Lake Thun

Lake Thun lies at the outlet of the Bernese Oberland. The Aare brings water from Lake Brienz while the Kander and Simme drain extensive Alpine areas. Since the Kander was diverted into the lake in 1714, its catchment has been unusually large relative to lake area, making it more responsive than its calm surface suggests.

Inflows arrive from different valleys and do not always react together. Rain over the Kander can create a different curve from meltwater in the Hasli valley. The Aare leaves through two channels in Thun. Historically, limited outlet capacity allowed major inflows to raise the lake despite open sluices.

Snowmelt and summer rain generally bring more water than winter. The Mühle and Scherzlig sluices regulate outflow, supported by additional flood works. Yet the lake is not an unlimited retention basin. When soils are saturated and several tributaries are high, development over hours and days matters most.

Lake elevation describes surface height, while Aare, Kander and Simme discharge measures volume per second. Read the sequence: water arriving from the valleys, the lake's response and what can leave at Thun. Different timestamps can explain an apparent mismatch.

This deep Alpine lake can warm quickly at the surface while retaining cold deep water. The Aare from Lake Brienz and the Kander can deliver locally cooler water, redistributed by wind. Surface readings help swimmers; understanding the ecosystem requires depth profiles.