SatVITS-Flood: Satellite Vegetation Index Time Series Flood detection
model for hyperarid regions
Abstract
We present the Satellite Vegetation Index Time Series model for
detecting historical floods in ungauged hyperarid regions
(SatVITS-Flood). SatVITS-Flood is based on observations that floods are
the primary cause of local vegetation expansion in hyperarid regions. To
detect such expansion, we used two time series metrics: (1) trend change
detection from the Breaks For Additive Season and Trend (BFAST-trend)
and (2) a newly developed seasonal change metric based on Temporal
Fourier Analysis (TFA) and the growing-season integral anomaly
(TFA-GSIanom). The two metrics complement each other by capturing
changes in perennial species following extreme, rare floods and
ephemeral vegetation changes following more frequent floods. Metrics
were derived from the time series of the normalized difference
vegetation index (NDVI), the modified soil-adjusted vegetation index
(MSAVI), and the normalized difference water index (NDWI), acquired from
MODIS, Landsat, and AVHRR. The timing of the change was compared with
the date of the flood and the magnitude of change with its volume and
duration. We tested SatVITS-Flood in three regions on different
continents with 40 years long, systematic, reliable gauge data. Our
results indicate that SatVITS-Flood can predict flood occurrence with an
accuracy of 78% and precision of 67% (Recall=0.69 and F1=0.68;
p<0.01), and the flood volume and duration with NSE of 0.79
(RMSE=15.4 Mm3 event–1), and R2 of 0.69 (RMSE=5.7 days), respectively.
SatVITS-Flood proved useful for detecting historical floods and may
provide valuable long-term hydrological information in poorly-documented
areas, which can help understand the impacts of climate change on the
hydrology of hyperarid regions.