Download OASIS Manual - HydroLogics, Inc.

5.2.0 BALANCE SHEET OUTPUT
The balance sheet output contains a report of every flow in and out, for every node in the system, for every time step of
simulation. It also reports basic information such as minimum flows, maximum flows, deliveries, shortages, evaporation,
elevation, and water quality. This provides a convenient way to track routing decisions across time and space. The balance
sheet does not write information that is specific to OCL.
As a security measure, OASIS is programmed to report any imbalance to this file, even though the continuity-of-flow
constraints (section 2.2.4) guarantee that there will be no imbalance. The only time you would see imbalance being reported
is when OASIS has stopped with an infeasible LP.
The file is always named balance.out and it always appears in the run directory. There is no way for you to change the file
name or path. The balance sheet output can be either on or off, depending on a flag in the control file (section 4.4.0). You
can also customize the output, as we will explain. OASIS writes information to this file at the end of every simulation year.
You should look at an example balance sheet file to help understand the format (Run OASIS to generate an example). The
balance sheet output consists of several balance sheets, printed one after another, down the page. Each balance sheet consists
of a balance summary for each node in the system (except terminal nodes). Each variable that pertains to the routing in and
out of that node is listed in a row, and each time step is in a column. Each balance sheet only covers a portion of the total
simulation time range. The method of deciding how many time steps, or columns, are in a balance sheet is called the
grouping. For example, at a daily time step, you could have a balance sheet for every week or every month. You define the
grouping in the Grouping field of the Balance Sheet Columns table (section 4.5.3 part N). The last column in every balance
sheet is a total (which can also be an average) over all the time steps in the balance sheet. If you do not use the Balance Sheet
Columns table, OASIS automatically chooses a grouping.
You can select which variables are printed as the rows of the balance sheet output in the Balance Sheet Rows table (section
4.5.3 part O). Most of the variables can be presented in two different ways. Any variables that are a type of flow can be
displayed in volume units per time step, or in flow units. Reservoir storage variables can also be displayed as elevations. In
this table, you can also specify whether a total will be reported for the variable. For flow units, reservoir storages or
elevations, and water quality, the total will actually be an average.
You tell OASIS how many decimal places to display with each value in the balance sheet through the Decimals field in the
Units table (section 4.5.3 part A).
Tips for searching the balance sheet file:
The balance sheet file can be huge, so when you want to see a particular time or a particular node, you should search for your
data using the capabilities of the software that you use to view the file. There are two tricks that can make your searching
more efficient:
To find a date. Each balance sheet begins with this text:
BALANCE SHEET for [date]
You will want to skip directly to the balance sheet that contains the date you are looking for. You can easily let your
software search for it once you know that the word for only appears in this line at the top of each balance sheet.
Suppose your balance sheets have an annual grouping method. If you wanted to go directly to the year 1966, you
would tell your software to search for the string:
for 1966
To find a node. The balance summary for each node begins with a row that says:
Node
[number]
You will want to skip directly to the node that you are looking for. You can easily let your software search for it
once you know that the word Node only appears at the top of each node’s balance summary. There are two spaces
between the word Node and the node number. Thus, to find node 567, you would tell your software to search for the
string:
Node
567
Note that the node numbers are aligned to the right-hand side, so if it is less than three digits, you will need more
spaces between the word and the node number.
-250-