Land use patterns arise from interactive processes between the physical environment and anthropogenic activities.While land use patterns and the associated explanatory variables have often been analyzed on the large s...Land use patterns arise from interactive processes between the physical environment and anthropogenic activities.While land use patterns and the associated explanatory variables have often been analyzed on the large scale,this study aims to determine the most important variables for explaining land use patterns in the 50 km^2 catchment of the Kielstau,Germany,which is dominated by agricultural land use.A set of spatially distributed variables including topography,soil properties,socioeconomic variables,and landscape indices are exploited to set up logistic regression models for the land use map of 2017 with detailed agricultural classes.Spatial validation indicates a reasonable performance as the relative operating characteristic (ROC) ranges between 0.73 and 0.97 for all land use classes except for corn (ROC = 0.68).The robustness of the models in time is confirmed by the temporal validation for which the ROC values are on the same level (maximum deviation 0.1).Non-agricultural land use is generally better explained than agricultural land use.The most important variables are the share of drained area,distance to protected areas,population density,and patch fractal dimension.These variables can either be linked to agriculture or the river course of the Kielstau.展开更多
Evolution of river systems under the background of human activities has been a heated topic among geographers and hydrologists. Spatial and temporal variations of river systems during the 1960s-2010s in the Yangtze Ri...Evolution of river systems under the background of human activities has been a heated topic among geographers and hydrologists. Spatial and temporal variations of river systems during the 1960s-2010s in the Yangtze River Delta （YRD） were investigated based on streams derived from the topographic maps in the 1960s, 1980s and 2010s. A list of indi- ces, drainage density （Dd）, water surface ratio （WSR）, ratio of area to length of main streams （R）, evolution coefficient of tributaries （K） and box dimension （D）, were classified into three types （quantitative, structural, and complex indices） and used to quantify the variations of stream structure. Results showed that： （1） quantitative indices （Dd, WSR） presented de- creasing trend in the past 50 years, and Dd in Wuchengxiyu, Hangjiahu and Yindongnan have decreased most, about 20%. Structurally, the Qinhuai River basin was characterized by sig- nificant upward R, and K value in Hangjiahu went down dramatically by 46.8% during the 1960s-2010s. Decreasing tendency in D was found dominating across the YRD, and de- creasing magnitude in Wuchengxiyu and Hangjiahu peaks for 7.8% and 6.5%, respectively in the YRD. （2） Urbanization affected the spatial pattern of river system, and areas with high level of urbanization exhibited least Dd （2.18 km/km2）, WSR （6.52%）, K （2.64） and D （1.42）, compared to moderate and low levels of urbanization. （3） Urbanization also affected the evo- lution of stream system. In the past 50 years, areas with high level of urbanization showed compelling decreasing tendency in quantitative （27.2% and 19.3%） and complex indices （4.9%） and trend of enlarging of main rivers （4.5% and 7.9% in periods of the 1960s-1980s and the 1980s-2010s）. In the recent 30 years, areas with low level of urbanization were detected with significant downward trend in Dd and K. （4） Expanding of urban land, construction of hydraulic engineering and irrigation and water conservancy activities were the main means which degraded the river system in the YRD.展开更多
基金the financial support from the China Scholarship Council(CSC)through a scholarship for the first author
文摘Land use patterns arise from interactive processes between the physical environment and anthropogenic activities.While land use patterns and the associated explanatory variables have often been analyzed on the large scale,this study aims to determine the most important variables for explaining land use patterns in the 50 km^2 catchment of the Kielstau,Germany,which is dominated by agricultural land use.A set of spatially distributed variables including topography,soil properties,socioeconomic variables,and landscape indices are exploited to set up logistic regression models for the land use map of 2017 with detailed agricultural classes.Spatial validation indicates a reasonable performance as the relative operating characteristic (ROC) ranges between 0.73 and 0.97 for all land use classes except for corn (ROC = 0.68).The robustness of the models in time is confirmed by the temporal validation for which the ROC values are on the same level (maximum deviation 0.1).Non-agricultural land use is generally better explained than agricultural land use.The most important variables are the share of drained area,distance to protected areas,population density,and patch fractal dimension.These variables can either be linked to agriculture or the river course of the Kielstau.
基金National Natural Science Foundation of China,No.41371046The Commonwealth and Specialized Program for Scientific Research,Ministry of Water Resources of China,No.201201072,No.201301075Natural Science Foundation of Jiangsu Province,No.BK20131278
文摘Evolution of river systems under the background of human activities has been a heated topic among geographers and hydrologists. Spatial and temporal variations of river systems during the 1960s-2010s in the Yangtze River Delta （YRD） were investigated based on streams derived from the topographic maps in the 1960s, 1980s and 2010s. A list of indi- ces, drainage density （Dd）, water surface ratio （WSR）, ratio of area to length of main streams （R）, evolution coefficient of tributaries （K） and box dimension （D）, were classified into three types （quantitative, structural, and complex indices） and used to quantify the variations of stream structure. Results showed that： （1） quantitative indices （Dd, WSR） presented de- creasing trend in the past 50 years, and Dd in Wuchengxiyu, Hangjiahu and Yindongnan have decreased most, about 20%. Structurally, the Qinhuai River basin was characterized by sig- nificant upward R, and K value in Hangjiahu went down dramatically by 46.8% during the 1960s-2010s. Decreasing tendency in D was found dominating across the YRD, and de- creasing magnitude in Wuchengxiyu and Hangjiahu peaks for 7.8% and 6.5%, respectively in the YRD. （2） Urbanization affected the spatial pattern of river system, and areas with high level of urbanization exhibited least Dd （2.18 km/km2）, WSR （6.52%）, K （2.64） and D （1.42）, compared to moderate and low levels of urbanization. （3） Urbanization also affected the evo- lution of stream system. In the past 50 years, areas with high level of urbanization showed compelling decreasing tendency in quantitative （27.2% and 19.3%） and complex indices （4.9%） and trend of enlarging of main rivers （4.5% and 7.9% in periods of the 1960s-1980s and the 1980s-2010s）. In the recent 30 years, areas with low level of urbanization were detected with significant downward trend in Dd and K. （4） Expanding of urban land, construction of hydraulic engineering and irrigation and water conservancy activities were the main means which degraded the river system in the YRD.
