Changes from the original module are written in bold text
This module requires the use of the module divrt_apply.prms.f that reads in the diversion and return data, which includes quantities and timing. This module reads in (inputs) the nodes to which diversions are subtracted and returns are added.
New dimensions of ndiv (number of diversions), and nretrn (number of returns) need to be added. Add MAXDIV for ndiv, and MAXRETRN for nretrn in /modules/setdims/setdims.f and /modules/include/fmodules.inc.
Muskingum routing of stream channel flows at a daily time step.
This module routes flows accumulated at user-defined nodes to downstream nodes.
The index of the downstream node. Each node has a node to which it passes water.
Node index for HRU surface runoff. Each HRU has a node to which surface runoff will go.
Node index for each diversion. Each diversion is subtracted from the accumulated flow at a node. Order of each diversion read in from divrt_apply.prms.f is the same as this order.
Node index for each return flow. Each return is added to the accumulated flow at a node. Order of each return read in from divrt_apply.prms.f is the same as this order.
Node index for subsurface reservoirs. Each subsurface reservoir has a node to which subsurface flow will go.
Node index for ground-water reservoirs. With standard PRMS modules, each ground-water reservoir has a node to which ground water will go . If module gwflow_prms_min_darcy.f (which moves ground water laterally from upslope to downslope reservoirs) is used, then only selected ground-water reservoirs would have an associated node (gw_node). In this case, gw_node = 0 for all other grournd-water reservoirs.
Index of the final node in the system. Every routing network has a final node that represents the mouth of the system.
Storage coefficient, in hours. Approximate travel time of a flood wave to the next node.
Routing weighting factor, from 0 to 0.5. It expresses the amount of attenuation of the flood wave.
Type of node: 0 = link; 1 = reservoir; 2 = diversion
Predicted flow at selected nodes, in cubic feet per second.
Predicted outflow at selected nodes, in cubic feet per second.
Order of computation for a particular node.
The daily diversion quantity for a node, in cubic feet per second. [divapp].
The daily return flow quantity for a node, in cubic feet per second. [divapp].
Area of each ground-water reservoir, in acres. [gwflow]
Subsurface reservoir area, in acres. [ssflow]
This module routes flows between user-defined nodes in a stream network using the Muskingum routing equation (Linsley and others, 1982, p. 275). This module is based on the fixroute module created by Tom Ryan of the U.S. Bureau of Reclamation (written communication, May 1998) that used a fixed routing time between nodes. The route_time parameter in the fixroute module was replaced with two new parameters, K_coef and x_coef , of the Muskingum routing equation.
The Muskingum routing equation assumes a linear relation of storage to the inflow and outflow characteristics. The Muskingum method is based on the equation
S is storage, in units of volume for a specific reach,
K is the storage coefficient (K_coef) , in hours,
x is a coefficient between 0 and 0.5 (x_coef) ,
I is inflow, and O is outflow, both in units of discharge.
Storage-routing equations are often based on the assumption that the average flow during a routing period, t, is equal to the average flow at the start and end times, t 1 and t 2 , of the routing period. The continuity equation can be expressed as:
[((I 1 + I 2 ) / 2) * t] - [((O 1 + O 2 )/ 2) * t] = S 2 - S 1 .
Outflow on day 2, O 2 , can be solved by substituting equation 1 for S in equation 2, and knowing the inflow at day 1, I 1 ; the inflow at day 2, I 2 ; and the outflow at day 1, O 1 . The storage equation, equation 2, can be written as:
c 2 = (K - Kx - 12) / (K - Kx + 12),
assuming a time step of one day; K is in units of hours. In the musroute module, c 0 , c 1 and c 2 are solved in the initialization function within MMS.
The three c constants are constrained to add numerical stability to the equation. If c 2 is less than or equal to zero because of a short travel time within a reach (less than daily), then c 1 = c 1 + c 2 and c 2 = 0.0. If c 0 is less than or equal to 0.0 because of a long travel time within a reach (more than daily), then c 1 = c 1 + c 0 and c 0 = 0.0.
After the flow is accumulated at a node, diversions are subtracted and return flows are added. The nodes are specified with div_node and retrn_node with associated quantities of diversion and return. If the amount of diversion is greater than the water available at the diversion node, the diversion is reduced to the water available, the flow from the diversion node is set to zero, a line of text is written to a file in the output directory with a file name the same as the specified dimension index name for the ndiv dimension, and a warning line of text is printed to the screen.
Linsley, R.K., Kohler, M.A., and Paulhus, J.L., 1982, Hydrology for engineers: New York, McGraw-Hill, p. 508.
URL for this page is http://pubsdata.usgs.gov/pubs/of/2002/ofr02362/htdocs/musroute-div/musroute_prms_divretrn.htm
Page contact: Mark Mastin (mcmastin@usgs.gov),
253-428-3600, ext. 2609
Last modified: Friday, 11-Jan-2013 03:19:49 EST
