From meteorological droughts to hydrological droughts: a case study of the Weihe River Basin, China

The standard precipitation index (SPI) and streamflow drought index (SDI) were used in this study to investigate the relationship between meteorological and hydrological droughts in the Weihe River Basin, the largest tributary of the Yellow River—the 6th longest river in the world and the “Mother River of China.” Results showed that (1) the frequencies of both meteorological droughts and hydrological droughts have showed an increasing trend in the last 50 years in the Weihe River basin; (2) there was a strong relationship between meteorological and the hydrological droughts, which can be linked with a simple linear function; (3) the relationship between meteorological and the hydrological droughts varied in space and time; and (4) the differences between meteorological and the hydrological droughts have become more significant during the last 50 years. The presented results not only play an important reference in understanding the relationships between meteorological and hydrological droughts, but also have practical applications for regional water resource managements at catchment scale.