| Abstract/Description or Keywords |
Nicola Lake is located northeast of Merritt in the Southern Interior of British Columbia. Figure 1 shows the location of Nicola Lake and the contributing watershed. The catchment area includes 2990km squared of the interior plateau, varying from semi-arid valley bottom to temperate mountains rising 2000 m above sea-level. Nicola Lake water levels have been controlled by a dam since the 1920s. The dam was rebuilt in 1986 to store more spring runoff for summer irrigation and maintaining fisheries flows through the fall and winter. The dam does not provide significant flood control benefits as average freshet inflow volumes far exceed the live storage capacity of the reservoir. It can, however, reduce peak discharge in the Nicola River downstream in moderate flood years if inflow forecasts are accurate and snowmelt is not too rapid. Inflow forecasts are done by the BC Ministry of Environment's River Forecast Centre in Victoria, and inflow prediction has been good except for years during which very high rainfall resulted in inflows much higher than forecast. The problems associated with the unexpectedly high releases in the spring of both 1990 and 1991 sparked a search for improved flow forecasting methods, and this document endeavours to find those. The document concludes by saying that an attempt to improved the forecasting of annual freshet inflow volumes to Nicola Lake has been made, and that the 1986 River Forecast Centre's Nicola Lake Inflow Model has been updated. It concludes that it is not possible to improve the 1986 model in any meaningful way, and that the model should continue to be used unchanged as it best predicts freshet inflows diring the low flow years. The document ends stating that during more high flow years, other data can be used to determine inflow in addition to the 1986 model. |
