Gdańsk is an important Polish city and harbour situated on the southern coast of the Baltic Sea in the Gulf of Gdańsk, in the lowland delta at the mouth of the Vistula River. At present Gdańsk has 460 thousand inhabitants and covers an area of 262 km2. The population and the area of the city have not changed over recent decades. In previous centuries the city was affected by severe floods, which caused considerable economic damage and the death of inhabitants. Most of these floods were caused by ice jams. The complicated system of rivers and channels within the city and in its close surroundings is called the Gdańsk Water Node (GWN ). The possible directions of flood hazard are: from the sea (Martwa Vistula), and from the main Vistula channel in the case of a breached left embankment. Flood hazard from the catchment of the RCh was not considered by city authorities. In July 2001, a devastating flash flood unexpectedly hit the city of Gdańsk. The paper presents this flood as a case study, without reference to other floods of similar character. It describes the city of Gdańsk, which is an important economic, cultural, scientific, political and industrial center, the system of rivers and channels within Gdańsk which form Gdańsk Water Node (GWN ), the precipitation regime, the course of the flood, and its effects. A special project was formulated after the flood with the aim of developing the proposal of new hydraulic engineering solutions in the GWN and in the catchment of Radunia Channel to prevent similar floods in the city in cases of rainfall similar to that of 2001. The paper also presents the implementation of the proposed engineering solutions.