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Effects of Climatic Change on Temperature and Thermal Structure of a Mountain Reservoir
Author(s) -
Lewis William M.,
McCutchan James H.,
Roberson Jennifer
Publication year - 2019
Publication title -
water resources research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.863
H-Index - 217
eISSN - 1944-7973
pISSN - 0043-1397
DOI - 10.1029/2018wr023555
Subject(s) - hypolimnion , environmental science , tributary , advection , global warming , climate change , mixed layer , hydrology (agriculture) , elevation (ballistics) , spring (device) , climatology , geology , atmospheric sciences , oceanography , eutrophication , geography , mechanical engineering , chemistry , physics , cartography , geotechnical engineering , organic chemistry , geometry , mathematics , nutrient , engineering , thermodynamics
A 35‐year monitoring record for the water column of Lake Dillon, a reservoir of the southern Rocky Mountains, shows near‐surface warming of 0.76 °C/decade and warming at all greater depths (55 m); warming was progressively smaller with depth. Annual heat budget of the lake increased (67 cal·cm −2 ·year −1 ; 0.089 W/m 2 ) as did Schmidt stability (41%). The mixed layer was affected by climatic conditions at the high elevation of the lake (2,750 m above mean sea level); heat fluxes were high during both the seasonal warming and cooling. Density gradients below the mixed layer were weak because of low water temperatures associated with high elevation. Annual cooling of the mixed layer was rapid following a brief initial stabilization and showed high interannual variability across years for a given month, which obscured any trend in mixed layer thickness that might have been caused by heat accumulation. The hypolimnion was warmed by advective heat exchange from tributary inflow and deep water withdrawal, not by carryover of fall or spring warming; advective warming by tributaries can be expected in many reservoirs.