Determining project scope and level of analysis

Hydraulic engineering contributions to stream design can be viewed as a three-dimensional process. The most important two dimensions are the type of project and the stage of the project.

The third dimension is the constraint of time and/or cost that is not strictly engineering related. The role of the hydraulic engineer in this third dimension is to apply the standards of professional engineering licensure. If time or cost prevents an analysis from meeting professional engineering standards, the engineer must inform project managers and act accordingly.

The level of detail required of a hydraulic analysis falls into one of three categories: rough estimation, standard engineering, and atypical complexity. Generally, the reconnaissance stage of a project requires a rough estimation level of detail, although many standard engineering procedures are not time consuming nor difficult to apply, so that often a reconnaissance stage can be supported with a greater level of detail. For the remaining project stages, standard engineering procedures are minimally required. However, depending on the project particulars, atypical complexity may be necessary.

Each project type, as identified in table 2, will have pertinent hydraulic parameters, computations, and an applicable level of detail. The scope of the hydraulic analysis is tied to the project, and each project type generally corresponds with a hydrology type as shown in table 3.

When providing hydraulic computations, the designer should also estimate uncertainties, be able to specify their source, and provide confidence limits. Engineering in a stream corridor requires field work. The greater the quantity or precision of results needed, the greater the amount of field data required. Time and human labor cost may be expected to rise accordingly.