The first data group consists of nine records that define parameters to control the simulation.

Title of simulation

TITLE - The title is specified as any combination of letters, symbols, or numbers of up to 80 characters in length. It will be printed in the output file for identification purposes but otherwise is not used. The remaining lines of the general information are read as formatted input so it is important that the numbers be placed in columns 21 to 30.

Number of branches

NBRCH and NJNCT - The number of branches is self evident and only the number of interior junctions, not total junctions, is input as the third record. An interior junction is one that connects two or more branches.

Number of interior junctions

NBRCH and NJNCT - The number of branches is self evident and only the number of interior junctions, not total junctions, is input as the third record. An interior junction is one that connects two or more branches.

Number of time steps to be modeled

NHR - The number of time steps in the simulation is calculated as the duration of the simulation divided by the SW time-step size, expressed in hours.

Number of time steps between midnight and the start of the simulation

JTS The time reference for the simulation is midnight of the first day of the simulation. This is specified to the model as the number of time steps from midnight to the start of the simulation. For example, if the simulation is to begin at 06:00 hours and the time-step size is 0.5 hours, the value specified for JTS is 6 divided by 0.5, which equals 12 time steps.

Number of time steps between printouts in FLOW.OUT

JGO The printout frequency is specified in terms of the number of time steps between printouts. For example, if tabular flow information is desired every 3 hours and the time-step size is 0.5 hours, the value of JGO is specified as 3 divided by 0.5, which equals 6 time steps.

Input units [0 = metric (length unit is meters except for river miles), 1 = English (length unit is feet except river miles)]. Make IENG consistent with LENUNI.

IENG - The length units are specified as either 1 = English (ft) or 0 = metric (meter), except that the distance to node points (specified in data group 2) is input as either miles or kilometers.

Time-step size in hours

DT The time-step size is input in hours. DAFLOW uses an iterative solution scheme, such that its solutions must converge to a given tolerance.

Maximum discharge of interest (“peak discharge”), discharge below QP/100000.0 will be considered to be zero

QP - DAFLOW assumes that discharges (cubic feet or meter per second), differences in discharges, and water volumes divided by the time-step size, which are less than a tolerance, to be insignificant (nearly zero). The model calculates the tolerance from a given “peak” discharge divided by 100,000. This peak discharge should be larger than the maximum discharge expected during the simulation. It follows that the accuracy of the model results can be no better than this tolerance value. If the tolerance value is set too small, the program may not converge because the tolerance is smaller than the round-off error of flows carried in computer memory.

Data group two consists of two types of records: (1) branch record, (2) node/subreach records.

Number of nodes (cross sections) in branch N

NXSEC, PF,  JNCU, and  JNCD - The branch record specifies the number of nodes (cross sections) in the branch, the fraction of flow at the upstream junction that enters the branch, and the upstream and downstream junction numbers. When more than one branch originates at a junction, the water that enters the junction is split between these outgoing branches. This is specified to the model as the fraction of flow to enter the branch. For example, if two branches receive equal amounts of flow from the junction, this value should be specified as 0.5 for each branch. If only one branch receives flow from a junction (the most common case), this value is specified as 1.0.

Fraction of flow at upstream junction to enter branch N

NXSEC, PF,  JNCU, and  JNCD - The branch record specifies the number of nodes (cross sections) in the branch, the fraction of flow at the upstream junction that enters the branch, and the upstream and downstream junction numbers. When more than one branch originates at a junction, the water that enters the junction is split between these outgoing branches. This is specified to the model as the fraction of flow to enter the branch. For example, if two branches receive equal amounts of flow from the junction, this value should be specified as 0.5 for each branch. If only one branch receives flow from a junction (the most common case), this value is specified as 1.0.

Junction number at upstream end of branch N

NXSEC, PF,  JNCU, and  JNCD - The branch record specifies the number of nodes (cross sections) in the branch, the fraction of flow at the upstream junction that enters the branch, and the upstream and downstream junction numbers. When more than one branch originates at a junction, the water that enters the junction is split between these outgoing branches. This is specified to the model as the fraction of flow to enter the branch. For example, if two branches receive equal amounts of flow from the junction, this value should be specified as 0.5 for each branch. If only one branch receives flow from a junction (the most common case), this value is specified as 1.0.

