Seite - 205 - in The Power of Urban Water - Studies in premodern urbanism

12 Ice Jamsand their Impact onUrbanCommunities 205 Fig. 1:Vienna, water level of the DanubeRiver, Tabor gauge (1 January to 31March 1784). The periodof the ice flood from28 February 1784 onwards ismarked witha rectangle. Fig. 2:Vienna, the areaof theVienna- Tabor gaugeand theAugartenarea according to the Josephinische Landesaufnahme (‘Josephinian land survey’), section71: Viennaandsur- roundings, detail (1773–1781). Thepresumable positionof the ice jam ismarkedwith the rectangle and thepositionof the Vienna-Tabor gauge at the Taborbridge with the circle. floods destroyednumerous bridges inVienna and caused severe damage to a large number of properties in the suburbs (nowwithin the outer districts of Vienna), such as Nussdorf to the north of the city centre. The severity of the conditions on the local populaceworsened as tem- peratures again fell below0°Con29February. The instrumental data from thewater gauge at Vienna-Tabor is at first glancemisleading. Thewater level reached itspeakon themorningof 27February (13 ft. 9 in.; 419cm)andstayed higher than 11 ft. (335cm) until the morning of 29 February. During the day, the water level decreased quickly and remained extremely low at 4 ft. (122cm) for several days from 1March onwards (Fig. 1). The explanation for these data is given in several reports of theWiener Zeitung. Ice floes started moving and got stuck in shallow areas and by bridges. A report from 3 March 1784 testifies to the presence of an ice jamnear the Augarten just some hundredmetres upstream from theVienna-Tabor gauge (Fig. 2): Schonam28. [Februar] desMittags brach es [dasEis] oberhalbNußdorf los, und fiengan sich inBewegung zu setzen.DesMorgensam29. erhielt dasEis indemDonauarmenächstWienebenfalls einigenTrieb, stemmtesich aber gleichAnfangs ander erstenDonaubrücke nächst demAugarten.HierwarenArbeitsleute vorhanden,wel- chedieEisschollen zerbrachen, umsie in leichterenGangzubringen. SiewurdengegenMittagszeit plötzlich von der Arbeit weggescheucht, da die Donau mit einemmächtigen Schwalle sich in schnelle Bewegung setzte. In ihremLaufewälztesieanbeydenSeitendesUfers,woesnichtganzsteilundsehrhochwar,mächtigeEisschollen übereinander hin, undbildete sich ein neues erweitertesUfer. […]