At least 132 square kilometers of urban area in SD were affected by floods on November 18

A research team from Instituto Tecnológico de Santo Domingo (INTEC) used free software to do the calculations

SANTO DOMINGO. - The Aerospace Sciences Research Group of the Instituto Tecnológico de Santo Domingo (INTEC) estimated that 132 square kilometers of urban area of ​​Santo Domingo and the National District they saw each other affected by flooding or overflowing of rivers and ravines during the rains caused by the atmospheric phenomenon that impacted the Dominican Republic last 1November 8th 2023.

When performing a experiment using the synthetic aperture radar sensor (SAR) of the Sentinel-1 satellite of the European Space Agency or with a open source from the United Nations Office for Outer Terrestrial Affairs (UNOOSA) en Google Earth Engine, the team made up of research teachers Edwin Sánchez Camilo, Iván Jiménez Durán y Martin Meléndez Valencia, they evaluated the aftermath of the floods in the area of Santo Domingo Oeste, Santo domingo norte and National District.

Sánchez specified that a SAR image, due to the behavior of the wave with respect to land and water, provides information where different levels of brightness and roughness can distinguish between vegetation, urban area and water.

“In our experiment procedure, the study area was delimited according to the limitations of the satellite pass and the flood reports from the Dominican authorities. The total urban area of ​​​​the image is approximately 310 km2, which means that approximately 42.5% of the urban area was affected by the meteorological phenomenon.

The INTEC team of researchers created a mosaic with images from November 6 to 16 with the software, because the orbit of the satellite and the physical capacity of the sensor take images of portions of the island. “The image shows flood water in blue on a Google Maps of the region of interest.”

The software performs calculations based on historical data (including land and population density) and compares the historical data with the results of processing the satellite information obtained.

“The calculation tells us that, based on historical information in the 2015 international database for population density, it is estimated that there were approximately 72,553 people exposed to the danger of flooding or river overflowing. “It is very likely that this information is outdated since the most recent census was carried out in 2022, seven years after the last update of the database,” the group warned.

After carrying out a visual inspection of the affected areas, it is observed that the highest density of flood indicator points and effect on the urban area are found around the Ozama and Isabela rivers, with a direct effect on areas of the National District and Santo Domingo Norte, respectively. This highlights the existing urban vulnerability to river flooding, highlights Meléndez.

INTEC researchers point out that institutions such as the National Meteorological Office (ONAMET) and the Emergency Operations Center (COE) use satellite images to verify cloud cover, the meteorological development of phenomena, estimate the amount of water per come, among others.

Likewise, space technology can be used to study the repercussions and consequences of meteorological phenomena, such as the one that impacted the country on November 18. It is also possible to study environmental phenomena, such as sargassum floods. The key lies in knowing how to use the information provided by each of the satellite sensors.

“You can use sensors in the visible spectrum (cameras) to naturally observe the development of any phenomenon, and the information from each pixel can be studied to design schemes for in-depth studies of the phenomenon. Other types of sensors, such as SAR radar, can be used to observe the earth from a point of view not allowed by cameras. For example, images are susceptible to cloud cover, that is, clouds can obscure vision when we try to see a phenomenon on land or sea. However, SAR sensors use the emission of electromagnetic waves and record the rebound of the waves on the surface of the land and sea, without being impacted by cloud cover,” Sánchez explained.