Junction number at downstream end of branch N

NXSEC, PF,  JNCU, and  JNCD - The branch record specifies the number of nodes (cross sections) in the branch, the fraction of flow at the upstream junction that enters the branch, and the upstream and downstream junction numbers. When more than one branch originates at a junction, the water that enters the junction is split between these outgoing branches. This is specified to the model as the fraction of flow to enter the branch. For example, if two branches receive equal amounts of flow from the junction, this value should be specified as 0.5 for each branch. If only one branch receives flow from a junction (the most common case), this value is specified as 1.0.

Header A header line follows the branch information to define the columns of data for the nodes or subreaches. The model ignores this line so it could be simply a blank line.

Node of data in record

I, X, IOUT, F, A1, A2, A0, SL, W1, and W2 - The node records define the node number, location of the node in miles or kilometers, an output flag, for each node and the initial flow, hydraulic-geometry parameters and slope for each subreach. The hydraulic-geometry exponents are independent of the system of units, but the hydraulic-geometry coefficients are dependent upon the units used. The number of node-records input must equal the number specified on the branch record. Node records are input in sequence starting with the node 1, at the upstream end of the branch. The node location is specified as the distance to the cross section from a reference point at or above the upstream end of the branch. The initial discharge, slope, and all coefficients apply to the subreach extending from the node for which it is specified to the next node downstream. For example, the value of A1 input for node 1 applies to the subreach extending from node 1 to node 2. Because there is no subreach downstream of the last node, only the river mile and output flag needs to be specified for the last node. The model is based on the assumption that tributaries enter the stream just upstream of the node. The initial discharge for subreach I, therefore, should include the effect of the tributary flow at node I. The output flag (IOUT) specifies whether or not the flow information for the node is to be printed in the output file. The data at each node is read as a free-field format, so it is not necessary to keep the numbers in any particular column or even to line them up. It is necessary that at least one blank space separate each number and that a number be available for each variable. Exponential formats (see slope) are acceptable. The formats shown in Table 1 are used if the file is created interactively using the program BDAFLOW (Jobson, 1989).

Distance of node I of branch N from reference point in miles

I, X, IOUT, F, A1, A2, A0, SL, W1, and W2 - The node records define the node number, location of the node in miles or kilometers, an output flag, for each node and the initial flow, hydraulic-geometry parameters and slope for each subreach. The hydraulic-geometry exponents are independent of the system of units, but the hydraulic-geometry coefficients are dependent upon the units used. The number of node-records input must equal the number specified on the branch record. Node records are input in sequence starting with the node 1, at the upstream end of the branch. The node location is specified as the distance to the cross section from a reference point at or above the upstream end of the branch. The initial discharge, slope, and all coefficients apply to the subreach extending from the node for which it is specified to the next node downstream. For example, the value of A1 input for node 1 applies to the subreach extending from node 1 to node 2. Because there is no subreach downstream of the last node, only the river mile and output flag needs to be specified for the last node. The model is based on the assumption that tributaries enter the stream just upstream of the node. The initial discharge for subreach I, therefore, should include the effect of the tributary flow at node I. The output flag (IOUT) specifies whether or not the flow information for the node is to be printed in the output file. The data at each node is read as a free-field format, so it is not necessary to keep the numbers in any particular column or even to line them up. It is necessary that at least one blank space separate each number and that a number be available for each variable. Exponential formats (see slope) are acceptable. The formats shown in Table 1 are used if the file is created interactively using the program BDAFLOW (Jobson, 1989).

Output flag (equal 1 if output in BLTM.OUT is desired for this node, 0 otherwise)

I, X, IOUT, F, A1, A2, A0, SL, W1, and W2 - The node records define the node number, location of the node in miles or kilometers, an output flag, for each node and the initial flow, hydraulic-geometry parameters and slope for each subreach. The hydraulic-geometry exponents are independent of the system of units, but the hydraulic-geometry coefficients are dependent upon the units used. The number of node-records input must equal the number specified on the branch record. Node records are input in sequence starting with the node 1, at the upstream end of the branch. The node location is specified as the distance to the cross section from a reference point at or above the upstream end of the branch. The initial discharge, slope, and all coefficients apply to the subreach extending from the node for which it is specified to the next node downstream. For example, the value of A1 input for node 1 applies to the subreach extending from node 1 to node 2. Because there is no subreach downstream of the last node, only the river mile and output flag needs to be specified for the last node. The model is based on the assumption that tributaries enter the stream just upstream of the node. The initial discharge for subreach I, therefore, should include the effect of the tributary flow at node I. The output flag (IOUT) specifies whether or not the flow information for the node is to be printed in the output file. The data at each node is read as a free-field format, so it is not necessary to keep the numbers in any particular column or even to line them up. It is necessary that at least one blank space separate each number and that a number be available for each variable. Exponential formats (see slope) are acceptable. The formats shown in Table 1 are used if the file is created interactively using the program BDAFLOW (Jobson, 1989).

