JOURNAL OF NATURAL RESOURCES ›› 2015, Vol. 30 ›› Issue (11): 1910-1921.doi: 10.11849/zrzyxb.2015.11.011

• Resource Evaluation • Previous Articles     Next Articles

Study on Spectral Response of Wetland Reed to Eutrophication by Multiscale Hyperspectral Remote Sensing

WANG Li-wena, b, c, WEI Ya-xinga, b, c   

  1. a. Center for Studies of Marine Economy and Sustainable Development, b. Liaoning Key Laboratory of Physical Geography and Geomatics, c. College of Urban and Environmental Science, Liaoning Normal University, Dalian 116029, China
  • Received:2014-09-26 Revised:2015-01-26 Online:2015-11-14 Published:2015-11-14

Abstract:

In recent years, most coastal estuarine wetlands were influenced by human activities which caused the eutrophication of water body. However, the worse situation of water eutrophication has controversy brought deep influence to social economy. The fast, stable, and correct way monitoring the water eutrophication of coastal estuarine was expected on different temporal and spatial scale. In this paper, hyperspectral remote sensing technology was adopted. It can extract the little change of vegetation’s nitrogen absorption. The data measured in field at three different times and the HJ-1A HSI hyperspectral remote sensing data were used. The hyperspectral feature of wetland vegetation reed located in coastal estuarine region was studied. The spatio-temporal response feature of reed to water eutrophication was researched based on three scales including leaf, canopy, and landscape scale. By this means, the wrong evaluation of water eutrophication induced by pulse effect of nutrients can be corrected. The results showed: There exists difference in the spectral features of leaf and canopy of reed when the nitrogen concentration of water are different; on leaf and canopy scales, all hyperspectral vegetation indices can respond to the change of total nitrogen concentration of water. Compared with leaf scale, the correlation of various hyperspectral vegetation indices with total nitrogen concentration of water on canopy scale was lower. Among them, TCARI/OSAVI index has obvious positive correlation with total nitrogen concentration of water (R2 was 0.73 on leaf scale, and R2 was 0.7 on canopy scale); on landscape scale, SVM model based on bootstrap was adopted to construct the estimation models of total nitrogen concentration based on hyperspectral index TCARI/OSAVI. The model was used on three time phases of HJ-1A HSI hyperspectral images. The precision validation showed good correlations between the simulated values and the measured values (R2=0.61, RMSE=2.96 mg/L). The spatial distribution maps of total nitrogen concentration of water in Shuangtaizi estuarine region acquired from the images of the three time phases showed obvious spatio-temporal distribution patterns. The research on three kinds of scales of leaf, canopy and landscape proved that the hyperspectral response feature of wetland vegetation can be used to estimate the water nitrogen concentration in coastal estuarine region to indicate the water eutrophication level of wetlands.

CLC Number: 

  • X87