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International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Volume XXXIX-B7, 2012
XXII ISPRS Congress, 25 August — 01 September 2012, Melbourne, Australia
EXTRACTING TEMPORAL AND SPATIAL DISTRIBUTIONS INFORMATION
ABOUT ALGAL GLOOMS BASED ON MULTITEMPORAL MODIS
Lü Chunguang *'
, Tian Qingjiu *
* International Institute for Earth System Science, Nanjing University, Nanjing 210093, hohai_rsandgis@163.com
Keywords: Taihu Lake; algal blooms; spatio-temporal distribution;
Commission VII, WG VII/3
ABSTRACT:
Based on MODIS remote sensing data, method and technology to extraction the time and space distribution information of algae
bloom is studied and established. The dynamic feature of time and space in Taihu Lake from 2009 to 2011 can be obtained by
extracted method. Variation of cyanobacterial bloom in the Taihu Lake is analyzed and discussed. The algae bloom frequency
index (AFI) and algae bloom sustainability index (ASI) is important criterion which can show the interannual and inter-monthly
variation in the whole area or the subregion of Taihu Lake. Utilizing the AFI and ASI from 2009 to 2011, it found some
phenomena that: the booming frequency decreased from the north and west to the East and South of Taihu Lake. The annual
month algae bloom variation of AFI reflect the booming existing twin peaks in the high shock level and lag trend in general. In the
subregion statistics, the IBD and ASI in 2011 show the abnormal condition in the border between the Gongshan Bay and Central
Lake. The date is obvious earlier than that on the same subregion in previous years and that on others subregion in the same year.
1. INTRODUCTION
Lake is one of the most important fresh water resources on the
planet. In recent years, eutrophication of many of lake in the
world is serious, because of human social economic activities
(Guo H, 2000; Liao M, Lin H, 2003). The significant signs are
frequent outbreaks and large scale to flourish of algae bloom.
Algae bloom refer to the phenomenon of accumulation of algae
due to the biomass of phytoplankton significantly higher than
average in water (Oliver R L et al, 2000). Under the action of
the external forces (such as wind and flow, etc), algae bloom
formed on the spectrum characteristics similar to terrestrial
vegetation (Dekker A G, 2001). Remote sensing had timeliness,
macroscopically and quality economy in environmental
monitoring. Consequently, remote sensing technology is used
with great advantage in monitoring the time and space
distribution of algae bloom (Huang J et al, 1999).
At present, there have been several researches on algae bloom
distribution of time and space and changing regularity. The
reproductive biology of Calanus Finmarchjcus was investigated
at a permanent station in the Norwegian Sea during a time
series between March and June 1997 (Head, R et al, 1999). It
implies that the reproduction of C. Finmarchicus in the
Norwegian Sea is to some extent decoupled from the
phytoplankton bloom (Head R et al, 1999). On the basis of the
spectral analysis, an applicable model was developed to extract
the cyanobacteria bloom information from multi-source remote
sensing images (Ma R et al, 2008). And then, the model was
used to acquire cyanobacteria bloom-covered area and its
spatial distribution (Ma R et al, 2008). Using available satellite
images, Duan reconstructed the spatial and temporal patterns of
" Lü Chunguang: PhD candidate in Nanjing University, China. The main research direction is water environment remote sensing.
algal blooms in Lake Taihu through the past two decades (Duan,
H et al 2009) Using MODIS satellite images and
Chlorophyll-a concentration data and adopting cyannobacteria
bloom evaluation method, Liu studied different type of
cyanobacteria bloom from 2004 to 2008 in Taihu Lake, and
explored the characteristics of cyanobacteria bloom and its
spatial and temporal variation, which provided pre-prevention
and early waning for cyanobacteria bloom (Liu J et al, 2011).
Based on the emergency remote monitoring in 2008, the
frequent region, changes in migration, and the relevancy to the
water quality objectives such as temperature were discussed to
support the emergency management of cyanobacteria bloom in
Taihu Lake (Jin Y et al, 2009).
Lake Taihu, the second freshwater largest lake in China is
located in Jiangsu and Zhejiang provinces at the junction, also
is in the south of the Yangtze River delta (Figure 1). The length
of the lake (from north to south) is 68.5 km and the width (from
east to west) is 56 km. The mean depth of the lake is 1.9 m, and
the maximum depth is 2.6 m. It is a typical shallow lake water
or depressions (Qin B Q et al, 2007).The rich water resources in
Taihu Lake Basin is the foundation of the development of
regional social economic conditions, but with population
growth, urban expansion and the acceleration of industrial
growth, the related problems of water environment of lakes are
more and more serious (Guo L, 2007). The recent bloom in
summer 2007 affected the Wuxi City nearby significantly,
causing drinking water sources to be severely polluted and
millions of people to be exposed to health hazards, which in
turn imperilled the social stability of the region (Yang M et al,
2007)
Our study was conducted to: 1) based on MODIS remote
sensing data study and establishes method and technology to
