|
The correction of the waters of the Swiss Jura consisted of a wide series of hydrological undertakings carried out in Switzerland in the region of the three lakes: Lake Morat connected to Lake Neuchatel by the Broye Canal, the latter connected to Lake Bienne by the Thielle Canal, an area called the "Seeland”. These projects included the operations of cleaning, restoration and diversion of rivers. The main works took place in three distinct phases during the 19th and 20th centuries. The correction has helped regulate the hydrology. It limits the risk of flooding, particularly in the areas covered by the Aare River. It has also added vast areas of valuable agricultural land through the drying out and subsequent sanitization and improvement of the swamps which used to lie between these three lakes, Many rivers have been corrected in Switzerland: e.g. the Rhône, has undergone several adjustments between the 19th century and the present day. However, the realignments in the Swiss Seeland are still the largest hydrological development in Switzerland.〔Daniel L. Vischer, ''Histoire de la protection contre les crues en Suisse'', p. 105.〕 At the foot of the Jura Mountains the region of the three lakes (Swiss Seeland) is part of the Rhine watershed. Each river of the region flows into the Aare River, which is a tributary of the Rhine. Before the works started in 1868, the Aare River did not flow into Lake Bienne, but divided into several branches after the city of Aarberg, to join the River Thielle, which flows into and out of Lake Bienne, near Büren an der Aare. Depending on weather and water conditions, the alluvial deposits and debris carried by the current would form banks damming the course of the Aare, resulting in rising waters upstream and unavoidable flooding, affecting the economic health of the whole area. The area affected by the correction extends for about 100 km between La Sarraz and Luterbach, currently impacting the cantons of Vaud, Fribourg, Neuchatel, Solothurn, Bern and Jura. == History == Archaeological research has shown that since the Bronze Age, the level of the three lakes and rivers rose several meters, and was already a threat to the population in 1500. As from the 15th century, chronicles have recorded regular floods in those areas as well as floods in the swamps in the “Grand Marais” of the Seeland area. On occasion, the level of the three lakes even rose to the point of spreading out into a single body of water. In 1651, the Aare River overflowed upstream of Solothurn and formed a "lake of Solothurn", spreading from the City and merging with the three combined lakes. According to Schneider, this marked the historic flood peak. All these floods had many consequences on the local population. From the second half of the 16th century, when the first complaints are recorded, the loss of crops and the high risk of epidemics of malaria caused people to abandon their villages. It is significant that the first proponent of the correction of the Jura Waters was Johann Rudolf Schneider, a doctor of medicine by profession. During the 18th and 19th centuries, increased flooding which affected the whole of Switzerland worsened the situation, forcing the authorities to take action.〔Schneider, quoted by Vischer, ''Histoire de la protection contre les crues en Suisse'', p. 106.〕 Several projects were initiated and actions taken, in particular the removal of various structures along the course of the Thielle to Brügg in 1674. In 1707, a map of the river Thielle from Lake Biel to its junction with the Aare was compiled and drawn by Samuel Bodmer, a lieutenant of artillery and Bernese Surveyor. In this publication, he proposed reducing the length of the course of the river by cutting through a meander. In 1749, first officer Antoni Benjamin Tillier, hired by the federal government to deal with the management of rivers, started deepening the bed of the river Thielle from Nidau to Brügg by excavation. Thereupon, two consecutive floods in 1831 and 1832 resulted in the creation of a referendum committee in Nidau. In the mid-1830s, the committee chaired by Johann Rudolf Schneider worked on a proposal to the diversion of the River Aare into Lake Bienne. In 1840, the Chief Engineer of the canton of Grisons, Richard La Nicca, was commissioned to study and execute the project.〔Vischer, p. 26〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Jura water correction」の詳細全文を読む スポンサード リンク
|