Initial flow in subreach I (between node I and I+1)

I, X, IOUT, F, A1, A2, A0, SL, W1, and W2 - The node records define the node number, location of the node in miles or kilometers, an output flag, for each node and the initial flow, hydraulic-geometry parameters and slope for each subreach. The hydraulic-geometry exponents are independent of the system of units, but the hydraulic-geometry coefficients are dependent upon the units used. The number of node-records input must equal the number specified on the branch record. Node records are input in sequence starting with the node 1, at the upstream end of the branch. The node location is specified as the distance to the cross section from a reference point at or above the upstream end of the branch. The initial discharge, slope, and all coefficients apply to the subreach extending from the node for which it is specified to the next node downstream. For example, the value of A1 input for node 1 applies to the subreach extending from node 1 to node 2. Because there is no subreach downstream of the last node, only the river mile and output flag needs to be specified for the last node. The model is based on the assumption that tributaries enter the stream just upstream of the node. The initial discharge for subreach I, therefore, should include the effect of the tributary flow at node I. The output flag (IOUT) specifies whether or not the flow information for the node is to be printed in the output file. The data at each node is read as a free-field format, so it is not necessary to keep the numbers in any particular column or even to line them up. It is necessary that at least one blank space separate each number and that a number be available for each variable. Exponential formats (see slope) are acceptable. The formats shown in Table 1 are used if the file is created interactively using the program BDAFLOW (Jobson, 1989).

Constant A1 in equation 3 for subreach I

I, X, IOUT, F, A1, A2, A0, SL, W1, and W2 - The node records define the node number, location of the node in miles or kilometers, an output flag, for each node and the initial flow, hydraulic-geometry parameters and slope for each subreach. The hydraulic-geometry exponents are independent of the system of units, but the hydraulic-geometry coefficients are dependent upon the units used. The number of node-records input must equal the number specified on the branch record. Node records are input in sequence starting with the node 1, at the upstream end of the branch. The node location is specified as the distance to the cross section from a reference point at or above the upstream end of the branch. The initial discharge, slope, and all coefficients apply to the subreach extending from the node for which it is specified to the next node downstream. For example, the value of A1 input for node 1 applies to the subreach extending from node 1 to node 2. Because there is no subreach downstream of the last node, only the river mile and output flag needs to be specified for the last node. The model is based on the assumption that tributaries enter the stream just upstream of the node. The initial discharge for subreach I, therefore, should include the effect of the tributary flow at node I. The output flag (IOUT) specifies whether or not the flow information for the node is to be printed in the output file. The data at each node is read as a free-field format, so it is not necessary to keep the numbers in any particular column or even to line them up. It is necessary that at least one blank space separate each number and that a number be available for each variable. Exponential formats (see slope) are acceptable. The formats shown in Table 1 are used if the file is created interactively using the program BDAFLOW (Jobson, 1989).

Constant A2 in equation 3 for subreach I

I, X, IOUT, F, A1, A2, A0, SL, W1, and W2 - The node records define the node number, location of the node in miles or kilometers, an output flag, for each node and the initial flow, hydraulic-geometry parameters and slope for each subreach. The hydraulic-geometry exponents are independent of the system of units, but the hydraulic-geometry coefficients are dependent upon the units used. The number of node-records input must equal the number specified on the branch record. Node records are input in sequence starting with the node 1, at the upstream end of the branch. The node location is specified as the distance to the cross section from a reference point at or above the upstream end of the branch. The initial discharge, slope, and all coefficients apply to the subreach extending from the node for which it is specified to the next node downstream. For example, the value of A1 input for node 1 applies to the subreach extending from node 1 to node 2. Because there is no subreach downstream of the last node, only the river mile and output flag needs to be specified for the last node. The model is based on the assumption that tributaries enter the stream just upstream of the node. The initial discharge for subreach I, therefore, should include the effect of the tributary flow at node I. The output flag (IOUT) specifies whether or not the flow information for the node is to be printed in the output file. The data at each node is read as a free-field format, so it is not necessary to keep the numbers in any particular column or even to line them up. It is necessary that at least one blank space separate each number and that a number be available for each variable. Exponential formats (see slope) are acceptable. The formats shown in Table 1 are used if the file is created interactively using the program BDAFLOW (Jobson, 1989).

