📰 Rain measurements from space can help predict landslide disasters


Destruction caused by a landslide after the intense rain on 15/02/2022 in Petropolis, Brazil. © Palácio do Planalto

Every year around the world, heavy rains cause numerous landslides, causing huge human and economic losses. Like the intense rain on February 15, 2022 in Brazil that triggered several landslides and mudslides in town (A city is an urban unit (a “human settlement” for…) of Petrópolis, killing more than 200 people. These events are especially common in Country (Country comes from the Latin pagus, which denoted a territorial and tribal division of extent…) of the intertropical band where the meteorological networks for measurement rain (Rain generally refers to precipitation of water in the state…) are often incomplete and poorly suited to understanding and predicting the rainfall conditions that trigger landslides, although extreme rainfall is likely to become more frequent due to climate change.

To compensate for this lack of data (In information technology (IT), data is an elementary description, often…)an international team, some of which scientific (A scientist is a person who is dedicated to the study of a science or sciences and who…) from the geoscience laboratory environment (The environment is everything that surrounds us. It is all the natural elements and…) of Toulouse (GET / OMP/ CNRS (The National Center for Scientific Research, better known by its acronym CNRS, is the largest…) / UT3 / IRD / CNES) assessed the capacity of constellation (A constellation is a set of stars whose projections on the roof…) satellite (Satellite may refer to:) GPM (administered by NASA (The National Aeronautics and Space Administration (“National Administration of…) and JAXA) to correctly measure the amount of rainfall that caused landslides. That strength (The word force can denote a mechanical power over things, and also, metaphorically, a…) of these satellite precipitation estimates are theirs availability (The availability of a piece of equipment or a system is a measure of performance that we…) throughtogether (In set theory, a set intuitively denotes a collection…) the globe since the 2000s. This study was conducted on 20 rain events that caused 80 to 10,000 landslides across world (The word world can refer to:) (Caribbean, Andes, Mediterranean, Africa (With an area of ​​30,221,532 km2 including the islands,…), Asia (Asia is one of the five continents or part of the supercontinents Eurasia or Afro-Eurasia in…) southeast). The satellite measurements made it possible to quantify the rain during the event, as well as the intensity of the decadal rain (that is, which statistically returns every 10 years) in the region. In 75% of cases with heavy rain of one or more days (The day or day is the interval that separates the sunrise from the sunset; it is…) (typically cyclones), the region containing the landslides corresponds to the slope areas where the rain intensity was much higher than the decadal rain and where the rain anomaly was the strongest since the beginning of the measuring satellites. On the other hand, in the case of intense rain lasting less than 8 hours, the satellite constellations were generally unable to record a particularly intense rain.

Despite this limitation, the study suggests that satellite constellations can already be used to understand the triggering of landslides, but also that precipitation predictions in time (Time is a concept developed by humans to understand…) real (“Nowcast”) provided by these same satellite constellations could become the basis for regional warning systems in areas lacking ground data.


In (a) the rainfall anomaly map, I (b), a topographic map where the study area is shown in identified in blue, shows the slope area where the slopes allow landslides (areas not shaded in ia). © GET

(a) R*, (ie the ratio of the 12-hour cumulative rainfall during the event to the 12-hour cumulative rainfall for a decade) derivative (The derivative of a function is the way to determine how much that function varies when…) rain product satellite (Satellite may refer to:) GSMaP during Typhoon Idai in March 2019 in Zimbabwe. Contours where R*>1 and R*>1.2 are in line white (White is the color of a body heated to about 5000°C (see…) dashed and solid white and landslides are represented by black dots.

To know more:
Marc, O., Jucá Oliveira, RA, Gosset, M., Emberson, R., & Malet, J. (2022). Global assessment of the ability of satellite precipitation products to retrieve landslide-triggering extreme precipitation events, Earth Interactions (published online ahead of print in 2022). Retrieved June 27, 2022.

Contact:
Marc Odin – Geosciences Environment Toulouse (GET / OMP / CNRS / Univ. Paul Sabatier (Paul Sabatier (November 5, 1854 in Carcassonne, France – August 14, 1941…) Toulouse) – odin.marc at get.omp.eu

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