Canadian Dam Association Bulletin - Winter 2018 - 17

climatologies were also used to
derive the Orographic Transposition
Factors (OTFs) and the spatial distribution of the PMP. This approach
is similar to that used in HMRs
55A, 57 and 59 that used the Storm
Separation Method (SSM) to quantify
orographic effects in topographically
significant regions. In contrast to the
SSM methodology, the OTF procedure is significantly more objective
and reproducible.
3.1. Orographic Effects
Orographic effects on rainfall are
explicitly captured in climatological
analyses that use precipitation data
from historical record. These historical rainfall amounts include precipitation that would have accumulated
without topography together with
the amount of additional precipitation (or decreased precipitation) that
accumulated because of the effects of
topography at a surrounding observation site. This relationship between
precipitation frequency climatology
and terrain is also recognized in the
WMO PMP Manual (WMO, 1986 pg.
54 and by the Australian Bureau of
Meteorology (Section 3.1.2.3 of Minty
et al., 1996). Although the orographic
effects at a particular location may
vary from storm to storm, the overall
effect of the topographic influence is
inherently included in the climatology of precipitation that occurred
at that location, assuming that the
climatology is based on storms of the
same type.
For the Elbow River basin, extreme
storm events (PMP-type storms)
include local storms (both individual
thunderstorms and MCSs) and general
storms. Thunderstorms/MCSs are the
primary controlling storm type of the
precipitation frequency climatology at
durations of 6 hours or less, while the
general storms are responsible for the
precipitation frequency climatology
values for durations of 24 hours and
greater. Hence, climatological analyses
of the rainfall data associated with
these storm types adequately reflects
the differences in topographic influences at different locations when evaluated by storm type and duration.
Canadian Dam Association * Winter 2018

The procedure used in this study
to account for orographic effects
determines the differences between
the climatological information at the
in-place storm location and the individual grid point. This is a departure from the SSM used in HMRs
55A, 57, and 59. The SSM used in
the HMRs is highly subjective and
is not reproducible. This is because
there are unknown variables involved
in the computation, specifically
what amount of rainfall would have

accumulated without the topography
(convergence only or free atmospheric
forces precipitation, e.g. HMR 55A
Section 7.1).
The OTF process used in this study
(as well as all AWA PMP studies
where topography plays a major role
in rainfall spatial distribution and
magnitude) reduces the amount of
subjectivity involved and provides
a dataset which is reproducible. By
evaluating the rainfall values for a
range of recurrence intervals at both

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Table of Contents for the Digital Edition of Canadian Dam Association Bulletin - Winter 2018

BOARD OF DIRECTORS
PRESIDENT’S MESSAGE
UPDATING PMP FOR THE ELBOW RIVER: COMPLEX TERRAIN, UNIQUE SOLUTIONS
KELOWNA 2017
CDA AWARDS
ANNUAL GENERAL MEETING 2017
YOUNG PROFESSIONALS UPDATE
DAMS AND DIKES, WIKI STYLE
2017 FINANCE REPORT
CDA 2018 CONFERENCE: THE MANAGEMENT OF AGING DAMS
CDA NEWS BRIEF
BUYERS’ GUIDE AND TRADE LIST
Canadian Dam Association Bulletin - Winter 2018 - Intro
Canadian Dam Association Bulletin - Winter 2018 - cover1
Canadian Dam Association Bulletin - Winter 2018 - cover2
Canadian Dam Association Bulletin - Winter 2018 - 3
Canadian Dam Association Bulletin - Winter 2018 - 4
Canadian Dam Association Bulletin - Winter 2018 - 5
Canadian Dam Association Bulletin - Winter 2018 - 6
Canadian Dam Association Bulletin - Winter 2018 - BOARD OF DIRECTORS
Canadian Dam Association Bulletin - Winter 2018 - PRESIDENT’S MESSAGE
Canadian Dam Association Bulletin - Winter 2018 - 9
Canadian Dam Association Bulletin - Winter 2018 - UPDATING PMP FOR THE ELBOW RIVER: COMPLEX TERRAIN, UNIQUE SOLUTIONS
Canadian Dam Association Bulletin - Winter 2018 - 11
Canadian Dam Association Bulletin - Winter 2018 - 12
Canadian Dam Association Bulletin - Winter 2018 - 13
Canadian Dam Association Bulletin - Winter 2018 - 14
Canadian Dam Association Bulletin - Winter 2018 - 15
Canadian Dam Association Bulletin - Winter 2018 - 16
Canadian Dam Association Bulletin - Winter 2018 - 17
Canadian Dam Association Bulletin - Winter 2018 - 18
Canadian Dam Association Bulletin - Winter 2018 - 19
Canadian Dam Association Bulletin - Winter 2018 - 20
Canadian Dam Association Bulletin - Winter 2018 - 21
Canadian Dam Association Bulletin - Winter 2018 - 22
Canadian Dam Association Bulletin - Winter 2018 - 23
Canadian Dam Association Bulletin - Winter 2018 - 24
Canadian Dam Association Bulletin - Winter 2018 - 25
Canadian Dam Association Bulletin - Winter 2018 - KELOWNA 2017
Canadian Dam Association Bulletin - Winter 2018 - 27
Canadian Dam Association Bulletin - Winter 2018 - CDA AWARDS
Canadian Dam Association Bulletin - Winter 2018 - 29
Canadian Dam Association Bulletin - Winter 2018 - ANNUAL GENERAL MEETING 2017
Canadian Dam Association Bulletin - Winter 2018 - 31
Canadian Dam Association Bulletin - Winter 2018 - YOUNG PROFESSIONALS UPDATE
Canadian Dam Association Bulletin - Winter 2018 - 33
Canadian Dam Association Bulletin - Winter 2018 - DAMS AND DIKES, WIKI STYLE
Canadian Dam Association Bulletin - Winter 2018 - 35
Canadian Dam Association Bulletin - Winter 2018 - 2017 FINANCE REPORT
Canadian Dam Association Bulletin - Winter 2018 - 37
Canadian Dam Association Bulletin - Winter 2018 - 38
Canadian Dam Association Bulletin - Winter 2018 - 39
Canadian Dam Association Bulletin - Winter 2018 - CDA 2018 CONFERENCE: THE MANAGEMENT OF AGING DAMS
Canadian Dam Association Bulletin - Winter 2018 - 41
Canadian Dam Association Bulletin - Winter 2018 - CDA NEWS BRIEF
Canadian Dam Association Bulletin - Winter 2018 - 43
Canadian Dam Association Bulletin - Winter 2018 - 44
Canadian Dam Association Bulletin - Winter 2018 - BUYERS’ GUIDE AND TRADE LIST
Canadian Dam Association Bulletin - Winter 2018 - 46
Canadian Dam Association Bulletin - Winter 2018 - cover3
Canadian Dam Association Bulletin - Winter 2018 - cover4
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