东江下游河网区土地利用变化及其对水体的生态影响

Land-use Change and Its Ecological Effect to the Water in Downstream River Network Area of Dongjiang Basin

论文以东莞市为研究区域,基于1990、2000、2009年3期遥感影像,采用土地利用变化速率、土地利用转移矩阵及景观指标,分析了近20 a东莞市土地利用变化过程及其对水体的生态效应。研究结果表明:①近20 a东莞市土地利用结构由农业用地、林地为主向城市建设用地为主迅速转变,耕地、园地、林地比例由1990年的23.56%、13.39%和28.73%下降为2009年的11.35%、3.26%和17.39%,与此同时建设用地面积比例则由20.21%增加为53.62%,此外,2000—2009年土地利用变化程度较1990—2000年更为剧烈;②东莞市农业用地面积逐年降低,单位面积化肥施用量减少58.30%,单位面积农药施用减少32.35%,表明农业面源污染在过去一段时间内具有减弱趋势,与此同时城镇建设用地下垫面增加导致的城市非点源污染威胁则逐渐增强,这一情形将随着城市化用地的继续扩展和水体总面积的减少而愈加严重;③东莞市水体景观优势程度逐渐下降,水体受人为干扰强烈。水库、河流缓冲带内建设用地比例明显增加,河道被人工化、渠道化程度增强。综合以上研究结果,东莞在城市化建设中应加强水资源的保护和管理;水污染防治中,在治理点源污染的基础上,加强城市下垫面非点源污染的防控。

Dongguan plays an great important role in the utilization of water resources around the Pearl River Delta and Dongjiang watershed.However,the rapid urbanization leads to severe land use change in this area.It＇s necessary to realize land use change characteristics and especially its ecological effect on the water.This kind of research would improve our strategies making on the land use planning and water resources management.Based on the multi-temporal remotely sensed data in 1990,2000 and 2009,this paper takes a research on the land-use change by using land-use change rate,land-use transfer matrix and land scope indicator.Then through several landscape indicators,the paper also describes water landscape and land-use landscape pattern in the buffer around the river and reservoir,in order to understand land-use change ecological effect to the water in Dongguan City.The conclusions can be drawn as follows：1） In recent two decades,the major land use type has changed into urban construction land from forest and agricultural land rapidly,the ratio of cropland,garden and forest has reduced from 23.56%,13.39%,28.73% in 1990 to 11.5%,3.26%,17.39% separately;while the urban construction land increases from 20.21% to 53.62% sharply,and the change rate of the land use during 2000-2009 is more severe than that in 1990-2000.2） The agriculture area decreased gradually,and the amount of fertilizer and pesticide use has been cut down by 58.30% and 32.35%,which means agriculture non-point source pollution reduces in recent period,meanwhile the increase of urban construction area leads to more urban non-point source pollution,this situation will be more aggravated accompanied with the expansion of urbanization and reduction in water area.3）Water landscape dominance decreases gradually,and water patch become more fragmentation and distributed;while in the reservoir and riparian buffer zone the proportion of construction land increases,and more artificial river channels lead to the reduction in the diversity of riparian habitat.On all accounts,Dongguan should strengthen the protection and management of water resource.In the water pollution control,based on the management of point source pollution,the city should enhance urban non-point source pollution prevention and control.