General Hydrology

CGU-CSSS 2014
ANNUAL MEETING
Banff Park Lodge, Banff, AB
Conference website:
www.ucalgary.ca/~cguconf
www.cgu-ugc.ca
www.csss.ca
SESSION: H6-2 General Hydrology, Part II
Conveners: S. Carey, McMaster University & W. Quinton, Wilfrid Laurier University
Monday, May 5th, 2014
Chairs: S. Carey & W. Quinton
Room: Summit
TIME
AUTHORS
TITLE
10:30
X. Fu, C.C. Kuo & T.Y. Gan
Change Point Analysis of Precipitation Indices
of Western Canada
10:45
C.C. Kuo, T.Y. Gan, M.
Hanrahan & S. Chan
Precipitation Frequency Analysis Based on
Regional Climate Simulations in Central Alberta
11:00
S. Gurrapu, J.-M. St. Jacques,
D. J. Sauchyn & K. Hodder
Flood Risk Variability in the Canadian
Southwestern Prairie Rivers
11:15
P.H. Whitfield & K.R. Shook
Changes to Autumnal Streamflow Features in
the Rocky Mountains of North American
11:30
C.C. Kuo, T.Y. Gan, M. Gizaw
& S. Chan
Potential Impact of Climate Change on Intensity
Duration Frequency Curves of Central Alberta
11:45
R. Soulis, D. Princz, H .
Farghaly & M. Naeem
MTO Intensity-Duration-Frequency (IDF) Curve
Renewal - Phase III: Validation of the
Interpolation Tool
Change Point Analysis of Precipitation Indices of Western Canada
1
2
X. Fu1, C.C. Kuo2 & T.Y. Gan2
Stantec Consulting Engineers, Lethbridge, AB
Dept of Civil & Environmental Engineering, University of Alberta, Edmonton, AB
Tel: 780-492-9376; Fax:780-492-8289; [email protected]
The Markov chain statistical technique and 20 years of historical meteorological data per climate
station was employed to gap fill few missing values of daily precipitation observed at 6 (or 7
stations?) long-term (≥ 50 years of data) climate stations of Western Canada. Statistical properties
of the gap filled precipitation data are compared with those of the original data (before gap filling)
to ensure that this approach preserves the statistical characteristics of the historical data. After gap
filling missing data, ten precipitation indices that represent magnitude and frequency of
precipitation properties were computed from those 7 stations and the other 23 stations without
any recorded gap. Next, the Wilcoxon Rank-Sum test was used to detect possible change points
of these precipitation indices. Based on results obtained for precipitation data collected over the
post-change point periods, there had been an increasing trend in the maximum number of
consecutive wet days and the annual maximum monthly 5-day precipitation, and a decreasing
trend in the maximum number of consecutive dry days over most of Western Canada. Except for
a small area located in southern British Columbia (BC), the annual total precipitation index of
many stations had increased but only about 1/3 of these increasing trends are statistically
significant. However, no consistent change was detected in the number of days when
precipitation is equal and greater than 10 mm or 20 mm, and indices for the annual monthly
maximum 1-day precipitation, precipitation that exceeds the 95 and 99 percentiles, and the simple
precipitation intensity index have decreased but only a few changes are statistically significant.
Based on the above results, the diurnal temperature range (DTR) of western Canada has
decreased, and predominant negative correlations between precipitation indices and DTR, it
seems that Western Canada has generally become wetter since the middle of the 20th century
partly because of narrowing of DTR.
