A.J. Cohen, A.D. Randall 1998 1.0 map USGS Open-File Report USGS OFR 96-395 Reston, VA U.S. Geological Survey http://water.usgs.gov/lookup/getspatial?ofr96395_pre Two maps, compiled at 1:1,000,000 scale, depict mean annual runoff, precipitation, and evapotranspiration in the part of the United States east of Cleveland, Ohio and north of the southern limit of glaciation. The maps are mutually consistent in that runoff equals precipitation minus evapotranspiration everywhere. The runoff map is based on records of streamflow from 503 watersheds in the United States and southernmost Canada, adjusted to represent 1951-80 and supplemented by records of precipitation at 459 stations. Precipitation at each station was partitioned into point estimates of runoff and evapotranspiration, which were constrained such that the evapotranspiration estimates varied smoothly across the region and decreased with increasing latitude and altitude, and the runoff estimates were consistent with measured runoff from nearby watersheds. A point estimate of runoff was allowed to equal mean runoff in a nearby watershed, or to be somewhat higher (or lower) if a compensating departure from mean watershed runoff could be inferred in distant parts of the watershed on the basis of altitude or regional trends. Then, precipitation contours were drawn to parallel runoff contours but differ from them by the magnitude of nearby estimates of evapotranspiration. These maps may slightly underrepresent mean precipitation and evapotranspiration in areas of high relief because most precipitation stations in such areas are in valleys. These 3 coverages were used to produce Open-File Report 96-395. Additional information about methodology can be found in this report Any application involving the need for digital regional runoff, precipitation, or evapotranspiration values. Possible uses include spatial data layer extraction, clipping, cartographic and illustrative display, estimation of amounts of water available for aquifer recharge, surface-water and ground- water modeling, and other analytical or comparative mapping. Procedures_Used: Author compiled contours as inked lines on the base plotted at 1:1,000,000 scale on scale-stable mylar. The contours were scanned on a Contex 8000 scanner at 200dpi and dumped into an rlc file. This rlc file was imported into PixelTrac software where the raster image was used to produce a vector file in dxf format. The dxf file was imported into ArcInfo and further transformed from a dxf file in scanner units to an ArcInfo coverage in real world coordinates. Rms error for this final transformantion was less than .010. The original source data was in Albers Projection, units meters, paramaters 29 30 00, 45 30 00, -96 00 00, 23 00 00. Checkplots on non-base stable materials were used to initially check for accuracy and completeness. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government. Although this Federal Geographic Data Committee-compliant metadata file is intended to document the data set in nonproprietary form, as well as in ARC/INFO format, this metadata file may include some ARC/INFO-specific terminology. (yyyymmdd) (example: Ground Condition) Complete None Planned -82.99601613 -66.61906681 47.31336359 39.99999887 none precipitation contours in the northeastern United States inlandWaters none Maine westward to Ohio and north of the southern limit of glaciation none Data was compiled at 1:1,000,000 scale. Caution should be exercised when using this data at any smaller scale. Coverage was created using data from 1951-80. Caution should be exercised when using this data for any other time period. Andy Cohen U.S. Geological Survey GIS Specialist (mailing and physical address)

