Section 8.0 of the report (13Kb PDF) describes the investigation of lake evaporation conducted for Phase 2.
The Penman-Monteith model was chosen for estimating evaporation from Okanagan Lakes, but due to a lack of direct measurements, the accuracy of the evaporation estimates is given within a fairly broad range.
The Penman-Monteith model was chosen for estimating evaporation from Okanagan Lakes, but due to a lack of direct measurements, the accuracy of the evaporation estimates is given within a fairly broad range.
It is recommended that direct measurements of lake evaporation be obtained so that evaporation can be modelled with greater precision.
Related Links:
- Summary Report – Section 8.0 Lake Evaporation (13Kb PDF)
- Mainstem Lake Evaporation Report (Environment Canada 2009)
Monitoring Lake Evaporation:
The Okanagan Basin Water Board was pleased to partner with Environment Canada on an important study to better understand what is happening to the Okanagan’s water supply.
The OBWB and Environment Canada launched three large yellow buoys – 3 metres (10 feet) tall by 1.8 metres (6 feet) wide – on Okanagan Lake to monitor lake evaporation for at least three years. Each buoy was equipped with special computer monitoring software that measures relative humidity on the lake surface, intensity of the sunshine, different temperatures and wind levels, and how evaporation on the lake is affected by these elements.
This study comes as the result of work done on the OBWB’s comprehensive Okanagan Water Supply and Demand Project, a three-year, $3 million project that looked at the valley’s water supply and found at least one piece of the puzzle missing… How much water is lost off Okanagan Lake through evaporation?
Initial estimates put lake evaporation at one metre per year. But the Okanagan is known to be a region with water supply challenges and estimates aren’t good enough when we are trying to effectively manage our water resources.
By determining how much water is lost to evaporation, the Okanagan will be in a better position to plan for these challenges, including drought.
The buoys were placed in the middle of Okanagan Lake – one buoy was located approximately 4 km north of the Okanagan Centre boat launch in Lake Country, a second in West Kelowna across from The Cove Resort, and a third about 4.5 km north of the Summerland boat launch..
The buoys include a flashing light that emit five flashes in 15-second intervals.