Abstract
Conceptually, drought is a water shortage due to reduced rainfall compared to long-term, normal baseline conditions specific to geographical extents with ecological, social, and economic consequences. Objective and operational definitions of drought depend on perspective. Meteorological definitions are based on temporary departures from climate averages as measured by metrics including the Standard Precipitation Index, which is based on low rainfall relative to average precipitation. Similarly, the Palmer Drought Severity Index approximates the long-term balance between precipitation and water use based on precipitation and temperature but does not identify short-term or developing drought. The Evaporative Demand Drought Index and the Standardized Precipitation Evapotranspiration Index6 can be computed for multiple time scales and can detect both fast-developing droughts (flash droughts of weeks to months) and seasonal and long-term droughts (months to years), but produce variation depending on estimation methods. Meteorological definitions of drought are modified for impacts on economic, social, and ecological sectors, although definitions are not mutually exclusive and can co-exist. Hydrological drought has effects on water flows and snowpack, measured by the Surface Water Supply Index, for example. Agricultural drought affects short-term soil moisture conditions for crop growth and is quantified with metrics such as the Crop Moisture Index (CMI). Socioeconomic drought measurements are used when water supplies do not meet demands for different goods, services, or activities. Because ecosystems are complex, ecological drought definitions currently are more conceptual than operational (e.g., “an episodic deficit in water availability that drives ecosystems beyond thresholds of vulnerability, impacts ecosystem services, and triggers feedbacks in natural and/or human systems”). Identification of drought and drought characteristics depends on the drought definition and metric being sought.
Keywords
ecological sites,
reseeding,
drought remote sensing
Citation
Reeves, Matt C.; Hanberry, Brice B.; Burden, Iric. 2020. Rapidly quantifying drought impacts to aid reseeding strategies. Rangelands. doi 10.1016/j.rala.2020.07.001.
