1964 Zagreb flood

1964 Zagreb flood

Water on Tratinska and Kranjčevićeva Street, Trešnjevka
Date	25–26 October 1964
Location	Zagreb, Yugoslavia
Deaths	17 direct
Property damage	160 billion Yugoslav dinars > US$100 mil­lion

On 25 October 1964, a devastating flood of the River Sava struck Zagreb, SR Croatia, SFR Yugoslavia (today the capital of Croatia). High rainfall upriver caused rivers and streams in the Sava catchment basin to swell and spill over their banks in many places throughout Slovenia and northern Croatia. The worst of the flooding occurred in Zagreb. Sava floods were a known hazard in the city, having affected the development of the area since the Roman times, and the 1964 flood did not have the largest extent. However, it occurred following several decades of large-scale industrialisation and urban growth which had caused the city to expand into the most flood-vulnerable areas. The quality of building construction and flood defences in the floodplain was mostly low. Regulation of the Sava and its tributaries upriver from Zagreb cut off many natural detention basins, such as fields and pastures, which caused water to pile up ahead of the city. To make matters worse, the soil was already saturated from a mid-month episode of fairly high rainfall. A second episode of high rainfall, during 22–25 October upriver in Slovenia, produced a record-high water wave in the Sava. At Zagreb's Sava River gauge, the water crested at 514 cm (16 ft 10 in) above zero level, exceeding the previous high water mark by more than half a metre (2 ft). This proved too much for the city's embankments. Around 60 km² (23 sq mi) of the city was flooded, including most neighbourhoods on the western side of the floodplain.

The worst-stricken areas were the working-class suburbs of Trnje and Trešnjevka. A network of arterial roads raised on small embankments failed to hold the water. In some areas single-storey houses were submerged whole. The onset of the flood was quick, the warnings came late and the intensity and height of the flood was not communicated to the residents in time. Many were unable to save their belongings and ended up stranded in attics and on the rooftops. The brunt of the flood lasted from 25 to 28 October as the water progressed through the city from west to east, mostly on the more populous left (northern) bank. The neighbourhoods on the right bank only saw groundwater flooding for the most part. The railway embankment and sandbag dykes successfully protected the northern and eastern part of the floodplain, and Donji grad and much of Peščenica were spared. A total of 17 people died in the flood. The living quarters of 183,000 people were flooded; 40,000 of these lost their homes. The damage was estimated to 160 billion Yugoslav dinars, or, alternatively, over US$100 million.^[1]

The flood was followed by urban redevelopment, changing Zagreb's cityscape. Around 26,000 new flats and houses were constructed in the next four years. The challenge of housing flood refugees led to the creation of several new planned neighbourhoods. Existing neighbourhoods where much of the housing had been condemned due to water damage were rebuilt, often as high-rise housing estates. Several factories were moved eastward from the flood-prone central part of the city. The disaster also prompted a rework of the flood defences on the Sava. The Sava embankments in Zagreb were reconstructed, raised and lengthened, and the river was channelised throughout the city. Diversion canals were built around several cities in the Sava basin, including the Sava–Odra–Sava Canal bypassing Zagreb. As a result, although there have been several destructive Sava Valley floods since 1964, their effects in Zagreb were limited to groundwater flooding in a few streets. However, changes in the riverbed are believed to have somewhat decreased the effectiveness of the defences as of the early 21st century.