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J. C. Blodgett

Publications and source records attributed to J. C. Blodgett.

34 records · Page 2Linked to original sources
USGS1984

Peak flow, volume, and frequency of the January 1982 flood, Santa Cruz Mountains and vicinity, California

The areal distribution of precipitation and flooding during the January 1982 storm in the Santa Cruz Mountains and vicinity was influenced by the orographic effect of the Santa Cruz Mountains. Precipitation depths ranged from 12.2 inches in 1 day on the west side to 1.33 inches on the east side. Unit peak discharge ranged from 626 cubic feet per second per square mile on the west side to 83 cubic feet per second per square mile on the east side. The median recurrence interval of peak flow on the west side is 22 years, whereas on the east side it is 6.8 years. Development of a relation between rainfall at Ben Lomond and runoff on the San Lorenzo River at Big Trees shows that the significant climatic factors that describe the flood hydrology of the basin are (1) precipitation for the 3 consecutive days including the day of peak flows and (2) precipitation for a 60-day duration prior to the peak. A study of historical floods and precipitation characterisitics in the San Lorenzo River basin suggests that major floods in the area are the product of (1) greater-than-normal antecedent precipitation for up to 60 days prior to the flood and (2) subsequent intense frontal-type storms immediately prior to the peak. (USGS)

California↗
USGS1984

Estimation of streamflow for selected sites on the Carson and Truckee rivers in California and Nevada, 1944-80

Daily mean and monthly discharges were estimated for 10 sites on the Carson and Truckee Rivers for periods of incomplete records and for tributary sites affected by reservoir regulation. On the basis of the hydrologic characteristics, stream-flow data for a water year were grouped by month or season for subsequent regression analysis. In most cases, simple linear regressions adequately defined a relation of streamflow between gaging stations, but in some instances a nonlinear relation for several months of the water year was derived. Statistical data are presented to indicate the reliability of the estimated streamflow data. Records of discharges including historical and estimated data for the gaging stations for the water years 1944-80 are presented. (USGS)

Water-Resources Investigations Report↗
USGS1982

Floodflow characteristics of Honcut Creek at State Highway 70 bridges near Live Oak, California

State Highway 70 crosses Honcut Creek near Live Oak about 3 miles upstream from its confluence with the Feather River by a series of three bridges separated by short approach embankments. The California Department of Transportation is planning to replace or widen the three bridges. This report evaluates flow characteristics of the existing and proposed crossings. The distribution of flow across the floodplain and water-surface elevation of Honcut Creek at the site are affected by levees, a natural channel constriction, agricultural improvements on the floodplain, and high water levels on the Feather River. The average recurrence interval for overbank flow is less than 2 years, and for flows equal to the flood of January 12, 1980 (discharge, 10,100 cubic feet per second), is about 2. 5 years. A flood with an average recurrence interval of 50 years would discharge about 19,000 cubic feet per second. Flooding caused by high stages on the Feather River has occurred seven times during the period 1964-80. For flows exceeding 20,000 cubic feet per second on Honcut Creek, and assuming present bridge conditions, backwater at the approach section about 400 feet upstream from the bridge is about 0.4 foot. If bridge l (left bank bridge) is eliminated, backwater conditions at the approach section would increase to 0.5 foot. Backwater effects extend upstream more than 3,000 feet when flows exceed about 5,000 cubic feet per second. The present arrangement of the bridges and approach embankments occupies about 66 percent of the channel (between the levee and high ground). Measurements of the average velocity of flow at a bridge range from l to 3.2 feet per second, depending on the flood stages of the Feather River. The maximum point velocity of flow measured during the 1979-80 flood season was 5. 6 feet per second. In general, flow velocities will be less than about 6 feet per second because flooding and high stages on the Feather River create ponded conditions at the bridge site. For present channel and bridge conditions, overbank flows are distributed among the three bridges in a proportion of about 10, 40, and 50 percent for flows from 2,850 to 8,480 cubic feet per second.

California↗
USGS1981

Floodflow characteristics of the Sacramento River in the vicinity of Gianella Bridge, Hamilton City, California

Floodflow, channel, and geomorphic data were assembled to evaluate the characteristics of flooding of the Sacramento River at the Gianella Bridge on State Highway 32 at Hamilton City, Calif. The bridge, constructed with a large center pier and drawrest structure in 1908, constricts floodflows at the site. Variations in river sinuosity, slope, and alinement between 1946 and 1980, indicate that channel changes are significant during short (2- or 3-year) intervals of time. Over long periods, however, the channel appears to be in equilibrium. The flood plain extends several miles upstream and downstream from the site. Soils on the flood plain are sandy-silt loam, easily eroded by streamflow. Overflow to the flood plain is limited by levees along both banks that are overtopped or bypassed when floods exceed 130,000 cubic feet per second in the main channel. Backwater in the main channel upstream from the bridge is about 0.6 feet for flows exceeding 159,000 cubic feet per seconds, and extends more than 1.9 miles upstream, depending on the magnitude of flooding. The bridge structure occupies about 12 percent of the channel during all flows. The distribution of flow at the bridge is affected by piers for about 13 percent of the channel width. Highest velocities of flow are 13 feet per second. (USGS)

Open-File Report↗
USGS1980

Flood data for the Sacramento River and Butte Basin, 1878 to 1978, Sacramento Valley, California

