Regional geohydrologic‐geomorphic relationships for the estimation of low‐flow statistics

Abstract

Many investigators have sought to develop regional multivariate regression models which relate low-flow statistics to watershed characteristics. Normally, a multiplicative model structure is imposed and multivariate statistical procedures are employed to select suitable watershed characteristics and to estimate model parameters. Since such procedures have met with only limited success, we take a different approach. A simple conceptual stream-aquifer model is extended to a watershed scale and evaluated for its ability to approximate the low-flow behavior of 23 unregulated catchments in Massachusetts. The conceptual watershed model is then adapted to estimate low-flow statistics using multivariate regional regression procedures. Our results indicate that in central western Massachusetts, low-flow statistics are highly correlated with the product of watershed area, average basin slope and base flow recession constant, with the base flow recession constant acting as a surrogate for both basin hydraulic conductivity and drainable soil porosity. INTRODUCTION Estimates of low-flow statistics are needed in water quality management and water supply planning and for the determination of minimum downstream release requirements from hydropower, irrigation, water supply, cooling plant and other facilities. Water quality management applications of low-flow statistics include the determination of wasteload allocations, discharge permits, and the siting of treatment plants and sanitary landfills. Many investigations have attempted to develop regional hydrologic models for the purpose of estimating low-flow statistics at ungaged sites from readily available geomorphic, geologic, climatic and topographic parameters. For example, Thomas and Cervione [1970], Tasker [1972], Parker [1977], Dingman [1978], Male and Ogawa [1982], Cervione et al. [1982], Downer [1983], Fennessey and Vogel [1990], and Vogel and Kroll [!990] have developed regional low-flow models in the New England region. Usually such models take the form Qd, T bo J•b•Yb2Yb3 ' ' ' = 1 •2 •'•3 (1) where Qa, r is the d-day, T-year low-flow statistic obtained from gaged flow records, the Xi are measurable drainage basin characteristics and the b i are parameter estimates obtained from multivariate regression procedures. Such models are generally developed using long-term streamflow data and associated basin characteristics from many sites. Regional statistical models of this type, frequently referred to as "state equations," are used widely in the United States for estimating flood flow statistics at ungaged sites. Newton and Herrin [1983] recommend such statistically based regional regression equations over the use of deterministic watershed models for estimating flood flows at ungaged Copyright 1992 by the American Geophysical Union. Paper number 92WR01007. 0043-1397/92/92 WR-01007 $05.00 sites. Their recommendations are based upon a large nationwide comparison of alternative methods for estimating flood flows at ungaged sites developed by several federal agencies. Unfort...

Applicability Assessment of Estimation Methods for Baseflow Recession Constants in Small Forest Catchments

“…This suggests that the MS, CE, and CH methods are overestimating the baseflow recession constant in the study area. In general, the baseflow recession constant ranged from 0.75 to 0.95 [14,33]. The recession constants of CR, AR(1), and VK methods fell within this range, whereas the recession constants of MS, CE, and CH were larger.…”

“…In this study, the mean value of the recession constants calculated from the AR(1) model was set to represent the recession constant of one forest catchment. When the streamflow is linearly related to the basin storage, Vogel and Kroll [14] calculated the recession constant with model error additives in log space. The baseflow recession constant is determined using the least squares method as follows:…”

“…Also, during the dry periods, periods having at least eight consecutive days were selected as recession periods [6,7,14,15]. The point from two days after the time of peak flow occurrence was set as the point at which the direct runoff ends, given the findings of previous studies and the size of the catchment area.…”

“…Based on the hydraulic theory about recession characteristics, several analytical approaches have also been presented to derive the recession constants [6,13]. These methods are based on the least-square method, and several previous studies have proposed these methods to be a better tool for recession analysis [6,9,13,14].…”

Comparative analysis between analytical approximations and numerical solutions describing recession flow in unconfined hillslope aquifers

“…Under strong assumptions, he found that the outflow from an aquifer with a concave floor had the form Ce -αt , with C being an arbitrary value depending on the initial conditions and α (generally known as recession coefficient) a positive constant dependent of the geometric configuration of the aquifer and its hydraulic conductivity. During the years, exponential decay relationships of the same type Q ~ e -αt were derived by Maillet (1905), Horton (1933), Nathan and McMahon (1990), Vogel and Kroll (1992), Brutsaert (1994), Shevenell (1996), Long and Derickson (1999), among others. Different approximations have also been proposed considering inclined aquifer floor, as proposed by Boussinesq (see Eq.…”