Multivariate Analysis to Assess Hydromorphic Response of Groundwater and Surface Water Systems.
dissertation consists of three chapters under the unifying theme of understanding human
impacts to groundwater-surface water systems. The overall objective of this research was
to illustrate how human impacts including urban storm water regulation and groundwater
withdrawals have altered groundwater and surface water interaction. In Chapter 1, the
behavior of groundwater elevat... read moreions in Boston is investigated to address the impact of
storm water recharge best management practices. Results illustrate that recharge
practices in Boston have resulted in a very small yet statistically significant increase
in groundwater elevations in Back Bay. Further, hybrid multivariate regression model
developed for the study are used to illustrate future storm water planning scenarios.
Chapters 2 and 3 explore the effect of human withdrawals in the characterization of
groundwater-surface water (gw-sw) behaviors using baseflow recession analysis. Baseflow
recession analysis generally falls into two categories: 1) a nonlinear (n≠1) or
2) a linear (n=1) relationship between baseflow (Q) and groundwater storage (S) assuming
a power low relationship given by Q=αSn. In Chapter 2, the difficulty in baseflow
recession analysis is investigated using traditional estimation procedures which require
no a priori assumption of the linearity of the gw-sw behaviors. Multiple factors
including a rigorous approach to fitting the lower envelope within the recession plot,
estimation of the time derivative of streamflow and including human water use into
baseflow recession are presented. Results illustrate highly variable estimates of the
baseflow recession parameters due to the estimation scheme employed; further, hypothesis
testing to test the ability to assess if watersheds do, in fact, behave linearly found
that few sites which exhibited linear behavior across all seasonal experiments
performed. In Chapter 3, linear behaviors are assumed to illustrate the effect of
including human withdrawals in estimation of baseflow parameters, which for the linear
assumption is termed the baseflow recession constant. The performance of traditional
estimators is compared to newly derived estimators; our results suggest that traditional
semi-log estimation approaches adapted to include withdrawal terms are preferred.
Further, analysis of variance methods are developed to identify factors which give rise
to variability in estimates of the baseflow recession constant. Among the factors
considered, both drainage density and human withdrawals were found to have significant
and similar explanatory power for the baseflow recession constant. Thus, results
document the importance of incorporating human withdrawals into models of the baseflow
response of a watershed. Chapter 1 has been published in the Journal of Hydrologic
Engineering (Thomas, B.F. and R.M. Vogel, Impact of storm water recharge practices on
Boston groundwater elevations, Journal of Hydrologic Engineering, 17(8), DOI:
Thesis (Ph.D.)--Tufts University, 2012.
Submitted to the Dept. of Civil Engineering.
Advisor: Richard Vogel.
Keywords: Civil engineering, Water resources management, and Hydrologic sciences.read less