Observation of Flooded Area in Bangladesh by MOS/MSR on an Allweather Condition

Abstract

Microwave sensor can measure the ground objects through cloud cover and some rain. Using 23 GHz and 31 GHz bands of MOS/MSR, the authors developed a technology to observe the flooded area in Bangladesh. The observation principle is to estimate the submerged land from the decreasing ratio of the radiance emitted from the land when it is flooded with water.
This measurement becomes possible because of the large difference of the emittance between water and solid land. Generally, the emittance from water is less than that from the solid land. This paper suggests a technique to measure the difference of two frequency radiance, 23 GHz minus 31 GHz, in order to avoid the disturbance caused by local variation of the ground physical temperature or caused by the change of atmospheric conditions.
Although the emissions from the solid land varies with the moisture content, an assumption was taken here that the constant moisture level could be maintained in the tropical soil in Bangladesh in the rainy season. Thus, the measurement accuracy of water ratio to the field of view can be estimated with maximum error about 10% or less.
Next, the sequentially observed MOS/MSR data for Bangladesh land during two years are analyzed by this technique. The results agree to the records of the hydrographs at three major rivers and at the lower stream regions.