How much snow is lost from during a winter season due to sublimation ?
The answer to this question is in particular important for hydropower production since the seasonal snow cover is the largest reservoir in many hydropower systems. Sublimation is the process when the snow (i.e. frozen water) becomes water vapor. The sublimation can be regarded as a leakage from the snow reservoir since this part of the stored water is lost from hydropower production. Knowledge about the amount of snow that is sublimated will result in improved scheduling of hydropower production. It will also improve water resources management in general since assessments of water availability is improved.
In SnowSub sublimation will be measured directly at selected field sites by continuous eddy covariance measurements. In addition, controlled experiments will be carried out in a climate container. These measurements will be used to develop new snow models that explicitly accounts for sublimation losses. The new snow models will be integrated into hydrological models that are used for forecasting inflows and planning of hydropower production. Hydropower companies (Statkraft and Skaregak) will test and evaluate the new models for selected cases when sublimation is expected to be important.
The knowledge and tools created in SnowSub will contribute to improved hydropower production, flood forecasting and water resources management.
Snow is the largest reservoir in many hydropower systems, which deliver green energy to the societies. This snow reservoir is leaking water to the air by the process known as sublimation. Snow that sublimates is lost from hydropower production. But what is the actual amount of “lost snow”? Until recently, Norway did not have any continuous eddy covariance measurements, which provide in-situ evapotranspiration and sublimation observations. This knowledge gap contributes to uncertainties in forecasted inflow into hydropower reservoirs during the snow melt season.
Hydrologic modelling is fundamental and critically important for water resource managers and hydropower operators to forecast inflow. Current snowpack models within operational hydrological software have very poor (if any) accounting of the sublimation process. Flux observations will directly contribute to operational model development, parameterization and validation. This is expected to result in improved scheduling of hydropower production. Having more predictive control over the losses through enhanced hydrological modelling would create value through improved ability to optimize production and “maintain stability, flexibility and security of supply in the energy system of the future”. An overall better understanding of snow processes will also lead to improved prediction of floods contributing to safety in the downstream regions.
SnowSub will consolidate, structure and develop snow research in the operational environments by engaging regional scale power production companies, experts in hydrologic modelling and field observations in a joint effort to assess model state, refine and validate forecasting routines. The focus is particularly on Norwegian power production, but with a long-term goal to reduce uncertainties in inflow forecasts within other regions where snowmelt contributes to streamflow. Improving hydropower production scheduling is important for transition towards zero-emission societies.