This article is a US Government work and is in the public domain in the USA.
Causes of systematic over- or underestimation of low streamflows by use of index-streamgage approaches in the United States†
Article first published online: 9 FEB 2011
This article is a US Government work and is in the public domain in the USA. Published in 2011 by John Wiley & Sons, Ltd.
Volume 25, Issue 14, pages 2211–2220, 1 July 2011
How to Cite
Eng, K., Kiang, J. E., Chen, Y.-Y., Carlisle, D. M. and Granato, G. E. (2011), Causes of systematic over- or underestimation of low streamflows by use of index-streamgage approaches in the United States. Hydrol. Process., 25: 2211–2220. doi: 10.1002/hyp.7976
- Issue published online: 5 JUL 2011
- Article first published online: 9 FEB 2011
- Manuscript Accepted: 2 DEC 2010
- Manuscript Received: 25 JUN 2010
- low streamflow;
- short-term streamgages;
- ungaged basins;
- intermittent streams;
- hydrologic similarity
Low-flow characteristics can be estimated by multiple linear regressions or the index-streamgage approach. The latter transfers streamflow information from a hydrologically similar, continuously gaged basin (‘index streamgage’) to one with a very limited streamflow record, but often results in biased estimates. The application of the index-streamgage approach can be generalized into three steps: (1) selection of streamflow information of interest, (2) definition of hydrologic similarity and selection of index streamgage, and (3) application of an information-transfer approach. Here, we explore the effects of (1) the range of streamflow values, (2) the areal density of streamgages, and (3) index-streamgage selection criteria on the bias of three information-transfer approaches on estimates of the 7-day, 10-year minimum streamflow (Q7, 10). The three information-transfer approaches considered are maintenance of variance extension, base-flow correlation, and ratio of measured to concurrent gaged streamflow (Q-ratio invariance). Our results for 1120 streamgages throughout the United States suggest that only a small portion of the total bias in estimated streamflow values is explained by the areal density of the streamgages and the hydrologic similarity between the two basins. However, restricting the range of streamflow values used in the index-streamgage approach reduces the bias of estimated Q7, 10 values substantially. Importantly, estimated Q7, 10 values are heavily biased when the observed Q7, 10 values are near zero. Results of the analysis also showed that Q7, 10 estimates from two of the three index-streamgage approaches have lower root-mean-square error values than estimates derived from multiple regressions for the large regions considered in this study. Published in 2011 by John Wiley & Sons, Ltd.