Drought Trend Analysis Based on the Standardized Precipitation–Evapotranspiration Index Using NASA’s Earth Exchange Global Daily Downscaled Projections, High Spatial Resolution Coupled Model Intercomparison Project Phase 5 Projections, and Assessment of Potential Impacts on China’s Crop Yield in the 21st Century

Abstract

Drought is among the costliest natural disasters on both ecosystems and agroeconomics in China. However, most previous studies have used coarse resolution data or simply stopped short of investigating drought projection and its impact on crop yield. Motivated by the newly released higher-resolution climate projection dataset and the crucial need to assess the impact of climate change on agricultural production, the overarching goal of this study was to systematically and comprehensively predict future droughts at unprecedented resolutions over China as a whole. rather than region-specific projections, and then to further investigate its impact on crop yield by innovatively using a soil water deficit drought index. Methodologically, the drought projections were quantified from very high resolution climate data and further predicted impacts on crop yield over China using the standardized precipitation–evapotranspiration index (SPEI) at a relatively high (25 km) spatial resolution from NASA’s Earth Exchange Global Daily Downscaled Projections (NEX-GDDP). The results showed that (1) overall, China is projected to experience a significant decrease in SPEI (−0.15/decade under RCP (representative concentration pathway) 4.5; −0.14/decade under RCP8.5). Seasonally, the decreasing rate of SPEI is projected to be largest in winter (−0.2/decade and −0.31/decade) and the least in summer (−0.08/decade and −0.10/decade) under respective RCPs. (2) Regionally, winter/spring will get drier, especially at high latitudes/altitudes (North China and Tibetan plateau), and summer/autumn will get wetter in southern China. (3) Both the frequency and duration for medium and severe drought are projected to decrease, while extreme drought, particularly in high latitudes/altitudes, is projected to increase. (4) The percentage of the potential crop production affected by drought would increase to 36% (47%) by 2100 under RCP4.5 (RCP8.5). Especially, the ratio impacted by extreme drought is projected to increase over time and with much worse magnitude under RCP8.5; thus, adaptive crop policies are expected to address such a risk.

The Drought Variability Based on Continuous Days without Available Precipitation in Guizhou Province, Southwest China

“…This finding is consistent with the previous study [49], which indicated that there was more rainfall in the south than that in the north, while there were less precipitation days in the south than in the north in Guizhou province. This finding is consistent with the previous study [50], which indicated that there was more rainfall in the south than in the north, while there were less precipitation days in the south than in the north in Guizhou province. The variable "number of Dnp" exhibited different spatial patterns in different seasons.…”

“…The aggravation of drought had seriously affected agricultural production during these two periods. According to data, the seasonal distribution of drought tends to be severe, and it will become drier in winter and spring in China, affecting crop growth and restricting agricultural production [24,50], especially in southwestern China, where 24% of agricultural areas are affected by drought [51,52]. In Northeast China, drought is accompanied by the spring maize growth period, and long-term drought will make it impossible to recover the phys- On the decadal scale, there were longest Dnp twice in 1960s with an average of 27 days each time; 5 times in 1980s with an average period of also 27 days each time; 3 times in 1990s with an average of 32 days; since 2000s, there was 9 times, with an average of 35.6 days; the average period was up to 37 days each time since 2010s.…”

“…The aggravation of drought had seriously affected agricultural production during these two periods. According to data, the seasonal distribution of drought tends to be severe, and it will become drier in winter and spring in China, affecting crop growth and restricting agricultural production [24,50], especially in southwestern China, where 24% of agricultural areas are affected by drought [51,52]. In Northeast China, drought is accompanied by the spring maize growth period, and long-term drought will make it impossible to recover the physiological functions and yield of maize [53].…”

Variation in Reference Evapotranspiration over the Tibetan Plateau during 1961–2017: Spatiotemporal Variations, Future Trends and Links to Other Climatic Factors

“…More importantly, the water budget and energy exchange in the region have a considerable impact on the intensity of the Asian monsoon and high pressure [35,36]. Guo et al concluded, by studying the trend of the evapotranspiration index of standard precipitation in China, that winter and spring in the TP will become drier in the 21st century [37]. Ye et al further found that the frequency of extreme drought events in the Qaidam Basin is the highest (3-6 times) in the TP [38].…”

On the Benefits of Bias Correction Techniques for Streamflow Simulation in Complex Terrain Catchments: A Case-Study for the Chitral River Basin in Pakistan

“…For instance, [22] investigated the future changes of precipitation at the local scale over China using NEX-GDDP and reported a "certain" reliability over the Han River, emphasizing the potential usefulness of this dataset for climate change impact studies at watershed scales. The author of [23] reported that, although NEX-GDDP offers potential improvements in reproducing monthly temperature and precipitation over China, it still exhibits region-dependent systematic errors. The author of [24] reported this dataset to be well in agreement with the observations on a monthly basis over southeast Asia; however, they also found significant biases, which were predominantly region-specific.…”