A National Assessment of Low-Streamflow Estimation Using a Physically Based Statistical Methodology

EPA Grant Number: R826888
Title: A National Assessment of Low-Streamflow Estimation Using a Physically Based Statistical Methodology
Investigators: Kroll, Charles , Vogel, Richard
Institution: SUNY College of Environmental Science and Forestry , Tufts University
EPA Project Officer: Louie, Nica
Project Period: September 1, 1998 through August 31, 2001 (Extended to December 31, 2003)
Project Amount: $363,500
RFA: Environmental Statistics (1998) RFA Text |  Recipients Lists
Research Category: Health , Ecosystems , Environmental Statistics


Objectives/Hypothesis: Low streamflow estimates are crucial for water quality management, issuing and/or renewing National Pollution Discharge Elimination System (NPDES) permits, planning water supplies, hydropower, and irrigation systems, and for assessing the impact of prolonged droughts on aquatic ecosystems. Unfortunately, there is no agreed upon methodology for estimating low streamflow statistics in the United States. The current methods for estimating low streamflow statistics are based on techniques recommended for flood frequency analyses. By combining recent advances and new methods in both physical and statistical hydrology with Geographic Information System mapping techniques, we will improve our ability to estimate low flow statistics in riverways throughout the entire United States. The methodology developed will provide water resource planners with a scientifically based procedure to estimate low streamflow statistics at both gauged and ungauged river sites throughout the United States. Physical-Statistical models developed will also aid in understanding the potential impact of global climate fluctuations on low streamflows.


This project is based on a large U.S. Geological Survey-database of streamflows at over 1670 unregulated sites from 21 water resource regions throughout the United States. These data will be combined with watershed information such as topography geormorphology, geology, hydrogeology, land use, land cover and climate to develop regional physical/statistical methods for the estimation of drought flows in each of the 21 regions. A comparative analysis of hydrologic techniques for the estimation of droughts in riverways throughout the entire United States will be performed, including Bootstrap and Jackknife simulations and analytical statistical comparisons of existing and proposed methodologies.

Expected Results:

One result of this study will be a comprehensive analysis of all important low-streamflow issues throughout the United States. A methodology for estimating low streamflows both at gauged and ungauged river sites will be developed, and for each region, a recommended procedure for estimating low streamflows will be established. In addition, the potential impact of global climate change on droughts throughout the United States will investigated to gain information useful to water resource planners and managers.

Estimated Improvement in Risk-Assessment or Risk-Management: This research will greatly improve our ability to predict droughts throughout the United States, and thus better assess the risk of point and nonpoint source pollution discharges on aquatic ecosystems. In addition, it will also aid in drought risk management for water supply, hydropower, and irrigation systems, as well as risk management under global climate change scenarios. Low stream flows are also used in health risk assessments which quantify the long term risk associated with exposure to carcinogenic substances in rivers. Therefore, this research will also lead to improvements in waste load allocations designed to minimize future long term health risks.

Publications and Presentations:

Publications have been submitted on this project: View all 13 publications for this project

Journal Articles:

Journal Articles have been submitted on this project: View all 5 journal articles for this project

Supplemental Keywords:

Risk Assessment, GIS Geographic Information Systems, Watershed Hydrology, Statistical Hydrology, Regional Hydrology,, RFA, Scientific Discipline, Economic, Social, & Behavioral Science Research Program, Air, Ecosystem Protection/Environmental Exposure & Risk, Hydrology, Ecosystem/Assessment/Indicators, Ecosystem Protection, exploratory research environmental biology, Chemical Mixtures - Environmental Exposure & Risk, climate change, Ecological Effects - Environmental Exposure & Risk, Ecological Effects - Human Health, Ecology and Ecosystems, Atmospheric Sciences, Ecological Risk Assessment, Environmental Statistics, Ecological Indicators, ecological exposure, flood frequency analysis, risk assessment, estimating low stream flow, global environmental data, meteorology, physical environmental statistics research, streams, environmental risks, drinking water supplies, low stream flow estimation model, water resource planners, mitigation strategies, physically based statistical methodology, hydropower, statistical models, aquatic ecosystems, ecosystem impacts, stream flow, data analysis, data collection, spatial-temporal methods, water quality, data models, global warming, innovative statistical models, statistical methodology, land use

Progress and Final Reports:

  • 1999 Progress Report
  • 2000 Progress Report
  • 2001
  • 2002
  • 2003
  • Final