Much is still unknown about the current permafrost and hydrological conditions of the Gates of the Arctic National Park and Preserve. This study addresses the question of how thermal and hydrogeologic properties of the subsurface may affect active layer dynamics and groundwater flow in the Nutuvukti Lake watershed. Results from the modeled hydrologic condition of the Nutuvukti Lake watershed will be useful for the National Park Service when creating monitoring protocols. Figure 1: Study area location. Map of A) northern Alaska, B) Gates of the Arctic National Park and Preserve, and C) Nutuvukti Lake Watershed study area (LCC Network). Active layer dynamics are important to modeling hydrogeology in permafrost environments (Evans et al., 2015; Liao & Zhuang, 2017). A heat conduction model is applied to three soil types present in the study area to simulate active layer thickness; organic material, silt, and colluvium. We use GIPL, a 1D finite difference heat conduction numerical model that simulates subsurface temperature with depth. Soil hydrothermal properties are considered in modeling the thermal and hydrological processes of the study site. A sinusoidal daily mean temperature variation was applied at the land surface, and thermal properties of the soil layers are based on soil core data and previous literature (Jafarov et al., 2012, Nicolsky et al., 2007; Romanovsky & Osterkamp, 2000; Speeter, 2015). Figure 2: A. Modeled temperature profiles of organic material with changing porosity, therefore water content, and B. Modeled active layer thickness with changing porosity. Preliminary model results indicate that active layer thickness in soil comprised of organic material can vary by several meters depending on its hydrologic properties. For example, changing porosity of a 15-meter-thick organic soil column between the range of 0.1 to 0.7 decreased the active layer from 3.0 meters to 0.7 meters respectively. This indicates that as more water is present in the soil, soil will thaw to thinner depths due to more latent heat of the phase change in water is consumed, thus, slowing the thaw front in the active layer during the summer. To study the effects of active layer dynamics on watershed hydrology, MODFLOW was used to simulate groundwater flow in the Nutuvukti Watershed. MODFLOW is a 3D finite difference groundwater flow model developed by the USGS. Three soil layer are considered for this watershed. The first layer represents the active layer, or supra-permafrost aquifer; the second layer represents permafrost with low hydraulic conductivity; and the third layer represents a sub-permafrost aquifer (Walvoord et al., 2012). Results from GIPL are used to inform the thickness of the supa-permafrost aquifer (Liao & Zhuang, 2017). As active layer thickness directly impacts shallow subsurface hydrology, model results help to assess how hydrology may be impacted by the distribution of different soil properties.听