Time: 15:30-16:30, 26th October 2017
Venue: Lecture Hall (221), Building No.16,Weijin Campus, Tianjin University
Speaker: Associate Prof. Yonggen Zhang, Institute of Surface-Earth System Science, Tianjin University
Topic: Parameter Estimation for Heterogeneous Subsurface Unsaturated Flow Modeling
Abstract: Unsaturated zone (vadose zone) is an intrinsic part of the hydrologic cycle, regulating the transfer of terrestrial water, energy, and carbon. Modeling of unsaturated flow and transport processes requires the spatial distribution of the soil hydraulic properties. Direct measurement of hydraulic properties is very expensive, difficult, and time consuming, especially for deep unsaturated zones. Pedotransfer functions and/or inverse modeling are attractive alternatives to estimate soil hydraulic parameters. Rosetta is widely used in soil sciences and hydrology. We present an improved set of hierarchical new Rosetta model that unify the water retention and Ks submodels into one, which can provide covariance matrix for those soil hydraulic parameters. In addition, we evaluated current pedotransfer functions that are used in different disciplines of the earth system models, such as in land surface models, general circulation models, soil sciences and hydrology. Heterogeneity of porous media is considered to the most challenging work in subsurface hydrology. We proposed two methods of parameterizing unsaturated zone hydraulic properties using a combination of k-means clustering of kriged soil texture data, pedotransfer functions, and model inversion. These models are calibrated and validated by infiltration experiments of Maricopa site at Arizona.
