Geology topics

W. R. Murphy

Publications and source records attributed to W. R. Murphy.

5 recordsLinked to original sources

USGS1984

Flooding in northwestern Hillsborough and southern Pasco counties, Florida, in 1979

Heavy rainfall in the late spring and summer of 1979 caused severe flooding in northwestern Hillsborough and southern Pasco counties, including north Tampa. May 7-9 rainfall for some stations had a recurrence interval in excess of 100 years; the August and September rainfall total had a recurrence interval in excess of 50 years. The frequency of flooding of streams and lakes in the study area for the May 7-9 storm ranged from less than 2 to 25 years; for the period August to October, recurrence intervals ranged from 3 to 25 years. Areas of maximum flooding for a 48-square-mile area of northwestern Hillsborough and southern Pasco Counties are indicated on 12 sheets of aerial photography. Drainage patterns, control structures, drainage basins, and existing and proposed urban developments are shown and related to flooding. Stage and streamflow hydrographs are shown for 12 lakes and 2 streams.

Florida↗

USGS1979

Flood profiles of the Pithlachascotee River, west-central Florida

Data defining the magnitude and frequency of flooding are provided for a nontidal 16-mile reach of the Pithlachascotee River in Florida. These data include areal flood-frequency relations and flood heights for the 2-, 2.33-, 5-, 10-, 25-, 50- , 100-, 200-, and 500-year recurrence intervals. Flood profiles are provided for the 2.33-, 5-, 10-, 100-, and 500-year recurrence intervals. Study results indicate that flood discharges in the study area are highly variable and are one-third to one-half of regional estimates. Differences between study area and regional estimates are due to large quantities of flood-water drainage to the regional aquifer system in the upper basin, a large karst area of about 138 square miles. Graded roads and bridges located at three sites along the upper study reach will be inundated by various frequency floods. Flood inundation maps can be prepared from flood data presented in this report.

Florida↗

USGS1978

Flood profiles for Peace River, south-central Florida

This report presents flood heights and profiles for a 70-mile reach of Peace River from Bartow to Arcadia, Fla. The flood heights were calculated using the U.S. Geological Survey step-backwater model. Profiles were prepared for floods having expected recurrence intervals of 2, 2.33, 5, 10, 25, 50, 100, 200, and 500 years. Flood-peak discharges used in the step-backwater analyses were determined by weighting stream gaging-station data with data from a regional analysis. Land-surface elevation data for 183 cross sections - including values of Manning 's roughness coefficient - also were used in the backwater analysis. Flood height data are generally accurate to + or - 0.5 foot. They indicate that most roads and two bridges in the study reach will be inundated by some of the floods evaluated. (Woodard-USGS)

Water-Resources Investigations Report↗

USGS1978

Magnitude and frequency of flooding on the Myakka River, Southwest Florida

Myakka River is a coastal stream that drains approximately 550 square miles in southwest Florida. Under natural conditions, Tatum Sawgrass, a large depression, served as a flood overflow area for the upper part of the Myakka River basin. A recently constructed (1974) dike system across the lower part of Tatum Sawgrass has reduced previously available storage, thereby affecting downstream flooding. An evaluation of the effects of Tatum Sawgrass dikes on flooding indi-cates that flood-peak discharges and flood heights having recurrence inter-vals of up to 25 years are increased. As a result, about 1,200 additional acres along Myakka River main stem may be inundated during 2-year flood conditions. Maximum effects include a 19 percent increase in flood-peak discharge at State Road 780 and a 0.8 foot increase in flood height near the downstream end of the study reach. Floods having recurrence intervals of 50 years or greater will over-top dikes and the storage capacity of Tatum Sawgrass will revert to natural condition capacity. As part of the evaluation, diked condition flood profiles, having recurrence intervals of 2, 5, 10, 25, 50, 100, 200, and 500 years were determined for the nontidal part of a 45-mile reach of Myakka River main stem, Clay Gully, and Blackburn Canal. These data indicate that Clay Gully flood water will overflow embankments at State Road 780 during the 2-year flood and will overflow the bridge on State Road 780 during the 25-year flood. Myakka River flood water will overflow embankments at State Road 72 and Border Road during 100-year flood conditions and at State Road 780 during 500-year conditions.

Florida↗

USGS1978

Flood profiles for Cypress Creek, west-central Florida

Flood profiles are included for selected recurrence-interval floods in west-central Florida for a 27-mile reach of Cypress Creek, for a 4-mile tributary reach, and for a 1.2-mile distributary reach. The procedure for constructing flood profiles is based on flood heights computed in a step-backwater analysis using the following data: 2-, 2.33-, 5-, 10-, 25-, 50-, 100-, 200-, and 500-year flood-peak discharges; data for 53 Cypress Creek channel cross sections, 11 tributary cross sections, and 7 distributary cross sections (including roughness coefficients); and stage-discharge relations. Computed flood heights are judged to be generally accurate to plus-or-minus 0.5 foot. Flood data presented can be used to delineate areal extent of flooding on topographic maps. This information can be used by local governmental agencies to control flood-plain development. (Woodard-USGS)

Water-Resources Investigations Report↗