Charles Kroll

Learn More
Models are needed that describe how topography and other watershed characteristics affect the chemical composition of runoff waters, yet little spatially distributed data exist to develop such models. A topographically driven flushing mechanism for nitrate (NO3 ) and dissolved organic carbon has been described in recent literature; however, this mechanism(More)
Although a vast amount of literature exists on the selection of an appropriate probubility distribution for annual maximum fluodflows, few studies huve examined which probability distributions ure most suitable to fit to sequences of annual minimum streamflow!;. Probabilily plots have been u!;ed widely in hydrology as a gruphicul uid to assess the goodnes!;(More)
Digital elevation models (DEMs) are representations of topography with inherent errors that constitute uncertainty. DEM data are often used in analyses without quantifying the effects of these errors. This paper describes a Monte Carlo methodology for evaluation of the effects of uncertainty on elevation and derived topographic parameters. Four methods for(More)
In most cases authors are permitted to post their version of the article (e.g. in Word or Tex form) to their personal website or institutional repository. Authors requiring further information regarding Elsevier's archiving and manuscript policies are encouraged to visit: Keywords: Hydroecology Ecohydrology Instream flow Ecodeficit Principal component(More)
Estimates of low streamflow statistics are required for a variety of water resource applications. At gauged river sites, the estimation of low streamflow statistics requires estimation of annual n-day minimum streamflows, selection of a probability distribution to describe annual minimums, and estimation of the distribution’s parameters. Using L-moment(More)
Generalized least squares (GLS) regional regression procedures have been developed for estimating river flow quantiles. A widely used GLS procedure employs a simplified model error structure and average covariances when constructing an approximate residual error covariance matrix. This paper compares that GLS estimator (b̂GLS MC ), an idealized GLS(More)
Conventional methods for estimating the average return period, E(T), and failure risk, R, generally ignore the impact of persistence in annual streamflows on associated probabilistic statements and streamflow statistics. Recent evaluations of streamflow observations indicate statistically significant serial correlations ~persistence! associated with annual(More)
[1] Estimators of low-streamflow statistics are often required for water quality and quantity management at gauged and ungauged sites. Here the technique of baseflow correlation is investigated as an estimator of the 7-day, 10-year low-streamflow statistic at ungauged sites. This method uses an information transfer technique to estimate streamflow(More)
[1] The base flow recession constant, Kb, is used to characterize the interaction of groundwater and surface water systems. Estimation of Kb is critical in many studies including rainfall-runoff modeling, estimation of low flow statistics at ungaged locations, and base flow separation methods. The performance of several estimators of Kb are compared,(More)