thumbnail

Channel degradation in southeastern Nebraska Rivers

By:
and
Edited by:
Ward Rim J.

Links

  • The Publications Warehouse does not have links to digital versions of this publication at this time
  • Download citation as: RIS

Abstract

Many stream channels in southeastern Nebraska were dredged and straightened during 1904-15. The resulting channels were both shorter and steeper than the original channels. Tests for time trends were conducted using the nonparametric Kendall tau test to see if the channels have responded to these changes. Tests were conducted on the stages associated with specific discharges and on measurement characteristics at gaging stations. Tests also were conducted on hydrologic forcing variables (annual mean precipitation, annual peak discharges, annual mean discharge, and annual mean base flows). The null hypothesis (that the data were free from trend) was rejected for stages associated with the mean of the annual discharges for 6 of 7 gaging stations in the study area, but was accepted for all 3 gages on the main stem of the Missouri River. The trends at the 6 streamflow gaging stations were for decreasing stages (degrading channels) for specific discharges. The rates of change ranged from about 0.2 to 0.5 m per decade. Mean stream bed elevations computed for individual discharge measurements at these streamflow gaging stations confirmed that the channels are degrading. However, neither the precipitation nor flow variables show evidence of trends. The tendency for the channels to degrade thus cannot be attributed to changes in runoff characteristics and are assumed to be a response to the channel modifications in the early 1900's. Indications are that the channels presently are continuing to degrade.

Additional Publication Details

Publication type:
Conference Paper
Publication Subtype:
Conference Paper
Title:
Channel degradation in southeastern Nebraska Rivers
Year Published:
1995
Language:
English
Publisher:
ASCE
Publisher location:
New York, NY, United States
Larger Work Title:
Watershed Management Symposium - Proceedings
First page:
250
Last page:
259
Conference Title:
Proceedings of the 1995 Watershed Management Symposium
Conference Location:
San Antonio, TX, USA
Conference Date:
14 August 1995 through 16 August 1995