Quoted from: Zhang, Ziya, Douglas L. Kane, and Larry D. Hinzman. "Development and application of a spatially‐distributed Arctic hydrological and thermal process model (ARHYTHM)." Hydrological Processes 14, no. 6 (2000): 1017-1044. https://doi.org/10.1002/(SICI)1099-1085(20000430)14:6%3C1017::AID-HYP982%3E3.0.CO;2-G
This model is comprised of two parts, one that simulates the drainage of the basin and one that simulateshydrological processes. Initially the drainage simulation is run once and does not change for a basin, whereasthe process simulations change as the initial co nditions and state variables change and/or the parameterschange.
Topographic delineation of a watershed
Hydrological response of a watershed is in¯uenced by many interacting factors, primary among which is topography. There are many articles that discuss the effect of topography on some aspect s of hydrological processes (Beven and Wood, 1983; Palacios and Cuevas, 1986; Silfer et al., 1987; Gary and Sen, 1994; Wolock and Price, 1994). The watershed topography serves as an important factor in determining the streamflow response of a basin to precipitation because it controls the movement of water within the basin. It also affects the spatial distribution within the watershed of ¯uxes such as surface and subsurface water, sediment, and dissolved chemicals. It is essential to correctly depict slope, aspect and drainage characteristics of a watershed for use in spatially distributed models.
Basic unit/element of the watershed. Generally, terrain surfaces may be represented by a series of discrete points, which are characterized by x, y, and z coordinates. Triangular and rectangular elements are often used as the basic uniform areas for mass and energy balances when conducting hydrological modelling (Silfer et al., 1987; James and Kim, 1990; Jones et al., 1990; Paniconi and Wood, 1993; Gary and Sen, 1994). Node-based models are also used (Wigmosta et al., 1994). In our model, similar to the work by Silfer et al.(1987), a triangular element scheme (Figure 1a) is used to represent the watershed. Utilization of triangle elements has certain advantages over other types of elements (Jones et al., 1990). Triangle elements conform more nearly to the three-dimensional geometry of an irregular watershed. It is more efficient to calculate the waterflow directions using triangu lar elements, as opposed to rectangular elements, because it is possible to®t a plane through the three points of the triangle whereas a rectangle must be ®t with a non-planar surface. Having created a basic unit area, we can calculate flow area, slope, drainage networks, ridges, drainage area and other related information needed when conducting physical simulations. It should be noted that the elements can be based upon a regularly or irregularly spaced grid.