Land Subsidence Monitoring Using Geographic Information System (GIS) Techniques in Akwa Ibom State, Nigeria

Akwa Ibom state of Nigeria is susceptible to subsidence as a result of complex interaction between anthropogenic activities and natural processes. As an area of subterranean fluid extraction, the study arose because of the need for subsidence monitoring so as to minimize the anticipated resultant risk. The study utilized water extraction data that was linked to an existing data base of the study area. To obtain the subsidence susceptibility index, the total water extraction data for each LGA was normalized and the data converted into grids and interpolated with Inverse Distance Weighted (IDW) tool of ARCMAP spatial analyst extension to create an isoline map. IDW is used to create a continuous surface from sampled point values. The resultant map showed the spatial distribution of the subsidence zones of High and Very High zones are found in emerging urban areas of Uyo, Ikot Ekpene and Ikot Abasi. This emphasizes the need for the population growth and the water supply needs of our urban centers to be monitored. It is recommended that an agency should be established to monitor land subsidence in the vulnerable areas identified by the study.