Flood Detection of South Asia Using Spaceborne GNSS-R Coherent Signals

LIU Qi1 ZHANG Shuangcheng1,2 NAN Yang3 MA Zhongmin1

(1.College of Geological Engineering and Geomatics, Chang'an University, Xi'an 710054)
(2.State Key Laboratory of Geo-Information Engineering, Xi'an 710054)
(3.GNSS Research Center, Wuhan University, Wuhan 430079)

【Abstract】Objectives: Flood monitoring not only plays an important role in flood prevention and mitigation, but also provides support for understanding the temporal and spatial evolution of floods and forecasting and warning. The global navigation satellite system-reflectometry (GNSS-R) measurement provides a new solution for flood monitoring. Methods: Firstly, we introduce a coherent signal detection method based on CYGNSS (cyclone global navigation satellite system) raw counts delay-Doppler map (DDM), and then analyze the changes of spatial range and time series before and after flood in South Asia are analyzed, based on the sensitivity of spaceborne GNSS-R signals to floods. Results: Research results show that, compared with the flood detection results of soil moisture active passive (SMAP), the monitoring range of the two methods in the dry season is similar. While in the rainy season, the detection range of the surface reflectivity is larger about 6.69%, and the detection range of the power ratio is smaller about 3.6%. Conclusions: The proposed method of using GNSS-R coherent signals to detect floods is more accurate than the surface reflectivity, and this method does not have to consider the influence of surface characteristics on the incoherent scattering power. It is a simple and effective method for flood detection.

【Keywords】 CYGNSS; coherent signal; flood detection; soil moisture active passive (SMAP); spaceborne GNSS-R;

【DOI】

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ISSN:1671-8860

CN:42-1676/TN

Vol 46, No. 11, Pages 1641-1648

November 2021

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