HydroGeoSphere/Channel Flow

Channel domains, can be set up using the following instructions, as outlined in Section 2.3.2.4 and in Equation 2.65. Default Channel Properties Unless the user modifies the default values, all channel zones in the domain will be assigned the default properties. The default values, Table 5.10, can be and are recommended to be modified to fit the model application. +Table 5.10Table 5.10: Default Values for Channel Properties Parameter Value Unit Shape Rectangle m Width 1 m Manning’s Friction Coefficient 0.0548 m−1/3 s River Bank Height 1 m Streambed Thickness 0.001 m Steambed Conductivity 1 × 10−4 m • • • Example Channel Flow Instructions As an example, the following set of instructions, with prefix.cprops file Figure 5.14, could be inserted into the prefix.grok file to produce a channel: use domain type channel properties file prefixl.cprops clear chosen segments choose segments polyline 2 0.0 10.0 20.0 100.0 10.0 10.0 new zone 1 clear chosen zones choose zone number 1 read properties channel one clear chosen nodes choose nodes all initial head surface elevation clear chosen nodes choose node 0.0 10.0 20.0 create node set inlet_node boundary condition type head name inlet_node_flux node set inlet_node time value table 0.0 20.0001 end end clear chosen nodes choose node 100.0 10.0 10.0 create node set outlet_node boundary condition type channel critical depth name cd_outlet_node node set outlet_node end clear chosen nodes choose nodes top block 0.0 99.5 9.0 11. 0.0 20. create node set internal_node boundary condition type flux nodal name internal_flux node set internal_node time value table 0.0 0.601818e-2 end end The channel domain example opens the property file prefix.cprops, shown in Figure 5.14, and creates a 1 m wide channel. The channel one properties are read into grok. Figure 5.14 !------------------------------------------ channel one type rectangle 1.0 friction 0.01 rill storage height 0.001 obstruction storage height 0.0 streambed thickness 0.3 streambed conductivity 1.0e-4 bank height 1.0 end Figure 5.14: Sample channel domain property file prefix.cprops • • • Dual nodes for channel flow Scope: .grok This instruction causes the channel flow scheme to use dual node approach. • • • Type rectangle Scope: .grok .cprops ChanWidth Channel Width [L]. The width of the rectangular channel. • • • Type trapezoid Scope: .grok .cprops ChanWidth Channel Width [L]. ChanTrapBankAngle Channel Bank Angle [degree]. The width of the bottom of the trapezoidal channel and the angle of the bank from the vertical line. • • • Type circle Scope: .grok .cprops ChanRadius Channel Radius [L]. The radius of the circular channel. • • • Type general Scope: .grok .cprops nChanTab The number of water depth values in the table. i=1, nChanTab, ChanTabD, ChanTabAF, ChanTabWP, ChanTabTW Tables for water depth, area of flow, wetted perimeter, and top width. A tabular form of data can be used to specify the area of flow, wetted perimeter, and top width for given depth values. • • • Friction Scope: .grok .cprops ChanFrictn Manning friction for the channel. Manning friction coefficient for the zone chosen. • • • Rill storage height Scope: .grok .cprops ChanRillStor Channel rill storage height. A minimum water depth required for flow. • • • Obstruction storage height Scope: .grok .cprops ChanOnstructStor Channel obstruction storage height. Obstruction storage height. • • • Streambed thickness Scope: .grok .cprops ChanStrmBedThick Thickness of streambed. Streambed thickness that defines the coupling between channel and subsurface. • • • Streambed conductivity Scope: .grok .cprops ChanStrmBedK Hydraulic conductivity of streambed. Streambed hyarulic conductivity together with thickness to define the coupling conductance between channel and subsurface. • • • Bank height Scope: .grok .cprops ChanBankHeight Height of river bank. River bank height to define the interaction between the channel and overland flow domains. • • •