Constant A0 in equation 3 for subreach I

I, X, IOUT, F, A1, A2, A0, SL, W1, and W2 - The node records define the node number, location of the node in miles or kilometers, an output flag, for each node and the initial flow, hydraulic-geometry parameters and slope for each subreach. The hydraulic-geometry exponents are independent of the system of units, but the hydraulic-geometry coefficients are dependent upon the units used. The number of node-records input must equal the number specified on the branch record. Node records are input in sequence starting with the node 1, at the upstream end of the branch. The node location is specified as the distance to the cross section from a reference point at or above the upstream end of the branch. The initial discharge, slope, and all coefficients apply to the subreach extending from the node for which it is specified to the next node downstream. For example, the value of A1 input for node 1 applies to the subreach extending from node 1 to node 2. Because there is no subreach downstream of the last node, only the river mile and output flag needs to be specified for the last node. The model is based on the assumption that tributaries enter the stream just upstream of the node. The initial discharge for subreach I, therefore, should include the effect of the tributary flow at node I. The output flag (IOUT) specifies whether or not the flow information for the node is to be printed in the output file. The data at each node is read as a free-field format, so it is not necessary to keep the numbers in any particular column or even to line them up. It is necessary that at least one blank space separate each number and that a number be available for each variable. Exponential formats (see slope) are acceptable. The formats shown in Table 1 are used if the file is created interactively using the program BDAFLOW (Jobson, 1989).

Bed slope of subreach, in ft/ft or m/m

I, X, IOUT, F, A1, A2, A0, SL, W1, and W2 - The node records define the node number, location of the node in miles or kilometers, an output flag, for each node and the initial flow, hydraulic-geometry parameters and slope for each subreach. The hydraulic-geometry exponents are independent of the system of units, but the hydraulic-geometry coefficients are dependent upon the units used. The number of node-records input must equal the number specified on the branch record. Node records are input in sequence starting with the node 1, at the upstream end of the branch. The node location is specified as the distance to the cross section from a reference point at or above the upstream end of the branch. The initial discharge, slope, and all coefficients apply to the subreach extending from the node for which it is specified to the next node downstream. For example, the value of A1 input for node 1 applies to the subreach extending from node 1 to node 2. Because there is no subreach downstream of the last node, only the river mile and output flag needs to be specified for the last node. The model is based on the assumption that tributaries enter the stream just upstream of the node. The initial discharge for subreach I, therefore, should include the effect of the tributary flow at node I. The output flag (IOUT) specifies whether or not the flow information for the node is to be printed in the output file. The data at each node is read as a free-field format, so it is not necessary to keep the numbers in any particular column or even to line them up. It is necessary that at least one blank space separate each number and that a number be available for each variable. Exponential formats (see slope) are acceptable. The formats shown in Table 1 are used if the file is created interactively using the program BDAFLOW (Jobson, 1989).

Constant W1 in equation 4 for subreach I

I, X, IOUT, F, A1, A2, A0, SL, W1, and W2 - The node records define the node number, location of the node in miles or kilometers, an output flag, for each node and the initial flow, hydraulic-geometry parameters and slope for each subreach. The hydraulic-geometry exponents are independent of the system of units, but the hydraulic-geometry coefficients are dependent upon the units used. The number of node-records input must equal the number specified on the branch record. Node records are input in sequence starting with the node 1, at the upstream end of the branch. The node location is specified as the distance to the cross section from a reference point at or above the upstream end of the branch. The initial discharge, slope, and all coefficients apply to the subreach extending from the node for which it is specified to the next node downstream. For example, the value of A1 input for node 1 applies to the subreach extending from node 1 to node 2. Because there is no subreach downstream of the last node, only the river mile and output flag needs to be specified for the last node. The model is based on the assumption that tributaries enter the stream just upstream of the node. The initial discharge for subreach I, therefore, should include the effect of the tributary flow at node I. The output flag (IOUT) specifies whether or not the flow information for the node is to be printed in the output file. The data at each node is read as a free-field format, so it is not necessary to keep the numbers in any particular column or even to line them up. It is necessary that at least one blank space separate each number and that a number be available for each variable. Exponential formats (see slope) are acceptable. The formats shown in Table 1 are used if the file is created interactively using the program BDAFLOW (Jobson, 1989).

