DETECTION OF SOIL MOISTURE BY REMOTE SURVEILLANCE

摘要: Three general regions of the electromagnetic spectrum are being used in feasibility studies remote sensing soil moisture - short-wave region, thermal long-wave and radar or micro-wave region. Simple solarimeters have been to correlate albedo values (ratio reflected incoming solar radiation depends on amount water surface soil) gravimetrically measured water-content layers. Albedo could also be delineate three classical stages drying. Studies suggested that a inertia concept monitor moisture, i.e. temperatures when they maximum minimum difference between them is related content. The governing principle microwave techniques derives from fact dielectric constant at frequencies quite large (80) whereas dry typically less than 5. A wide range wavelengths has soil-moisture detection by fractions centimeter tens centimeters depth layer monitored varied few millimeters centimeters. Microwave however, suffer need know order resolve moisture-induced emittance changes, always require specific knowledge type viewed. Cloud-cover (encountered satellite based programs), salinity, presence vegetation create problems for these techniques. Some primary benefits include ability predict crop yields, pest outbreaks, plant disease. It an aid management crops rangelands.