Preliminary GIS ‐Based Mapping of Shallow Engineering Soil Properties in Koodbur District, Hargeisa Using GIS

ABSTRACT

Hargeisa is experiencing rapid growth in population density and infrastructure development, leading to significant challenges in urban planning and resource management. This study aims to address these issues by utilizing Geographic Information System (GIS) tools to map and visualize the spatial patterns of critical geotechnical soil attributes in the Koodbur District of Hargeisa. Eight trial pits were excavated throughout the district to a depth of 2 m, and representative soil samples were collected and analyzed in accordance with ASTM standards. The trial point data was analyzed in QGIS using the Inverse Distance weighting interpolation method. The IDW method was used to generate continuous preliminary spatial estimates of the investigated soil properties between the sampled location. The northern area was predominantly coarsely‐grained, consisting of soils with gravel contents ranging from 10% to 16% and sands between 66.3% and 71%. In contrast, southern parts had fine soils within a range from 57.8% to 71%. In the southern part, fine soil with Moderate plasticity was found based on Atterberg limits (liquid limit, 14.4%–40%; plastic limit, 11.3%–24.25%; plasticity indices 3.1%–15.76%), but some northern soils exhibited no plasticity. The peak dry density ranged between 1.55 g/cm ³ and 2.065 g/cm ³ , whereas the optimum moisture content was between 11.66% and 21.43%. Internal friction angles within the samples ranged from 25.87° to 38.3°, and cohesion from 0 to 8.43 kPa. The specific gravity measurements for soil ranged from 2.60 to 2.70. The study demonstrates the potential of GIS‐based mapping to organize and visualize locally derived geotechnical information for preliminary planning and prioritization of future site‐specific investigations.