1989 年 9 巻 1 号 p. 5-13_1
The northern part of Oman is characterized by an arid climate with an average annual precipitation of less than 100 mm. Under such conditions it is very important to estimate the infiltration and evaporation properties from soil surface especially after rainfalls in terms of the effective use of land and water resources. Dry Index (DI) was developed to evaluate the surface soil moisture content from NOAA AVHRR imageries.
The underlying premise of the NOAA AVHRR image analysis is that spectral reflectance in the visible and near infrared bands and the emittance in the thermal band depend on the surface soil moisture content. For the purpose of verifying the premise and evaluating the final image output, experiments were carried out in the laboratory using soil samples obtained from the study area and radiometers which have similar spectral regions corresponding to the NOAA AVHRR.
Dry Index was applied to the NOAA image for the rainfall during April 24-May 4, 1981. The results of the NOAA image analysis for soil moisture are as follows :
(1) Dry Index (DI) was effective for obtaining information on the surface soil moisture and the arid environment.
(2) The time series analysis of DI revealed the rate of drying of surface which in turn shows the possibility of estimating the characteristics of the water holding capacity of surface soil.
(3) The results, thus obtained, will be applicable for the developments of land and water resources in the arid regions.