Water Stewardship Information Sources
| ID | 1467 |
|---|---|
| Citation | Polar Geoscience Ltd. 2012. Phase 3 Okanagan Basin Water Supply and Demand Project: Projected Water Supply and Use in the Okanagan Basin (2011-2040) - Okanagan Basin Water Accounting Model Results. Prepared for Okanagan Basin Water Board. |
| Organization | OBWB |
| URL | http://obwb.ca/wsd/wp-content/uploads/2014/07/OWSD_Phase3_Scenarios.pdf |
| Abstract/Description or Keywords | This report summarizes a selection of Okanagan Basin water supply and use projections for 2011 to 2040. The projections are based on the Phase 3 modeling using the Okanagan Basin Water Accounting Model (OBWAM) and its supporting models: the Okanagan Basin Hydrology Model (OBHM) and the Okanagan Water Demand Model (OWDM). Phase 3 modeling has been conducted by RHF Systems Ltd. with support from the OBWB, Agriculture and Agri-Food Canada, and Environment Canada. Polar Geoscience Ltd. was retained by the OBWB to provide technical and analytical support during Phase 3. Based on the Phase 3 projections for the 2011-2040, the following key points are made: Future climate: ﾕ Temperatures in the Okanagan are projected to generally increase throughout the year, however, year to year variability is high. ﾕ Precipitation projections are mixed and highly variable but tend to suggest increases during winter. ﾕ The proportion of rain to snow is expected to generally increase, resulting in reduced snowpacks, particularly at lower elevations. These snowpacks may also be subject to increased mid-winter melt periods. ﾕ Snowmelt is projected to occur earlier and because of reduced snowpacks, runoff from meltwater is expected to decrease. However, this is offset by rain-generated runoff that is expected to increase considerably over the winter. Surface water supply: ﾕ Annual runoff is expected to increase overall, with much of this resulting from the increased runoff between October and March due to increased rain and mid-winter meltwater. Decreased runoff is expected between May and July as a result of the advancement of the freshet period. Runoff is expected to be about the same in August and September. ﾕ Year to year variability in runoff is expected to increase, particularly in winter. ﾕ Prolonged drought has a dramatic impact on surface water availability. After five consecutive years, up to 50% less surface water runoff in total is produced relative to normal conditions. Surface water extraction: ﾕ Surface water extractions represent about 68% of the total water used in the Okanagan. ﾕ During late summer, surface water extractions from the tributary streams generally exceed the natural supply, and in Mission Creek for example, extractions in late summer are double the available natural supply; in future they may be nearly triple. In order to meet water demands, regulation of the available water supply through upland and main-stem reservoirs is and will continue to be paramount. Given the projections for reduced snowpacks, earlier freshet and increased rain-generated runoff in future, water managers may have to consider modifying their storage capabilities and current reservoir operation strategies in order to successfully meet future demands. ﾕ Assuming climate change alone (Scenario Group A), water extractions in most months will increase modestly (5-10%), except in April when it will increase by 40%, and in late fall when it will increase by up to 20%. ﾕ If the population increases at the expected 1% per year and if agricultural water use efficiency improved at its expected rate (Scenario Group B), surface water extraction should not dramatically change in future. ﾕ A population boom with urban sprawl (Scenario Group C) is projected to increase overall surface water requirements by 20-30% throughout the year. ﾕ An increase in the agricultural land base under irrigation (Scenario Group D) is expected to increase overall water extractions by 5-10% throughout the irrigation months. ﾕ A worst case scenario of population boom and agricultural expansion (Scenario Group E) is projected to increase overall water extractions by 30-40% during spring and summer and by 50-70% during the winter. ﾕ Improvements in water use efficiency (Scenario Group F) will mitigate the worst-case scenario (Scenario Group E) by roughly 5% during spring and summer, and up to 20% in the winter. Net inflows to main-stem lakes: ﾕ Net inflows to the main-stem lakes are projected to increase considerably between November and April. During these months the effect of climate change is dominant over the land use and population factors. By May, climate change is responsible for slight reductions in net inflow to Kalamalka-Wood and Okanagan Lakes, however these are not universally projected downstream, given the regulation of Okanagan Lake and River. By June, climate change is projected to decrease net inflows to Okanagan Lake by 38%, and under the worst-case scenario (Scenario Group E), a further 18% reduction is projected. Projected reductions in runoff and increased extractions in July, August and September further exacerbate conditions and maintain negative net inflows to Okanagan Lake under all future scenarios. Fortunately, with Okanagan Lake and Okanagan River regulation, downstream lakes are projected to maintain positive, albeit modestly lower, net inflows over the summer months. water supply, climate change, allocation, watershed management |
| Information Type | report |
| Regional Watershed | Okanagan |
| Sub-watershed if known | |
| Aquifer # | |
| Comments | |
| Project status | complete |
| Contact Name | Lars Uunila |
| Contact Email | [email protected] |