425 Jordan Rd

Troy NY 12180-8349 USA 1-888-275-8747 518-285-5601 acohen@usgs.gov This coverage is a product of the U.S. Geological Survey's Regional Aquifer-Systems Analysis Program. Windows_NT, 4.0, Intel ARC/INFO version 7.2.1 A.D. Randall 1998 map Open-File Report USGS OFR 96-395 Reston VA U.S. Geological Survey http://pubs.er.usgs.gov/usgspubs/ofr/ofr96395 The final phase for release of this dataset to the public is USGS review and approval. Criteria used in the review process include positional accuracy and precision with respect to source, contextual accuracy, attribute accuracy, topological consistency, and appropriate metadata. Reviews of this coverage were made by George Casey (USGS Hartford, CT), and Doug Freehafer (USGS Troy, NY) in May 1998. All review comments were addressed. Reviews are on file at USGS Troy, NY. Chain-node topology present. See Attribute_Accuracy_Report: This metadata set for mean annual precipitation and the companion runoff and evapotranspiration data sets (ofr96395_run and ofr96395_eva) are mutually consistent in that they were drawn so that precipitation minus runoff equals evapotranspiration at every location and in that areal distribution of precipitation data influenced runoff contours, and areal distribution of runoff data influenced precipitation contours, as explained by Randall (1996). The runoff contours were drawn first (see ofr96395_run). After some quality control checks and revisions of the runoff map, a map of mean annual precipitation was drawn such that the precipitation contours parallel runoff contours and are consistent with the point precipitation data. Maps of precipitation, runoff, and evapotranspiration more detailed and accurate than found in this metadata set and its companions could be prepared by a more comprehnesive approach that first quantified the relation of precipitation to altitude and other orographic factors, then calibrated those results against concurrent watershed runoff to ensure that contours of precipitation, runoff, and evapotranspiration are mutually consistent. Average annual precipitation is a statistical concept whose true value at any specific horizontal position can never be absolutely known. The positional accuracy of the companion runoff contours was evaluated statistically by comparison with runoff from watersheds initially excluded from the analysis as explained in ofr96395_run. No comparable test was made for precipitation contours, but the fact that one of three mutually consistent data sets was found to be somewhat improved from previous interpretations reflects favorably on the other two data sets. Quality-control tests were used to detect blunders in drawing or compiling precipitation contours. 1. Contours as compiled and plotted by GIS were visually compared on a light table with author's linework. Any departure greater than about 3 linewidths over distances longer that about 1 centimeter were marked for correction. Localized departures, mostly instances of linear arcs that did not exactly match the author's curved contours, were generally ignored. 2. Geographic Information Systems software was used to create a three dimensional surface from the runoff contours, and a similiar surface from the companion precipitation contours, by the Delauney method of triangulation. These surfaces were resampled to generate lattices having a spacing of 4 miles between lattice points, and runoff was subtracted from precipitation in each lattice block. Discrepancies between the array of evapotranspiration values thus computed and the evapotranspiration zones as delineated by the author enabled several mislabeled contours and minor misinterpretations in placement of contours to be detected. U.S. Geological Survey 1998 map USGS Open-File Report USGS OFR 96-395 Reston, VA U.S. Geological Survey 1000000 mylar (yyyymmdd) complete USGS OFR 96-395 (example: contours from Fig. 4, page 25) See Supplemental_Information 1992-1999 First draft of metadata created by acohen using FGDCMETA.AML ver. 1.32 01/11/99 on ARC/INFO data set r:\district_gis\northeast\meteor\1m\ofr96395_pre 19991209 Vector Point 6 String 256 Lambert Conformal Conic 41.25 46.25 -74.25 23 0.00000 0.00000 coordinate pair 1.00092279911 1.00092279911 Meters North American Datum of 1927 Clarke 1866 6378206.4 294.98 Value1 = mean annual precipitation, in inches. Value2 = not used none U.S. Geological Survey Ask USGS - Water Webserver Team mailing

445 National Center

Reston VA 20192 1-888-275-8747 (1-888-ASK-USGS) http://answers.usgs.gov/cgi-bin/gsanswers?pemail=h2oteam&subject=GIS+Dataset+ofr96395_pre Although this data set has been used by the U.S. Geological Survey, U.S. Department of the Interior, no warranty expressed or implied is made by the U.S. Geological Survey as to the accuracy of the data and related materials. The act of distribution shall not constitute any such warranty, and no responsibility is assumed by the U.S. Geological Survey in the use of this data, software, or related materials. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government. Export Full coverage zipped 1 http://water.usgs.gov/GIS/dsdl/ofr96395_pre.e00.gz None. This dataset is provided by USGS as a public service. 20041108 U.S. Geological Survey Ask USGS -- Water Webserver Team mailing

445 National Center

Reston VA 20192 1-888-275-8747 (1-888-ASK-USGS) http://answers.usgs.gov/cgi-bin/gsanswers?pemail=h2oteam&subject=GIS+Dataset+ofr96395_pre FGDC Content Standards for Digital Geospatial Metadata FGDC-STD-001-1998