the service for planning and management of the watershed.