Analysis of flood-flow frequency, flow duration, and channel-forming flow for the James River in South Dakota

Abstract

The James River, which originates in North Dakota and joins the Missouri River near Yankton, South Dakota, is about 747 miles long, with about 474 river miles located in South Dakota. The James River basin includes 21,116 square miles, with 14,428 square miles located in South Dakota. Bankfull capacity of the James River in South Dakota ranges from a minimum of about 200 cubic feet per second in the northern portion to a maximum of about 10,000 cubic feet per second near the mouth. Discharges that produce bankfull conditions on much of the river in South Dakota occur on an average of once in about 2 years. The 10-year flood flows, which range from 1 ,620 cubic feet per second (at the gage near Stratford) to 8,870 cubic feet per second (at the gage near Scotland), cause major flooding on most of the river in South Dakota. The river also has potential for extended periods of low or zero flow, especially in the northern portion within South Dakota. Generally, low flows occur from late summer until spring snowmelt. The James River at Columbia had zero flow for 623 consecutive days from July 13, 1958, through March 26, 1960. The channel pattern (channel alignment) has changed little since 1922. This channel stability indicates that channel formation is approaching a state of equilibrium. It does not appear that velocities in the river are sufficient to carry the sediment being delivered by the tributaries. INTRODUCTION Background In 1984, a Federally appointed Garrison Diversion Unit Study Commission recommended major changes in the Garrison Diversion Unit (GDU) in North Dakota (Garrison Diversion Unit Commission, 1984). On May 12, 1986, the Garrison Diversion Unit Reformulation Act of 1986 was signed into law. There are eight specific study areas identified within the Reformulation Act (H.R. 1116), seven of which are directly associated with impacts to the James River. The Reformulation Act directs the Secretary of Interior to submit a comprehensive report to the Congress as soon as practicable but not later than the end of fiscal year 1988 (Amended Section 5(C)(1) Public Law 89-108). The U.S. Bureau of Reclamation is the lead agency for evaluating the potential effects of GDU on the James River in South Dakota. As part of this evaluation, the Bureau requested that the U.S. Geological Survey conduct the flood-frequency, flow-duration, and channel-forming-flow studies that are summarized in this report. Objectives The objectives of this study were to analyze flood-flow frequency, flow duration, and channel-forming flow for the James River in South Dakota. Flood-flow frequency analyses also were made for certain tributaries within the James River basin. The study effort was limited to the analysis of existing discharge records. The drainage area for the entire basin within South Dakota was determined. A separate drainage-area map report was prepared (Benson and others, 1987). Physical Setting The James River, which originates in North Dakota and joins the Missouri River near Yankton, S. Dak., is about 7^7 mi long, with about 474 river miles located in South Dakota (fig. 1). The total area of the James River basin is 21,116 mi 2 , with 14,428 mi 2 located within South Dakota. Additional information concerning the river setting and hydrology can be found in a previous study by Benson (1983). The gaging stations for which discharge records were analyzed as a part of this study are identified on figure 1. Data for continuous-record gaging stations operated by the U.S. Geological Survey within the James River basin in South Dakota are included in table 1 (main-stem stations) and in table 2 (tributary stations). ANALYSIS OF FLOOD FREQUENCY Statistical flood-flow frequency analyses were made for the main-stem gaging stations and .for gaged tributaries that have 10 or more years of continuous record. The analyses were made by using the log-Pearson Type III frequency distribution based on procedures recommended by the U.S. Water Resources Council (1981). The frequency analyses were made on two sets of flow data for the mainstem locations and for the tributary gages. The first frequency analyses were made for the instantaneous peak flow data stored in the Water Data Storage and Retrieval System (WATSTORE) Peak Flow File for each gaging station. The second frequency analyses were made for data sets containing the maximum daily mean discharge which occurred at each gaging station during the months of June, July, and August of each year (that is, a summer discharge). The analyses were made on the maximum daily mean discharge because instantaneous peak flow data are not generally available for the months of June, July, and August. Inspection of flow data on the James River indicates that the maximum daily mean discharge generally is within 5 percent of the instantaneous peak flow occurring on that same day. NORTH DAKOTA SOUTH DAKOTA