New Standardized Base Flow Index for Identification of Hydrologic Drought in the Red River of the North Basin

There is an increasing interest in finding effective alternatives for groundwater drought indices due to the scarcity of groundwater data. The objective of this research is to improve hydrologic drought identification by developing a new standardized base flow index (SBFI), in which base flow is used as a substitute for precipitation in the well-known standardized precipitation index. SBFI was applied to the Red River of the North Basin and compared with the standardized streamflow index (SSFI) and a new standardized direct runoff index (SDRI). SDRI showed the capability of preidentification of droughts. It was found that SBFI was less affected by short events, especially in the transitions from dry to wet conditions, due to the retarding effects of base flow. SBFI also exhibited more consistency in identification of the drought summit from upstream to downstream. These SBFI characteristics improve drought identification as a proxy for the SSFI and other groundwater drought indices. (C) 2020 American Society of Civil Engineers.