S. D. Waltemeyer 1996 Equations for estimating the magnitude of peak discharges for recurrence intervals of 2, 5, 10, 25, 50, 100, and 500 years were updated for New Mexico. The equations represent flood response for eight distinct physiographic regions of New Mexico. Additionally, a regional equation was developed for basins less than 10 square miles and below 7,500 feet in mean basin elevation. Flood-frequency relations were updated for 201 gaging stations on unregulated streams in New Mexico and the bordering areas of adjacent States. The analysis described in this report used data collected through 1993. A low-discharge threshold was applied to frequency analysis of 140 gaging stations. Inclusion of these low peak flows affects the fitting of the lower tail and the upper tail of the distribution. Peak discharges can be estimated at an ungaged site on a stream that has a gaging station upstream or downstream. These estimates are derived using the drainage-area ratio and the drainage-area exponent from the regional regression equation of the respective region. Flood-frequency estimates for 201 gaged sites were weighted by estimates from the regional regression equation. The observed, predicted, and weighted flood-frequency data were computed for each gaging station. A maximum observed peak discharge as related to drainage area was determined for eight physiographic regions in New Mexico. Peak-discharge data collected at 201 gaging stations were used to develop a maximum peak-discharge relation as an alternative method of estimating the peak discharge of an extreme event. application/pdf 10.3133/wri964112 en U.S. Geological Survey ; Branch of Information Services [distributor], Analysis of the magnitude and frequency of peak discharge and maximum observed peak discharge in New Mexico reports