Abstract
Droughts are one of the most devastating natural disasters, which impose increasing risks to humanity and the environment in the 21st century. The recent and continuous drought in China has led to detrimental effects on the local environment and societies in Yunnan Province, thus there is an urgent need to monitor the spatial and temporal evolution of the drought. The characteristics of the spatial distribution of drought processes and the impact of droughts on soil moisture and water storage remains unclear. In this study, the direction, magnitude, start time, and duration of droughts were investigated, based on Total Water Storage Anomalies (TWSA) of Gravity Recovery and Climate Experiment (GRACE), Climate Change Initiative Soil Moisture (CCI SM), and observed precipitation data. The spatial patterns of TWSA trends at each time duration segment suggest that the evolution of drought processes is very complex, and can be clustered into three zones. The spatial distribution of TWSA revealed that the drought status lasted more than one year longer in the north and east parts compared to other parts of Yunnan Province. Water losses occurred in the south part, while water gains were found in the central, north, and east parts of Yunnan Province, from 2002 to 2014, indicating a higher possibility of droughts in the south part in the future. Both de-seasonalized TWSA and CCI SM effectively captured the serious drought from 2009 to 2010 in Yunnan, and their spatial patterns were found to be consistent. The drought detected from CCI SMA had a one-month lag and TWSA had a two-month lag, in comparison to the meteorological drought from precipitation data, which indicates that the drought data derived from CCI SMA and TWSA are better able to represent the impact of droughts, particularly on agriculture. The contribution of surface SM changes in TWSA was determined to be about 41.94%, suggesting that variations in soil moisture only explain less than half of the total water storage change. GRACE observations and CCI SM can be used as important indicators of the spatial distribution of the drought process and its impact on the environment and local communities, which will improve the management of water resources and early detection and monitoring of droughts.
Highlights
Droughts are one of the most devastating natural disasters,which have affected more than half the world, resulting in an average annual loss of US $60 billion to $80 billion [1]
We identified the spatial patterns of the two clusters from the spatial distribution of the trend of total water gains to losses during the study period (Figure 5l) in Yunnan Province
The meteorological drought occurring in individual months did not lead to significant changes in Total Water Storage (TWS) and Climate Change Initiative Soil Moisture (CCI SM), indicating that the single-month meteorological drought may have had a less serious effect on soil moisture and water storage. These results suggest that the droughts described using CCI Soil Moisture Anomalies (CCI SMA) and Total Water Storage Anomalies (TWSA) are more fit to represent the effects of droughts, especially on agriculture
Summary
Droughts are one of the most devastating natural disasters ,which have affected more than half the world, resulting in an average annual loss of US $60 billion to $80 billion [1]. Population growth, and climate change, the number of drought-affected areas could be further increased, and drought severity would be more aggravated, due to the shortage of water [3]. It is pertinent to note that severe droughts usually occurred in Southern China, especially in the southwest region [7,8,9], which is humid, with relatively heavy precipitation. These droughts have greatly impacted local societies and environment, where there is a developing economy and higher population. The accurate monitoring and prediction of droughts are very important to protect socio-economic stability and agriculture
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