This paper deals with the estimation f o r the percentage of impervious area by land-use categories classified from the satellite remote sensing imagery. The test area is KOMATU watershed,4.64km², located in MIYAZAKI city. The area is divided into 14 zones for the estimation.
The percentages are also manually interpreted from aerial photographs observed in 1962,1966,1973,1983, and 1987. Then, these results are compared each other to check the ac curacy of estimation.
From this investigation, the followings are clarified;
1) The overall percentages of impervious area in the whole test area change rapidly from 42%to 77 % in the observed terms of aerial photographs.
2) The manually interpreted percentages from the aerial photograph contain about 10% error caused by the misjudgment.
3) High multiple-correlation coefficients are obtained between the percentages derived from the aerial photograph and one from the satellite imagery; 0.74 for LANDSAT-MSS,0.81 for MOSMESSR and 0.91 for SPOT-HRV.
4) The discrepancies between them are 16% for LANDSAT-MSS,19% for MOS-MESSR,13%for SPOT-HRV in the worst sub-area and less then 10% except for the zones where contain the error caused by the misjudgment of aerial photograph and the geometric error of imagery. From these results, it is confirmed that the satellite imagery is useful for the evaluation of groundwater recharge.