FAQ 4.1 How can I view error messages?

Answer. When you start the execution of a task block then the task block will color purple, which means that the task is active. After some time, the task block may color yellow or green. When it is yellow it means that one or more of the executed programs detected an error. When the task block is green then the executed programs executed correctly. You can check the error message and other progress messages in the log-file of the various programs as follows.

Figure 4 Viewtext screen : example log-file.

FAQ 4.2 I get error messages related to the network which I just created or updated with the network editor Netter and I cannot find anything wrong. Do you have suggestions for actions to carry out?

Answer. When you get errors after you have created or updated a network schematization you can carry out the following actions to find the cause:

• Move the nodes in the network editor and check if you might have 2 nodes on the same location. This may occur when you push the mouse button two times by accident when you design your network schematization.
• Switch on the flow direction of the links and check if the flow direction is correct. You can switch on the flow direction of the links under the network editor Netter by selecting menu option: “Options” > “Options” > At the settings window select sheet “Link” (see Figure 5) > Set at “Show direction” the item “Defined” on.
• Check the various number of upstream and downstream links at the various nodes. See the RIBASIM Version 7.00 User manual (file RIBASIM Version 7.00 User manual V6.pdf) table 7.10.
• Check if the validity of the type of the downstream links especially for the diversion and bifurcation nodes. See the RIBASIM Version 7.00 User manual (file RIBASIM Version 7.00 User manual V6.pdf) table 7.10.
• Check if your schematization has a loop. See FAQ 3.2. how to deal with loops.

Figure 5 Network editor Netter settings window under menu item Options > Options.

FAQ 4.3 Where can I view the actual simulation timestep?

Answer. RIBASIM simulates on a monthly, half monthly, decade (10 daily), weekly or daily basis. When you start a new application then the time step size is a month which is the default time step. This means that the time step dependent model data, like the irrigation demand of the fixed irrigation nodes, must be specified for each month. You can check the actual simulation time step as follows.

You can also directly view the time step definition file Timestep.dat under Windows explorer. The file is stored in the Fixed sub-directory of your basin Rbn-directory, for example for model with name Virgin this file is stored in the directory \Virgin.rbn\Fixed.

You may change the simulation time step as well. The procedure is outlined at the next FAQ 4.4.

FAQ 4.4 How can I change the simulation timestep?

Answer. Best moment to define and set the simulation time step is when you start with your application. The defined simulation time step determines the time step dependent model data, thus when you set the simulation time step on monthly then you must specify 12 values for data like the irrigation demand of fixed irrigation nodes. The procedure to set the simulation time step is as follows:

Basically, any simulation time step definition can be simulated by RIBASIM but in the Fixed data menu system the definition of the Christian and Shamsi calendars for 12, 24, 36 and 53 time steps are included as those time steps are the most commonly used.

Normally RIBASIM simulates on the defined monthly, half monthly, decade or weekly time step unless you specify that you want to simulate daily. You can switch the daily simulation option on at the task block Specify simulation control data (see Figure 9).

FAQ 4.5 Can I simulate with a daily timestep?

Answer. Yeas you can. You can switch the daily simulation option on at the task block “Specify simulation control data” (see Figure 10).

FAQ 4.6 Does RIBASIM take into account leap years ?

Answer. Yes. RIBASIM considers leap years. The length of each time step in days is specified in the time step definition file e.g. the one shown for Christian monthly time steps (Figure 11) and you specify as well for which time step an extra day must be added for leap years. When you create a daily hydrological time series then you must include this extra day for leap years.

FAQ 4.7 How can I export simulation results to Ms Excel ?

Answer. All simulation results are stored in a result file per type of node e.g. the fixed irrigation node results are stored in the file Fixirrig.his. The file type is always “His”. You can make graphs and export all RIBASIM results using the program Ods_View available under the “Results : on chart” menu item. Two procedures for the export of results in the His-files can be used. The first procedure is by making a graph of the results and next select the menu item “Copy data to Clipboard (Paste in Excel)”. See Figure 12. The second procedure is under Ods_view where you have to export the results to a Csv-file (comma separated values). The Csv-file can be opened under Ms Excel outside RIBASIM and data can be converted to columns.

FAQ 4.11 How can I compare the results of two or more cases?

Answer. RIBASIM contains the utility Case Analysis Tool (CAT) with which you can compare and combine the results of various simulation cases. The requirements are:

1. The simulation cases must be executed for the same schematization.
2. The simulation cases must be completed (task blocks up to “Post processing of simulation results” must be green).

The utility is available at the RIBASIM title screen Icon gallery at icon “Open and analyse”. Below the procedure to generate a combined graph of the flow in the most downstream link of our Virgin river basin for the Base case and the Scenario A case.

