The GIS-Windshield Survey methodology is most applicable in small to very small watersheds with a limited number of potential targets for pollution reduction. Some GIS data is required, but the detail of the data can vary greatly.
A windshield survey means, essentially, “observing a watershed while driving along a road” (WDNR, 47). While it sounds simplistic, in a small watershed it can often provide more or equivalently detailed data than even the highest-precision spatial models. The Wisconsin Adaptive Management Handbook, which encourages the use of Windshield Surveys to gather information that traditional data sources do not have readily available, provides this information regarding what data can be gather through a Windshield Survey.
When combined with other sources of data, these windshield survey results can become very powerful tools in targeting. Recall from Nowak and Pierce’s disproportionality framework that these more social or behavioral factors are both main contributors to nutrient pollution runoff and sometimes the most difficult to identify. Using a windshield survey with GIS or other local knowledge, watershed groups can more easily account for both biophysical and social factors within a disproportionality framework.
Case Study: Windshield Survey Applications in Iowa
[The information herein is from a 2007 presentation by Adam Kiel Entitled “targeting in Iowa water Quality Projects”. View the Entire Presentation HEre.]
The Iowa DNR employs a number of tools for watershed assessment including land-use assessment, in-stream assessment, sediment delivery calculator, and LiDAR (Light Detection and Ranging). For Land-Use Assessment, they combine available GIS data with standardized windshield survey results to enhance their data capability. They have at their disposal tablet computers equipped with ArcView GIS to allow for on-site data input. ArcView is loaded with the Watershed Boundary, Field Boundaries, and an aerial image. The surveyor then collects point and land-use data. The image below provides a sample of data gathered and the format in ArcViewer. The data are then used to identify areas of concern, to be used for targeting of BMPs within these small watersheds.