title: The principle of 'maximum energy dissipation': a novel thermodynamic perspective on rapid water flow in connected soil structures.
abstract: Preferential flow in biological soil structures is of key importance for infiltration and soil water flow at a range of scales. In the present study, we treat soil water flow as a dissipative process in an open non-equilibrium thermodynamic system, to better understand this key process. We define the chemical potential and Helmholtz free energy based on soil physical quantities, parametrize a physically based hydrological model based on field data and simulate the evolution of Helmholtz free energy in a cohesive soil with different populations of worm burrows for a range of rainfall scenarios. The simulations suggest that flow in connected worm burrows allows a more efficient redistribution of water within the soil, which implies a more efficient dissipation of free energy/higher production of entropy. There is additional evidence that the spatial pattern of worm burrow density at the hillslope scale is a major control of energy dissipation. The pattern typically found in the study is more efficient in dissipating energy/producing entropy than other patterns. This is because upslope run-off accumulates and infiltrates via the worm burrows into the dry soil in the lower part of the hillslope, which results in an overall more efficient dissipation of free energy.
authors.affiliation: Institute of Water and Environment, Technische Universität München, Munich, Germany. e.zehe@bv.tum.de
authors.forename: Erwin
authors.initials: E
authors.lastname: Zehe
authors.forename: Theresa
authors.initials: T
authors.lastname: Blume
authors.forename: Günter
authors.initials: G
authors.lastname: Blöschl
mesh_terms: D000818:Animals; D003198:Computer Simulation; D017753:Ecosystem; D019277:Entropy; D005374:Filtration; D008962:Models, Theoretical; D009835:Oligochaeta; D012987:Soil; D013816:Thermodynamics; D014872:Water Movements
chemical_list: D012987:Soil