A comprehensive plan is presented for researching methods of flood-data analysis and information transfer for foothill areas, and for establishing a hydrologic data-collection network in the foothill areas of Colorado. The research will concentrate on three areas: 1. Developing methods to analyze flood peaks in foothill areas by using gaging-station records to obtain annual arrays of snowmelt and rainfall peaks. 2. Investigating techniques for flood information transfer, using physical and climatic characteristics. 3. Testing and, if required, verifying hydrologic models. The available gaging-station data consists of records from 81 active and ^3 discontinued gaging stations. The National Weather Service operates 53 recording and 70 nonrecording precipitation gages, and has kj& storm observers within the project boundaries. The Soil Conservation Service is installing a network (SNOTEL) of ^6 automated snowpack monitors. A data-collection network will be established in areas of data deficiencies, consisting of streamflow stations, crest-stage gages, and precipitation stations.

Peak flows in the foothills region of Colorado are attributable to two meteorologic sources--snowmel t and rainfall. As part of a study of the hydrology of foothills streams in Colorado, charts from streamflow gages on unregulated streams were examined to determine the source of peak-flow events. Snowmelt-runoff peaks were distinguished from rainfal1-runoff peaks on the basis of daily and seasonal occurrence, hydrograph shape, and local weather conditions. Peak-flow data for snowmelt runoff and rainfall runoff are presented for 69 streamflow-gaging stations in the South Platte River, the Arkansas River, and the Colorado River basins. ApproachMcCain and Ebling (1979) outlined a comprehensive plan for the collection and analysis of flood data for selected streams in the foothills regions of Colorado. Based on this earlier work, the study of foothills region flood hydrology is being conducted. In the first phase of the study, a peak-flow data base was established and is presented in this report. Flow characteristics were compiled for 69 streams in the South Platte River, the Arkansas River, and the Colorado River basins. The major river basins of Colorado are shown in figure 1. Gage-height charts, weather records, and indirect discharge measurements were examined, and peak-flow events were identified as originating from either snowmelt runoff or rainfall runoff.Personnel from the Colorado District analyzed rainfal1-runoff and snowmeltrunoff data bases and also used other techniques of investigations. Topics included in these analyses and techniques of investigations were: (1) Flood-frequency analysis of rainfall-runoff and snowmelt-runoff data; (2) Methods for at-a-site integration of snowmelt and rainfall flood-frequency curves; (3) Coordination of mixed-population flood-frequency analysis with investigations of geomorphic, stratigraphic, botanic, and paleohydraulic techniques; and (k) Definition of areas dominated by either snowmelt-runoff or rainfal1-runoff peak flows. This study will provide the means to identify the needs and amount of additional data collection for foothills streams in Colorado.Although foothi11-type streams occur adjacent to all mountainous areas in Colorado, severe floods produced by rainfall appear to be extremely rare for streams in the basins of the North Platte River and the Rio Grande (McCain and Ebling, 1979)-For this reason, streams in these two basins were not included in the study. The data presented in this report include snowmelt-and rainfallproduced peak flows from 27 streamflow-gaging stations in the South Platte River basin, 13 in the Arkansas River basin, and 29 in the Colorado River basin, shown in figures 2, 3, and k, respectively.

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