Environmental characterization

 
Subbasin planning has two main phases: assessment of the watershed and development of strategies to deal with habitat limitations identified in the assessment. Hence, the assessment precedes the planning phase.

A major part of the assessment is the characterization of habitat conditions in the subbasin and the identification of natural and human controlled constraints on species of interest. Various methods exist to relate characteristics of the environment to the performance of species of interest such as EDT. EDT may be the appropriate assessment tool for many, but probably not all, fish species of interest to planners. Subbasin planners may find other methods more appropriate to their species of interest, availability of information or for other reasons. Regardless of the method chosen, the data and information used should be consistent across both aquatic and terrestrial environments, well documented and usable with other analytical methods.

The environmental characterization involves the assembly of available physical and biological data and information in electronic form at a common geographic scale (see information organization) and subsequent conversion of this data into the input formats required by the analytical models. The web-based EDT Stream Reach Editor is a tool for organizing and documenting environmental data and converting it into the attributes that are input to the EDT model. It is also a convenient and useful tool for organizing and displaying environmental data even if other analytical tools are used.

The baseline environmental characterization should capture two scenarios: the current condition, and a template condition. The template is a representation of the restoration potential. It is used as a reference condition against which to compare the existing conditions to define change and indicate a direction for needed improvement. In most cases, it is not a management alternative. It is generally an historic reconstruction adjusted for irreversible (anthropogenic or natural) changes although other reference conditions are possible. The template is sometimes referred to as the normative condition. In this context it defines the maximum restoration scope of a subbasin plan.

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