Potential of a SAR Small-Satellite Constellation for Rapid Monitoring of Flood Extent

Natsumi Kitajima,Shinjiro Kanae,Xudong Zhou,Dai Yamazaki,Rie Seto,Wenchao Ma

doi:10.3390/rs13101959

Natsumi Kitajima, Shinjiro Kanae + Show 4 more

Open Access

https://doi.org/10.3390/rs13101959

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Abstract

Constellations of small satellites equipped with synthetic aperture radar (SAR) payloads can realize observations in short time intervals independently from daylight and weather conditions and this technology is now in the early stages of development. This tool would greatly contribute to rapid flood monitoring, which is usually one of the main missions in upcoming plans, but few studies have focused on this potential application and a required observation performance for flood disaster monitoring has been unclear. In this study, we propose an unprecedented method for investigating how flood extents would be temporally and spatially observed with a SAR small-satellite constellation and for evaluating that observation performance via an original index. The virtual experiments of flood monitoring with designed constellations were conducted using two case studies of flood events in Japan. Experimental results showed that a SAR small-satellite constellation with sun-synchronous orbit at 570 km altitude, 30-km swath, 15–30° incidence angle, and 20 satellites can achieve 87% acquisition of cumulative flood extent in total observations. There is a difference between the results of observation performance in two cases because of each flood’s characteristics and a SAR satellite’s observation system, which implies the necessity of individual assessments for various types of rivers.

Highlights

Swift assessment of the location and extent of damage caused by disasters is vital to real-time situational awareness and effective measures in the response phase of disaster management [1,2]
The revisit rates and mean revisit time remain almost unchanged with the variation of P, while the maximum revisit time exhibits different behavior that roughly improves as P increases
We investigated how flood extents could be observed using synthetic aperture radar (SAR) smallsatellite constellation on a spatial and temporal scale

Summary

Introduction

Swift assessment of the location and extent of damage caused by disasters is vital to real-time situational awareness and effective measures in the response phase of disaster management [1,2]. In the case of flood disasters, adverse weather conditions and surface inundation typically obstruct field surveys, especially at night. Remote sensing technologies can offer useful solutions in such situations; in particular, satellite-based synthetic aperture radar (SAR) has great potential for flood detection [3]. SAR can penetrate clouds and rain and collect observations independently from sunlight [4]. Satellite as a platform facilitates observation over wide swathes and global coverage of remote areas, which cannot be achieved with aircrafts or unmanned aerial vehicles (UAVs) [5]. SAR satellites play an important role as powerful tools for flood detection across vast regions under unfavorable weather conditions by day or night

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