Robust Response of Streamflow Drought to Different Timescales of Meteorological Drought in Xiangjiang River Basin of China

Meteorological drought can evolve into all aspects of hydrologic system such as soil layer, groundwater, and river discharge, leading to agricultural drought, groundwater drought, and streamflow drought, respectively. How does it propagate? Is there any strong relationship between meteorological drought and others? These issues need further understanding regarding different climate regions. In this paper, monthly SRI and SPEI at different timescales during 1976 and 2005 were utilized to understand how streamflow drought responded to meteorological drought in Xiangjiang river basin, a semihumid basin of Central China. Impressive findings included that strong correlations between SRI and SPEI were found. SPEI of 2-month timescale behaved best when correlating with SRI (R = 0.79). Longer timescales of SPEI seemed not to be useful for streamflow drought identification. At seasonal scale, higher correlation coefficients were obtained during dry season, whereas lower coefficients were found in wet season. The maximum.. reached up to 0.89 in November at 2-month timescale. Besides, robust response relation between streamflow drought and meteorological drought was also found. The average response rate (R-r) was considerably high (75.4%), with the maximum obtained at 2-month timescale (R-r = 82.9%). Meanwhile, important seasonal difference of response rate has also been pointed out.