Impact of satellite rainfall and soil moisture products on landslides and floods prediction over the Italian territory

Luca Ciabatta(1), Luca Brocca(1), Christian Massari(1), Tommaso Moramarco(1), Giulia Fanelli(2), Diana Salciarini(2), Claudio Tamagnini(2), Giulia Panegrossi(3), Anna Cinzia Marra(3), Daniele Casella(3), Paolo Sanò(3), Stefano Dietrich(3), Simone Gabellani(4), Silvia Puca(5), Wolfgang Wagner(6), 2015, Impact of satellite rainfall and soil moisture products on landslides and floods prediction over the Italian territory, Earth Observation for Water Cycle Science 2015, ESA-ESRIN, Frascati, Italy, 20-23/10/2015,

The ever increasing availability and accuracy of satellite rainfall and soil moisture products is opening new perspectives in the hydrology and civil protection fields, providing new valuable sources of information for flood and landslide prediction. Despite the abundance of this kind of data, the use of satellite products for such purposes in well gauged regions is still very scarce, most likely due to measurement (bias, accuracy) and resolution issues (both spatial and temporal). Satellite rainfall and soil moisture products have been employed for flood and landslide prediction throughout the Italian territory. For an assessment of performances obtained by satellite products, hydrometeorological ground observations of rainfall, temperature and discharge derived from the monitoring network of the Italian Civil Protection Department (period 2010 - 2014) are used. The satellite rainfall products here considered are_ 1) the Tropical Rainfall Measurement Mission (TRMM) Multi - satellite Precipitation Analysis (TMPA) 3B42 - RT product, 2) the H05 product from the H - SAF project, and 3) an experimental daily satellite rainfall product obtained by merging instantaneous rainfall rate estimates from cross - track and conical scanning microwave radiometers. Additionally, the satellite soil moisture products provided by the Advanced SCATterometer (ASCAT) and the Soil Moisture and Ocean Salinity (SMOS) mission are used. In this work, on one hand, satellite rainfall observations are used to drive a continuous rainfall - runoff model (MISDc, Brocca et al., 2011). On the other hand, satellite soil moisture data are used to define the initial conditions for a physically - based slope stability model (TRIGRS, Baum et al., 2008), applied in the Umbria region (central Italy), allowing the estimation of the landslide susceptibility over the territory. The modelled landslide susceptibility, obtained with ground and satellite observations, has been compared with a landslide inventory available in the study area. For the investigated period, MISDc model has been used for flood simulation over different basins in Italy (e.g., Brenta, Tanaro, Tevere, Volturno, ...). For landslide susceptibility evaluation, TRIGRS model has been initialized in two different ways. The first considers modelled soil moisture data computed by a Soil Water Balance model forced with in situ meteorological observations (rainfall and air temperature). The second uses satellite soil moisture products in place of modelled data. The analysis has encompassed some significant storm events occurred in the recent years. As far as the floods prediction is concerned, results highlighted that both bias correction and model recalibration are preliminary steps to be carried out for using properly satellite rainfall data. After performing these steps, satellite rainfall data have allowed to achieve results comparable with those obtained by forcing MISDc model with observed data, confirming the feasibility of using satellite rainfall estimation in hydrological applications. As regards the landslide susceptibility analysis, 102 although spatial and temporal resolution of satellite soil moisture data could be considered too coarse, satisfactory results are obtained as demonstrated from the comparison with the landslide inventory map.

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