Geology topics

Jeffrey T. Armbruster

Publications and source records attributed to Jeffrey T. Armbruster.

7 recordsLinked to original sources

USGS1979

Field verification of reconstructed dam-break flood, Laurel Run, Pennsylvania

A one-dimensional dam-break flood routing model is verified by using observed data on the flash flood resulting from the failure of Laurel Run Reservoir Dam near Johnstown, Pennsylvania. The model has been developed on the basis of an explicit scheme of the characteristics method with specified time intervals. The model combines one of the characteristic equations with the Rankine-Hugoniot shock equations to trace the corresponding characteristic backward to the known state for solving the depth and velocity of flow at the wave front. The previous version of the model has called for a modification of the method of solution to overcome the computational difficulty at the narrow breach and at any geomorphological constraints where channel geometry changes rapidly. The large reduction in the computational inaccuracies and oscillations was achieved by introducing the actual "storage width" in the equation of continuity and the imaginary "conveyance width" in the equation of motion. Close agreement between observed and computed peak stages at several stations downstream of the dam strongly suggests the validity and applicability of the model. However, small numerical noise appearing in the computed stage and discharge hydrographs at the dam site as well as discrepancy of attenuated peaks in the discharge hydrographs indicate the need for further model improvement.

Pennsylvania↗

USGS1979

Regional stochastic generation of streamflows using an ARIMA (1,0,1) process and disaggregation

An ARIMA (1,0,1) model was calibrated and used to generate long annual flow sequences at three sites in the Juniata River basin, Pennsylvania. The model preserves the mean, variance, and cross correlations of the observed station data. In addition, it has a desirable blend of both high and low frequency characteristics and therefore is capable of preserving the Hurst coefficient, h. The generated annual flows are disaggregated into monthly sequences using a modification of the Valencia-Schaake model. The low-flow frequency and flow duration characteristics of the generated monthly flows, with length equal to the historical data, compare favorably with the historical data. Once the models were verified, 100-year sequences were generated and analyzed for their low flow characteristics. One-, three- and six- month low-flow frequencies at recurrence intervals greater than 10 years are generally found to be lower than flow computed from the historical flows. A method is proposed for synthesizing flows at ungaged sites. (Kosco-USGS)

Water-Resources Investigations Report↗

USGS1979

Flow routing in the Susquehanna River Basin: Part III -- Routing reservoir releases in the Tioga and Chemung rivers system, Pennsylvania, and New York, 1977

Channel-routing models were used to route hypothetical releases from reservoirs in the upper Tioga River basin, Pennsylvania. These releases were routed northward down the Tioga River to Lindley, Erwins, and Corning, New York: combined with flows routed down the Cohocton River from Campbell to Corning, New York; and then routed southeastward down the Chemung River from Corning to Chemung, New York. The models used to route the flows of Cohocton and Chemung Rivers accounted for bank-storage discharge and streamflow depletion by well pumpage. In general, 17 water years of concurrent streamflow data were available for model calibration and verification. Three hypothetical reservoir releases were made from the reservoirs and routed to Wilkes-Barre, Pennsylvania, using the models developed in this study and models developed downstream to Wilkes-Barre in a previous study. A hypothetical makeup water requirement of 65 cubic feet per second was assumed. Two historical low-flow periods were investigated. The first hypothetical release investigated was a constant 100 cubic feet per second, and the second release was a constant 70 cubic feet per second. The third scheme was a hypothetical release of 100 cubic feet per second for three days followed by a constant 70 cubic feet per second for the duration of the period considered. Constant 100 cubic feet per second releases arrived downstream more quickly than constant 70 cubic feet per second releases for both test periods, but delivered more water than required to satisfy the assumed makeup requirement. The third release scheme was generally the most efficient of the three schemes tested. Although inherent modeling errors exist in all the simulated data, the accuracy of the estimated routed reservoir releases at the downstream sites is considered good.