Before you start the exercise below you should first run and save the complete simulation “Base case” for the time period January 1971 till December 1980.

FAQ 4.12 How can I make a flow composition computation?

Answer. With a flow composition computation, you can trace the water of the various sources thru the river basin network. You can make 2 types of flow composition computations:

Type 1 : the flow components are the default flow components.

Type 2 : the flow components are defined by the user.

If you want to do type 1 “Default flow components” then you only have to switch on the item “Flow composition (default)” at the task block “Specify simulation control data” (see Figure 22).

If you want to do type 2 “User defined flow components” then you must:

1. Create a new water quality scenario directory in the Lookup-directory.
2. Define the flow components in the file Substa.dat.
3. Create a lookup table file in the water quality scenario directory for each defined flow component. The lookup table file must contain only one table with index 1 and all values in the table are equal to 1.
4. Assign to each node the correct flow component: specify the value 1 as the lookup table index at the water quality model data for the correct flow component.
5. Switch on the item “Flow composition (user defined)” at the task block “Specify simulation control data” (see Figure 22).

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FAQ 4.13 I have created a network schematization and when I save it I get message and errors on my screen. What can I do?

Answer. It might occur that you get error messages while designing and saving your river basin network schematization under the network editor Netter. The cause is that your network is not complete or not correct. Some common mistakes are for example that you have added 2 nodes on the same location (because you pushed twice the left mouse button) or the flow direction is incorrect or you are not using the right link types at diversion and bifurcation nodes. To find out what is wrong some suggestions for further actions:

1. View log files and read the error messages carefully.
2. Check the type of the downstream links of the diversion, bifurcation, surface water reservoir and groundwater reservoir node. See RIBASIM User manual table 7.8, 7.9 and 7.10 for an overview which link types to use at each node type.
3. Under the network editor Netter you must move each node a little bit and check if an isolated node was at the same location.
4. Check if the link flow direction is the downstream direction.

FAQ 4.14 I get error message related to the source priority list. What to do?

Answer. The source priority list is automatically generated when you save your new or updated river basin network schematization. If this was not done well and an error was generated referring to the source priority list then the following actions could be carried out to solve this problem:

• Your network should be correct before the source priority list is generated well. See FAQ 4.13 for the actions to do.

Push the “Generate” button at the window of the source priority list editor. See Figure 23 . The source priority list is generated.

FAQ 4.15 I get an error message related to the simulation sequence. What to do?

Answer. The simulation sequence is the downstream order of the nodes in which they are processed in RIBASIM. It is automatically generated when you save your new or updated river basin network schematization. If this was not done well and an error was generated like:

Error from sub Yseq :

Number of nodes in the simulation sequence (= 5)

is less than number of nodes in the network (= 46)

Check simulation sequence

The following actions could be carried out to solve this problem:

1. Your network should be correct before the simulation sequence is generated well. See FAQ 4.13 for the actions to do.
2. Under RIBASIM: at the network editor Netter move (replace) one of the nodes in your network schematization, save the network and exit Netter. This will trigger the generation of  the updated simulation sequence.

If the error still occurs after the above actions, then you can solve the problem by carrying out:

1. Under RIBASIM: go to the edit network (Netter) so you have your network on your screen.
2. Next under the Windows Explorer: go to the directory 'Work' in your rbn directory (if your model name is Komati then it is \Komati.rbn\Work) and delete the file Seqfil.dat.
3. Return to RIBASIM: at the netwerk editor (Netter) you move one node to another location, save your network and exit Netter. This will trigger the generation of a new simulation sequence stored in file Seqfil.dat.

FAQ 4.16 Can I run many cases at once under the case management tool?

Answer. Yes. You can run several simulation cases in batch mode at the Case Management Tool. You must carry out the following actions:

FAQ 4.17 Can I make my own analysis framework in which RIBASIM is a separate component e.g. using several batch files?

Answer. Yes you can. If you want to make a large number of runs for a RIBASIM model outside the standard user interface in a self-designed batch mode or combine RIBASIM with other components then this can be easily implemented. An example batch setup has been provided with the RIBASIM Version 7.01.21 software. You can mail to Ribasim.info@Deltares.nl for the latest info.

FAQ 4.18 The warning about “equidistant time steps” is shown at the results on chart. How can I skip this warning?

Answer. The message may appear when you are making your selections at the program Ods_view on parameter, location and time steps at the “Results on Chart”. See Figure 24. You can avoid this warning as follows: at program Ods_view menu item “Options” > Switch off option “Warn for non-equidistant time steps”