Contrasting Influences of Human Activities on Hydrological Drought Regimes Over China Based on High‐Resolution Simulations

Abstract

How human activities have altered hydrological droughts (streamflow deficits) in China during the past five decades (1961-2016) is investigated using the latest version (v2.0) of PCR-GLOBWB model at high spatial resolution (~10 km). Although both human activities and climate variability have significant effects on river flows over China, there are large regional north-south contrasts. Over northern China, human activities generally intensify hydrological droughts. We find that human activities exacerbated drought deficit by about 70-200% from 2004 to 2015. In contrast, droughts over southern China are generally alleviated by human activities. For instance, irrigation and water management (such as reservoir operation and water abstraction) increase drought StDef (standardized drought deficit volume) by about 80% in the Yellow River (north) but reduce it by about 20% in the Yangtze River (south). Human activities slightly reduce drought deficit in the Yangtze River due to the combination of large reservoir storage and low ratio of agriculture consumption to abstracted irrigation water. In contrast, hydrological drought is aggravated in the semiarid Yellow River basin because of high water consumption from agricultural sectors. This study suggests that human activities have contrasting influences on hydrological drought characteristics in the northern (intensification) and southern (mitigation) parts of China. Therefore, it is critical to consider the variable roles of human activities on hydrological drought in China when developing mitigation and adaptation strategies. Plain Language Summary China faces unprecedented challenges for water resources management under a changing climate, which is expected to lead to more frequent and severe droughts in the future. Of particular importance is streamflow drought, which jeopardizes regional water supply and local ecosystem services. On one hand, human activities through reservoir operation can effectively alleviate drought by releasing water during the low flow period. But on the other hand, water abstraction to meet sectoral water demand (such as irrigation) could exacerbate the streamflow deficit. To what extent such human activities differ across regions is not clear. In this study, we use a physically based hydrological and water resources model to investigate how human activities have altered streamflow droughts in China during the past five decades (1961-2016). We find that human activities generally alleviate streamflow droughts in the southern region (e.g., Yangtze River) but intensify them in the northern part of China (e.g., Yellow River). Our research highlights the contrasting geographical differences of human influences on hydrological drought across China, which can be useful for making more effective drought adaptation strategies.

Evolution characteristics and relationship of meteorological and hydrological droughts from 1961 to 2018 in Hanjiang River Basin, China

“…In summer, rainfall is abundant, and reservoir storage will increase the occurrence of hydrological droughts. When droughts occur in other seasons, the release of water from the reservoir reduced the occurrence of hydrological drought and also reduced the occurrence of extreme drought events, which further proved that human activities that represented by reservoir water transfer and storage have obvious impacts on hydrological drought in the basin (Yang et al 2020). The meteorological drought duration and drought intensity of the basin are less than the hydrological drought duration except for Huangjiagang Station, indicating that the release of water from the reservoir in the dry season has a mitigation effect on the later hydrological drought events downstream.…”

NASA’s MODIS/VIIRS Global Water Reservoir Product Suite from Moderate Resolution Remote Sensing Data

“…Moreover, the Murray-Darling river basin experienced the longest four-year reservoir-based hydrological drought on record from 2006 to 2010. However, the majority of the prior studies of droughts across the globe [60][61][62][63][64][65][66] considered only streamflow variations in their assessments of hydrological drought. This is because continuous long-term reservoir data with a high temporal resolution are lacking at a global scale (either for use in analysis or for the calibration of global hydrological models).…”

“…This is because continuous long-term reservoir data with a high temporal resolution are lacking at a global scale (either for use in analysis or for the calibration of global hydrological models). Neglecting the reservoir storage component in hydrological drought assessment can lead to biases and uncertainties, as water is increasingly consumed, stored, and diverted through water management activities (i.e., reservoir operations) [66,67]. Therefore, this product can fill in this crucial research gap and can help stakeholders, water managers, and policymakers to improve existing hydrological drought management practices.…”

Improving Reservoir Outflow Estimation for Ungauged Basins Using Satellite Observations and a Hydrological Model

“…Over the past half century, many dams and reservoirs have been built around the world for flood risk management, domestic water use, hydropower generation, irrigation, and transportation (ICOLD, 2007). Hydrological processes are becoming increasingly influenced by human activities, which is more difficult to understand and predict than natural hydrological drivers (Bonnema & Hossain, 2019; Rossi et al, 2009; Yang et al, 2020). Global population growth and climate change will lead to more frequent extreme events (Ashoori et al, 2017; Chen et al, 2016), so reservoir operations will become increasingly important in regulating water resources.…”