Gypsum Content Horizontal and Vertical Distribution of An-Najaf and Al-Kufa Cities' Soil by Using GIS

Abstract

An-Najaf province considered one of the mostimportant cities in Iraq, which is facing rapid populationgrowth and continuous development in constructions such ashousing, hotels, bridges and shopping malls. Therefore, thisstudy aims to create a database for the gypsum content in AnNajaf province (Najaf center and Al-Kufa city). To evaluatethe spatial variability of gypsum content, 464 boreholes and insitu tests were selected and analyzed using GeographicInformation System (GIS). To achieve that, the adoptedmethod consisted of four steps: (1) data collection; (2)geotechnical data georeferencing; (3) interpolation methodsand (4) establishment of maps. Nine geotechnical maps wereproduced for depths (0, 2, 4, 6, 8, 10, 12, 14, 16, and 35) m.Results showed that the largest part of the study area for thedepths from 0-4 m had a gypsum content ranged between 10-25% (moderately gypsiferous), whereas the depths from 4-8 mhad a gypsum content ranged between 3-10% (slightlygypsiferous), and the depths from 8-35 m had a gypsumcontent ranged between 0.3-3% (very slightly gypsiferous).This concludes that the layers from 0-4 m are exceeding theallowed limits (10% gypsum content), which may affect thestability of constructions due to the high levels of groundwaterin Najaf province