The USGS conducts various studies of streamflow statistics for data collected at streamflow-gaging stations. Streamflow statistics for gaged streams and methods for estimating those statistics for ungaged streams are used by water resource planners and managers for designing infrastructure, managing floodplains, and protecting life, property, and aquatic resources. The most recent USGS studies of streamflow statistics for Alaska are presented in reports on flood frequency, flow duration, low-flow frequency, and streamflow record extension.
Return to Water
Methods for accessing data and estimating streamflow statistics for Alaska are provided in USGS reports and, for selected locations, in the online StreamStats tool. These studies use data from USGS streamflow data-collection stations, available online at NWISWeb.
Flood Frequency Studies
Flood frequency analysis uses a series of annual peak-streamflow, or flood, data recorded for a stream to develop a statistical expression of flood probability for that stream, such as the 1-percent chance flood (sometimes called the 100-yr flood). Regression equations relating flood frequency statistics for a group of gaged streams to physical or climatic characteristics of their respective drainage areas provide a tool for estimating flood frequency statistics at ungaged areas. The USGS most recently revised flood frequency regression equations for Alaska and conterminous basins in Canada in 2016.
Flow Duration and Low-Flow Frequency Studies
Flow duration statistics, such as the 98-percent duration flow, describe the daily mean discharge in a stream that is exceeded a given percentage of the time. Low-flow frequency statistics, such as the 7-day, 2-yr low flow, refer to the discharge that occurs on a certain number of consecutive days that is associated with a certain exceedance probability. Regression equations relating these streamflow statistics for a group of gaged streams to physical or climatic characteristics of their respective drainage areas provide a tool for estimating the streamflow statistics at ungaged areas. The USGS has developed selected flow-duration and low-flow frequency regression equations for Alaska and conterminous basins in Canada.
Cook Inlet Basin StreamStats
StreamStats is a web-based application that facilitates access to data and computation tools and streamlines estimation of streamflow statistics. StreamStats is presently available in Alaska only for the Cook Inlet Basin. In addition to providing previously computed information for a streamgage location, Cook Inlet Basin StreamStats automates delineation of a drainage basin for a user-selected location, determination of the drainage area and mean annual precipitation, and computation of flood frequency estimates using those basin characteristics. The development of the Cook Inlet Basin StreamStats application is described in the most recent USGS Alaska flood-frequency report, U.S. Geological Survey Scientific Investigations Report 2016-5024.
Streamflow Record Extension
Daily streamflow values for a short-record streamgage can be estimated from data for a longer-record index streamgage when the daily values for the overlapping period are closely correlated. Streamflow record extension creates a continuous string of daily values at the short-record streamgage for the period of record of the longer-record streamgage.
The USGS has approved streamflow records extension data for selected gaged streams. The data, methods of analysis, and accuracy of the estimated discharges are available in the accompanying reports.
Stream | Publication |
---|---|
Selected gaged streams in the Susitna River Basin | USGS Scientific Investigations Report 2012-5210 |
North Fork and Middle Fork Fortymile Rivers, through water year 2019 | USGS Scientific Investigations Report 2020-5003 |
North Fork and Middle Fork Fortymile Rivers, through water year 2020 | USGS Scientific Investigations Report 2021-5014 |
Below are related science to this project.
Flood Frequency Studies in Alaska
Flow Duration and Low-Flow Frequency Studies in Alaska
NWISWeb provides real-time and historic surface water data for USGS streamgages.
Flood Frequency Data Collection, Alaska and Conterminous Basins in Canada
Flood Frequency Data and 2022 Observed Flood Probability for Two Streamgages in the Delta River Basin, Alaska, 1963-2022
Flood Frequency Data for a Streamgage in the Hulahula River Basin, Alaska, 2011-2021
Flood Frequency Data and 2020 Observed Flood Probability for Selected Streamgages in the Fortymile River Basin, Alaska, 1911-2020
Flood Frequency Data Collection, Alaska and Conterminous Basins in Canada
Extended Seasonal Discharge Records for Selected Streamgage Sites in the Fortymile River Basin, Alaska, 1976-2020
National Water Information System web interface (NWISweb)
The National Water Information System (NWIS) web application provides access to real-time and historical surface-water, groundwater, water-quality, and water-use data collected at approximately 1.5 million sites across all 50 states.
