Geology topics

David A. Eash

Publications and source records attributed to David A. Eash.

26 records · Page 2Linked to original sources

USGS2006

Flood of May 23, 2004, in the Turkey and Maquoketa River basins, northeast Iowa

Severe flooding occurred on May 23, 2004, in the Turkey River Basin in Clayton County and in the Maquoketa River Basin in Delaware County following intense thunderstorms over northeast Iowa. Rain gages at Postville and Waucoma, Iowa, recorded 72-hour rainfall of 6.32 and 6.55 inches, respectively, on May 23. Unofficial rainfall totals of 8 to 10 inches were reported in the Turkey River Basin. The peak discharge on May 23 at the Turkey River at Garber streamflow-gaging station was 66,700 cubic feet per second (recurrence interval greater than 500 years) and is the largest flood on record in the Turkey River Basin. The timing of flood crests on the Turkey and Volga Rivers, and local tributaries, coincided to produce a record flood on the lower part of the Turkey River. Three large floods have occurred at the Turkey River at Garber gaging station in a 13-year period. Peak discharges of the floods of June 1991 and May 1999 were 49,900 cubic feet per second (recurrence interval about 150 years) and 53,900 cubic feet per second (recurrence interval about 220 years), respectively. The peak discharge on May 23 at the Maquoketa River at Manchester gaging station was 26,000 cubic feet per second (recurrence interval about 100 years) and is the largest known flood in the upper part of the Maquoketa River Basin.

Iowa↗

USGS2004

Flood of June 4, 2002, in the Indian Creek Basin, Linn County, Iowa

Severe flooding occurred on June 4, 2002, in the Indian Creek Basin in Linn County, Iowa, following thunderstorm activity over east-central Iowa. The rain gage at Cedar Rapids, Iowa, recorded a 24-hour rainfall of 4.76 inches at 6:00 p.m. on June 4th. Radar indications estimated as much as 6 inches of rain fell in the headwaters of the Indian Creek Basin. Peak discharges on Indian Creek of 12,500 cubic feet per second at County Home Road north of Marion, Iowa, and 24,300 cubic feet per second at East Post Road in southeast Cedar Rapids, were determined for the flood. The recurrence interval for these peak discharges both exceed the theoretical 500-year flood as computed using flood-estimation equations developed by the U.S. Geological Survey. Information about the basin and flood history, the 2002 thunderstorms and associated flooding, and a profile of high-water marks are presented for selected reaches along Indian and Dry Creeks.

Iowa↗

USGS2004

Flood of June 4-5, 2002, in the Maquoketa River Basin, east-central Iowa

Severe flooding occurred on June 4-5, 2002, in the Maquoketa River Basin in Delaware, Dubuque, Jackson, and Jones Counties, following thunderstorm activity over east-central Iowa. The rain gage at Cascade, Iowa, recorded a 14-hour rainfall of 6.0 inches at noon on June 4. Radar indications estimated as much as 8 to 10 inches of rain fell in the upper-middle part of the Maquoketa River Basin. Peak discharges on the Maquoketa River at Monticello of 47,500 cubic feet per second (recurrence interval estimated to be greater than 500 years as computed using flood-estimation equations developed by the U.S. Geological Survey), and at the Maquoketa River near Maquoketa streamflow-gaging station of 47,900 cubic feet per second (recurrence interval about 50 years), were determined for the flood. The peak discharge of the 2002 flood is nearly equal that of the 1944 flood (48,000 cubic feet per second), the largest flood on record in the Maquoketa River Basin. The 2002 flood is the largest known flood in the North Fork Maquoketa River Basin. A peak discharge of 22,600 cubic feet per second (recurrence interval about 110 years) was determined for the flood at the North Fork Maquoketa River near Fulton gaging station. Information about the basin and flood history, the 2002 thunderstorms and associated flooding, and a profile of high-water marks are presented for selected reaches along the Maquoketa and North Fork Maquoketa Rivers.

