ABSTRACT
Droughts are multidimensional and can be both natural and anthropogenic. The natural factors include temperatures, winds, relative humidity, and rainfall. Anthropogenic factors can be categorized into deforestation and overutilization of water sources. Compared to other natural disasters such as floods, hurricanes, earthquakes, and epidemics, droughts are very difficult to predict; they develop gradually and are long lasting. The complex nature of droughts onset-termination has made it acquire the title—the creeping disaster. Droughts can have severe and crippling effects on the environment, agriculture, health, economy, and society with far-reaching effects on both the areas where they occur and the areas that have relations with those where the drought occurs. Drought monitoring in the past has been carried out using climate and meteorological data to facilitate decision-making. However, the use of remote sensing techniques has proved to be an effective and valuable source of timely and spatially continuous data for drought monitoring and mapping. Drought can be monitored effectively using various indices such as normalized difference vegetation index (NDVI), normalized difference water index (NDWI), or normalized multiband drought index (NMDI). Remote sensing satellites have frequent revisit time, which enables acquiring of imagery at an interval of a few days’ to a few weeks’ time for the same location, thus providing time series of data needed for drought monitoring. The current chapter deals with one such estimation of drought using several indices, which can capture drought monitoring.