Streamflow data at various locations were assembled for the Sacramento River between Red Bluff and Meridian, Calif., and for Butte Basin, which serves as an overflow basin during periods of flooding. Data were obtained from various Federal and State agencies and private sources to document the magnitude of flooding from 1875 to 1978. The assembled data include annual maximum flood stages and discharges for the period of record at gaging stations, and flood stages at numerous staff gages, crest-stage gages, and high-water mark sites throughout the study area. Tabulations of floodflow measurements made at or near gaging stations, including the cross-sectional area of the channel and velocities, are presented. Cross sections of the Sacramento River near Chico Landing surveyed in 1978 and earlier surveys to show the size of Butte Basin have been included. A detailed list of references is presented giving the sources of the data included in this report. Many of these sources present detailed descriptions of flooding at various sites. (USGS)

Open-File Report↗
USGS1974

Hydraulic analysis of floodflows in Butte Basin at State Highway 162, Glenn and Butte counties, California

Inundation of State Highway 162 across Butte Basin at the latitude of Butte City results from overland floodflow from the Sacramento River and flooding on Butte Creek. Flooding of Butte Basin from the Sacramento River will occur whenever flow in the main channel at Butte City exceeds 90,000 cubic feet per second (2550 cubic metres per second), a discharge with a recurrence interval of about 3 years. The distribution of floodflow across the basin is not uniform. During the flood of January 24, 1970, 84 percent of the total discharge resulted from overland flow from the Sacramento River and 16 percent from flooding on Butte Creek. When flooding in Butte Basin is severe enough to affect State Highway 162, overflow across the road first occurs between bridges 11-21 and 11-22. The construction of bridges or culverts at two locations between bridges 11-21 and 11-22 would increase the period of time that the road is usable. Analysis of the present roadway, bridge geometry, and ground elevations adjacent to the roadway indicates that backwater is less than 0.6 foot (0.2 metre) for flows of the magnitude experienced during the flood of January 24, 1970. The concurrent maximum velocity of flow at the bridges is 6.8 feet per second (2.1 metres per second). Part of the backwater is caused by ground elevations adjacent to the roadway that are, at many locations, higher than the road crown. If the roadway embankment were raised to prevent overtopping by a flood equivalent to that of January 24, 1970, without increasing the capacity or number of the bridges, backwater greater than 0.5 foot (0.2 metre) would result upstream from 6 of the 15 bridges on State Highway 162, and velocities would be excessive. Additional bridge openings to discharge a total of 37,800 cubic feet per second (1070 cubic metres per second) would be required for at least six locations if backwater and velocity were to be kept to levels similar to those observed for present conditions. During the flood of November 12, 1973, water-surface elevations recorded in several of the overflow channels of Butte Creek were higher than those observed during the January 1970 flood even though the discharge was less. The higher water-surface elevations in 1973 probably resulted from vegetal growth in the channels and consequent reduction in the capacity of the channel to carry floodflows.

Open-File Report↗
USGS1971

Water temperatures of California streams, San Francisco Bay subregion

A summary of water-temperature records is presented for data collected through September 1968 in the San Francisco Bay Subregion of California. This report is one of a series covering the 11 hydrologic subregions of the State and includes data for 87 stream sites. Water temperatures, in degrees Celsius, are summarized by months, years, and for the period of record. A description is included to identify each station where data were collected. A tolerance interval analysis indicated that 99 percent of the point water-temperature observations, determined either with thermograph probes or hand-held thermometers, should be ±0.6°C of the mean water temperature at the 95-percent confidence level. The probable total error ranges from ±0.8°C for periodic data to ±1.4°C for thermograph data.

California↗
USGS1968

Determination of channel capacity of the Merced River downstream from Merced Falls Dam, Merced County, California

This study evaluates the adequacy of a reach of the Merced River between Merced Falls and the confluence with the San Joaquin River to carry flood releases from New Exchequer and McSwain Dams and Reservoirs. The flood release from these reservoirs is to be restricted so that flows will not exceed 6,000 cfs (cubic feet per second) in t he Merced River at the gaging station near Stevinson (about 5 miles upstream from the mouth). Computed floodwater profiles based on channel conditions in late 1967 and observed water-surface profiles for historic floods were used in the analysis. The conclusions reached are contingent on there being no levee failures during periods of high flow. Evaluation of historical flood records at gaging stations between Merced Falls and Stevinson indicates that a reduction in peak discharge occurs as the floods traverse the study reach. Reduction in peak discharge is dependent on river stage, prior river flows, magnitude of tributary inflow, bank storage and infiltration to the ground-water reservoir, and diversion for irrigation. For example, in late June 1967 a peak discharge of 9,860 cfs at Merced Falls was reduced by irrigation diversions to 6,850 cfs at a site 3 miles downstream and further reduced to 6,490 cfs at the gaging station near Stevinson. Backwater effect from high stages on t he San Joaquin River will increase stages on the Merced River and the effect may extend as far as 8 miles up stream from the junction of the two rivers. Backwater may cause some overbank flooding along the 8-mile reach when Merced River flows at Stevinson exceed 4,000 cfs . Most of the area subject to such inundation lies between levees that are a considerable distance--up to half a mile-- from the main channel . In the reach upstream from the backwater effect, a discharge of 4, 500 cfs near Stevinson will cause flooding at two locations, one of which is about 10 miles upstream an the other about 18.5 miles upstream from the confluence . When the discharge is 6,000 cfs , additional sites will be inundated, particularly the 20.5-mile reach of channel downstream from the Highway 99 crossing. A discharge of 6,000 cfs will pass through all bridge openings in the reach but overbank flooding may occur if debris should lodge against the bridge piers and significantly reduce the waterway area . Peak flows in Dry Creek, as measured 18.7 miles upstream from the mouth of Dry Creek, will be attenuated due to channel storage and will increase the discharge of the Merced River at Cressey by only about 50 per cent of t he Dry Creek peak discharge. Furthermore, Dry Creek seldom carries floodflows during periods of high water on the Merced River.

California↗