Pemantauan Pertumbuhan Padi Menggunakan L-Band SAR Berbasis Teori Dekomposisi: Studi Kasus Subang

Abstract

Food problems in Indonesia cannot be avoided, although Indonesia is often referred to as an agricultural country where predominant livelihood is farming. As a matter of fact, there are still a lot of food shortages along increasing number of inhabitants. Rice is the main staple food in Indonesia, therefore monitoring rice field is important information for better agricultural planning. Monitoring with optical remote sensing would be on stake for Indonesia or tropical regions considering high cloud cover. SAR (Synthetic Aperture Radar) provides an alternative in the provision of data for such purposes, especially with polarization technology. As a system that has its own energy source, irrespective to source of solar energy, a SAR system can operate day and night in virtually all weather conditions, because microwaves can penetrate clouds, smoke and rain. This property is very useful for time sensitive applications such as sensing of agricultural crops or natural disasters. Earlier studies primarily focused on the use of backscatter data. Further development of the SAR technology allows analysis of fully polarization SAR data, which are generally more complex than backscattering-based analysis. Fully polarization SAR analysis procedures that are currently inviting attention is the polarimetric decomposition. This study discusses an application of the Cloude-Pottier decomposition theory in assessment of growth phase of Ciherang rice. Using this theory, a complex fully polarimetric data can be converted into three units of analysis, i.e. Entropy (H), Alpha Angle (􀄮) and Anisotropy (A). In this study, blocks of rice cultivation owned by PT. Sang Hyang Seri, provided major field information for detailed analysis. This research indicated that the Cloude-Pottier decomposition theory was able to describe characteristics of different levels of rice growth. The analysis showed that Entropy played an important role in distinguishing plants age. Distribution of entropy corresponded to various phases of rice growth. Aging rice plants tend to coincide to increasing value of entropy. Entropy became smaller in young rice plants, because of a decrease in the number of leaves or density of plant canopy and therefore soil contribution was dominant. Although the alpha angle was found useful to describe scattering type, this parameter is less visible to contribute significantly to the interpretation of data.