New York, Pennsylvania↗

USGS1977

Flow routing in the Susquehanna River Basin: Part I - Effects of Raystown Lake on the low-flow frequency characteristics of the Juniata and lower Susquehanna Rivers, Pennsylvania

A flow-routing model was used to simulate 17 water years of daily streamflows at five sites. The sites were Mapleton Depot and Newport, Pennsylvania, on the Juniata River, and Harrisburg and Marietta, Pennsylvania, and Conowingo, Maryland, on the Susquehanna River. The purpose for the simulations was to determine the effects of a new reservoir, Raystown Lake, on the low-flow frequency characteristics of these sites. Raystown Lake is on Raystown Branch Juniata River, a tributary to the Juniata River. Output from a reservoir-regulation model of Raystown Lake was used as input to the flow-routing models. In addition, a reservoir-routing model was developed for the hydroelectric power dams on the lower Susquehanna River. Low-flow frequency curves, based on the post-Raystown Lake simulated flows, were compared to similar curves based on pre-Raystown observed data. The comparison indicated that operation of the lake will cause estimated increases in the 7-day 10-year low flows ranging from 420 cfs at Mapleton Depot to 290 cfs at Marietta and Conowingo over the 7-day 10-year low flows for pre-Raystown conditions. Although inherent modeling errors exist in all of these simulated data, the overall quality of the simulated flows and the low-flow frequency curves is considered good. (Woodard-USGS)

Pennsylvania↗

USGS1976

Technical manual for estimating low-flow frequency characteristics of streams in the Susquehanna River basin

This report presents procedures for estimating low-flow frequency characteristics for streams in the Susquehanna River basin. The techniques can be used at ungaged sites as well as sites where insufficient data are available to make a reliable estimate. Streams have been divided intp two types--major and minor. Major streams are the Susquehanna, West Branch Susquehanna, Juniata, and Chemung Rivers. Points on these streams with drainage areas of more than 2,000 mi 2 (5,180 km 2 ) are included in this category. Points on these streams with drainage areas of less than 2,000 mi 2 fall into the minor stream category. Generally minor streams are herein defined as those draining less than 2,000 mi 2 (5,180 km 2 ). Multiple -regression techniques have been used to develop relations for estimating the 1-, 3-, 7-, 30-, and 183-day duration low flows at recurrence intervals of 10, 20, SO and 100 years for annual series data and the 1 - , 3-, 7-, and 30-day duration low flows, at the same recurrence intervals, for six individual months, May through October, inclusive.

Water-Resources Investigations Report↗

USGS1976

An infiltration index useful in estimating low-flow characteristics of drainage basin

Regionalization of low flows using basin characteristics has not produced satisfactory results because the effect of geology has not been included. In the Susquehanna River basin, ground-water discharge from the regolith is the primary source of low flows. This paper describes the development of an infiltration index, which, by characterizing the regolith, provides improved estimates of low-flow characteristics. The index is based on a simple numerical weighting of relative infiltration capacities. By including this index, the standard errors of estimate of the derived relations were reduced by a minimum of 11 percent and a maximum of 66 percent. Results obtained indicate that the infitration index developed in this analysis might be used successfully in other regions of country for investigations of this type. In addition using this index, drainage area and mean annual precipitation were also found to be significant in estimating low flows.

New York, Pennsylvania, Maryland↗

USGS1970

A proposed streamflow data program for South Carolina

An evaluation of the available streamflow data in South Carolina was made to provide guidelines for planning future surface-water data programs. The basic elements in the evaluation procedure were (1) establishment of objectives and goals of the program, (2) examination and analysis of all available data to determine which goals have already been met, (3) consideration of alternate methods of meeting the remaining goals, and (4) identification of elements that should be included in the future program. Four categories of data form the framework of program design. They are: current-purpose data, planning and design data, data to define long-term trends, and stream environment data. An accuracy goal for planning and design data of an equivalent of 25 years of record was specified for principal streams and an equivalent of 10 years of record was specified for minor streams. It was found that many of the goals could be met by generalizing data for gaged basins by regression analysis. Appropriate changes could be made in the present data program based on this fact. A streamflow data program based on the guidelines developed in this study is proposed for the future.

South Carolina↗