Hello,
I'm aware that my question is not really GRASS related, but none of our
GIS experts can help me, so I hope someone here can point me to a
relevant paper or study.
I want to aggregate daily rainfall data of 3 rain gauges in a small
catchment for input in a lumped hydrological model
Herefore, I am using a weighted average, based on the relative area of
the respective Thiessen polygons.
Now I'm looking for a technique to determine the uncertainty on the
result, based on the variability between the 3 rain gauges.
If someone can help me, this would be greatly acknowledged!
Thanks,
Wouter Buytaert
HI,
I'm not so sure about using Thiessen is a really good option. I know
that usually is the easier way, but Goovaerts, P (2000) in
"Geostatistical approaches for incorporating elevation into the spatial
interpolation of rainfall (Journal of Hydrology, 228 (1-2):113-129)"
presents a really good analysis of the different techniques (prior to
incorporate the elevation data) and some tools to improve the
estimations, toghether with analysis of accurancy. He also conclude that
Kriging is a better option.
D.
Hello,
I'm aware that my question is not really GRASS related, but none of our
GIS experts can help me, so I hope someone here can point me to a
relevant paper or study.
I want to aggregate daily rainfall data of 3 rain gauges in a small
catchment for input in a lumped hydrological model
Herefore, I am using a weighted average, based on the relative area of
the respective Thiessen polygons.
Now I'm looking for a technique to determine the uncertainty on the
result, based on the variability between the 3 rain gauges.
If someone can help me, this would be greatly acknowledged!
Thanks,
Wouter Buytaert
-----------------------------------------
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It's informative and essential.
Wouter,
I've done extensive work with precipitation data in the Ohio River Valley in the U.S. (~450,000 km^2) looking at both raingauge and radar derived precipitation accumulations. Generally, I have only looked at monthly, seasonal, and annual amounts. In complex terrain I just have no feel for the strength of the orographic influence at shorter time scales. Having said that, however, from some research that has been done, I know that for isolated storms (some flash flood producing convective events) there can be terrain focusing of the storm cells.
I have used the techniques suggested by Goovaerts (cited below) using ordinary kriging with variable means, but I have not verified the estimates independently yet.
I certainly would like to have a better understanding of the orographic influence at shorter time scales, especially in the Appalachian Mountains of the U.S. which generally have local relief on the order of 1000 m.
Regards,
Tom Adams
DrakeGis wrote:
HI,
I'm not so sure about using Thiessen is a really good option. I know
that usually is the easier way, but Goovaerts, P (2000) in
"Geostatistical approaches for incorporating elevation into the spatial
interpolation of rainfall (Journal of Hydrology, 228 (1-2):113-129)"
presents a really good analysis of the different techniques (prior to
incorporate the elevation data) and some tools to improve the
estimations, toghether with analysis of accurancy. He also conclude that
Kriging is a better option.
D.
Hello,
I'm aware that my question is not really GRASS related, but none of our
GIS experts can help me, so I hope someone here can point me to a
relevant paper or study.
I want to aggregate daily rainfall data of 3 rain gauges in a small
catchment for input in a lumped hydrological model
Herefore, I am using a weighted average, based on the relative area of
the respective Thiessen polygons.
Now I'm looking for a technique to determine the uncertainty on the
result, based on the variability between the 3 rain gauges.
If someone can help me, this would be greatly acknowledged!
Thanks,
Wouter Buytaert
-----------------------------------------
Stay ahead of the information curve.
Receive GIS news and jobs on your desktop daily.
Subscribe today to the GIS CafeNews newsletter.
[ http://www10.giscafe.com/nl/newsletter_subscribe.php ]
It's informative and essential.
--
Thomas E Adams
National Weather Service
Ohio River Forecast Center
1901 South State Route 134
Wilmington, OH 45177
EMAIL: thomas.adams@noaa.gov
VOICE: 937-383-0528
FAX: 937-383-0033