Since Israel launched Operation Iron Swords, transforming it into the most violent total war in the history of the Gaza Strip, Israel has claimed to target only members and locations of the resistance factions. However, it has claimed the lives of over 27 thousand civilians and destroyed infrastructure in most regions of Gaza. As the bombing operations continue and the difficulties persist in reaching neighborhoods and cities in Gaza, there are conflicting estimates regarding the scale of destruction up to now.
Many researchers are trying to follow and measure the damage that occurred in the buildings and infrastructure of the Strip using open-source data. Among those efforts, researchers from the Center for Advanced Spatial Analysis at the University College London adapted a new interactive map originally developed to estimate the damage in Ukraine, applying it to Gaza. The tool can estimate the number of damaged buildings and the number of inhabitants before the war in a given area inside the Gaza Strip.
The “Gaza damage map” tool has been used by several media outlets in reports comparing the scale of destruction in Gaza before and after the war. Its use, however, goes beyond this. It is also available for free to anyone wanting to know if their home or that of their relatives was destroyed, whether they are inhabitants of the Strip or they have relatives or friends there.
Estimating Affected Buildings and Inhabitants
The colored overlay in the interactive map serves as a scale indicating the extent of damage to affected buildings. The yellow color represents a low damage probability (70%), and the scale gradually escalates to red then purple, indicating progressively increased damage. Users can click on the “draw an area of interest” option on the left of the screen to choose a particular area of the Strip on the map, rather than the entire Gaza region.
To understand how the tool functions, one can examine the Ezbet Beit Hanoun neighborhood, heavily impacted and documented through high-resolution satellite images taken before and after the war, published by media outlets. The residential block in the northern part of the neighborhood near the road was bulldozed, and areas with lower inhabitant density in the middle and north-east suffered significant damage. Airstrikes also destroyed many residential complexes in the south-west.
When designating the neighborhood with a rectangle as an area of interest, the map displays the probable damage, enabling researchers or users to estimate the approximate number of affected buildings and people, as well as the percentage in relation to the neighborhood's population before October 10.
In Ezbet Beit Hanoun, for instance, the tool estimates 321 to 425 damaged buildings (73 to 97%), represented by colors ranging from yellow to purple based on the destruction index mentioned earlier. The tool also estimates the pre-war population of this particular neighborhood at 7,453, with 4,756 to 6,304 residing in areas now likely to have been bombed.
How Does the Gaza Damage Map Work?
The Gaza Damage Map works by using Synthetic Aperture Radar (SAR) images, a system used to generate 2D images or reconstitute 3D structures of elements on the ground. It was widely used in academic studies around building damage by international institutions such as NASA following the 2020 Beirut port explosion. NASA explains the use of the radar system to detect building damage as follows: “Radar devices send pulses of microwaves towards the Earth’s surface and listen to the reflections of those waves. Radar waves can penetrate cloud cover, vegetation and the darkness of night to detect changes that may not appear in satellite images taken in visible light. […] When buildings are damaged or fall, the amplitude and phase of the radar wave reflections change in those areas and indicate to the satellite that something has changed on the ground.”
The tool detects affected areas by measuring the change in the intensity of radar waves reflected on the Sentinel-1 satellite before and after October 10, 2023, adjusting the signal noise range for both periods. Once potentially damaged areas are identified, the damage probability map is combined with the Microsoft Building Footprint map, and the footprints of buildings that have undergone significant change are then classified as damaged. This allows the estimated number (and proportion) of damaged buildings within the area to be obtained.
To approximate the number of people affected in a specific area, population data is extracted from the “LandScan” statistical program, developed by the U.S. Oak Ridge National Laboratory, which creates population estimates by integrating current data on building structures, occupancy rates, and infrastructure. However, these are only estimates and are subject to some level of error. The data also predates the current conflict and is not intended to be interpreted as a tally of actual victims.
Map Data Intersects With UN Data
To evaluate the accuracy of the above-mentioned damage detection algorithm, its results are matched to damage points identified by the United Nations Satellite Office (UNOSAT) for verification, which are created by manually combing through high-resolution satellite images and marking damaged buildings. Below is the same photo of Ezbet Beit Hanoun, with white dots indicating the areas of damage identified by UNOSAT.
In the image, the colored overlay represents a map reflecting probable damage. Darker colors indicate a higher likelihood of significant changes due to the bombing after October 10, 2023. It is also noticeable that a large number of white dots, confirming places bombed according to the United Nations, are present in the same dark-colored areas.
The damage points identified by UNOSAT can be viewed or obscured through the “Layers” tab in the upper right corner of the interactive map. It should be noted that UNOSAT conducted its damage assessment in the Gaza Strip on November 7, 2023, determining the damage that occurred in the Strip as a result of the bombing since then.
Locating the Geographical Positions of Damaged Areas
To add another layer of validation to the data provided by the interactive map, the tool provides geotagged snapshots of strikes and destruction in Gaza under the “Layers” tab at the top right, displayed on the map as blue triangles at each location that was either completely or partly destroyed, and they are photographed and located.
These images and geodata are sourced from Geoconfirmed, a global geolocation network in conflict and disaster areas that is community-managed by hundreds of professionals. Clicking on a geolocated damaged location opens a panel at the top right of the screen, displaying a brief description of the event, date, a link to media displaying the damage from the ground, and a link to the coordinates of the location.
In the example below, the blue triangle indicates a location confirmed to have suffered bombing damage and has been geolocated. Clicking on the triangle opens a side window indicating that that place is the International Eye Hospital in Tal Al-Hawa, Gaza City, which was the target of an airstrike. By clicking on “Media Source,” a photo of the Eye Hospital appears from the ground, showing the damage it suffered.
Clicking on “geolocation” directs the researcher to the following tweet, which uses the visual characteristics of the building itself and neighboring buildings to determine the location of the image and attach its coordinates. It should be noted that further media research revealed that the International Eye Hospital was subsequently completely destroyed.
Not all locations have been independently verified by the tool's creators, and they are automatically added to the map when available. These geographic locations, however, constitute an important additional source of primary information.
The Gaza Damage Map uses a previously developed and tested methodology to provide estimates of damage to buildings in the Russia-Ukraine war and in the earthquakes in Turkey and Syria early last year. The data is updated approximately once or twice a week as new satellite images are collected. Although some of the information provided by the tool are only estimative, especially regarding the number of potentially affected individuals, it is useful for researchers to quickly obtain an overview of affected areas in the Gaza Strip and build on it later, while taking the margin of error into account.
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