USGS Perennial/Intermittent Stream Team By Chris A. Sanocki, U.S. Geological Survey
The U.S.Geological Survey has assembled a team of people around the country to address issues related to perennial and intermittent stream coding in digital data. Surface water streams were originally classified as perennial or intermittent on maps by the USGS during the topographic map compilation process. The map content later served as the data source for digital data production, including the development of the National Hydrography Dataset (NHD). However, there are variations in the stream classification across the country, in part due to the long topographic mapping process, changes in mapping standards, and variations in data collection and compilation methodology.
How big a problem is the perennial/intermittent coding? Where are the problems greatest and need the most attention? Are large parts of the region/state fairly good? Should efforts focus on areas where classifications are poor or erroneous?
The USGS evaluation team would appreciate your input on the following:
1. Assess the extent of the problem for your applications 2. Assess the ability to improve the situation 3. Recommend approaches the USGS team could/should take
Try to be brief since there are many people contributing. Your feedback will be incorporated into a document that will represent a regional concern by upper Midwest states.
So what can the USGS do to classify streams better than what we have in a way that doesn't cost a lot of money? There might be two parts to this. One is to fix the bad cartographic coding, and the other is to improve the quality of the hydrologic classification. There is some very promising work in NHDPlus, StreamStats, and other studies, that could alleviate the problem. The availability of geospatial databases dealing with precipitation, landcover, hydrography, along with some sound hydrologic algorithms, could produce an improvement to the existing classifications.
Please provide your comments to Chris Sanocki as soon as possible:
Chris A. Sanocki USGS GIS Specialist Member USGS perennial/Intermittent stream team U.S. Geological Survey 2280 Woodale Drive Mounds View, MN 55112