This study presents the assessment and prediction of spatially distributed peak flood events for 5, 25 and 100 years of return periods through the integrated application of modified rational method, Geo statistics and GIS(s) in the Upper Blue Nile basin of Tana sub basin with the generated point map of 721208 over Gilgel_Abay, 323900 over Gumara and 443928 over Rib watersheds. The results from the Geo Spatial Semi variogram exponential modeling of peak flood events indicated that the Speed, Propagation, Flux and Wave celerity of maximum flood magnitude diminished as it travels from top to down slope zone of drainage channels with a change of separation distance (h). Generally, the followed three points described; how the peak flood magnitude or flux varies in space or with a change of mean separation distance (h) or Lag distance size intervals? 1) With a mean range ( Lag Distance) of 687.57 meter the magnitude of peak flood reduced by a mean semi variance or loss rate percentage value of 6.38%, 5.22% and 5.23% over Gilgel Abay sub basin for 5, 25 and 100 years of return period respectively. 2). For a mean separation distance of 2023.01 meter the magnitude of peak flood reduced by 1.94%, 1.932% and 1.47% over Rib sub basin for 5, 25 and 100 years of return period respectively and 3) Lastly; With a mean distance of 2853.16 meter the flood magnitude diminished by 6.97%, 3.29% and 3.24% over Gumara sub basin for 5, 25 and 100 years of return period respectively.