Simulation and Analysis of the Dynamic Characteristics of Groundwater in Taliks in the Eruu Area, Central Yakutia

The perennially unfrozen zones (taliks) in the Eruu area of central Yakutia have a complex stratigraphic structure, and the dynamic characteristics of groundwater in this region have been insufficiently studied. This study analyzed the results of the explorations and geophysical studies conducted by the Melnikov Permafrost Institute of the Siberian Branch of the Russian Academy of Science. In addition, we simulated and analyzed the dynamic characteristics of groundwater in the area based on hydro-meteorological data, snow data, and remote sensing data. During the process, the dynamic changes in the attributes of aquifers due to the seasonal freeze-thaw processes of soils, including the active layer, were also taken into account. The results showed the following: (1) According to the analysis of the measured data on water levels in hydrogeological observation well 14E/2014, the difference between the simulated and measured values of groundwater levels in monitoring wells for over 99% of the measurements was less than 0.1 m. The average difference between the measured (excluding missing values) and simulated values of groundwater level in the monitoring wells was 0.028 m/d. (2) The annual average water level in the study area declined. The simulated value dropped at a rate of 0.10 m/a, with only a gap of 0.01 m/a with the measured value. Meanwhile, the simulated water head was greatly influenced by the terrain, especially in the central area, where the head decreased rapidly from the perimeter toward the lakes (8.9 m/km on average). (3) From 1 September 2014 to 31 August 2015, the mean value of the simulated discharge in the study area was 3888.39 L/d, which was in line with the results of previous monitoring (the average flow was 4147.20 L/d and 3715.20 L/d in 2014 and 2015, respectively). This study can provide a reference for the reasonable exploitation and utilization of groundwater under the influence of the distribution of perennially unfrozen zones, or taliks, and provides an effective three-dimensional modeling method for quantifying the analysis of groundwater dynamics in permafrost regions.