FLOOD09697

• County: Statewide
• Community: Nationwide
• Basin: Statewide
• Title: Mathematical Modeling of a Sociological and Hydrologic Decision System
• Date: 6/1/1978
• Prepared By: Institute for Social Science Research on Natural Resources, Utah State Univ.
• Floodplain - Doc Type: Educational/Technical/Reference Information

CHAPTER VI

COMPUTER MODEL OF THE SOCIAL SYSTEM

Introduction

Once the equations are calibrated and interre-
lated through common variables, translation into a
computer model consisls of programming the calcula-
tions indicated by the formulas, entering the dala and
constants used 10 adjust the model to a particular sys-
tem, and constructing a user manual. Afterwards, sim-
ulation and sensitivity analyses can be performed. The
ability to do these analyses is one of the main benefits
of a system model as it is used to develop a belter
understanding of key relationships.

Outline of Computer Model

The computer model (see right side column of
Figure 5.1) is programmed from the mathematical mod-
el presented in the last chapter. The solid lines indi-
cate various paths followed, given the particular re~
sponse estimated by an equation within the compuler
program_ The second numbers to the right refer to the
labeled sections of the compuler program and output
discussed later in this chapler. The program is listed
in Appendix F. The particular equations used to mod-
el the study area were derived by a calibration proce-
dure from the general equations of Table 5.9. The
equations applied are summarized in Table 6.1. The
variables are defined in Table 6.2.

Most of the blocks within the cenler column of
Figure 5.1 are rectangular. These boxes represent
equations which, with one exception (Section 2), have
been calibrated before insertion wilhin the model and
cannot be changed by the model operator. The two
triangles, on the other hand, represent IF statements
whose threshold levels are established by operation of
the model and which can stop continuation of the
evaluation process or, in other words, cause a proposal
to be rejected.

Another set of IF statements provides additional
information but is not shown separately on the flow
chart. These act at the same time as the initial deci-
sion agency evaluation, but cannot stop the process
within the model. Rather they are used to signal SOme
deficiency in a desired characleristic of a flood con.
trol proposal. They occur in Section 5 in Figure 5.1
as discussed in Chapter V for IF statements BI 10 B3.

Interrelationship of Physical
and Social Systems

The block on the left of Figure 5.1 represents
the hydrologic system. The lines going to the block
represenl the effects of the social system on the hydro-
logic system, and the lines coming from this block rep-
resent the effect of the hydrologic system upon the
social system. These effects may be direct or indirect.
The solid line going to the hydrologic system from
the "Action by the Implementation Agency," depicts
thai the parameters of the hydrologic system are af-
fected by flood control action. The broken lines com-
ing from the hydrologic system box mean lhat al
least one variable in each of the equations to which
they lead is affected by the hydrologic system. In this
case, this connection is primarily with public flood
experience related variables.

Dashed.line relationships show connections for
which explicit equations have not yet been developed
but lead to equations in the social model some of
who,e variables reflect differences in the hydrologic
situation. Each of the rectangular boxes has either a
solid or broken line leading from lhe hydrologic sys-
tem to it.

The sociological and hydrologic componenls of
the total system cannot be separated from each other
without giving a distorted picture because the para.
meters of one are changed by the other. The inter-
relation,hip of urban sprawl and runoff is an example.
Urban sprawl is related to population growth and geo-
graphy as well as other physical and social faclors such
as the availablityand cost of transportation, water
supply, etc. The cost and benefit of flood control
proposals given the same physical conditions also var-
ies with the social environment.

Computer Programs

The computer program for modeling the social
system is wrilten in Fortran IV. One version of the
program was used for sensitivity analysis, and another
was used for simulation. The sensitivity analysis pro-
gram is in Appendix F. The introduction of that ap-
pendix explains differences between the two versions.
Use of the computer program of the social system en-

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