Implications of Upstream Flow Availability for Watershed Surface Water Supply across the Conterminous United States

Kai Duan, Ge Sun, Peter V. Caldwell, Steven G. McNulty, Yang Zhang

Research output: Contribution to journalArticlepeer-review

12 Scopus citations


Although it is well established that the availability of upstream flow (AUF) affects downstream water supply, its significance has not been rigorously categorized and quantified at fine resolutions. This study aims to fill this gap by providing a nationwide inventory of AUF and local water resource, and assessing their roles in securing water supply across the 2,099 8-digit hydrologic unit code watersheds in the conterminous United States (CONUS). We investigated the effects of river hydraulic connectivity, climate variability, and water withdrawal, and consumption on water availability and water stress (ratio of demand to supply) in the past three decades (i.e., 1981–2010). The results show that 12% of the CONUS land relied on AUF for adequate freshwater supply, while local water alone was sufficient to meet the demand in another 74% of the area. The remaining 14% highly stressed area was mostly found in headwater areas or watersheds that were isolated from other basins, where stress levels were more sensitive to climate variability. Although the constantly changing water demand was the primary cause of escalating/diminishing stress, AUF variation could be an important driver in the arid south and southwest. This research contributes to better understanding of the significance of upstream–downstream water nexus in regional water availability, and this becomes more crucial under a changing climate and with intensified human activities.

Original languageEnglish (US)
Pages (from-to)694-707
Number of pages14
JournalJournal of the American Water Resources Association
Issue number3
StatePublished - Jun 2018

Bibliographical note

Funding Information:
This work was supported by the National Science Foundation EaSM program (AGS-1049200) awarded to North Carolina State University (NCSU), and the Joint Venture Agreement between Eastern Forest Environmental Threat Assessment Center (EFE-TAC), U.S. Department of Agriculture Forest Service, and NCSU (16-JV-11330110-037).

Publisher Copyright:
© 2018 American Water Resources Association. This article is a U.S. Government work and is in the public domain in the USA


  • planning
  • rivers/streams
  • runoff
  • simulation
  • time series analysis
  • water supply


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