Iowa↗

USGS2003

Main-channel slopes of selected streams in Iowa for estimation of flood-frequency discharges

This report describes a statewide study conducted to develop main-channel slope (MCS) curves for 138 selected streams in Iowa with drainage areas greater than 100 square miles. MCS values determined from the curves can be used in regression equations for estimating floodfrequency discharges. Multivariable regression equations previously developed for two of the three hydrologic regions defined for Iowa require the measurement of MCS. Main-channel slope is a difficult measurement to obtain for large streams using 1:24,000-scale topographic maps. The curves developed in this report provide a simplified method for determining MCS values for sites located along large streams in Iowa within hydrologic Regions 2 and 3. The curves were developed using MCS values quantified for 2,058 selected sites along 138 selected streams in Iowa. A geographic information system (GIS) technique and 1:24,000-scale topographic data were used to quantify MCS values for the stream sites. The sites were selected at about 5-mile intervals along the streams. River miles were quantified for each stream site using a GIS program. Data points for river-mile and MCS values were plotted and a best-fit curve was developed for each stream. An adjustment was applied to all 138 curves to compensate for differences in MCS values between manual measurements and GIS quantifications. The multivariable equations for Regions 2 and 3 were developed using manual measurements of MCS. A comparison of manual measurements and GIS quantifications of MCS indicates that manual measurements typically produce greater values of MCS compared to GIS quantifications. Median differences between manual measurements and GIS quantifications of MCS are 14.8 and 17.7 percent for Regions 2 and 3, respectively. Comparisons of percentage differences between flood-frequency discharges calculated using MCS values of manual measurements and GIS quantifications indicate that use of GIS values of MCS for Region 3 substantially underestimate flood discharges. Mean and median percentage differences for 2- to 500-year recurrence- interval flood discharges ranged from 5.0 to 5.3 and 4.3 to 4.5 percent, respectively, for Region 2 and ranged from 18.3 to 27.1 and 12.3 to 17.3 percent for Region 3. The MCS curves developed from GIS quantifications were adjusted by 14.8 percent for streams located in Region 2 and by 17.7 percent for streams located in Region 3. Comparisons of percentage differences between flood discharges calculated using MCS values of manual measurements and adjusted-GIS quantifications for Regions 2 and 3 indicate that the flood-discharge estimates are comparable. For Region 2, mean percentage differences for 2- to 500-year recurrence- interval flood discharges ranged between 0.6 and 0.8 percent and median differences were 0.0 percent. For Region 3, mean and median differences ranged between 5.4 to 8.4 and 0.0 to 0.3 percent, respectively. A list of selected stream sites presented with each curve provides information about the sites including river miles, drainage areas, the location of U.S. Geological Survey streamflowgaging stations, and the location of streams crossing hydrologic region boundaries or the Des Moines Lobe landform region boundary. Two examples are presented for determining river-mile and MCS values, and two techniques are presented for computing flood-frequency discharges.

Iowa↗

USGS2001

Techniques for estimating flood-frequency discharges for streams in Iowa

A statewide study was conducted to develop regression equations for estimating flood-frequency discharges for ungaged stream sites in Iowa. Thirty-eight selected basin characteristics were quantified and flood-frequency analyses were computed for 291 streamflow-gaging stations in Iowa and adjacent States. A generalized-skew-coefficient analysis was conducted to determine whether generalized skew coefficients could be improved for Iowa. Station skew coefficients were computed for 239 gaging stations in Iowa and adjacent States, and an isoline map of generalized-skew-coefficient values was developed for Iowa using variogram modeling and kriging methods. The skew map provided the lowest mean square error for the generalized-skew- coefficient analysis and was used to revise generalized skew coefficients for flood-frequency analyses for gaging stations in Iowa. Regional regression analysis, using generalized least-squares regression and data from 241 gaging stations,was used to develop equations for three hydrologic regions defined for the State. The regression equations can be used to estimate flood discharges that have recurrence intervals of 2, 5, 10, 25, 50, 100, 200, and 500 years for ungaged stream sites in Iowa. One-variable equations were developed for each of the three regions and multi-variable equations were developed for two of the regions. Two sets of equations are presented for two of the regions because one-variable equations are considered easy for users to apply and the predictive accuracies of multi-variable equations are greater. Standard error of prediction for the one-variable equations ranges from about 34 to 45 percent and for the multi-variable equations ranges from about 31 to 42 percent. A region-of-influence regression method was also investigated for estimating flood-frequency discharges for ungaged stream sites in Iowa. A comparison of regional and region-of influence regression methods, based on ease of application and root mean square errors, determined the regional regression method to be the better estimation method for Iowa. Techniques for estimating flood-frequency discharges for streams in Iowa are presented for determining (1) regional regression estimates for ungaged sites on ungaged streams; (2) weighted estimates for gaged sites; and (3) weighted estimates for ungaged sites on gaged streams. The technique for determining regional regression estimates for ungaged sites on ungaged streams requires determining which of four possible examples applies to the location of the stream site and its basin. Illustrations for determining which example applies to an ungaged stream site and for applying both the one-variable and multi-variable regression equations are provided for the estimation techniques.

