Hydrologic Intermediaries - a Missing Link between Modelers and Stakeholders

Abstract:

Applied hydrologic modelers commonly see their role as providing an objective, quantitative tool that can predict the impacts of changes to hydrologic systems. Stakeholders commonly see hydrologic models as a tool that can integrate all the hydrologic factors and provide clear and reliable predictions. Unfortunately, the modelers often intentionally avoid building models to address specific predictions, preferring to build more general models. Meanwhile, stakeholders may not have the technical background to know which questions to ask regarding possible influences on their predictions of interest. In addition, both parties approach the topic of uncertainty very differently: modelers aim to quantify uncertainty broadly and statistically while stakeholders inherently interpret prediction uncertainties in the context of risk to their objectives. Given the distance between modelers and stakeholders on important issues, it seems that there is a critical role for an intermediary who can guide a stakeholder in the full use of a hydrologic model to answer stakeholder-specific questions.

We present an example case in the Upper Santa Cruz River Basin, Arizona, where a calibrated groundwater model, developed by the Arizona Department of Water Resources, is used to guide land and water use planning efforts by a non-profit organization (Arizona Land and Water Trust). The aim of the Trust is to compare possible land-use changes to promote the health of a desert river. The river currently sees enough year-round effluent-supported streamflow to support a riparian gallery forest, and the larger valley is an important north-south migration corridor. Increasing residential development pressure is likely to significantly change land and water use patterns in the basin. We document a series of analyses that were developed to help the staff of the Trust to understand the influences of these changes on streamflow. These include the effects of: the locations of water use changes; the timing, duration, and magnitude of the water use change; asymmetric impacts of increased versus decreased water use; and the timing (seasonality and annual variations) of the assessment of the impacts. We conclude with a post-assessment of the value added by our intermediary efforts to the use of the models by the Trust for water resources management.