A calculation model for the spatial distribution and reserves of ground ice-A case study of the Northeast China permafrost area

Ground ice is solid water that exists in permafrost. The spatial distribution and reserve estimation of ground ice has been a challenging issue in permafrost studies. A model for mapping the spatial distribution and calculating the reserve of ground ice was developed. By using the borehole data and soil parameters, the strata in different geomorphic units were classified into, from top to bottom, cultivated soil, clay, silty clay, sandy soil, gravel soil, and bedrock. The ground ice calculation range in its extent and depth was determined for different geomorphic units. The thickness and reserve of ground ice were obtained by using the material composition of soil theory and the GIS spatial calculation method. The model results were compared with the survey data and showed 72.3% accuracy. For the Northeast China permafrost area, above 20 m depth, the average thickness of ground ice was 2.3 +/- 1.1 m, and the reserve was 1045.5 km3. This work provides a framework to enable permafrost researchers to map the spatial distribution and estimate the reserve of ground ice. The results lay foundations for studies in climate disaster, hydrological cycle, succession of ecological environment, cold region engineering stability and so on.