2Λ· Assumptions
Made in Preparing the Problem
Statement
39
1967; Butcher et al, 1969; Young et al, 1969; Weiss and Beard, 1970.] On
the other hand, controlled water releases within the system are executed
each month because (a) hydrologic data are provided on a monthly basis
by such federal agencies as the U.S. Bureau of Reclamation and the U.S.
Geological Survey, and (b) demands (consumptive and nonconsumptive)
on the system are specified month by month. The monthly time frame for
reservoir operation has been widely used by other investigators [Hufschmidt, 1962; Wallace, 1966; McLaughlin, 1967; Young etal, 1969; Hall
and Dracup, 1970].
2. As presently formulated, the model of the river basin does not take
into account flood damages. Since these damages can be correlated with
average monthly flows [Hufschmidt, 1962; Hufschmidt and Fiering, 1966],
the model can be modified to rectify this omission if desired.
3. Reservoir inflows over the life of the project are assumed to be known
and deterministic. In arid and semiarid areas the record of reservoir inputs
will contain, in many instances, a sequence of subnormal flows called the
"critical period." This critical-period hydrology has been used in many
instances for the evaluation of optimal long-term policies for planning
[Hall and Dracup, 1970].
4. It has been assumed that future demands on the system are deterministic. However, the mathematical model can incorporate any likely demand sequence, and the sensitivity of decisions to changes in the demand
sequence can be ascertained.
5. Water quality has been omitted in forming the model because the
model pertains to the quantity of water only; thus the surface water in a
river system has been treated as a homogeneous commodity. How to implement the basic model to accommodate water quality is discussed in
Chapter 6.
6. The operating policy of the system has been limited to energy generation by constant-head reservoirs.
7. Alternative sources of water and alternative ways of satisfying water
needs can be included in the model if they exist, but have not been specifically included. In particular, ground water, used solely for crop irrigation (as is the current practice in the high plains of West Texas) or in
conjunction with surface water supplies, is an example of an alternative
source. See the work of Milligan [1970] for typical relations to use in the
optimization of the conjunctive use of ground water and surface water.
Other ways of meeting water requirements are ground-water recharge,
recycling of industrial water, reclamation of waste water, and avoidance of
flood damage by flood-plain zoning.
The water resources system itself will be assumed to consist of a river
Made in Preparing the Problem
Statement
39
1967; Butcher et al, 1969; Young et al, 1969; Weiss and Beard, 1970.] On
the other hand, controlled water releases within the system are executed
each month because (a) hydrologic data are provided on a monthly basis
by such federal agencies as the U.S. Bureau of Reclamation and the U.S.
Geological Survey, and (b) demands (consumptive and nonconsumptive)
on the system are specified month by month. The monthly time frame for
reservoir operation has been widely used by other investigators [Hufschmidt, 1962; Wallace, 1966; McLaughlin, 1967; Young etal, 1969; Hall
and Dracup, 1970].
2. As presently formulated, the model of the river basin does not take
into account flood damages. Since these damages can be correlated with
average monthly flows [Hufschmidt, 1962; Hufschmidt and Fiering, 1966],
the model can be modified to rectify this omission if desired.
3. Reservoir inflows over the life of the project are assumed to be known
and deterministic. In arid and semiarid areas the record of reservoir inputs
will contain, in many instances, a sequence of subnormal flows called the
"critical period." This critical-period hydrology has been used in many
instances for the evaluation of optimal long-term policies for planning
[Hall and Dracup, 1970].
4. It has been assumed that future demands on the system are deterministic. However, the mathematical model can incorporate any likely demand sequence, and the sensitivity of decisions to changes in the demand
sequence can be ascertained.
5. Water quality has been omitted in forming the model because the
model pertains to the quantity of water only; thus the surface water in a
river system has been treated as a homogeneous commodity. How to implement the basic model to accommodate water quality is discussed in
Chapter 6.
6. The operating policy of the system has been limited to energy generation by constant-head reservoirs.
7. Alternative sources of water and alternative ways of satisfying water
needs can be included in the model if they exist, but have not been specifically included. In particular, ground water, used solely for crop irrigation (as is the current practice in the high plains of West Texas) or in
conjunction with surface water supplies, is an example of an alternative
source. See the work of Milligan [1970] for typical relations to use in the
optimization of the conjunctive use of ground water and surface water.
Other ways of meeting water requirements are ground-water recharge,
recycling of industrial water, reclamation of waste water, and avoidance of
flood damage by flood-plain zoning.
The water resources system itself will be assumed to consist of a river