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G. R. Martin

Publications and source records attributed to G. R. Martin.

7 recordsLinked to original sources
USGS2002

Estimating mean annual streamflow of rural streams in Kentucky

Mean annual streamflow ( Q a ), defined as the mean of the series of annual mean streamflow values, was determined for selected rural stream sites in Kentucky. Streamflow data for the available period of record through the 1999 water year (October 1, 1998-September 30, 1999) at 235 continuous-record streamflow-gaging stations with at least 5 years of record located in and adjacent to Kentucky were used in the analysis. Record-extension procedures were applied for selected gaging stations to reduce time-sampling error and, thus, improve estimates of the long-term Q a . Techniques to estimate the Q a at ungaged stream sites in Kentucky were developed. One-, two-, and three-variable regression equations that included total drainage area, station latitude minus 36 degrees, and mean basin elevation as explanatory variables were developed by use of ordinary- and generalized-least-squares regression. The three-variable regression equation has an approximate average standard error of prediction of 13.7 percent. The one- and two-variable equations exhibit geographical biases, and the indicated standard errors of prediction may poorly estimate the true prediction errors, depending upon the location in the State. Therefore, the three-variable equation should be used for estimating mean annual streamflow of rural streams in Kentucky whenever possible.

Water-Resources Investigations Report↗
USGS2000

New site coefficients and site classification system used in recent building seismic code provisions

Recent code provisions for buildings and other structures (1994 and 1997 NEHRP Provisions, 1997 UBC ) have adopted new site amplification factors and a new procedure for site classification. Two amplitude-dependent site amplification factors are specified: F a for short periods and F v for longer periods. Previous codes included only a long period factor S and did not provide for a short period amplification factor. The new site classification system is based on definitions of five site classes in terms of a representative average shear wave velocity to a depth of 30 m (V¯ s ). This definition permits sites to be classified unambiguously. When the shear wave velocity is not available, other soil properties such as standard penetration resistance or undrained shear strength can be used. The new site classes denoted by letters A - E, replace site classes in previous codes denoted by S1 - S4. Site classes A and B correspond to hard rock and rock, Site Class C corresponds to soft rock and very stiff / very dense soil, and Site Classes D and E correspond to stiff soil and soft soil. A sixth site class, F, is defined for soils requiring site-specific evaluations. Both F a and F v are functions of the site class, and also of the level of seismic hazard on rock, defined by parameters such as A a and A v ( 1994 NEHRP Provisions ), S s and S l ( 1997 NEHRP Provisions ) or Z ( 1997 UBC ). The values of F a and F v decrease as the seismic hazard on rock increases due to soil nonlinearity. The greatest impact of the new factors F a and F v as compared with the old S factors occurs in areas of low-to-medium seismic hazard. This paper summarizes the new site provisions, explains the basis for them, and discusses ongoing studies of site amplification in recent earthquakes that may influence future code developments.

Earthquake Spectra↗
USGS1995

Flow duration of Kentucky streams through 1990; historical and monthly flow characteristics, including the effects of reservoirs

This report presents flow-duration tables and plots for selected streamflow sites in Kentucky with three or more years of continuous record through 1990. Flow duration describes the frequency with which given streamflows are equalled or exceeded. The flow-duration tables were computed using daily mean discharge values for the entire period specified and for each month of the period specified. Only complete years of record were used for the computation. For sites where the streamflow is affected by regulation, separate tables are presented for the period before regulation (unregulated), the period of record after regulation (regulated) and the entire period of record (historical). Flow-duration plots are also presented for each station using the data for the entire period specified. Where practicable, several flow-duration plots are shown together. This includes stations on the same stream, such as main-stem stations, and stations within the same watershed. For stations affected by regulation, which have up to three sets of data available for one station (unregulated, regulated, and historical), the three plots are shown together to clearly illustrate the influence of regulation in augmenting low flows and reducing high flows.

Open-File Report↗
USGS1994

Surface-water-quality assessment of the Kentucky River Basin, Kentucky: Fixed-station network and selected water-quality data, April 1987 through August 1991

This report describes selected data-collection activities and the associated data collected during the Kentucky River Basin pilot study of the U.S. Geological Survey's National Water-Quality Assessment Program. The data are intended to provide a nationally consistent description and improved understanding of current water quality in the basin. The data were collected at seven fixed stations that represent stream cross sections where constituent transport and water-quality trends can be evaluated. The report includes descriptions of (1) the basin; (2) the design of the fixed-station network; (3) the fixed-station sites; (4) the physical and chemical measurements; (5) the methods of sample collection, processing, and analysis; and (6) the quality-assurance and quality-control procedures. Water-quality data collected at the fixed stations during routine periodic sampling and supplemental high-flow sampling from April 1987 to August 1991 are presented.

Kentucky↗
USGS1992

A comparison of surface-grab and cross sectionally integrated stream-water-quality sampling methods

Stream sampling for water quality data has commonly employed simple surface-grab procedures as opposed to more involved, cross sectionally integrated techniques. Paired samples for analysis of selected constituents were collected over various flow conditions at four sites to evaluate differences between the two sampling methods. Concentrations of dissolved constituents were not consistently different. However, concentrations of suspended sediment and the total forms of some sediment-associated constituents, such as phosphorus, iron, and manganese, were significantly lower in the surface-grab samples than in the cross sectionally integrated samples. The largest median percent difference in concentration for a site was 60% (total recoverable manganese). Median percent differences in concentration for sediment-associated constituents considering all sites grouped were in the range of 20-25%. The surface-grab samples underrepresented concentrations of suspended sediment and some sediment-associated constituents, thus limiting the applicability of such data for certain purposes. An association was also demonstrated between site streamflow characteristics and the observed differences.

Water Environment Research↗
USGS1991

Low-flow characteristics of Kentucky streams

Low-flow characteristics were determined for 136 continuous-record and 212 low-flow partial-record streamflow gaging stations in Kentucky. Low-flow frequency curves were developed for the continuous-record gaging stations from daily mean streamflows for unregulated periods of 10 years or more. Through graphical correlation with data from one or more of the continuous-record stations, estimates of selected low-flow frequency values were also made at each of the partial-record stations. Techniques are presented to estimate the 7-day 2-year and 7-day 10-year low-flow frequency values for ungaged, unregulated streams in Kentucky. These frequency values were determined at each of the continuous-record gaging stations and were related to basin characteristics and streamflow indices using multiple linear regression. The most significant variables for estimating the 7-day 2-and 10-year low-flow values from the analysis were drainage area and streamflow-variability index. The equations developed to estimate the 7-day 2-year and the 7-day 10-year low flows have a standard error of estimate of 71 and 90 percent, respectively.

Water-Resources Investigations Report↗