Abstract. Flood field survey capabilities in the NWS have undergone significant improvements with the arrival of new Global Positioning System technology and automated survey mapping software. Commercial Global Positioning System mapping software, in conjunction with pocket sized Global Positioning System receivers, now enable highly accurate horizontal post storm positioning of damage areas by field survey crews. When used with vertical leveling equipment, referenced to nearby National Geodetic or other agency elevation monuments, estimates of the flood inundation profile can be obtained. Such profiles are useful in estimating the position, extent and severity of flooding related to Federal Emergency Management Agency flood maps. Post-storm evaluation of flooding through such field techniques also presents the opportunity to assess and identify new flood prone areas outside the 100 year flood plain. This information can be used as graphic overlays in the NWS Advanced Weather Information Processing System, aiding NWS staff in flood warning decision making.

This paper examines the effectiveness of conducting a field survey using current technology. A test of field survey techniques was conducted on a Flash Flood event, generated by Hurricane Dennis (2005) over Southwest Georgia on Okapilco Creek in the towns of Moultrie in Colquitt County and Sylvester in Worth County. The results of the survey are presented, along with a comparison with FEMA Flood plain maps and demographics of the population affected. Processes, procedures, strengths and weaknesses of field survey technology are discussed. The resulting adjustments to D2D graphic overlays of flood prone areas are demonstrated.