Assessment of the Nature, Distribution and Causes of Land Subsidence in Central and Northern Saudi Arabia

Wednesday, 17 December 2014
Abdullah Othman1, Mohamed Sultan1, Hassan Al Harbi2, Ahmed Youssef2, Mohamed Ahmed1,3, Mustafa Emil1, Yesser Zabramwi2, Saeed Alzahrani2, Alla Bahamil2 and Kyle Chouinard1, (1)Western Michigan University, Kalamazoo, MI, United States, (2)SAUDI GEOLOGICAL SURVAY, Jeddah, Saudi Arabia, (3)Suez Canal University, Ismailia, Egypt
Numerous land subsidence events have been recently reported from central and northern parts of the Kingdom of Saudi Arabia in Hail, Al Qassim, Al Jowf, and Buraydah Provinces. In some cases, these incidences resulted in losses in life and property. In this study, an integrated (field, geologic, remote sensing) approach is applied to accomplish the following: (1) identify the spatial distribution and extent of areas affected by subsidence (TASK I), (2) identify the factor(s) causing such subsidence (TASK II), and (3) identify areas threatened by such phenomena across northern and central parts of the Kingdom using criteria extracted from TASK II (TASK III). A three-fold approach was applied: (1) visits were conducted to collect field observations from reported subsidence locations, (2) spatial correlations were implemented in a web-based GIS environment for the reported subsidence locations in relation to relevant co-registered static datasets (e.g., rock and soil types, geologic structures) and temporal datasets (e.g., groundwater extraction, landuse/landcover, distribution and magnitude of earthquakes), (3) subsidence rates were extracted applying the Small BAseline Subset (SBAS) radar interferometric technique and using European Remote Sensing satellite-1 (ERS-1), ERS-2, and the Environmental Satellite (Envisat) data sets. Our findings (from radar interferometric studies) indicate that the distribution of areas undergoing subsidence are consistent/correlate with: (1) reported subsidence locations, but reveal many additional unreported subsidence locations, (2) irrigated lands, especially those witnessing a progressive increase in agricultural activities with time; (3) outcrops of the Saq sandstone aquifer system, the main source for fresh groundwater in the Kingdom, (4) outcrops the Minjur limestone formation that are subject to karstification; and (5) urban centers lacking appropriate sewage and drainage systems.