The Impact of Climate Change on Metal Transport in a Lowland Catchment

Abstract

This study investigates the impact of future climate change on heavy metal (i.e., Cd and Zn) transport from soils to surface waters in a contaminated lowland catchment. The WALRUS hydrological model is employed in a semi-distributed manner to simulate current and future hydrological fluxes in the Dommel catchment in the Netherlands. The model is forced with climate change projections and the simulated fluxes are used as input to a metal transport model that simulates heavy metal concentrations and loads in quickflow and baseflow pathways. Metal transport is simulated under baseline climate ("2000-2010") and future climate ("2090-2099") conditions including scenarios for no climate change and climate change. The outcomes show an increase in Cd and Zn loads and the mean flux-weighted Cd and Zn concentrations in the discharged runoff, which is attributed to breakthrough of heavy metals from the soil system. Due to climate change, runoff enhances and leaching is accelerated, resulting in enhanced Cd and Zn loads. Mean flux-weighted concentrations in the discharged runoff increase during early summer and decrease during late summer and early autumn under the most extreme scenario of climate change. The results of this study provide improved understanding on the processes responsible for future changes in heavy metal contamination in lowland catchments.

Keywords: Baseflow; Climate change; Lowland catchment; Metal transport; Modeling; Quickflow.

Fig. 1

Study area Dommel catchment and the geological profile along the dotted line (A–A′). M1–M10 represents the measurement locations where Cd and Zn locations have been measured. G1–G6 represents the discharge gauging stations. ZW Zuid-Willemsvaart canal, WH Wilhelmina canal, BE Beatrix canal, EH Eindhoven canal. Sources: REGIS VII.1 (Vernes et al. 2005); VHA (AGIV 2014a); TOP10NL (Kadaster 2015)

Fig. 2

Daily observed versus simulated discharge for the period 2001–2010 at the Bossche Broek gauging station

Fig. 3

Mean contribution of Cd and Zn loads in quick- and baseflow to the total area-specific Cd and Zn loads in the quickflow dominated area (a, b) and the baseflow-dominated area (c, d). T total area-specific loads, Q contribution of loads in quickflow, B contribution of loads in baseflow

Fig. 4

Projected mean area-specific Cd and Zn loads for baseline (a, b), NoCC (c, d), and WH (e, f) climate conditions (μg m⁻² day⁻¹)

Fig. 5

Projected monthly-averaged hydrological fluxes under current and future climate conditions in a the quickflow-dominated area and b the baseflow-dominated area. 1–12 = January–December. Q discharge, fQS quickflow, fGS baseflow, GH G_H, WH W_H

Fig. 6

Projected monthly-averaged flux-weighted Cd (a) and Zn (b) concentrations in the discharged runoff at the outlet of the catchment. 1–12 = January–December