Models in Irrigation andWater Management - Practices of Irrigation and On-farm Water Management - page 382

is not explicitly described (or unknown, i.e., like a “black box”) in this type of
model. In this model, empirically derived formulas (relies upon experiments and
observations) are used to predict the required output. The empirical data are derived
from a limited sample of projects.
Various modelers or researchers categorized/classified models under different
perspectives. Definitions of different category of models are summarized below:
10.2.2.3 Conceptual Model
Conceptual models (sometimes called abstract models) are theoretical models.
A theoretical model often assumes away many complications while highlighting
limited aspects of the object. A conceptual model is a representation of some phe-
nomenon, data, or theory by logical and mathematical objects such as functions,
relations, tables, stochastic processes, formulas, axiom systems, rules of inference.
The conceptual model is concerned with the real world view and understand-
ing of data. Conceptual models are qualitative models that help highlight important
connections in real world systems and processes. They are used as a first step in the
development of more complex models. A conceptual model may include a few sig-
nificant attributes to augment the definition and visualization of entities. No efforts
need to be made to invent the full attribute population of such a model. A conceptual
model may have some identifying concepts or candidate keys noted, but it explicitly
does not include a complete scheme of identity, since identifiers are logical choices
made from a deeper context. From the conceptual model, the mathematical model
and validation experiment can be constructed.
For example, the development of computer models capable of realistic simu-
lations of tornadic storms and tornadoes provide a means for careful quantitative
evaluation of the physical processes which yield tornadoes.
Features of conceptual model:
- Conceptual models are a tool through which detailed technical concepts can be
summarized in a non-technical way, and presented to end users.
- Conceptual models provide a physical background upon which the understanding
derived from various scientific disciplines (e.g., ecology, chemistry and geology)
can be integrated with the perspectives of other stakeholder groups for addressing
management issues.
- Conceptual models help users to understand the often complex processes in a
system (e.g., how things work, what drives these things, and major impacts) and
demonstrate the links between them.
- Conceptual models can help users to identify any gaps in scientific understanding,
monitoring, or natural resource management plans.
10.2.2.4 Mathematical and Statistical Models
Mathematical and statistical models involve solving relevant equation(s) of a system
or characterizing a system based upon its statistical parameters such as mean, mode,