University of Bristol - Historical Photographs of China reference number: NA16-097. Image from an album in The National Archives referenced as ‘HONG KONG 3. Views of Hong Kong from the 1860s to the 1920s' (CO 1069-446). According to the Hong Kong Observatory, the highest record of daily rainfall ever recorded in Hong Kong, is 534.1 millimetres - the 19th July 1926 rainstorm. See https://www.hko.gov.hk/en/blog/00000135.htm. The building in the background is probably the Wan Chai Pak Tai Temple (灣仔北帝廟), built in 1863.
Flooding due to the 19th July 1926 rainstorm, at the stone nullah, Wan Chai (灣仔), Hong Kong
Black and white photograph
The National Archives, London