Principal component analysis of watershed hydrochemical response to forest clearance and its usefulness for chloride mass balance applications

Abstract

[1] Application of the simple watershed chloride mass balance (CMB) method over areas of historical forest clearance is highly uncertain because the CMB method requires a steady state assumption, while the beginning, duration, and end of the transient period between preclearance and postclearance steady states is unknown. To address this difficulty, principal component analysis (PCA) with groundwater chemistry data is explored for the Piccadilly Valley in the Mount Lofty Ranges in South Australia, incorporated with hydrological modeling. The results indicate that PCA provides a potentially useful tool to identify postclearance dynamic hydrochemical response. Processes during the postclearance transient period, such as the release of historical soil chloride together with the chargebalance cations, alter ionic ratios from a steady state condition, which make the hydrochemical signals from the transient processes distinguishable from other processes by PCA. For the studied watershed, the effect of postclearance transient processes accounts for 24% of major-ion data variance, in comparison to 43% resulting from the effects of precipitation diluting and evapotranspiration concentrating processes. The PC scores associated with the transient processes are shown to be useful for estimating the timing of the postclearance transient, and estimating chloride concentration of groundwater recharge at the preclearance and postclearance steady states, even under conditions where the new steady state has not yet reached or the preclearance hydrochemical signal is lost.

Determination of groundwater recharge mechanism in the deep loessial unsaturated zone by environmental tracers

“…to quantify the recharge rate from precipitation (Leaney et al, 2003;Scanlon et al, 2009). The second is the steady state of chloride concentration in soil water that corresponds only to precipitation input and is free of the impacts from fertilizer application and land use change (Guan et al, 2013;Peck and Hurle, 1973). This forms the basis of Equation 2 to quantify the recharge rate from piston flow in soil.…”

Modelling the effects of land cover and climate change on soil water partitioning in a boreal headwater catchment

“…Climate change and vegetation development are interlinked and often coevolve (Walther, 2010). Climate change impacts can be observed in the long term, for instance, from precipitation and runoff data (Serreze et al, 2000;Meng et al, 2016), whereas the impacts of land cover change can be expressed rapidly in runoff and water chemistry responses (Séguis et al, 2004;Guan et al, 2013). In some cases, climate change has been found to influence the hydrology of systems less dramatically than land use/land cover change (Schilling et al, 2010;Li et al, 2017), whilst others came to the opposite conclusion (Legesse et al, 2003;Liu et al, 2013).…”

Anodic Treatment of Ni-Cu Alloy in a Deep Eutectic Solvent to Improve Electrocatalytic Activity in the Hydrogen Evolution Reaction

“…The principal component analysis is a multivariate statistical tool used to analyze the variability of a dataset. Several studies have used PCA in surface and groundwater studies [23][24][25].…”