| Description |
Climate change is projected to modify the hydrologic cycle across scales, but the relative impact climate change will have on water resources systems compared to other influencing factors remains uncertain. The performance of water storage reservoirs, for example, will not only be altered by climate-change-modified precipitation, runoff, evaporation, and transpiration, but also by additional factors such as water demand. Using a case study set in the western United States, this thesis presents an investigation of the relative importance of climate change modified hydrologic processes and water demand on reservoir feasibility. A modeling framework comprised of a river system model (MODSIM-DSS) and a precipitation (rainfall and snowfall) driven runoff model (Snowmelt Runoff Model) was created, calibrated and validated for the White River watershed and river system in northwest Colorado and northeast Utah. After validation, a proposed reservoir in the Utah segment of the White River was inserted into the modeling system. Based on climate change projections of impacts to hydrologic processes, scenarios reflecting climate change modified precipitation, temperature, and evaporation were defined and combined with a future water demand scenario including energy development and urban growth requirements. The scenarios were analyzed with the modeling system to quantify the relative impact of the altered hydrologic processes and increased water demand on reservoir feasibility. The results showed a reduction in precipitation has a greater effect than the projected increase in temperature and evaporation on the inflows to the proposed reservoir and performance of the reservoir. For a 7 percent decrease of precipitation there was an 8 percent reduction in runoff volume over a simulated ten-year period. This decrease was shown to have the greatest impact on the amount of water stored in the reservoir and the amount readily available for downstream use. In a simulation of the combined effects of precipitation, temperature and evaporation modification the reservoir was found to be impacted significantly with insufficient storage to meet downstream demands. Although significant, the impacts of the climate change modified hydrologic processes on reservoir feasibility were found to be insignificant compared to the impacts of future water demands. |