Precipitation Frequency Analysis Based on Regional Climate Simulations in Central
Alberta
1
C.C. Kuo1, T.Y. Gan1, M. Hanrahan2 & S. Chan3
Dept of Civil & Environmental Engineering, University of Alberta, Edmonton AB
Tel: 780-492-9376; Fax:780-492-8289; [email protected]
2
Department of Atmospheric Sciences, Lyndon State College, VT 05851, USA
3
Drainage Services, City of Edmonton, Edmonton, Alberta
A Regional Climate Model (RCM), MM5 (the Fifth Generation Pennsylvania State
University/National Center for Atmospheric Research mesoscale model), is used to
simulate summer precipitation in Central Alberta. MM5 was set up with a one-way,
three-domain nested framework, with domain resolutions of 27, 9, and 3 km, respectively,
and forced with ERA-Interim reanalysis data of ECMWF (European Centre for MediumRange Weather Forecasts). The objective is to develop high resolution, grid-based
Intensity–Duration–Frequency (IDF) curves based on the simulated annual maximums of
precipitation (AMP) data for durations ranging from 15-min to 24-h. The performance of
MM5 was assessed in terms of simulated rainfall intensity, precipitable water, and 2-m
air temperature. Next, the grid-based IDF curves derived from MM5 were compared to
IDF curves derived from six RCMs of the North American Regional Climate Change
Assessment Program (NARCCAP) set up with 50-km grids, driven with NCEPDOE
(National Centers for Environmental Prediction-Department of Energy) Reanalysis II
data, and regional IDF curves derived from observed rain gauge data (RG-IDF). The
analyzed results indicate that 6-h simulated precipitable water and 2-m temperature agree
well with the ERA-Interim reanalysis data. However, compared to RG-IDF curves, IDF
curves based on simulated precipitation data of MM5 are overestimated especially for
IDF curves of 2-year return period. In contract, IDF curves developed from NARCCAP
data suffer from under-estimation and differ more from RG-IDF curves than the MM5
IDF curves. The over-estimation of IDF curves of MM5 was corrected by a quantilebased, bias correction method. By dynamically downscale the ERA-Interim and after bias
correction, it is possible to develop IDF curves useful for regions with limited or no rain
gauge data. This estimation process can be further extended to predict future grid-based
IDF curves subjected to possible climate change impacts based on climate change
projections of GCMs (general circulation models) of IPCC (Intergovernmental Panel on
Climate Change).
Flood Risk Variability in the Canadian Southwestern Prairie Rivers
S. Gurrapu1,2, J.-M. St. Jacques1,2, D.J. Sauchyn1,2 & K. Hodder1
1
Department of Geography, University of Regina, Regina, SK
Phone: 306-337-2298, 306-337-2293, 306-337-2299, 306-585-5127
Email: [email protected], [email protected], [email protected],
[email protected]
2
Prairie Adaptation Research Collaborative (PARC), University of Regina, SK
The hydroclimate of the Canadian Prairies is strongly influenced by atmosphere-ocean oscillations such as
the Pacific Decadal Oscillation (PDO) and the El Niño-Southern Oscillation (ENSO). The negative phase of
PDO typically produces heavier snowpack and streamflow compared to the positive phase. In addition, La
Niña episodes co-occurring during the negative phase of PDO also produce higher snowpack and
streamflow in prairie rivers. However, a general assumption is made in flood frequency analysis that the
annual peak flow records are independently and identically distributed, which might lead to gross under- or
over-estimation of the true long-term flood risk. This study identifies how flood risk in rivers of the
southwestern prairies is modified by the low-frequency PDO and higher-frequency ENSO. Daily averaged
annual peak flow records were stratified according to the PDO phase and ENSO state and fit to a LogPearson III (LP3) distribution. Flood risk at each of the gauging stations was observed to be significantly
different in each phase of the PDO. Less significant differences were seen with ENSO, but there were still
differences in the flood risk depending on whether in an El Niño or La Niña state. To ensure these
differences were not due to sampling error or unequal lengths of the data, a regional index approach was
employed to reveal greater floods in the negative phase of PDO and in the La Niña state of ENSO.
Changes to Autumnal Streamflow Features in the Rocky Mountains of North American
P.H. Whitfield1,2,3 & K.R. Shook4
Centre for Hydrology, University of Saskatchewan, Saskatoon, SK
Phone: (403) 673-3236, Email: [email protected]
2
Department of Earth Science, Simon Fraser University, Burnaby, BC
3
Environment Canada, Vancouver, BC
4
Centre for Hydrology, University of Saskatchewan, Saskatoon, SK
Phone: (306) 652-0065, Email: [email protected]
1
In a warming/warmed climate in mountainous regions we would expect to see a transition from
early winter snowfall to rainfall events. These rainfall events can result in the generation of
runoff by direct overland flow or rain-on-snow runoff or increase the soil moisture status
depending on antecedent conditions. This stands in contrast to the situation in colder conditions
where early winter precipitation tends to occur as snowfall and contributes only to the
accumulation of the seasonal snowpack. In many published studies, changes in the autumnal
climate and hydrology are obvious, but non-significant, because the variability in timing and
magnitude of runoff events. In this study an alternative approach is presented. Shifts in frequency
and duration of autumn rainfall and snowfall are detected from 128 climate stations in the Rocky
Mountains. Similarly, floods occurring in September through December are detected from 128
hydrometric stations in the Rocky Mountains using a baseflow filter. Trends in these events with
respect to flood magnitude, frequency, and duration are then assessed. While significant changes
in all flood attributes are detected at only about 10% of the sites, this is much greater than
expected by chance alone. The spatial distribution of these events and changes in their nature
show important changes in autumnal hydrology as rainfall and rain-on-snow events increase and
suggest that the progression of a shift towards an increasing number of autumnal floods is being
observed.
