Drought Risk Assessment based on PDSI in the Daqinghe Watershed, North ChinaShaohua Liu, Huiyong Huang, Gang Hu, Hui Wan, Yongyan Wu, Yibo Yan and Sidong ZengMATEC Web Conf., 246 (2018) 02043DOI: https://doi.org/10.1051/matecconf/201824602043