DRAINING OF THE KAHOVKA WATER RESERVOIR CAUSED BY THE
RUSSIAN BLOWING OF THE HYDROELECTRIC PLANT DAM

Abstract. On June 6, 2023, the Russian military blew up the Kakhovska HPP dam. During the day, large areas of the Kherson region and the nearest cities (Kherson and Oleshki) were flooded. In addition to flooding, this case led to the gradual draining of the Kakhovske reservoir, pollution of the Black Sea, restoration of the Dnipro riverbed, and the formation of a complex hydrological structure of medium and large reservoirs and watercourses.

Methods. Multispectral satellite images were provided by the European Space Agency (Sentinel-2A). They used to separate areas flooded with water with a high degree of accuracy. Lower quality images from NASA's Terra, Aqua and NOAA-20 satellites were also used.

Results. The surface area of the Kakhovske reservoir was 2,061 km² before the destruction of the dam. 3 days after the breakthrough, approximately a quarter of the reservoir area (553 km², 27.3%) was drained, mainly in the northeast. This is explained by shallower depths and the outflow of water downstream. The water intakes of large cities (Nikopol, Zaporizhzhia, Energodar), which are located within relatively shallow parts, have dried up. The water receded relatively evenly, the most on the left bank.

On June 13th there were formed the separate reservoirs with an area of 200-400 km² at the reservoir. The old bed of the Dnipro began to be restored. Water moved for 300 m from the city of Nikopol to the old channel. 15.06 observations were impossible due to cloud cover.

On 18.06 the riverbed of the Dnipro River was restored. They began to form secondary watercourses that connected the Dnipro with the reservoirs from which the remaining water left. The reservoir stopped providing its economic and ecosystem services — water could not be obtained for drinking water supply, electricity generation, and irrigation. The water intake of the North Crimean Canal was exposed. This date can be considered the day of the termination of the Kakhovske reservoir. Its remaining area was 655 km².

As of June 20, the area of reservoirs was 509.3 km², decreasing by 24%. The old channel of the Dnipro River is clearly distinguished. Numerous channels of small and medium watercourses were formed. The water level decreased by 10 m. On 21.06, the reservoir area decreased to 460.39 km², after another 3 days it decreased by 165.25 km² to 295.14 km² (14.3%), i.e. by 50 km² every day. The channel area was 123.73 km², i.e. 6% of the reservoir area. June 25 area was 289.24 km². On June 28, precipitation led to an increase in the area to 318.27 km² (15.44%).

Conclusion. We witnessed perhaps the world’s only unplanned draining of a large reservoir caused by a terrorist attack. The consequences are there: the drainage of the water intake of the North Crimean Canal will lead to the loss of productivity of part of agricultural land. Most of the remaining water basins will dry up, except of the lakes formed as a result of draining Kakhovske reservoir. Water from them is drained by a system of small watercourses that will follow each other until vegetation appears. After they dry up, the area of the reservoir will decrease by about 6% compared to the initial area.

It is not yet known what scenario will be chosen to restore the Kakhovske reservoir. One of the initiatives involves the transfer of plots to agricultural production. Their area on the right bank is 72,701.1 hectares, and on the left — 116,192.3 hectares, respectively — the latter are not yet available for use due to invasion.

Keywords: Kakhovske reservoir, dam, drainage.