Potential Impact of Climate Change on Intensity Duration Frequency Curves of Central
Alberta
1
C.C. Kuo1, T.Y. Gan1, M. Gizaw1 & S. Chan2
Dept of Civil & Environmental Engineering, University of Alberta, Edmonton, AB
Phone: 780-492-9376; Fax:780-492-8289; [email protected]
2
Drainage Services, City of Edmonton, Edmonton, AB
Under the effect of climate change, warming likely means that there will be more water vapour in
the atmosphere and extreme storms are expected to occur more frequently and in greater severity,
resulting in municipal Intensity-Duration-Frequency (IDF) curves with higher intensities and
shorter return periods. A regional climate model, MM5 (the Pennsylvania State University /
National Center for Atmospheric Research numerical model), was set up in a one-way, threedomain nested framework to simulate future summer (May to August) precipitation of central
Alberta. MM5 was forced with climate data of four Global Climate Models for the baseline 19712000 and 2011-2100 based on the Special Report on Emissions Scenarios A2, A1B, and B1 of
Intergovernmental Panel on Climate Change. Due to the bias of MM5's simulations, a quantilequantile bias correction method and a regional frequency analysis was applied to derive projected
grid-based IDF curves for central Alberta. In addition, future trends of air temperature and
precipitable water which affect storm pattern and intensity were investigated. Apparently, future
IDF curves show a wide range of increased intensities especially for storms of short durations (≤
1-h). Conversely, the upward shift of future IDF curves (increased intensities) because of
increased air temperature and precipitable water (e.g., projected to be about 2.9 ºC and 29 % in
average by 2071-2100, respectively) means a decrease in return periods of future storms of
similar intensity and duration. Results of this study imply that the impact of climate change could
increase the future risk of flooding in central Alberta.
MTO Intensity-Duration-Frequency (IDF) Curve Renewal - Phase III: Validation of the
Interpolation Tool
R. Soulis1, D. Princz1, H. Farghaly2 & M. Naeem2
1
Department of Civil and Environment Engineering, University of Waterloo, Waterloo, ON
Email: [email protected]
2
Design and Contract Standards Office, Highway Standards Branch,
Ontario Ministry of Transportation, St. Catharines, ON Phone: 905-704-2089,
Email: [email protected] , [email protected]
This paper will describe the work-in-progress, primarily to validate the Intensity-DurationFrequency Curve web interface previously developed for the Design and Contract Standards
Office at the Ministry of Transportation Ontario (MTO). Results will be validated using data
from nearby jurisdictions and by expanding the database to include data recorded at non-network
weather stations within Ontario.
Overall validation of the system will use the recently available results for selected US Great
Lakes states. We expect a good match with some differences due to analysis methods. For
example, the US studies use a three-parameter IDF equation while the MTO model uses a twoparameter version.
Validation of the procedural alternatives selected for the MTO analysis will be performed using
the Ontario Phase I and Phase II results. The base case will be methods recommended in the
MTO Drainage Management Technical Guidelines (1989) for station analysis and the MTO
square grid technique for regionalisation
A weighting technique developed in a previous phase of the project will be adapted to produce a
quality control measure that can be used to manage entry of non-network data. Preliminary tests
suggest that the technique may allow detection of time trends.
Finally, the project will produce an improved web interface that will allow the users to download
their requested storm data, as well as specify specific storm parameters, and provide an onscreen
graphic representing their hydrological footprint.