Below are publications about this project.
Extending seasonal discharge records for streamgage sites on the North Fork Fortymile and Middle Fork Fortymile Rivers, Alaska, through water year 2020
Extending seasonal discharge records for streamgage sites on the North Fork Fortymile and Middle Fork Fortymile Rivers, Alaska, through water year 2019
Estimating flood magnitude and frequency at gaged and ungaged sites on streams in Alaska and conterminous basins in Canada, based on data through water year 2012
Streamflow record extension for selected streams in the Susitna River Basin, Alaska
Estimating annual high-flow statistics and monthly and seasonal low-flow statistics for ungaged sites on streams in Alaska and conterminous basins in Canada
NWISWeb provides real-time and historic surface water data for USGS streamgages.
USGS StreamStats
StreamStats is a Web-based tool that provides streamflow statistics, drainage-basin characteristics, and other information for USGS streamgaging stations and for user-selected ungaged sites on streams. When users select the location of a streamgaging station, StreamStats provides previously published information from a database. When users select a site on an ungaged stream,
National Water Information System (NWIS) Mapper
The National Water Information System (NWIS) Mapper provides access to over 1.5 million sites contained in the USGS National Water Information System (NWIS), including sites where current and historical surface-water, groundwater, springs, and atmospheric data has been collected. Users can search by site type, data type, site number, or place.
Below are partners associated with this project.
- Overview
The USGS conducts various studies of streamflow statistics for data collected at streamflow-gaging stations. Streamflow statistics for gaged streams and methods for estimating those statistics for ungaged streams are used by water resource planners and managers for designing infrastructure, managing floodplains, and protecting life, property, and aquatic resources. The most recent USGS studies of streamflow statistics for Alaska are presented in reports on flood frequency, flow duration, low-flow frequency, and streamflow record extension.
Return to Water
Methods for accessing data and estimating streamflow statistics for Alaska are provided in USGS reports and, for selected locations, in the online StreamStats tool. These studies use data from USGS streamflow data-collection stations, available online at NWISWeb.
(Credit: Janet Curran, USGS ASC. Public domain.) Flood Frequency Studies
Flood frequency analysis uses a series of annual peak-streamflow, or flood, data recorded for a stream to develop a statistical expression of flood probability for that stream, such as the 1-percent chance flood (sometimes called the 100-yr flood). Regression equations relating flood frequency statistics for a group of gaged streams to physical or climatic characteristics of their respective drainage areas provide a tool for estimating flood frequency statistics at ungaged areas. The USGS most recently revised flood frequency regression equations for Alaska and conterminous basins in Canada in 2016.
Flow Duration and Low-Flow Frequency Studies
Flow duration statistics, such as the 98-percent duration flow, describe the daily mean discharge in a stream that is exceeded a given percentage of the time. Low-flow frequency statistics, such as the 7-day, 2-yr low flow, refer to the discharge that occurs on a certain number of consecutive days that is associated with a certain exceedance probability. Regression equations relating these streamflow statistics for a group of gaged streams to physical or climatic characteristics of their respective drainage areas provide a tool for estimating the streamflow statistics at ungaged areas. The USGS has developed selected flow-duration and low-flow frequency regression equations for Alaska and conterminous basins in Canada.
(Public domain.) Cook Inlet Basin StreamStats
StreamStats is a web-based application that facilitates access to data and computation tools and streamlines estimation of streamflow statistics. StreamStats is presently available in Alaska only for the Cook Inlet Basin. In addition to providing previously computed information for a streamgage location, Cook Inlet Basin StreamStats automates delineation of a drainage basin for a user-selected location, determination of the drainage area and mean annual precipitation, and computation of flood frequency estimates using those basin characteristics. The development of the Cook Inlet Basin StreamStats application is described in the most recent USGS Alaska flood-frequency report, U.S. Geological Survey Scientific Investigations Report 2016-5024.
Streamflow Record Extension
Daily streamflow values for a short-record streamgage can be estimated from data for a longer-record index streamgage when the daily values for the overlapping period are closely correlated. Streamflow record extension creates a continuous string of daily values at the short-record streamgage for the period of record of the longer-record streamgage.
