Drought duration and severity are two properties that are usually needed for drought analysis. To characterize the correlation between the two drought properties, a bivariate distribution is needed. A new method based on entropy theory is proposed for constructing the bivariate distribution that is capable of modeling drought duration and severity with different marginal distributions. Paramete...

Based on analysis on statistic parameters including mean, coefficient of variation and serial correlation of drought, the foresaid parameters on drought duration and severity were studied. The extreme drought duration and severity expressions were developed. Taking Dongzhou Reservoir as an example, the related design parameters were calculated. [Nature and Science 2003;1(1):62-66].

The Ningxia Hui Autonomous Region of China (Ningxia) is an important food production area in northwest China severely affected by drought. The Standardized Precipitation Index (SPI) and Standardized Precipitation Evapotranspiration Index (SPEI) were calculated based on monthly meteorological data to explore climate change and variation in drought intensity, duration, frequency, and spatial exte...

the present research was planned to evaluate the skill of linear stochastic models known as arima and multiplicative seasonal autoregressive integrated moving average (sarima) model in the quantitative forecasting of the standard runoff index (sri) in karkheh basin. to this end, sri was computed in monthly and seasonal time scales in 10 hydrometric stations in 1974-75 to 2012-13 period of time ...

A streamflow drought event, defined by applying the threshold level approach on streamflow time series, is composed of three parameters: duration, severity and magnitude. This study reveals statistical characteristics on streamflow drought event parameters and detects spatial and temporal trends in the streamflow drought in terms of frequency, duration and severity in Nebraska. The studies are ...

Droughts produce a complex set of negative economic, environmental, and social impacts across a country or region. Using monthly standardized Precipitation Index (SPI) values, drought characteristics, namely, drought duration, severity, interval time and minimum SPI values, were determined. Two exponential distributions were used to model drought duration and interval time, respectively; gamma ...

Common weaknesses of current drought indexes were analyzed. First, most of the current indexes are not precise enough in detecting the onset, end, and accumulated stress of drought. Second, they do not effectively take into account the aggravating effects of runoff and evapotranspiration, which build up with time. Third, they have a limited usefulness in monitoring ongoing drought because they ...

Drought is one of the most damaging environmental phenomena. In general, drought is a temporal reduction of environmental moisture status relative to the mean state. Because of the complexity of drought, it is often studied only by separate aspects of the phenomenon (e.g. meteorological drought, soil drought, etc.). Hence, approaches to drought identification are variable. The theory of drought...