Hydrogeomorphic Segments and Hydraulic Microhabitats of the Niobrara River, Nebraska—With Special Emphasis on the Niobrara National Scenic River

The Niobrara River of Nebraska is an ecologically and economically important resource, renowned for its biological diversity, paleontological richness, and abundant recreational opportunities. The steady, dependable flow of the Niobrara River makes it an important source of irrigation water for local agriculture, which is the foundation of the regional economy. The geographic setting and physiography of the Niobrara River Valley facilitate the convergence, hybridization, and survival of at least five terrestrial ecosystem community types within a relatively narrow corridor. This unique quality was recognized by the United States Congress in 1991 when a portion of the river was granted Federal protection under the Wild and Scenic Rivers Act of 1968. The 76-mile (mi) reach of river is now recognized as the Niobrara National Scenic River (hereinafter referred to as the “Scenic Reach”) near Valentine, Nebr. and is cooperatively managed by a consortium of private landowners, and State and Federal agencies. The 28-mile reach of the Niobrara River upstream from the Missouri River (hereinafter named the “Recreational Reach”) are protected within the Missouri National Recreational River.

The Nebraska Department of Natural Resources’ (NDNR) recent designation of the hydraulically connected surface- and groundwater resources of the Niobrara River Basin as “fully appropriated” (Nebraska Department of Natural Resources, 2007) has emphasized the importance of understanding linkages between the physical and ecological dynamics of the Niobrara River so it can be sustainably managed. Among the key questions identified for study by an interagency working group are:
1. What flow regime is needed to maintain the present quantity and diversity of stream physical habitats that distinguish the Niobrara as a healthy ecosystem?
2. What frequency, duration, and timing of infrequent hydrologic disturbances (floods, droughts, ice jams) are neededto maintain a dynamic equilibrium of fluvial geomorphic processes to sustain the present channel character?

To begin to address either question, an understanding of the Niobrara River’s present channel character and associated diversity of stream physical attributes is necessary. Additionally, an investigation of Niobrara River channel hydraulics may assist in understanding channel adjustment and maintenance processes, as well as flood plain connectivity. Numerous scientific studies have investigated the physical and hydraulic attributes of the Niobrara River along isolated reaches; however, none have placed these characteristics within a spectrum of fluvial settings at the basin scale. Such a study may provide the physical context for water-management strategies and serve as a framework for integrated physical and biological investigations.

In cooperation with the Nebraska Game and Parks Commission (NGPC), the U.S. Geological Survey (USGS) investigated the hydrogeomorphic and hydraulic attributes of the 330-mi reach of the Niobrara River from Dunlap Diversion Dam in western Nebraska to the confluence with the Missouri River in northeastern Nebraska.

View the report.

Related Publications

Geomorphic Segmentation, Hydraulic Geometry, and Hydraulic Microhabitats of the Niobrara River, Nebraska—Methods and Initial Results

Contact

Jason Alexander
U.S. Geological Survey
5231 South 19th Street
Lincoln , NE 68512-1271
(402) 328-4132

Keywords

instream flow, Nebraska, Niobrara River, geomorphology, habitat

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