Illinois, Iowa, Minnesota, Missouri, Nebraska, Sou↗

USGS2000

Volumes of recent floods and potential for storage in upland watershed areas of Iowa

Substantial flooding at various locations throughout the United States, particularly during and after the Upper Mississippi River Basin flood of 1993, has resulted in analysis and discussion of both structural and nonstructural methods of watershed management to control flooding. The Upper Mississippi River Basin flood of 1993 resulted in the formulation of a Scientific Assessment and Strategy Team (SAST) to assist and advise decision makers about the positive and negative effects of flood-control measures and habitat restoration (Scientific Assessment and Strategy Team, 1994). SAST recognized the role of upland processes and the interconnectivity of a management strategy on other parts of the river system. If upland areas are considered for inclusion in an overall management strategy related to flooding, an analysis of watershed that have been flooded and the amount of runoff generated during those floods is needed. During the autumn of 1997, the U.S. Geological Survey (USGS), in cooperation with the U.S. Environmental Protection Agency, began a study to determine the volume of water associated with recent flood events in parts of the Midwestern United States and a preliminary evaluation of the potential upland areas for storage of flood-waters in selected watersheds. This analysis, although preliminary, may be useful in determining the feasibility of conducting additional, more detailed studies into the role of upland areas in a watershed management strategy. The methods and results of this preliminary hydrologic study are presented in this report.

Iowa↗

USGS1996

Description, instructions, and verification for Basinsoft, a computer program to quantify drainage- basin characteristics

Basinsoft is a computer program developed to utilize digital cartographic data to quantify 27 selected morphometric characteristics and optional area-weighted characteristics for a drainage basin. The programs comprising Basinsoft were written in Arc Macro Language (AML), a post-processing language written to run in ARC/INFO, a proprietary geographic information system (GIS). Basinsoft requires the generation of four source-data layers, three coverages and one lattice, representing the drainage-divide, hydrography, hypsography, and a lattice elevation model of a drainage basin, and the attribution of the three source-data layer coverages. Preprocessing of these data layers is facilitated by specialized utility AML programs. Compared to manual methods of measurement, Basinsoft significantly decreases the amount of time and effort required to quantify selected characteristics for drainage basins, particularly when a large number of drainage basins need to be processed. The automaticity of Basinsoft and its utility programs facilitate implementation of Basinsoft without requiring extensive GIS experience. Basinsoft was developed entirely using AML to ensure portability between platforms running ARC/INFO version 7.0 or later. Statistical comparison tests indicate Basinsoft quantifications are not significantly different from manual topographic-map measurements for 9 of 10 basin characteristics tested. The results also indicate that elevation contours generated by ARC/INFO from l:250,000-scale digital elevation model (DEM) data are over-generalized when compared to elevation contours shown on l:250,000-scale topographic maps, and that quantification of basin-slope thus is underestimated using DEM data. A qualitative comparison test indicated that the Basinsoft module used to quantify basin slope is valid and that differences in the quantification of basin slope are due to sourcedata differences.

Water-Resources Investigations Report↗

USGS1994

Suspended sediment and stream discharge in Bloody Run and Sny Magill watershed, water year 1992

Hydrologic data were collected in the Bloody Run and Sny Magill watersheds in Clayton County, Iowa during the 1992 Water Year (October 1, 1991 to September 30, 1992) to provide data on suspended sediment and stream discharge from these watersheds. Suspended-sediment samples were collected daily during normal flow and several times during rainstorms. Stream stage was recorded continuously and stream-discharge measurements were made monthly to develop a stage-discharge relation. Data on drainage-basin morphology and precipitation were quantified to help understand the variability in sediment and stream discharge. The total suspended-sediment discharge for Water Year 1992 was 2,720 tons at site BR1 on Bloody Run and 1,940 tons at site SN1 on Sny Magill Creek The daily median suspended-sediment discharge was 1.1 tons at both sites BR1 and SN1. The maximum daily mean stream discharge (205 cubic feet per second) at site BR1 on Bloody Run occurred on November 1, 1991. The median daily discharge at BR1 for the 1992 Water year was 24 cubic feet per second or 0.70 cubic feet per second per square mile (ft 3 /s/mi 2 ). The maximum daily mean stream discharge at site SN1 on Sny Magill Creek was 90 cubic feet per second which occurred on April 20, 1992. The median daily discharge at site SN1 for the 1992 Water Year was 15 cubic feet per second or 0.54 ft 3 /s/mi 2 .

Iowa↗