Abstract:
Affecting more people than other natural hazards, drought may lead to enormous decrease in crop production and also in the amount of poultry and livestock, and thus endangering food security and economy. Developing an appropriate drought indicator and a timely and accurate drought monitoring system has been a motivation for scientists in the last two decades. Vegetation conditions valued via remotely sensed indices have been used as indicators for agricultural drought since the 1980s. However, the anomalies in vegetation performance do not always signify droughts. Wild fire, extreme temperature, flood, pesticides or lack of fertilizers can all cause the vegetation stress. One of the major goals for this dissertation is to evaluate and investigate vegetation drought stress and other vegetation stresses using remote sensing techniques. The other major goal is to estimate the root-zone soil moisture levels beneath various crop canopies using satellite data and ground observations. Since soil moisture is the primary indicator for agricultural drought, accurate and reliable soil moisture estimates have important implications for drought monitoring.
