IHA Congress 2011 - Session 4b - Ken Adams

1. Manitoba Hydro’s Experience with Reservoir Evaporation IHA 2011 World Congress Ken Adams Senior Vice-President, Power Supply

2. Manitoba Climate ____Climate Zone____ North: Subarctic South: Humid Continental TemperatureNorthSouth July: 23°/9° 25°/13°C January: -19°/-31° -12°/-23°C PrecipitationNorthSouth Rain (mm): 348 389 Snowfall (cm): 186 125 Canada USA

3. Manitoba Lakes and Reservoirs Province of Manitoba Total 650,000 km2 Lakes 94,000 km2 Manitoba Hydro reservoirs Existing lakes 31,110 km2 or 93% of total Impoundments 2,490 km2 or 7% of total Regulation Mode Hydropower 27% Multi-Use 73%

4. Manitoba Climate Manitoba Lakes Precipitation rates > evaporation rates Net water gain Impoundments Evapotranspiration rates of flooded land < evaporation rates of new reservoir area Net loss Annual Precipitation

5. Manitoba Net Loss Estimates Annual evaporation rates ~100 mm greater than evapotranspiration Positive net precipitation across province Incremental Net Loss 8.3 m3/MWh system average 0.0002% of water supply Annual Precipitation and Evaporation

6. Appropriateness of m3/MWhin Manitoba Intensity measure rather than an absolute measure Illogical if water is considered a scarce resource Measure should allocate losses to all users Measure should be related to impacts of incremental evaporation There may be no incremental impacts on others

7. Conclusions Consider Only Incremental Evaporation Regulation of existing lakes Creation of new reservoirs Allocate Responsibility for Incremental Losses to All Beneficial users Relevance of Measure Should be related to impacts, if any, of incremental losses to other users Should be based on absolute losses Energy based measure is inappropriate in Manitoba