Constant W2 in equation 4 for subreach I

I, X, IOUT, F, A1, A2, A0, SL, W1, and W2 - The node records define the node number, location of the node in miles or kilometers, an output flag, for each node and the initial flow, hydraulic-geometry parameters and slope for each subreach. The hydraulic-geometry exponents are independent of the system of units, but the hydraulic-geometry coefficients are dependent upon the units used. The number of node-records input must equal the number specified on the branch record. Node records are input in sequence starting with the node 1, at the upstream end of the branch. The node location is specified as the distance to the cross section from a reference point at or above the upstream end of the branch. The initial discharge, slope, and all coefficients apply to the subreach extending from the node for which it is specified to the next node downstream. For example, the value of A1 input for node 1 applies to the subreach extending from node 1 to node 2. Because there is no subreach downstream of the last node, only the river mile and output flag needs to be specified for the last node. The model is based on the assumption that tributaries enter the stream just upstream of the node. The initial discharge for subreach I, therefore, should include the effect of the tributary flow at node I. The output flag (IOUT) specifies whether or not the flow information for the node is to be printed in the output file. The data at each node is read as a free-field format, so it is not necessary to keep the numbers in any particular column or even to line them up. It is necessary that at least one blank space separate each number and that a number be available for each variable. Exponential formats (see slope) are acceptable. The formats shown in Table 1 are used if the file is created interactively using the program BDAFLOW (Jobson, 1989).

Boundary conditions must represent the average flow during the time step. For example, the first boundary condition should represent the average flow between time 0 and the end of the first time step. For the first time step, all boundary conditions should be entered because DAFLOW assumes all unspecified boundary conditions to be zero. After the first time step, however, DAFLOW assumes all boundary conditions remain constant unless specifically changed. The third data group is used to input boundary conditions and consists of two types of records.

Number of new boundary conditions to be input for this time step

NBC The first record for each time step specifies the number of boundary conditions that have changed for this time step (NBC). A line for each boundary condition that has changed must follow. For example, if NBC=0, no records are required but if NBC = 5, five records must follow.

Branch number for new boundary condition

N, I, and TRB - The second type of record specifies the branch number, node number, and flow for the changed boundary condition. Data group 3 must be input for each time step of the simulation. The first record is always required, whereas the second record is only required if one or more boundary conditions are changed.

Node number for new boundary condition

N, I, and TRB - The second type of record specifies the branch number, node number, and flow for the changed boundary condition. Data group 3 must be input for each time step of the simulation. The first record is always required, whereas the second record is only required if one or more boundary conditions are changed.

New boundary flow for branch N, node I

N, I, and TRB - The second type of record specifies the branch number, node number, and flow for the changed boundary condition. Data group 3 must be input for each time step of the simulation. The first record is always required, whereas the second record is only required if one or more boundary conditions are changed.

TITLE - When DAFLOW is linked to MODFLOW, input information is required in addition to what is contained in the flow.in file. This information is contained in a file that has file type DAFG in the MODFLOW name file. The first 80 characters of the first three lines of the DAFG file are simply read in as text and printed in the MODFLOW output file for information purposes. It is recommended that the first line contain identifying information, and the second two lines contain column headings to identify the eight data fields that will follow. Examples of the column headings are shown in figure 7, which contains input data for the example shown in figure 2.

TITLE - When DAFLOW is linked to MODFLOW, input information is required in addition to what is contained in the flow.in file. This information is contained in a file that has file type DAFG in the MODFLOW name file. The first 80 characters of the first three lines of the DAFG file are simply read in as text and printed in the MODFLOW output file for information purposes. It is recommended that the first line contain identifying information, and the second two lines contain column headings to identify the eight data fields that will follow. Examples of the column headings are shown in figure 7, which contains input data for the example shown in figure 2.

TITLE - When DAFLOW is linked to MODFLOW, input information is required in addition to what is contained in the flow.in file. This information is contained in a file that has file type DAFG in the MODFLOW name file. The first 80 characters of the first three lines of the DAFG file are simply read in as text and printed in the MODFLOW output file for information purposes. It is recommended that the first line contain identifying information, and the second two lines contain column headings to identify the eight data fields that will follow. Examples of the column headings are shown in figure 7, which contains input data for the example shown in figure 2.

TITLE2 - Following the bed properties and linkage information is another line of text information that can be used to identify the three parameters that are input as the last line of the file.