The USGS has approved streamflow records extension data for selected gaged streams. The data, methods of analysis, and accuracy of the estimated discharges are available in the accompanying reports.
Stream Publication Selected gaged streams in the Susitna River Basin USGS Scientific Investigations Report 2012-5210 North Fork and Middle Fork Fortymile Rivers, through water year 2019 USGS Scientific Investigations Report 2020-5003 North Fork and Middle Fork Fortymile Rivers, through water year 2020 USGS Scientific Investigations Report 2021-5014 (Credit: Janet Curran, USGS ASC. Public domain.) - Science
Below are related science to this project.
Flood Frequency Studies in Alaska
Flood frequency statistics for streamgages and methods for estimating flood frequency statistics at ungaged sites in Alaska and conterminous basins in Canada are presented in U.S. Geological Survey Scientific Investigations Report 2016-5024. This report revised methods for obtaining basin characteristics and regional skew, and presents new streamflow magnitude and frequency statistics for gaged...Flow Duration and Low-Flow Frequency Studies in Alaska
Flow duration and low-flow frequency statistics for streamgages and methods for estimating flow-duration and low-flow frequency statistics at ungaged sites in Alaska and conterminous basins in Canada are presented in U.S. Geological Survey Water Resources Investigations Report 2003-4114. - Data
NWISWeb provides real-time and historic surface water data for USGS streamgages.
Flood Frequency Data Collection, Alaska and Conterminous Basins in Canada
This data collection of U.S. Geological Survey data releases provides the source data and results of flood frequency analyses and annual exceedance probability estimation for selected observed floods in Alaska and conterminous basins in Canada. The data include streamgage information, PeakFQ input and output, flood frequency parameters, flood frequency estimates for selected annual exceedance probFlood Frequency Data and 2022 Observed Flood Probability for Two Streamgages in the Delta River Basin, Alaska, 1963-2022
This data release provides the source data and results of a flood frequency analysis and annual exceedance probability estimation for a flood that occurred on July 11, 2022 in the Delta River Basin, Alaska. Data are provided for two streamgages that had at least 10 years of peak-flow record. The data include streamgage information, PeakFQ input (.txt and .PSF files) PeakFQ output (.PRT, .EXP, andFlood Frequency Data for a Streamgage in the Hulahula River Basin, Alaska, 2011-2021
This data release provides the source data and results of a flood frequency analysis for a streamgage in the Hulahula River Basin, Alaska. Data are provided for one streamgage that had at least 10 years of peak-flow record. The data include streamgage information, PeakFQ input (.txt and .PSF files) PeakFQ output (.PRT, .EXP, and .JPEG files), flood frequency parameters, flood frequency estimates fFlood Frequency Data and 2020 Observed Flood Probability for Selected Streamgages in the Fortymile River Basin, Alaska, 1911-2020
This data release provides the source data and results of a flood frequency analysis and annual exceedance probability estimation for a flood that occurred on June 22, 2020 in the Fortymile River Basin, Alaska. Data are provided for two streamgages that had at least 10 years of peak-flow record. The data include streamgage information, PeakFQ input (.txt and .PSF files) PeakFQ output (.PRT, .EXP,Flood Frequency Data Collection, Alaska and Conterminous Basins in Canada
This data collection of U.S. Geological Survey data releases provides the source data and results of flood frequency analyses and annual exceedance probability estimation for selected observed floods in Alaska and conterminous basins in Canada. The data include streamgage information, PeakFQ input and output, flood frequency parameters, flood frequency estimates for selected annual exceedance probExtended Seasonal Discharge Records for Selected Streamgage Sites in the Fortymile River Basin, Alaska, 1976-2020
Daily mean discharge is needed for water resource management of selected streams in the Fortymile River Basin. The U.S. Geological Survey, in cooperation with the U.S. Bureau of Land Management, developed a technique for estimating seasonal discharge at two short-record streamgage sites in the basin and evaluated the accuracy of the estimated records. Daily mean discharge values were estimated forNational Water Information System web interface (NWISweb)
The National Water Information System (NWIS) web application provides access to real-time and historical surface-water, groundwater, water-quality, and water-use data collected at approximately 1.5 million sites across all 50 states.
