Retention time of lakes in the Larsemann Hills oasis, East Antarctica

Abstract. The study gives first estimates of water transport scale for five lakes located in the Larsemann Hills oasis (69º23' S, 76º20' E) in the East Antarctica. We estimated the lake retention time (LRT) as a ratio of the lake volume to the income and outcome terms of a lake water balance equation. The LRT was evaluated for lakes of epiglacial and land-locked types, and it was assumed that these lakes are monomictic with water exchange existing during a warm season only. We used hydrological observations collected in 4 seasonal field campaigns to evaluate the LRT from the outcome and income terms of the water balance equation. For the epiglacial lakes Progress/LH57 and Nella/Scandrett/LH72, the LRT was estimated of 12–13 and 4–5 years, respectively. For the land-locked lakes Stepped/LH68, Sara Tarn/LH71 and Reid/LH70, our results show a big difference in the LRT calculated from the outcome and income components of the water balance equation. The LRT for these lakes vary depending on the methods and errors inherent to them. We suggested to rely on the estimations from the outcome surface runoff since they are based on the hydrological measurements with better quality. Lake Stepped/LH68 exchange water within less then 1.5 years. Lake Sara Tarn/LH71 and Lake Reid/LH70 are the endorheic ponds with the water exchange through mostly evaporation, their LRT was estimated as 21–22 years and from 8–9 years, respectively. To improve the estimates of the LRT, the hydrological observations are needed to monitor the lakes and streams during the warm season with the uniform observational program.