5. Discussion
The ongoing increase of air temperature, changes in precipitation, and permafrost degradation affect the hydrological cycle via seasonal redistribution of water balance elements, changes in soil wetness and ALT, intensification of ground and surface water runoff exchange (Makarieva, 2019a; Rawlins et al., 2010; Shiklomanov & Lammers, 2013; Tananaev et al., 2016; Walvoord & Kurylyk, 2016; IPCC, 2014).
For example, according to Krogh and Pomeroy (2019), hydrological modelling results at Havikpak Creek Research Basin suggest that the maximum peak snow accumulation will increase by 70%, snowcover period will decrease by 26 days, ALT will deepen by 0.25 m, and evapotranspiration will increase by 18% in northwestern Canada over the 21st century.
According to Fang and Pomeroy’s (2020) modelling, the Marmot Creek Research Basin in the Front Ranges of the Canadian Rockies will warm up by 4.7 ˚C and receive 16% more precipitation, 84 mm decrease in snowmelt and 49 days shorter snow-cover period by 2091 -2099. The streamflow changes will be significant: 236% higher in spring months and 12% lower flows in summer and 13% higher flows in early fall.
In these studies as in ours, special observational data from research catchments were used to obtain predictive comprehensive estimates of changes in various elements of the water balance and variable states. In a global review of the runoff formation studies in Northern catchments, it was indicated that there are no modern works on this topic in Russia (Tetzlaff et al., 2014). Russia has significantly lagged behind other Northern countries (mainly Canada and the USA) in instrumental studies of hydrological processes in cold regions over the past 20-30 years. Although some of the first integrated scientific permafrost and hydrological stations in the world were established in Russia (the Bomnak water balance station (from 1934), the Kolyma water balance station (from 1948)), there is not a single ongoing integrated research watershed in the mountain permafrost zone in Russia at present.
There is a lack of data from Russia, particularly considering that approximately 85% of the total terrestrial runoff of the Arctic Ocean is supplied by rivers draining from the Russian Federation and most of it is generated in mountainous areas (Aagaard & Carmack, 1989; Makarieva et al., 2019b). Increasing flows to the Arctic Ocean could lead to a significant impact on the thermohaline circulation, sea ice formation etc. (Arnell, 2005; Weatherly and Walsh, 1996).
The information for parameterizing and improving hydrological models can be integrated from short-term studies in certain landscapes and watersheds where it would be expensive to maintain research facilities longer-term (especially in hard-to-reach regions). The concept of such studies was proposed by Vinogradov (1988); he called it “nonstationary research watersheds and plots”. The idea was further developed by Vinogradova and Vinogradov (2014) and Gartsman and Shamov (2015) who called this approach a “mobile watershed”. According to this approach, one or several indicative watersheds or plots are selected in the study area. The research visits are short-term (approximately from 2-3 weeks to 2 months) and last for several years.
Conducting short-term intensive observations on specially selected representative watersheds, allows the formulation of a general idea of ​​the conditions of runoff formation and hydrological phenomena of the territory in question, and most importantly, approximate quantitative assessment of the parameters of mathematical models of hydrological processes (Vinogradov & Vinogradova, 2014). However, if the data collection is not carried out with the intent of model development and parametrization, or refining existing methods for calculating flow characteristics, such observations lose most of their value and do not justify the investment.
The three-year extensive observations at the Suntar-Khayata Station can be regarded as a good example of such an approach. Among other expeditions to remote regions we may mention historical studies at the Putorano Plateau in 1988-1990 (Reports…, 1988-1990), recent studies at Chukotka (Tregubov et al., 2020) and the Lena River delta (Tarbeeva et al., 2020). We emphasize the need for open access to the detailed hydrometeorological data of such research sites which can provide the opportunity for multi-criteria assessment of hydrological models in different conditions found in the permafrost zone (e.g. Fang et al., 2018; Makarieva 2017, 2018a; Rasouli et al., 2019).