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

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.