Root Distribution Parameters

The root spatial distribution can be specified using the Root Distribution Parameters dialog window. The following two- and three-dimensional root distribution functions are implemented in HYDRUS [Vrugt et al., 2001ab]:

where Xm, Ym, and Zm are the maximum rooting lengths in the x-, y-, and z- directions [L], respectively; x, y, and z are distances from the origin of the plant (tree) in the x-, y-, and z- directions [L], respectively; px [-], py [-], pz [-], x* [L], y* [L], and z* [L] are empirical parameters (x*, y*, and z* are in Fig. 36 indicated as Depth of Maximum Intensity or Radius of Maximum Intensity; parameters px, py, and pz are assumed to be equal to one for x> x*, y> y*, z> z*, respectively [Vrugt et al., 2002]), and b(x,z) and b(x,y,z) denote two- and three-dimensional spatial distribution of the potential root water uptake [-]. See Vrugt et al. [2001, 2002] for different configurations of the normalized spatial distribution of potential root water uptake rate.

The equations above are given and used in absolute coordinates, i.e., they are independent of any actual selection in GUI. The x and y coordinates are identical to x and y coordinates for the geometry of the transport domain. The only exception is that the beginning of the z coordinate for the root distribution starts at the highest located node of the entire transport domain (again independent of any actual selection).

This dialog is available only when Root Water Uptake is selected in the Main Processes window.