Persisting rains at the end of September, 1570, in the area around the St. Gotthard pass and farther east lead to devastating floods. In Canton Uri the water destroyed almost all bridges and severely damaged the mule track over the St. Gotthard pass which had to be repaired by the residents under high cost. The picture shows the disaster in the Maggia Valley (Canton Ticino), where a huge amount of jammed driftwood dammed the Maggia River below the village of Mogno diverting the flow to the inhabited area. Dozens of houses, 14 mills, 75 barns and all streets and bridges were destroyed, and large tracks of fertile land were overwhelmed. One victim was claimed (Pfister 1999: 233).
Reports about floods are preserved in chronicles, and later on also in weather diaries or as flood marks since the Middle Ages. Most of the chroniclers compared the dimension of a flood with previous events. They described the magnitude of floods in the form of standard narratives, referring to specific landmarks in the built environment around the bridge, which had served as scale also for earlier generations. For example, we read in the anonymous “Chronicle of the wars against Milan”: “In 1511 on the celebration day of St. Mary Magdalene [22nd July, 1511] the Rhine River in Basel had become so high that they took servants from the guilds, who were asked to bring the salt in the storehouse from the lower x to the other higher above. Then, the level of the Rhine River rose so rapidly
, that we were afraid of a flood similar to the tremendous one that had happened 31 years ago . Finally, the water rose until the sailor’s bridge pillar.” From this description about the oriel and the pillar decorated with a coat-of-arms it is concluded that the height of the 1511 flood may be compared to that on 13th June, 1876.
After 1641 many severe floods are also documented in the form of flood marks attached at the so-called Schönbein house situated Oberer Rheinweg 93 in Kleinbasel. After 1808 daily gauge readings are available, which have been replenished with measurements of the discharge since 1908, so that cross references can be made between different indicators. The largest floods of river Rhine in Basel were reconstructed in this way since 1268. It is conspicuous that no severe flood is known between 1876/1882 and 1999 (Wetter et al. 2011). Documentary flood information is duly taken into account by the Federal Government and the Cantons within in the framework of disaster management.
Little is known about the frequency of severe (winter) storms prior to the onset of the meteorological network in 1864, because narrative evidence was so far hardly considered. Only the outstanding winter storm “Prisca” was so far reconstructed in some detail. On 18th January, 1739 it swept across France, South-West Germany and Switzerland devastating forests, towers, houses and barns (Pfister et al. 2010). The month of January 1739 was characterized by a unique series of violent storms over the North Atlantic Ocean and Europe, apart from the severe winter storm “Lothar” on 26th December 1999, which had about the same force. However, this extreme event did not persist in the collective memories of those who experienced them. Numerous storms causing substantial damage on buildings and forests like “Prisca” and “Lothar” are documented in Euro-Climhist.
Avalanches are reported only relatively late in the written sources, mainly because literacy in remote Alpine valleys had been far lower than in urban areas. The first short descriptions of destructive avalanche disasters in Switzerland date from the Late Middle Ages; however, they become more detailed only from the mid-18th century onwards. In addition, it plays an important role whether those reports had been written down based on third-party narrations or they reflect singular and occasional observations – such as the famous natural scientist Horace-Bénédict de Saussure (1740-1799) from Geneva reporting from an avalanche rushing down near Amsteg (Canton Uri) in 1795 – or they had been documented by Alpine residents with a broad local knowledge on avalanches. Father Placidus Spescha (1752-1833) is a remarkable person in this context: He grew up as a shepherd’s boy in Trun (Canton Grisons), who then received higher education in the monasteries of Disentis and Einsiedeln, and later on undertook numerous first ascents in the Vorderrhein region besides working as a priest in several parishes. In his reports, both based on older eye-witnesses of the 1749 and 1808 disasters and on his own observations for the avalanches of winter 1817, he shows an excellent understanding for the causes and the course of avalanches; furthermore, he also suggested building new Alpine model villages to reduce the risk of avalanches for the Alpine residents (Rohr 2014).