1990—2018年赤水河流域土地利用变化分析

Study on the characteristics of land use change in Chishui River Basin from 1990 to 2018

土地利用的变化可以直接反映人类活动程度,赤水河作为长江流域上游的重要支流,在共抓长江大保护的时代背景下,掌握其土地利用动态变化有利于土地优化管理和区域可持续发展。利用1990—2018年共7期土地利用数据,根据区域特点,整合水田、旱地、林地、草地、水域、城乡建设用地、未利用地7种土地利用类型,从分布格局、土地利用单一动态度、土地利用转移矩阵方面对赤水河流域土地利用类型的空间分布与时空变化进行分析。结果表明:赤水河流域各土地利用类型面积占比为林地>旱地>水田>草地>城乡建设用地>水域>未利用地,林地分布广泛,集中分布在赤水河流域下游,旱地多分布在流域上游,水田多分布在流域下游,草地和城乡建设用地多沿河谷分布;各土地利用类型动态度变化随时间逐渐升高,其中草地、城乡建设用地在2015—2018年动态度变化明显提高;受退耕还林政策的影响,林地与旱地间的转化较多,且2006—2015年转化程度高于1990—2000年,而2006—2015年、2015—2018年草地、城乡建设用地与其他土地利用类型间的转化明显增多。赤水河流域GDP总量增长速率逐年升高,与城乡建设用地增长速率相比,2015—2018年有所减缓,城乡建设用地单位面积经济产出逐年降低,土地利用效率有待提高。

Changes of land use can directly reflect the extent of human activities.The Chishui River is an important tributary of the upper reaches of Yangtze River Basin.In the context of the great protection of the Yangtze River,mastering the dynamic changes of land use is conducive to land optimization management and regional sustainable development.Based on the land use data of seven periods from 1990 to 2018,and according to the regional characteristics,seven land use types,i.e.paddy field,dry land,forest land,grassland,water area,urban and rural construction land,and unused land were integrated to analyze the spatial distribution and temporal and spatial changes of land use types in Chishui River Basin in terms of distribution pattern,single dynamic degree of land use,and land use transfer matrix.The results showed that the area proportions of land use types in Chishui River Basin was in the order of forest land>dry land>paddy field>grassland>urban and rural construction land>water area>unused land.The forest land was widely distributed,mainly concentrated in the lower reaches of Chishui River Basin.Dry lands were mostly distributed in the upper reaches of the basin,and paddy fields were mostly distributed in the lower reaches of the basin.Grassland and urban and rural construction land were mostly distributed along the river valley.The dynamic degree of each land use type gradually increased over time.The dynamic changes of grassland,urban and rural construction land increased significantly from 2015 to 2018.Affected by the policy of returning farmland to forest,there has been more conversion between forest land and dry land,and the degree of conversion in 2006-2015 was higher than that in 1990-2000.The conversion of grassland,urban and rural construction land and other land use types increased significantly in 2006-2015 and 2015-2018.The total GDP growth rate of Chishui River Basin had been increasing year by year and,compared with the growth rate of urban and rural construction land,it had slowed down from 2015 to 2018.The economic output per unit of construction land area had been decreasing year by year,so the land use efficiency needed to be improved.