Ohamobi, Sylvester Ikechukwu. 
  
  
IAPRS, Vol. XXXHI, Amsterdam, 2000 
  
  
  
  
  
  
  
  
  
  
‘ . Degree of Soil Suitability , Restrictive 
- Feature 
. PROPERTY ; Good (g) Fair (f) Poor (p) (Res. Feat.) 
Depth to Bedrock . oou cuis 100-150 S300 dt Depth to rock 
Shrink Swell : Low . Moderate ~~. High (V.High) Shrink Swell 
“Engineering Soil Class UNIFIED GEOP SLCL Olkwik ; s | 
: ol ns : SW, SP, With PIS P1596 : Low :. 
GC, SM,SC 0.15. CH, MH, OL ; Strength 
i e OH, Pt | : 
AASHTO . 0-4 8-May « 8 
Slpe(X) . - 5 | “is 15-25 >25 : Slope 
Layer Thickness : Eug 4 ; 
(cm) | ie M 2150 - 75 - 150: «75 Thin layer 
5 Stontness (wt.%) - «6.25 ry 62.5 - 125... <125 : : Layer stones 
Depth to Water table (cm) e > a 30-90 . <30 Wetness 
* Soildrainage. , —. : ' Exc- to somewhat poorly... Poor 
"M.W.dr poorly drained | drainage 
drained and very poorly 
drained 
  
  
| TABLE 4. SOIL SUITABILITY RATING FOR ROAD FILLS 
24 Suitability Classification and Mapping 
The system (ILWIS - GIS) used the final current land evaluation (LE) column in the suitability tables to match each corresponding 
mapping unit in the soil map (figure 2) to produce good, moderate and poor suitability units. These attribute suitability maps were 
used as inputs. in the land suitability analysis for road allocation by overlaying the five suitability maps using ILWIS,- GIS facilities 
for the final road allocation map. : 
3. RESULTS AND DISCUSSIONS 
The results-of the land evaluation, interpretation of the attributes’ engineering properties and ILWIS - GIS processes were the 
production of five. interpreted attribute tables leading to the final current land evaluations (LE), the five suitability maps and the final : 
road allocation maps. 
31 ^ LocalRoadand'Street —— 
The local road and street suitability map showed only good and poor units. Within the three landscapes of the study area (Plateau, 
Piedmont and Valley), the LRS map indicated that all piedmont landscape units are good for road allocation, while the plateaux and 
valley are poorly suited. a 
32 ^ Road Fills 
The road fills attribute map showed the same trend as the local roads and streets map, rating all units in the piedmont as good and 
those of the valleys and plateaux as poor. This rating was according to the interpretation table for the road fills. 
$35 Sands and Gravel 
The attribute map of sands and gravel showed three classes of units rated as good in the upper slope of piedmont, moderate in the ° 
lower slope and poor for the slope-vales complex of the valleys and plateaux. This means that sands and gravel sourcing is better 
done in the upper slope of the piedmont than at any other part of the study area. 
  
1062 : International Archives of Photogrammetry and Remote Sensing. Vol. XXXIII, Part B7. Amsterdam 2000.