子牙河流域湿地动态变化特征分析

Analysis on Dynamic Characteristics in the Wetlands of Ziya River Basin

为了了解子牙河流域湿地的动态变化特征,本文使用2000、2004、2009和2014年间4景Landsat TM/ETM+/OLI夏季遥感影像,通过目视解译、改进的归一化差异水体指数、归一化植被指数、景观格局指数对湿地面积、水域、植被和景观格局变化等方面进行了研究。研究结果表明:2000、2004、2009、2014年间,子牙河流域湿地面积分别为1 861.99、1 890.42、1 823.19和1 885.43km^2;湿地水面面积分别为为463.14、629.74、562.69和796.69km^2;湿地植被面积分别为1 025.22、936.55、1 058.76和764.34km^2。景观格局指数方面,斑块密度(PD)逐年增加,最大斑块指数(LPI)在8.16~8.46之间;周长面积分维数(PAFRAC)基本处于1.46左右;香浓多样性指数(SHDI)随时间上升,香浓均匀度指数(SHEI)逐年提高。结果表明:湿地面积总体呈增加趋势,但增加的湿地面积主要是人工湿地,自然湿地面积还需要继续恢复;湿地水域主要分布在研究区域的东部和西部,中部较为缺水;湿地植被面积以2009年面积最大,生长状况最好,而到2014年面积、长势有所下降,还需要加强对植被的恢复;研究区域景观越来越破碎化,各类型景观分布越来越均匀,受到人类的干扰越来越大。人们在恢复湿地面积同时,还需要注意防止湿地破碎化,保护自然湿地。

In order to understand the dynamic characteristics of wetlands in Ziya River Basin,the 2000-2014(2000,2004,2009 and 2014,respectively)Landsat TM/ETM+/OLI remote sensing images were used.The methods of visual interpretation,modified normalized difference water index(MNDWI),normalized vegetation index(NDVI)and landscape pattern metrics were used to study the change of wetland area,water area,vegetation and landscape pattern.Some results were gained as follows:From 2000 to 2014,the wetland areas were 1 861.99,1 890.42,1 823.19 and 1 885.43 km^2,respectively.Water surface areas were 463.14,629.74,562.69 and 796.69 km^2,respectively,and wetland vegetation areas were 1 025.22,936.55,1 058.76 and 764.34 km^2 respectively.The results of patch density(PD)increased year by year;the results of large patch index(LPI)were between 8.16~8.46;The results of perimeter area fractal dimension(PAFRAC)were at about 1.46;The Shannon diversity index(SHDI)and Shannon evenness index(SHEI)rise over continually.The results presents that the wetland areas overall showed an increasing trend,while area of natural wetlands area initially reduced and subsequently increased.However,the wetland area in 2014 was even less than that in 2000.Generally,the area of artificial wetlands was increased consistently.Water areas mainly distribute in the east and west of the study area,while the middle area was short of water.Area of the wetland vegetation in 2009 reached the largest of the 4 periods and had the largest proportion of growing well vegetation,whereas in 2014,both the area and growth conditions were begun to declined,which means that it is necessary to strengthen vegetation restoration.The landscape of the study area were becoming increasingly fragmented;the distribution of the various types of landscape were becoming more and more uniform;the human-derived interference was intensifying.Therefore,the wetlands management and restoration should be kept enhancing.People should not only enlarging wetland area,but also consider preventing and reducing fragmentation of wetlands,as well as controlling the degree of human disturbance,so as to returning the wetlands.