Efiong-Fuller, Emmanuel O. 
  
  
Point No. E_- Coordinate N-Coordinate 
1 E, pre N, 
= 
2 E, N; 
3 E, N, 
~~ 
4 E, a N, 
n-] E Smet N., 
: E Ni 
1 E TN 
1 
Table 5. Computation of Area Using Coordinates 
Multiply along the dashed lines and find the sum; 
this is C,. Then multiply along the full lines and find 
the sum; this is C,. Required Area-A- 2 (C - C.). 
  
  
  
6. DISCUSSION AND CONCLUSION 
The result of this study has shown that erosion mapping and monitoring could be performed using aerial photographs and 
very simple instruments; the areal extent and the rates of erosion could be determine quantitatively. Such quantitative 
parameters are important and useful in two main respects. Firstly, it is possible to predict future trends of the erosion 
activity using the computed rates, and necessary warning issued in advance. Secondly, remedial measures could be 
planned accurately and timely, thus avoiding the damage to property that would have been caused. This will also enable 
better and sustainable land management policies to be formulated. 
Furthermore the result shows that the portion ofthe ravine to the north east of the University of Uyo has been encroaching 
at the rate of about 0.6 hectares or 26.80 metres per annum between 1969 and 1978; and at the rate of about 0.5 hectares or 
20.87 metres per annum between 1978 and 1988. These rates compare favourably with previously obtained estimates for 
different parts of the ravine. For instance a rate of 32.90 metres per annum was obtained by Usoro (1977) using ground 
measurement. De Silva (1980) obtained rates of 23.45m and 30.04m for different parts ofthe ravine; he used a combination 
of aerial photographs and ground measurements. 
REFERENCES 
DeSilva,G.,1980 Induced gullying in the periphery of Uyo Town Proceedings of the 23rd Annual Conference of the 
Nigerian Geographical Association. pp. 238-292. 
Efiong-Fuller, E. O., 1979. Spatial Aerotriangulation using Instrumental and Semi Analytical Methods. Unpublished M. Sc. 
Thesis Department of Surveying, Faculty of Engineering, Ahmadu Bello University, Zaria, Nigeria 
Ituen E. B., 1988 Soil Conservation a prerequisite for the Development of Akwa Ibom State. Seminar paper, Centre for 
Development Studies, University of Cross River State, Uyo. 
Usoro, E.J., 1977 Erosion Problem in the Cross River State. Report of Research Project undertaken in the Department of 
Geography, University of Calabar. 
  
394 International Archives of Photogrammetry and Remote Sensing. Vol. XXXIII, Part B7. Amsterdam 2000.