丹江口水库总磷浓度遥感反演及其时空特征研究

Remote Sensing Retrieval of Total Phosphorus Concentration in Danjiangkou Reservoir and Its Spatial and Temporal Characteristics

水体中总磷(TP)的浓度是水质参数中的主要指标之一,借助遥感技术的时效性、宏观性和经济性的优势,反演其时空分布特征信息,对于调查、管理和保护水库生态系统是必要的。研究选取覆盖丹江口水库的多期Landsat 8 OLI遥感影像,结合现场的水体采样实测数据,利用不同的波段组合,分别采用线性回归和非线性模型对水体的TP浓度进行遥感反演,分析TP浓度的时空特征和变化规律。结果表明:(1)TP浓度与可见光波段组合相关性较好,丰水期回归的相关系数最高为0.746,枯水期回归的相关系数最高为0.684;(2)TP浓度在不同时期差异性显著,丰水期浓度总体低于枯水期;(3)库区TP浓度的空间变化明显,水库中心区TP浓度相对于整个库区较低,沿库周围水体和河流入库口TP浓度为全库最高区域,而且常年处于高浓度状态;(4)自丹江口水库蓄水以来,TP浓度高值明显减少,与近年来水库实施的生态保护政策有关。

The concentration of total phosphorus(TP) in water is one of the main indexes of water quality parameters. Using the advantages of timeliness, macrocosm and economy of remote sensing technology to invert TP spatio-temporal distribution information is necessary to investigate, manage and protect reservoir ecosystems. We select multi-phase Landsat 8 OLI remote sensing images covering Danjiangkou Reservoir,combine with the measured data of water sampling in the field, use different band combinations, linear regression and nonlinear model to retrieve the TP concentration of water body and analysis spatio-temporal characteristics and variation of TP concentration. The result shows that:(1) the correlation between TP concentration and visible light band combination is good, the highest correlation coefficient of regression in flood season is 0.746, and the highest correlation coefficient of regression in dry season is 0.684;(2) TP concentration has significant difference in different periods, and the concentration in flood season is lower than that in dry season;(3) The spatial variation of TP concentration in reservoir area is obvious, and TP concentration in reservoir center is lower than that in whole reservoir area. The TP concentration in the water around the reservoir and the river inlet is the highest in the whole reservoir, and it is in a high concentration state all the year round;(4) Since the storage of Danjiangkou Reservoir, the TP concentration has decreased significantly, which is related to the ecological protection policy implemented in recent years.