Hydrological, meteorological, and watershed controls on the water balance of thermokarst lakes between Inuvik and Tuktoyaktuk, Northwest Territories, Canada

• Published in: Hydrology and Earth System Sciences
• Main Authors: Wilcox, Evan J., Wolfe, Brent B., Marsh, Philip
• Format: Text
• Language: English
• Published: 2023
• Subjects: Arctic; Northwest Territories; Canada; Mackenzie Delta; Tuktoyaktuk; Inuvik; Hess; Climate change; Thermokarst; Tundra
• Online Access: https://doi.org/10.5194/hess-27-2173-2023; https://hess.copernicus.org/articles/27/2173/2023/

Thermokarst lake water balances are becoming increasingly vulnerable to change in the Arctic as air temperature increases and precipitation patterns shift. In the tundra uplands east of the Mackenzie Delta in the Northwest Territories, Canada, previous research has found that lakes responded non-uniformly to year-to-year changes in precipitation, suggesting that lake and watershed properties mediate the response of lakes to climate change. To investigate how lake and watershed properties and meteorological conditions influence the water balance of thermokarst lakes in this region, we sampled 25 lakes for isotope analysis five times in 2018, beginning before snowmelt on 1 May and sampling throughout the remainder of the ice-free season. Water isotope data were used to calculate the average isotope composition of lake source water ( δ I ) and the ratio of evaporation to inflow ( E / I <svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="19pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="cbc7a668b3b60477cad2ca373e846eda"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="hess-27-2173-2023-ie00001.svg" width="19pt" height="14pt" src="hess-27-2173-2023-ie00001.png"/></svg:svg> ). We identified four distinct water balance phases as lakes responded to seasonal shifts in meteorological conditions and hydrological processes. During the freshet phase from 1 May to 15 June, the median E / I <svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="19pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="22ea8fb3c86c26a7e61eff46bfad0b65"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="hess-27-2173-2023-ie00002.svg" width="19pt" height="14pt" src="hess-27-2173-2023-ie00002.png"/></svg:svg> ratio of lakes decreased from 0.20 to 0.13 in response to freshet runoff and limited evaporation due to lake ice presence that persisted for the duration of this phase. During the following warm, dry, and ice-free period from 15 June to 26 July, ...