December 16, 2020: PhD public defense – Antoine Di Ciacca – Spatially distributed recharge and groundwater – surface water interactions in groundwater models - KULeuven

Name: Antoine Di Ciacca

Date: December 16, 2020

This is an online event streamed from the Kasteel Arenberg auditorium, Leuven.

Spatially distributed recharge and groundwater – surface water interactions in groundwater models: from the field to the catchment scale

Groundwater flow and solute transport in temperate lowland areas are strongly influenced by groundwater recharge and interactions with surface water (rivers and ditches). Groundwater recharge refers here to the fraction of precipitation that infiltrates through the soil and vegetation to reach the groundwater table. In temperate lowland areas, groundwater is generally shallow, which complicates the processes involved in groundwater recharge. Furthermore, some plants, called phreatophytes, can extract water directly from the groundwater, which may lead to groundwater discharge.

This thesis presents an attempt to improve the representation of groundwater recharge and groundwater interactions with surface water in catchment scale (100–1000 km²) groundwater models. The general approach used in this work is a bottom-up upscaling: processes are first studied at the field scale (~1–1000 m²) and then the acquired knowledge is applied at the catchment scale. First, this thesis introduces a new formula to calculate the water exchange between groundwater and surface water in groundwater models. Second, a modeling study of a plot covered by grass and phreatophyte trees is presented. Third, we tested different approaches to simulate groundwater recharge and interactions with surface water in a groundwater model of the Kleine Nete catchment (northeastern Belgium). These approaches included our new formula derived in the second chapter, the phreatophytes trees conceptualization used in the third chapter, as well as a recent method to account for shallow groundwater and a new way to represent small-scale variability of vegetation, soil and elevation in groundwater recharge calculations.

The results of this research highlight the relevance of using our new formula to simulate water exchange between groundwater and surface water. Moreover, we showed that the shallow groundwater tables need to be accounted for to simulate groundwater recharge in lowland temperate environments.

Promotor:

  • Jan Vanderborght (KULeuven)

SCK CEN mentors:
  • Bertrand Leterme (SCK CEN)

Click here for a list of obtained PhD degrees.