ByWater Resources Mission Area, Drought, Hurricane Florence, Hurricane Harvey, Hurricane Irma, Hurricane Isaias, Hurricane Jose, Hurricane Maria, Hurricane Matthew, Hurricane Michael, Hurricane Nate, Hurricane Sandy, San Francisco Bay and Sacramento-San Joaquin Delta Estuary, Hurricane Marco, Hurricane Laura - Publications
Below are publications about this project.
Extending seasonal discharge records for streamgage sites on the North Fork Fortymile and Middle Fork Fortymile Rivers, Alaska, through water year 2020
Daily mean discharge records are needed for management of selected streams in the Fortymile River Basin. The U.S. Geological Survey, in cooperation with the U.S. Bureau of Land Management, updated a technique for estimating seasonal (partial year) discharge at two short-record streamgage sites in the basin and evaluated the accuracy of the estimates. Daily mean discharge values were estimated forAuthorsJanet H. CurranExtending seasonal discharge records for streamgage sites on the North Fork Fortymile and Middle Fork Fortymile Rivers, Alaska, through water year 2019
Daily mean discharge values were estimated for May 20–September 30 for 1976–82 and 2006–18 for the U.S. Geological Survey North Fork Fortymile River and Middle Fork Fortymile River streamgage sites in Alaska. A relation between study streamgage discharge and discharge for an index streamgage on the main-stem Fortymile River for a concurrent period in 2019 was developed using the maintenance of varAuthorsJanet H. CurranEstimating flood magnitude and frequency at gaged and ungaged sites on streams in Alaska and conterminous basins in Canada, based on data through water year 2012
Estimates of the magnitude and frequency of floods are needed across Alaska for engineering design of transportation and water-conveyance structures, flood-insurance studies, flood-plain management, and other water-resource purposes. This report updates methods for estimating flood magnitude and frequency in Alaska and conterminous basins in Canada. Annual peak-flow data through water year 2012 weAuthorsJanet H. Curran, Nancy A. Barth, Andrea G. Veilleux, Robert T. OursoStreamflow record extension for selected streams in the Susitna River Basin, Alaska
Daily streamflow records for water years 1950–2010 in the Susitna River Basin range in length from 4 to 57 years, and many are distributed within that period in a way that might not adequately represent long-term streamflow conditions. Streamflow in the basin is affected by the Pacific Decadal Oscillation (PDO), a multi-decadal climate pattern that shifted from a cool phase to a warm phase in 1976AuthorsJanet H. CurranEstimating annual high-flow statistics and monthly and seasonal low-flow statistics for ungaged sites on streams in Alaska and conterminous basins in Canada
Methods for estimating daily mean flow-duration statistics for seven regions in Alaska and low-flow frequencies for one region, southeastern Alaska, were developed from daily mean discharges for streamflow-gaging stations in Alaska and conterminous basins in Canada. The 15-, 10-, 9-, 8-, 7-, 6-, 5-, 4-, 3-, 2-, and 1-percent duration flows were computed for the October-through-September water yearAuthorsJeffrey B. Wiley, Janet H. Curran - Web Tools
NWISWeb provides real-time and historic surface water data for USGS streamgages.
USGS StreamStats
StreamStats is a Web-based tool that provides streamflow statistics, drainage-basin characteristics, and other information for USGS streamgaging stations and for user-selected ungaged sites on streams. When users select the location of a streamgaging station, StreamStats provides previously published information from a database. When users select a site on an ungaged stream,
National Water Information System (NWIS) Mapper
The National Water Information System (NWIS) Mapper provides access to over 1.5 million sites contained in the USGS National Water Information System (NWIS), including sites where current and historical surface-water, groundwater, springs, and atmospheric data has been collected. Users can search by site type, data type, site number, or place.
ByWater Resources Mission Area, Central Midwest Water Science Center, Colorado Water Science Center, Dakota Water Science Center, Maryland-Delaware-D.C. Water Science Center, New England Water Science Center, New Jersey Water Science Center, New Mexico Water Science Center, New York Water Science Center, South Atlantic Water Science Center (SAWSC), Upper Midwest Water Science Center, National Water Quality Laboratory - Partners
Below are partners associated with this project.