Assessing streamflow sensitivity to temperature increases in the Salmon River Basin, Idaho

Abstract

Increased temperatures are occurring in the Salmon River Basin (SRB) of Idaho and are anticipated to continue increasing in the future, leading to complex changes in climate and water resources. To address these concerns, the objective of this study was to evaluate streamflow changes/sensitivity when temperatures increase. A hydrological model, the Variable Infiltration Capacity (VIC) model, was applied to simulate streamflow under thirty temperature increase scenarios (i.e., rising 0.1°C per step to 3°C). It was found that the annual mean streamflow decreased whenever temperatures increased in the SRB. Streamflow increases in winter and decreases in spring and summer but is barely affected by temperature in autumn. On a monthly basis, streamflow responses varied in response to rising temperatures. When temperature increased, the streamflow increase occurred from November to February, and it decreased from May to July. The analysis also discovered linear relationships between rising temperatures and streamflow changes throughout the year, with the exception of June and July, which revealed logarithmic correlations. Results obtained by daily streamflow analysis showed that center time occurred 10–30d earlier when temperatures increased 2°C and 15–45d earlier when temperatures increased 3°C. Finally, the Richards–Barker Index (R–B Index), a flashiness index, also increased with rising temperatures, and a higher R–B Index causes bank erosion problems. Changes in the streamflow due to the temperature increases have a significant implication both for the water management and ecological processes.