The variation and propagation characteristics of meteorological,
hydrological and agricultural droughts in mainland China
Abstract
Drought, a natural hazard, greatly damages environment, agriculture,
hydrology and thus, economy and our society at large. The national-scale
variation and propagation characteristics of different types of droughts
are critical for developing strategies and policies, while information
is limited in China. This research investigated the evolution and
propagation characteristics of three types of droughts using
standardized indices; Standardized Precipitation Index (SPI),
Standardized Soil Moisture Index (SSI) and Standardized Runoff Index
(SRI) representing meteorological, agricultural and hydrological
droughts based on precipitation (PPT), soil water storage (SWS) and
baseflow-groundwater runoff (BGR), respectively at multi-timescales in
different sub-regions of mainland China over 1948-2010. The most
appropriate probability density distributions of PPT, SWS and BGR were
selected for the calculation of drought indices and wavelet analysis was
used to reveal their periodical characteristics. Modified Mann-Kendall
trend test was used to compare the trend among drought indices. Pearson
correlation coefficients were calculated to identify the lags of SPI
with SSI and SRI. In general, SPI showed an agreement with the
historical severe or extreme drought events at different sub-regions.
The main periods of SSI were closer to SPI than SRI, indicating stronger
connections of agricultural drought with meteorological drought. A
weaker connection between meteorological and agricultural/hydrological
droughts at shorter timescales was observed in northwestern arid and
semi-arid regions. The propagation from meteorological to agricultural
or hydrological droughts were well denoted by the lagged time (months)
from SPI to SSI or SRI at a timescale ranged from 0 (mostly located in
south China) to 5 months (mostly located in northeastern China) for
certain timescale. The study provides crucial information and guidance
to the policy makers in developing drought management strategies at
regional to national scale and their critical time of action.