NDVI In Drought Analysis

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3.2. Preparation of NDVI in drought analysis. The vegetation cover of a particular region is one of the major indicators of assessing drought on a global scale. Monitoring vegetation on a spatial and temporal basis can highlight growth and stress of vegetation. The most common satellite-derived index is based on the behavior of vegetation in response to rainfall and amount of moisture available across a region. Various forms of vegetation indices based on remote sensing data have been used to monitor vegetation that indirectly monitor drought, with the most widely adopted being the Normalized Difference Vegetation Index, NDVI. Kriegler, et al. (1969) were the first to propose NDVI and it is calculated by rationing the difference of the red…show more content…
Different surface features absorbed and reflect radiation according to their physical, chemical and biological properties. In other words, LST is in direct correlation to the moisture content of earth features. LST is often used with NDVI to identify stress crops on a temporal basis to map out drought affected crops. Carlson (1990) showed that the sensitivity of surface temperature to soil moisture variations differs for the leaf and surface soil around the plants, and tends to much greater between areas of bare soil rather than across the leaves. This basic idea is the basis for determining the scatter space to monitor the soil moisture content. For this reason, soil moisture alone is a poor indicator of drought as the reflectance may depend on the soil texture, organic matter, angle of incidence or surface cover and surface reflectance. In this case study, the LST was calculated from LANDSAT 8 TIRS (using Band 10 and 11) in ArcGIS 10.0 with raster calculator using the following sets of…show more content…
That is, temperature is lowest in the higher altitude in the highlands of PNG, and gradually increases towards the low lying areas as altitude increases. Depending on their severity, the depleting rainfall and higher frost rate often lead to water shortages, crop losses and famine. These increase the vulnerability of the human population to disease, and dry the vegetation--making it more susceptible to fire. The main variations in temperature patterns that occurs within and between regions result from physiographic factors arising from differences in altitude, relative position within the PNG landmass and latitude. The major range that stretches along the length of the island of New Guinea is one of the vast mountain ranges of the world with major peaks over 4,000 meters high and many highland areas over 2,000 meters high. The range is densely forested but contains well-populated fertile valleys, occupied for up to 9,000 years that support a large section of the population. The topography is so rugged that some of these valleys were practically cut off until this century, and even now many valleys can only be accessed by air or on foot. Elevation is a critical geographical factor in assessing drought in higher altitude areas. This is because, the effects of climate change varies with altitude differences, corresponding to temperature, rainfall and other meteorological
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