Abstract
Under the background of global climate change, drought is causing devastating impacts on the balance of the regional water resources system. Hydrological drought assessment is critical for drought prevention and water resources management. However, in China to assess hydrological drought at national scale is still challenging basically because of the difficulty of obtaining runoff data. In this study, we used the state-of-the-art passive microwave remote sensing techniques in river runoff modelling and thus assessed hydrological drought in Mainland China in 1996–2016. Specifically, 79 typical hydrological stations in 9 major basins were selected to simulate river runoff using the M/C signal method based on a high-resolution passive microwave bright temperature dataset. The standardized runoff index (SRI) was calculated for the spatial and temporal patterns of hydrological drought. Results show that passive microwave remote sensing can provide an effective way for runoff modelling as 92.4% and 59.5% of the selected 79 stations had the Pearson correlation coefficient (R) and the Nash-Sutcliffe efficiency coefficient (NS) scores greater than 0.5. Especially in areas located on Qinghai-Tibet Plateau in the Inland and the Southwest River Basin, the performance of the M/C signal method is quite outstanding. Further analysis indicates that stations with small rivers in the plateau areas with sparse vegetation tend to have better simulated results, which are usually located in drought-prone regions. Hydrological drought assessment shows that 30 out of the 79 stations present significant increasing trends in SRI-3 and 18 indicate significant decreasing trends. The duration and severity of droughts in the non-permanent dry areas of the Hai River Basin, the middle reaches of the Yangtze River Basin and the Southwest of China were found out to be more frequent and severe than other regions. This work can provide guidance for extending the applications of remote sensing data in drought assessment and other hydrological research.
Highlights
As one of the most complex natural phenomena, droughts with extreme severity can tremendously influence crop production, water resources, natural ecology, producing destructive impacts on the ecosystem and social-economic development in the world [1].Under the background of climate change, such influences show an increasing trend, which has led to great attention from both the scientific community and the public worldwide [2].For example, in Europe, central Europe is frequently affected by drought due to significant precipitation and temperature variations
The main objectives of this study are to discuss the utility of microwave remote sensing data for drought assessment and to reveal the patterns of hydrological drought over the last few decades in Mainland China, as well as to gain a better understanding of drought disasters in areas lacking in long-term station observed data but frequently hit by drought hazards, such as the northern Tibet, the Tarim Basin, the Yunnan-Guizhou Plateau and remote areas in northeastern China
To explore the utility of microwave remote sensing data for runoff modelling and drought assessment in Mainland China, we combined the M/C signal method with the standardized runoff index (SRI) algorithm based on the MEASUREs high-resolution passive microwave remote sensing Tb observation dataset for 79 typical stations in the 9 major basins across Mainland
Summary
As one of the most complex natural phenomena, droughts with extreme severity can tremendously influence crop production, water resources, natural ecology, producing destructive impacts on the ecosystem and social-economic development in the world [1].Under the background of climate change, such influences show an increasing trend, which has led to great attention from both the scientific community and the public worldwide [2].For example, in Europe, central Europe is frequently affected by drought due to significant precipitation and temperature variations. As one of the most complex natural phenomena, droughts with extreme severity can tremendously influence crop production, water resources, natural ecology, producing destructive impacts on the ecosystem and social-economic development in the world [1]. China is facing a very severe shortage of water resources. Drought disasters are constantly occurring, causing extremely serious economic losses in China [6]. During 1997–2009, with extreme droughts occurring almost every two years, the affected area and economic losses nationwide were significantly higher than the average of the recent 30 years [7]. According to the China’s Ministry of Water Resources, 29,258,800 hectares of crops were affected by drought in 2009, and 89 cities struggled with water shortages, causing economic losses of about $176,630,000,000 billion [8]. Several severe drought events including the mega-drought in Sichuan Province and Chongqing
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