Hi Bob
Thank you for the useful references
I forgot to mention the fact that sometime when you detrend hydraulic
head data using topography it could happen that the remaining
residuals show a pure nugget effect (i.e. all the spatial continuity
is described by the trend).
Then, (do you agree?) if you use depth to water (i.e. calculate the
residuals subtracting the elevation) you could still have a trend.
Sometime, in mountain you have that the water depth decreases with
elevation: this is because the "water table" surface is not parallel
with topography but converges to topographic surface going downhill.
Bye
Sebastiano
At 01.04 22/08/2006, Bob Harrington wrote:
M.J. Abedini wrote:
Another issue regarding detrending concerns with variogram modeling
when trend coefficients are not given (i.e., unknown). I found
literature on this issue very disparate. Any comments regarding
unified approach on variogram modeling will be greatly appreciated.
This is not a unified approach, but considering Sebastiano
Trevisani's suggestion of using topography as an external drift
variable for kriging hydraulic head, the residual is simply depth to
water from the land surface. Depth to water is typically available
(or easily derivable from the DEM and head data) and the residual
variogram could be modeled directly from depth to water.
--
Bob Harrington, Hydrologist
Inyo County Water Department
163 May St.
Bishop, CA 93514
(760) 872-1168
[EMAIL PROTECTED]
+
+ To post a message to the list, send it to [email protected]
+ To unsubscribe, send email to majordomo@ jrc.it with no subject
and "unsubscribe ai-geostats" in the message body. DO NOT SEND
Subscribe/Unsubscribe requests to the list
+ As a general service to list users, please remember to post a
summary of any useful responses to your questions.
+ Support to the forum can be found at http://www.ai-geostats.org/
+
+ To post a message to the list, send it to [email protected]
+ To unsubscribe, send email to majordomo@ jrc.it with no subject and "unsubscribe
ai-geostats" in the message body. DO NOT SEND Subscribe/Unsubscribe requests to the
list
+ As a general service to list users, please remember to post a summary of any
useful responses to your questions.
+ Support to the forum can be found at http://www.ai-geostats.org/
