LESSER SLAVE RIVER WEIR - LOW FLOW STRUCTURE MODIFICATIONS AND FLOW SIMULATION

摘要

Lesser Slave Lake supports a diverse fishing community and also serves as a source of tourism. As water leaves the lake through its only outlet, it becomes the Lesser Slave River. The river system was regulated in the early 1980's with the construction of a weir at the outlet of the lake and the straightening of meandering river channels. The intent was to reduce flooding along the river and to stabilize lake levels. There are now concerns related to the delivery of adequate flows downstream of the weir to meet minimum riparian flow requirements as proposed in the current Watershed Management Plan. A key area of concern is low flows under ice covered conditions which affects water quality and, hence, the aquatic life. Alberta Environment & Sustainable Resource Development (AESRD) and Alberta Transportation have designed a modified lake outlet structure that is intended to provide the required minimum riparian flow during low flow conditions without altering the existing lake level regime. The selected design option also has an improved fishway to support the lake's integral fish habitat function. This paper presents the hydraulic design basis for the various options considered and their impact on the Lesser Slave Lake Levels. Lake level simulations were carried out using a water balance model.