Instream Flows for Recreation: A Handbook on Concepts and Research Methods

Home Browse Search

identify a range of flows acceptable to users, but the method has several limitations. Another major problem is that good use data are often difficult to find. While almost any managing agency collects use data, the data are often too coarse. In order to execute this method well, you need daily use information disaggregated into the different types of use (each of which may have different flow needs). Few resource managers have this kind of information available. Other problems with this method include its inability to examine flow needs for potential opportunities (e.g. flow needs for boating in a by -pass channel that a dam has kept dry for 50 years), the inability to develop incremental flow relationships (it simply provides a range of acceptable flows), and its total lack of information on long -term flow needs to maintain or create riparian or channel features important to recreation opportunities. Keys to Success Successfully using this method requires careful collection and application of use data. Data is most valid when verified from multiple sources and checked for reasonableness by interviews with longtime users or resource managers. In fact, these people can often provide more useful information about use than data from mechanical counters or registers, even though the latter are more quantitative. Summary This is a useful method for getting a quick feel for certain flow needs and may lead to a 34 legitimate determination in some specific situations, particularly if the resources for larger studies are not available. This method, however, offers no information about the quality of recreation experiences and is based on potentially misleading relationships between use and flows. As a stand -alone method, this technique has major limitations. As a scoping element in a more comprehensive study, however, it can prove useful. Information about use and the seasonality of that use should be examined during the resource assessment stage of any study, and by associating a range of flows with seasonality, researchers can get a feel for the range of flows to explore in greater detail. This preliminary determination is particularly helpful for suggesting sampling frames for survey efforts or choosing good times of the year for resource reconnaissance (field trips by the study team). PROFESSIONAL JUDGMENT METHODS This refers to a variety of techniques that have in common the use of a resource specialist who makes reasoned flow need estimates from short but strategically conducted resource reconnaissance and an accumulated general knowledge of the issues. These methods are best used to explore indirect impact issues associated with river geomorphology or riparian changes, although they can also be used to examine direct impact issues such as navigation, whitewater, fishability, or aesthetics. These methods are often used to check the reasonable- ness of results from other analyses as well. Output from these methods can come in a variety of forms, although they tend to lean toward descriptive rather than quantitative presentations, particularly for geomorphic or riparian issues. These methods often begin and end with a single -visit to the resource (judgments based on multiple visits usually focus on other methods and do not strictly fit in this category). In many cases, the judgment is not made in an obviously systematic manner, but there is no reason the approach could not be applied in more methodical ways to show explicit links between various assumptions, on- site observations, and final recommendations.