APPLICATION OF REMOTE SENSING TO MAPPING OF EXPANSIVE SOILS AND ROCKS IN OMAN 
Anil K. Bagchi!, Amer A. Al Rawas?, Ali Al Barwani? 
Associate Professor, Lecturer and Undergraduate Student, respectively. 
Department of Civil Engineering, Sultan Qaboos University, P.O.Box 33, Al-Khod, 123, Sultanate of Oman 
1,2,3 
Commission VII, Working Group 6 
KEY WORDS: Remote Sensing, Soil, Classification, Mapping, Multispectral. 
ABSTRACT: 
Presence of expansive soil increases cost and time for many civil engineering construction projects. Identification of 
the expansive soils and rocks using remote sensing, which involves less ground visits, should be useful. This has 
therefore been taken up as an ongoing research in the Civil Engineering Department of Sultan Qaboos University 
using the facility available in the Remote Sensing Center. The Center is equipped with a PC based system, consisting 
of a number of PC's, duly networked, and appropriate peripherals. The software in use is ERDAS. 
A large scale geotechnical mapping program was carried out covering the entire country. The geotechnical 
information including the subsurface soil profile and soil characteristics were collected from more than seventy towns. 
A brief report on the ground situation is included. 
The remote sensing phase of the investigation started with identification of a few training samples. Next job is to 
develop a signature, a rather elaborate exercise in finding statistical parameters which can represent the training 
samples. Identification of expansive soil is thereafter tried using the supervised classification technique, following the 
maximum likelihood decision rule. Success and applicability of one or the other of the methods depend upon the 
nature of the data structure, uniqueness of the signature, statistical distances between the signatures, nature of 
information class being sought, spectral bands used etc. All these were kept in view and studied at appropriate places. 
All the three groups of spectral bands - visual, infra-red and microwave- have been applied for the investigation. 
The data source is restricted to the satellites JERS and Landsat TM. The final result of classification appears in the 
form of a classified map. 
1. INTRODUCTION depending upon the upward movement. As a 
consequence of the structural damage evidenced, the 
Expansive soils and rocks are those which undergo potential problems associated with the Omani expansive 
volumetric changes upon wetting and drying. These soils and rocks have been recognised and preventive 
materials swell when the moisture content is increased measures are being incorporated into new designs and 
and shrink when the moisture content is decreased. The ^ construction works. 
moisture change can be due to natural sources such as 
rainfall or manmade sources such as surface irrigation, Studies in the possibility of applying remote sensing 
broken water supply and sewers, and leakages from technique to identify and map the expansive soils and 
swimming and feature pools. These materials cause rocks has therefore been undertaken in the remote 
distress and damage to engineering structures founded sensing centre of Sultan Qaboos university of Oman. The 
on them. It was reported that the annual cost of damage Center is equipped with a PC based system, consisting of 
from expansive soils in the United States alone exceeds $ a number of PC’s, duly networked, and appropriate 
10 billion, Steinberg (1992). peripherals. The software in use is ERDAS. It is an on- 
going research and the present paper is a status report. 
Oman has experienced a tremendous urban expansion in 
the last two decades. This expansion was accompanied 
by a sharp increase in water consumption which means 2. EXPANSIVE SOILS AND ROCKS IN OMAN 
that considerable amounts of water are infiltrating into 
the ground. Several structures have suffered from varieus The regional geology of northern Oman is dominated by 
types of damage due to wetting of the foundation soil, the Oman mountains and is geologically distinct from 
from water ingress into the ground. The structural cracks the rest of the Arabian Peninsula. The problems of 
are observed in different types of structures such as ground heave experienced in Oman are predominantly 
residential houses, garden walls, roads and open related to the presence of smectite clay minerals with 
drainage channels. The pattern of cracks seems to vary 
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International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B7. Vienna 1996