Project Overview

Full Title
Development of StreamStats in the Upper French Broad River Basin, North Carolina: A Pilot Water-Resources Web Application

Location
 Transylvania, Henderson and Buncombe Counties

Partner Agencies
North Carolina Department of Transportation

Project Chief
Chad Wagner
cwagner@usgs.gov

Period of Project
2007 - 2008

Team Members
Kirsten Tighe
Silvia Terziotti

Science Topic
Hydrologic and Geospatial data

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Upper French Broad StreamStats

Project Summary

Background

The Studies Act of 2004 (North Carolina Senate Bill 1152) requested the North Carolina Geographic Information Coordinating Council (GICC) and Department of Environment and Natural Resources (DENR) develop a plan to improve the mapping and digital representation of surface waters for the state. Subsequently, the Hurricane Recovery Act of 2005 (Senate Bill 7) was enacted to aid nineteen (19) counties in Western North Carolina impacted by Hurricanes Frances and Ivan in 2004. Through this bill, Phase I of the Stream Mapping Project was initiated for the 19 counties in Western North Carolina. The goal of the project is to provide a more accurate, current, and complete mapping of rivers, streams, and other water bodies in the state by developing a local resolution (approximately 1:4,800 scale) National Hydrography Dataset (NHD). The local-resolution data does not have a defined scale, but is dependent on the source datasets used to create the stream network. The best available combination of digital orthophotography, digital terrain models derived from Light Detection and Ranging (LIDAR) and existing hydrography was used to create the local resolution NHD. Although the highly detailed stream delineation is a great asset to the state, the real utility in the stream mapping product will be realized in the applications that can be built utilizing the data.

StreamStats is a “Web-based Geographic Information System (GIS) application that was developed by the U.S. Geological Survey (USGS) in cooperation with Environmental Systems Research Institute, Inc. (ESRI) to provide access to an assortment of analytical tools that are useful for water-resources planning and management”. StreamStats allows users to easily obtain streamflow statistics, basin characteristics, and descriptive information for USGS data-collection sites and selected ungaged sites. StreamStats also allows users to identify stream reaches upstream and downstream from user-selected sites and obtain information for locations along streams where activities occur that can affect streamflow conditions. This functionality can be accessed through a map-based interface with the user’s Web browser or through individual functions requested remotely through other Web applications (Ries and others, 2008).

StreamStats provides an accurate, consistent and fast process for computing basin characteristics and streamflow statistics. Streamflow statistics for gaged sites are immediately accessible without the need to obtain the original publications containing the original statistics. Examples of streamflow statistics that can be obtained from StreamStats include the 1-percent exceedance level flood, mean annual flow, and 7-day, 10-percent exceedance level low flow. Examples of basin characteristics that can be computed in StreamStats include drainage area, stream slope, mean annual precipitation and percentage of forested area (Ries and others, 2008). These data are valuable for making decisions related to bridge design, floodplain delineation, water-supply, and sustaining stream quality and ecology.

Objective

The objective of the pilot project is to develop and implement the StreamStats application for the Upper French Broad River basin in western North Carolina utilizing the local resolution NHD product and 20-foot DEMs (derived from LIDAR), with the most current regional streamflow regression equations and datasets pertinent to the various cooperating agencies. Issues related to dataset development and application implementation that might affect stream mapping in North Carolina and(or) other areas of the country with similar resolution datasets will be addressed and documented such that subsequent implementations can be more efficient and cost-effective.

Scope

The scope of the pilot project includes the Upper French Broad River Basin in Western North Carolina upstream of USGS gaging station 03451500 (French Broad River at Asheville, NC). The drainage area of the study area is 944 square miles (mi2) consisting of a wide variety of land cover types ranging from densely forested headwater areas to agricultural land and impervious urban areas. The Upper French Broad River basin was sub-divided into 5th level (10-digit) hydrologic units using the 20-foot DEM derived from LIDAR data. The basin was further be subdivided into catchment areas, which are subwatersheds for each stream segment in the local-resolution NHD. Basin characteristics (i.e. drainage area, percent urbanized, slope) were derived for these catchment areas. The basin characteristics are used (1) to characterize watersheds that have been selected by the user through automated basin delineation and stream navigation functions and (2) as input parameters to regional flood frequency and low-flow (once an updated low-flow regionalization is completed) equations for computation of various return period streamflow estimates. The local resolution digital streams (NHD) for the Upper French Broad River basin were indexed with USGS streamgage locations to provide an example of how the NHD can be applied to other pertinent electronic datasets (water-supply intakes, waterwater discharges, bridges, BMPs, etc.) that are critical for stakeholder business practices. The local resolution NHD is also be used to display the stream network in the StreamStats application.