Process_Description:
Excerpt from Anna Klene's dissertation (Klene, A. E. Climate and Urbanization in Barrow, Alaska. Ph.D. dissertation, Department of Geography, University of Delaware, 2005.)
Drew constructed a detailed soil map of the Barrow area in 1957. At that time, five major soils were recognized on the North Slope: Lithosols, Regosols, Arctic Brown, Tundra, and Half Bog. The last four were recognized in the Barrow area and were listed in order of increasing soil moisture. Arctic Brown was considered the only mature soil, the others were thought to either not have had enough time to develop or development had been impeded because of constant saturation (Drew, 1957). Polygons show systematic soil development as cryoturbation and uplift change the soil regime, and this was incorporated into the map. Thaw depths appeared to be related to soil type, with Arctic Brown soils thawing deeper than the others.
However, in the early 1990s soil scientists proposed a new Gelisol order to the soil survey (ICOMPAS, 1996), which would reclassify cold region soils. In the U.S. Soil Classification, soils are differentiated on six levels, listed here from most general to most specific: order, suborder, great group, subgroup, family, and series. This new order (1 of 12 total) contains soils found in the presence of permafrost and indicates that characteristics of freezing and thawing are important in determining the properties of these soils (Soil Survey Staff, 1999). Features such as ice wedges and ice lenses, irregular horizons, downward mixing of organic matter, and granular, platy and vesicular structures in the horizons are prevalent. Gelisol is derived from the Latin word gelare, meaning to freeze, and all soils within this order end in the letters el (Soil Survey Staff, 1999, 126). These soils comprise 13% of the soils in the world, making them the second most common order (Soil Survey Staff, 1999, 120).
Drew s soil map was reclassified using the new soil taxa (Table 2) by Bockheim et al. (1999) as part of their work on the carbon distribution and content of near-surface permafrost. This map has eight soil classes (Figure 3). Earlier work showed that ice wedges underlie approximately 65% of the Barrow area (Brown, 1967), while approximately 50 to 75% of the overall soil volume within the upper 2 m may be due to interstitial ice and lenses (Sellmann et al., 1975). The digital version of the updated soils map was overlaid on a USGS base map (USGS, 1955), which was produced from aerial photos of similar vintage to those used by Drew (1957), and adjusted using an affine transformation. It was then converted into WGS 84, UTM Zone 4 and another affine transformation was performed to further reduce errors in alignment. As a third step, the map was rubbersheeted using the adjusted BLM landcover map (Figure 1) as a base. The eastern and western boundaries of small thaw lakes and streams were used as stationary points to align the maps, because while these do experience erosion (Sellmann et al., 1975) they do so at lesser rates than the other features depicted on the map (i.e. the north and south ends of the thaw lakes and ocean and lagoon coastlines).
A series of changes have occurred to the Barrow landscape in the 50 years since the soil map was originally drafted and some modifications were made to account for these. Aquaorthel soils were assumed to exist in the basins of the two drained thaw lakes in the center of the study area (J.G. Bockheim, personnal communcation). These lakes were artificially drained in the 1950s, after Drew had mapped the area. A small lake near Footprint Lake and another near the town gravel pit were also categorized this way as personal observation has shown that they no longer have standing water. To update the map further, the road network was overlain and recatagorized as gravel to reflect village development since the map was originally created. This map was then rasterized to 30 x 30 m pixels to match the landcover map.
Reanalysis of the original aerial photos used in the creation of Drew s soils map would allow for a more accurate map to be made directly using the coordinates of the georectified images. Plans are underway to reprocess these photos (W. Manley, pers. communcation), and an improved soils map may be produced in the near future.
Empirically based estimates for soil thermal properties near Barrow are available for several locations near Barrow in different soil types (Lord et al., 1972; Nakano and Brown, 1972; McGaw et al., 1978; Outcalt et al., 1989) that can be incorporated into the soils map. Using these other sources in conjunction with the map allowed the development of estimated soil properties for each new soil class (see Table 3).