Geology topics

Research about Iowa, Minnesota, North Dakota, South Dakota, Wisconsin

Source-linked reports with geographic coverage including Iowa, Minnesota, North Dakota, South Dakota, Wisconsin.

3 recordsLinked to original sources

USGS2015

Methods for estimating flow-duration curve and low-flow frequency statistics for ungaged locations on small streams in Minnesota

Knowledge of the magnitude and frequency of low flows in streams, which are flows in a stream during prolonged dry weather, is fundamental for water-supply planning and design; waste-load allocation; reservoir storage design; and maintenance of water quality and quantity for irrigation, recreation, and wildlife conservation. This report presents the results of a statewide study for which regional regression equations were developed for estimating 13 flow-duration curve statistics and 10 low-flow frequency statistics at ungaged stream locations in Minnesota. The 13 flow-duration curve statistics estimated by regression equations include the 0.0001, 0.001, 0.02, 0.05, 0.1, 0.25, 0.50, 0.75, 0.9, 0.95, 0.99, 0.999, and 0.9999 exceedance-probability quantiles. The low-flow frequency statistics include annual and seasonal (spring, summer, fall, winter) 7-day mean low flows, seasonal 30-day mean low flows, and summer 122-day mean low flows for a recurrence interval of 10 years. Estimates of the 13 flow-duration curve statistics and the 10 low-flow frequency statistics are provided for 196 U.S. Geological Survey continuous-record streamgages using streamflow data collected through September 30, 2012. The study area includes 196 streamgages located within Minnesota and 50 miles beyond the State’s borders in North Dakota, South Dakota, Iowa, and Wisconsin. The study area was divided into five regions that were developed in a previous study using the concept of hydrologic landscape units. Geographic information system software was used to calculate 18 characteristics investigated as potential explanatory variables in regression analyses for each streamgage drainage basin. Trend analyses indicated statistically significant trends in summer 7-day low flows that were not related to precipitation patterns for 19 streamgages. For 16 of these streamgages, the streamflow record was subset using structural change analysis to identify the most recent period of record without a significant trend. The three remaining streamgages with significant trends were excluded from the final analysis because the effective period of record without a significant trend was less than 10 years. Because several streams in this study have zero flow as their minimum reported flow, weighted left-censored regression was used to analyze the flow data in an unbiased manner, with weights based on the number of years of record. A total of 115 regression equations were developed in this study to calculate flow-duration curve and low-flow frequency statistics for ungaged locations in the study area. In addition, data from 25 pairs of streamgages were used to develop drainage-area ratio equations that can be used to estimate streamflow statistics at ungaged locations on streams that have a streamgage in another location. Streamflow statistics estimated using regional regression and drainage-area ratio equations were compared among regions. For regions A, D, and E, drainagearea ratio equations were more accurate than regional regression equations for flows, but regional regression equations were more accurate for high flows. For region F, regional regression equations were consistently more accurate than drainage-area ratio equations. For region BC, the pattern in accuracies of regional regression and drainage-area ratio equations between low flows and high flows was not consistent. Equations developed in this study apply only to stream locations where flows are not substantially affected by regulation, diversion, or urbanization. All equations presented in this study will be incorporated into StreamStats, a web-based geographic information system tool developed by the U.S. Geological Survey. StreamStats allows users to obtain streamflow statistics, basin characteristics, and other information for user-selected locations on streams through an interactive map.

Iowa, Minnesota, North Dakota, South Dakota, Wisco↗

USGS2003

Relation of periphyton and benthic invertebrate communities to environmental factors and land use at selected sites in part of the upper Mississippi River basin, 1996-98

The Upper Mississippi River Basin is one of the hydrologic systems selected for study by the National Water-Quality Assessment (NAWQA) Program of the U.S. Geological Survey. NAWQA utilizes a multi-disciplinary approach to explain factors that affect water quality. Part of the NAWQA design addresses the relation of land use and environmental factors to periphyton and benthic invertebrate communities in streams. This report focuses on a 122,000 square kilometer area of the Mississippi River Basin, including the Twin Cities metropolitan area (TCMA). The northeastern part of the study area is forested, the southwestern part is agricultural, and the central part is transitional between forest and agriculture. Sampling sites were selected based on a process that identified small streams in predominantly forested, agricultural, and urban settings, and large river sites on the Mississippi River and major tributaries. Periphyton and benthic invertebrate communities were evaluated at each site. Compared to the forested site, periphyton density and biovolume in small streams generally increased as nutrient concentrations associated with urban and agricultural land use increased. Periphyton communities varied within agricultural and urban streams, indicating that physical and chemical factors other than land use also affect periphyton communities. Benthic invertebrate communities also are affected by land use and associated stream habitat. There were few intolerant taxa (Ephemeroptera and Plecoptera) in urban streams, potentially due to high streamflow variability and contaminants from runoff. Ephemeroptera taxa richness was greatest in the agricultural streams. The most abundant Ephemeroptera taxa were those tolerant to high concentrations of suspended sediment. Richness of Plecoptera and Trichoptera taxa were greatest in the forested stream. Biological communities in the St. Croix and Minnesota River generally reflected relatively homogeneous land uses. Biological communities in the Mississippi River reflected changes in water quality and physical habitat as the Minnesota and St. Croix Rivers join the Mississippi River. Periphyton density and biovolume, and the relative abundance of blue-green algae density increased in the Mississippi River at the confluence compared to the Minnesota and St. Croix Rivers. Relative abundance of benthic invertebrate taxa richness and diversity generally decreased downstream in the large rivers as urban and agricultural land use become more prevalent. Impoundments and dredging of the Mississippi River in and downstream from the TCMA exacerbate effects of increasing river size to produce a more lake-like system.

Iowa, Minnesota, North Dakota, South Dakota, Wisco↗

USGS2000

Water quality in the upper Mississippi River basin, Minnesota, Wisconsin, South Dakota, Iowa, and North Dakota, 1995-98

The report summarizes major findings about water quality in part of the upper Mississippi River basin that emerged from an assessment conducted from 1995 to 1998 by the NAWQA Program. Water quality is discussed in terms of local and regional issues and compared to conditions in the other 36 NAWQA study units assessed to date. Findings are also explained in the context of selected national benchmarks, such as those for drinking-water quality and the protection of aquatic organisms. Finally, this report includes information about the status of aquatic communities and the condition of instream habitat. Many topics covered in the report reflect concerns of officials of State and Federal agencies, water-resource managers, and members of stakeholders groups who provided advice and input during the assessment.

Iowa, Minnesota, North Dakota, South Dakota, Wisco↗