; ; . ; Nb. S ; ; ; Internatiot 
International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B7. Istanbul 2004 E 
  
The watershed storage, S, and the curve number CN are related 
by, 
25400 
S 2 ———— — 254 (5) L3 
Runoff d 
The parameter CN, having a range of values between 0 and 100, 
called the curve number. In this method, a curve number (CN) 
is assigned to each watershed or portion of watershed based on 
soil type, land use and treatment, and antecedent moisture 
condition. (Hydrology Handbook, 1996). 
  
In this study, we focused to improve characterization of 
hydrologic condition of basin by using data acquired from 
Landsat satellites. Spatial data obtained from remote sensing 
was processed using digital image processing techniques in 46 ° 10 20 Kilamsters 
order to identify model inputs as land cover/use, drainages, — — 
  
  
  
  
  
F 
Digital Elevation model integrated into GIS, processed with the Figure 3 Hydrological soil map 
aid of Hydrological HMS program into Arcview derived 2 
physical characteristics of drainage basin area such slope, 4. DISCUSSION AND RESULTS 
aspect, sub-divided basins areas. (Figure-2) 
f Fs 
  
Classified Landsat images integrated Geographic Information 
System with Hydrological soil map applied Soil Conservation 
Soil Curve Number Method to calculated curve numbers 
distribution of sub-basin area. To estimate curve numbers and 
runoff depth for the entire sub-basin, vector coverage of soil 
showing the HSG, and land cover and land use classification 
(Anderson et al., 1976) were overlain each other. The soil layer 
and classified image were both converted a 30 meters grid cell 
[n this wor 
very useful 
with 30 r 
effecting v 
rainfall an 
changed a 
2 dis T Due to lac 
size in order to calculate curve number and runoff depth value. 
: : been able 
Curve numbers were calculated by means of National NEN 
; ; dal catchment: 
Engineering Handbook (NEH 4) chapter 4 guidelines. aii 
rainfall/rur 
technologi 
  
basin area, 
a model cc 
based on 
hydrologic 
  
  
  
  
Figure 2 Sub-basin area 
Soil maps of rural areas are supplied by KHGM (General 
Directorate of Rural Services) in relation with 1:25000-scale 
topographic maps. Soils are classified into four hydrologic soil 
groups, which are A, B, C, D; each group was used to 
Abdiissela 
Triple dia 
Turkey, H 
determine curve number. Soils in group A have well drained, in 244. 
group B moderately-drained, in group C poorly drained, in 
group D very poorly drained. (Figure 3) Anderson, 
À land us 
  
remote ser 
Print. Offi 
  
  
  
Assefa M. 
runoff de 
Figure 4 Curve Numbers 1987 Computers 
Runoff depth distribution of the basin was calculated by using Qihao Wei 
curve number distribution values with in case of total daily 85 runoff wi 
mm rain fall in the GIS as layer. Environme 
270