A data porting tool for coupling models with different discretization needs

Abstract

The presented work is part of a larger research program dealing with developing tools for coupling biogeochemical models in contaminated landscapes. The specific objective of this article is to provide the researchers a tool to build hexagonal raster using information from a rectangular raster data (e.g. GIS format), data porting. This tool involves a computational algorithm and an open source software (written in C). The method of extending the reticulated functions defined on 2D networks is an essential key of this algorithm and can also be used for other purposes than data porting. The algorithm allows one to build the hexagonal raster with a cell size independent from the geometry of the rectangular raster. The extended function is a bicubic spline which can exactly reconstruct polynomials up to degree three in each variable. We validate the method by analyzing errors in some theoretical case studies followed by other studies with real terrain elevation data. We also introduce and briefly present an iterative water routing method and use it for validation on a case with concrete terrain data.

A Shallow Water Model for Water Flow on Vegetated Hillslope

“…However, to be closer to reality, we have used GIS data for the soil surface of Paul's Valley and accomplished a theoretical experiment: starting with a uniform water depth on the entire basin and using different cover plant densities, we run the 2D version of our scheme (a flow modulus of ASTERIX) on a hexagonal network. To generate an arbitrary hexagonal network from an arbitrary raster GIS data, we use the method introduced in [26]. Figure 11 shows that the numerical results are consistent with direct observations concerning the water time residence in the hydrographic basin.…”

“…A very special class of models are cellular automata which combine microscale physical laws with empirical closure relations in a specific way to build up a macroscale model, e.g. CAESAR [8,24]. In this paper, we introduce a model that extends the shallow water equations and takes into account the presence of vegetation on the soil surface.…”

A Shallow Water Model for Hydrodynamic Processes on Vegetated Hillslope. Water Flow Modulus

“…Unfortunately, we do not have data for the water distribution, plant cover density and measured velocity field in a hydrographic basin to compare our numerical results with. However, to be closer to reality, we have used GIS data for the soil surface of Paul's Valley and accomplished a theoretical experiment: starting with a uniform water depth on the entire basin and using different cover plant densities, we run our model, ASTERIX based on a hexagonal cellular automaton [10]. Figure 2 shows that the numerical results are consistent with direct observations concerning the water time residence in the hydrographic basin.…”

“…The next step is to define the approximations of the boundary integrals in (11). We approximate an integral ψ| ∂ ω(i, j) of the form (10) by considering the integrand ψ to be a constant function ψ (i, j) (ψ i , ψ j ), where ψ i and ψ j are some fixed values of ψ on the adjacent cells ω i and ω j , respectively. Thus,…”

“…Figure 2 shows that the numerical results are consistent with direct observations concerning the water time residence in the hydrographic basin. Figure 3 shows the results for the water content in Paul's Valley basin obtained with our models ASTERIX and CAESAR-Lisflood-OSE [10,9]. This variable q is in fact the relative amount of water in the basin at the moment of time t:…”