Marcel G. Schaap

Learn More
variables as input (e. In many vadose zone hydrological studies, it is imperative that the al., 1998). Far fewer alternatives exist for unsaturated soil's unsaturated hydraulic conductivity is known. Frequently, the Mualem–van Genuchten model (MVG) is used for this purpose be-hydraulic conductivity. Although some pedotransfer cause it allows prediction of(More)
[1] A Shan-Chen–type multiphase lattice Boltzmann (LB) model was applied to observed computed microtomography data from water-air and water-Soltrol displacement experiments in a glass bead porous medium. Analysis of the Bond, Reynolds, and Capillary numbers for these systems showed that capillary forces were dominant removing the need to model viscous,(More)
This study focuses on spatial variability of throughfall water and chemistry and forest floor water content within a Douglas fir (Pseudotsuga menziesii, Franco L.) forest plot. Spatial patterns of water and chemistry (NH 4 + , NO 3-, SO 4 2-, Cl-, Mg 2+ , Ca 2+ , Na + and K +) were compared and tested for stability over time. The spatial coefficient of(More)
[1] While pedotransfer functions (PTFs) have long been applied to estimate soil hydraulic parameters for unsaturated flow and solute transport modeling, the uncertainty associated with the estimates is often ignored. The objective of this study is to evaluate uncertainty of the PTF-estimated soil hydraulic parameters and its effect on numerical simulation(More)
[1] Feedbacks among vegetation dynamics, pedogenesis, and topographic development affect the " critical zone " —the living filter for Earth's hydrologic, biogeochemical, and rock/ sediment cycles. Assessing the importance of such feedbacks, which may be particularly pronounced in water-limited systems, remains a fundamental interdisciplinary challenge. The(More)
The structure of the critical zone (CZ) is a result of tectonic, lithogenic, and climatic forcings that shape the landscape across geologic time scales. The CZ structure can be probed to measure contemporary rates of regolith production and hillslope evolution, and its fluids and solids can be sampled to determine how structure affects CZ function as a(More)
  • Navin K C Twarakavi, Jirka S ˇ Imůnek, M G Schaap
  • 2009
[1] In the past, texture-based classification of soils has been used for grouping soils in variably saturated water flow and solute transport studies. Classification of soils becomes especially important for large-scale studies where the spatial and temporal variability in the hydraulic properties of soils exceeds the field sampling capabilities. Although(More)
Introduction The study of geomorphic systems—the analysis of the processes that shape the Earth's surface and their associated landforms—has been dominated by field research endeavors (Bennett et al., 2015). This field tradition of geomorphic research can be traced back to the world's early explorers, which provided the impetus for physiographic mapping and(More)
Several of us in the department were pleased to learn that our SWES-led Critical Zone Observatory project received renewed funding of $1 million per year for five years from the National Science Foundation starting October 1, 2013. This project, first funded in 2009, brings together faculty, staff and students not only within SWES, but across the UA's(More)