Creating New Models

Abstract

For some watershed simulation modeling purposes, simulation models must be created and not merely adapted and/or parameterized. This is particularly true for ecological simulation modeling. Instead of adopting a simulation model that is parameterized for a local watershed, simulation model development environments are used to develop a locally explicit model. Figure 7.1 compares modeling environments and models. Software models, such as those discussed previously in Chapter 5, offer the user a complete mathematical formalization of a set of watershed processes. Associated with the model are data import and export, data storage and retrieval, and model execution interfaces. Various types of data output and data visualization capabilities are often provided for internal and/or external output analysis. Through visualization and analysis of output, decisionmakers become better informed with respect to potential consequences of alternative watershed management decisions. Modeling environments exist to allow the efficient development and use of models. They typically provide user interface, data storage and retrieval, libraries of submodels, and simulation modeling primitives to which the user adds the actual modeling equations and the initializing system state information. In this chapter we explicitly look at software options targeted for each of these purposes.