X hits on this document

PDF document

Parameter Sensitivity in Hydrologic Modeling - page 137 / 163

401 views

0 shares

0 downloads

0 comments

137 / 163

map-based methods in that map features can be “zoomed-in” or magnified to better understand flow paths. In this study each area was digitized two ways: by attempting to incorporate the effect of urban infrastructure such as major highways, and by disregarding this infrastructure. The on-screen digitizing results show that area and longest flow path measurements for Area 3 closely resemble

results derived from derived using paper

automated processes using DEMs,

map-based

methods.

This

result

associated

with

physically

measuring

parameters

with

more so indicates a map

than results that errors wheel and

planimeter largely contribute to the variation in area and longest flow path for Area 3. For on-screen digitizing of larger areas, the measurement error the subjective nature of the delineation process is small when compared error due to hand-held measurement techniques applied to paper maps.

values due to to the

6.1.3

Parameter Extraction Using Automated Methods

DEM analysis in WMS (Watershed Modeling System) and CRWR-PrePro presents errors associated with data resolution and accuracy in describing the physical characteristics of a surface. DEM resolution affects the channel length, area, slope, and perimeter measurements. If the DEM resolution is too low, small changes in terrain are not observed and small areas may not accurately be described. If the resolution of the DEM is very high, channel lengths become larger due to more tortuous flow paths. This study showed that flow paths for the 10 meter DEM were longer than flow paths for the 30 meter DEM for all three areas as determined in both WMS and CRWR-PrePro. For Area 1 there was a 4%

127

Document info
Document views401
Page views401
Page last viewedWed Dec 07 08:45:05 UTC 2016
Pages163
Paragraphs3546
Words25756

Comments