- Dear list members,

I want to perform kriging of water quality indicators

measured in stations along a river course, so Can you

help me with references about kriging along streams in

a river basin?? is there software to perform this kind

of analysis???

Thanks in advance for your help,

Oscar Javier García-Cabrejo

Master in Hydrosystems, Civil Engineering Department

Pontificia Universidad Javeriana

Bogota, Colombia

South America

_________________________________________________________

Do You Yahoo!?

La mejor conexión a internet y 25MB extra a tu correo por $100 al mes. http://net.yahoo.com.mx - Dear Oscar,

It sounds like you need kriging in a single dimension. If so, I think what

you need to do is a kind of coordinate transformation, for example using

river mile as your distance vector. You would also need to pay attention to

the dates of the samples. Variation in time might obscure spatial trends

along the river's course if you just have a few sampling events at different

times for the stations.

If you have data in space as well as time, there are several methods for

space-time interpolation. Constructing correlograms for data vs time on

paired stations could give you an idea of what constitutes a data pair for

kriging purposes in terms of the time lag between them. Methods will differ

depending on whether it is the time or space dimension that is more densely

sampled.

References on techniques include the following:

For straightening rivers (which might be more involved than you need):

Barabas, N., Goovaerts, P. and P. Adriaens. 2001. Geostatistical assessment

and validation of uncertainty for three-dimensional dioxin data from

sediments in an estuarine river. Environmental Science & Technology, 35(16):

3294-3301.

For space-time data:

Pebesma and de Kwaadsteniet (1997) Mapping spatial and temporal variation of

groundwater quality in the Netherlands. In GeoENVI - Geostatistics for

Environmental Applications, eds., Soares et al, pp. 139-151. Kluwer

Academic Publishers, Netherlands.

Kyriakidis and Journel (1999) Geostatistical space-time models: A review.

Mathematical Geology (not sure which volume etc.)

Heuvelink et al (1996) Spatio-temporal kriging of soil water content. In

Geostatistics Wollongong '96, eds Baafi and Schofield. pp. 1020-1030.

Kluwer Academic Publishers,Netherlands.

Noémi

-----Original Message-----

From: oscar garcia [mailto:osgarcia@...]

Sent: Thursday, February 24, 2005 11:56 AM

To: ai-geostats@...

Subject: [ai-geostats] Kriging along streams

Dear list members,

I want to perform kriging of water quality indicators

measured in stations along a river course, so Can you

help me with references about kriging along streams in

a river basin?? is there software to perform this kind

of analysis???

Thanks in advance for your help,

Oscar Javier García-Cabrejo

Master in Hydrosystems, Civil Engineering Department

Pontificia Universidad Javeriana

Bogota, Colombia

South America

_________________________________________________________

Do You Yahoo!?

La mejor conexión a internet y 25MB extra a tu correo por $100 al mes.

http://net.yahoo.com.mx - Noemi, the idea of transforming to a one-dimensional situation,

distance along river, was the first one I got. Then, I rejected

it because it will not work for river networks; it will for a

single sections without joints though. Space-time modelling may

be complicated by the fact that there will be a strong

correlation with future observations downstream, but not with

observations upstream because water flows down; this may call

for another translation of space-time using flow speed to get

to a space-time coordinate system where the usual models make

sense.

--

Edzer

Noemi Barabas wrote:> Dear Oscar,

--

>

> It sounds like you need kriging in a single dimension. If so, I think what

> you need to do is a kind of coordinate transformation, for example using

> river mile as your distance vector. You would also need to pay attention to

> the dates of the samples. Variation in time might obscure spatial trends

> along the river's course if you just have a few sampling events at different

> times for the stations.

>

> If you have data in space as well as time, there are several methods for

> space-time interpolation. Constructing correlograms for data vs time on

> paired stations could give you an idea of what constitutes a data pair for

> kriging purposes in terms of the time lag between them. Methods will differ

> depending on whether it is the time or space dimension that is more densely

> sampled.

>

> References on techniques include the following:

>

> For straightening rivers (which might be more involved than you need):

>

> Barabas, N., Goovaerts, P. and P. Adriaens. 2001. Geostatistical assessment

> and validation of uncertainty for three-dimensional dioxin data from

> sediments in an estuarine river. Environmental Science & Technology, 35(16):

> 3294-3301.

>

> For space-time data:

>

> Pebesma and de Kwaadsteniet (1997) Mapping spatial and temporal variation of

> groundwater quality in the Netherlands. In GeoENVI - Geostatistics for

> Environmental Applications, eds., Soares et al, pp. 139-151. Kluwer

> Academic Publishers, Netherlands.

>

> Kyriakidis and Journel (1999) Geostatistical space-time models: A review.

> Mathematical Geology (not sure which volume etc.)

>

> Heuvelink et al (1996) Spatio-temporal kriging of soil water content. In

> Geostatistics Wollongong '96, eds Baafi and Schofield. pp. 1020-1030.

> Kluwer Academic Publishers,Netherlands.

>

>

> Noémi

>

>

>

> -----Original Message-----

> From: oscar garcia [mailto:osgarcia@...]

> Sent: Thursday, February 24, 2005 11:56 AM

> To: ai-geostats@...

> Subject: [ai-geostats] Kriging along streams

>

>

> Dear list members,

>

> I want to perform kriging of water quality indicators

> measured in stations along a river course, so Can you

> help me with references about kriging along streams in

> a river basin?? is there software to perform this kind

> of analysis???

>

> Thanks in advance for your help,

>

> Oscar Javier García-Cabrejo

> Master in Hydrosystems, Civil Engineering Department

> Pontificia Universidad Javeriana

> Bogota, Colombia

> South America

>

> _________________________________________________________

> Do You Yahoo!?

> La mejor conexión a internet y 25MB extra a tu correo por $100 al mes.

> http://net.yahoo.com.mx

>

>

>

>

> ------------------------------------------------------------------------

>

> * By using the ai-geostats mailing list you agree to follow its rules

> ( see http://www.ai-geostats.org/help_ai-geostats.htm )

>

> * To unsubscribe to ai-geostats, send the following in the subject or in the body (plain text format) of an email message to sympa@...

>

> Signoff ai-geostats

Edzer Additional space-time references

- 2003, De Iaco, S, Myers, D.E., and Posa, D., The Linear Coregionalization Model and the Product-Sum Space-Time Variogram. Mathematical Geology 35, 25-38
- 2002, S. De Ioca, D.E. Myers and D. Posa,
Space-time variograms and a funct\
ional form for total air pollution measures.
*Computational Statistics and Da\ ta Analysis*41, 311-328. - 2000, S. De Iaco, D.E. Myers and D. Posa, Total Air Pollution and
Space-Tim
e Modeling. in Monestiez P., Allard D. and Froidevaux R., Eds,
*geoENV III, Geostatistics for Environmental Applications*, Kluwer Academic Publ., 45-56 - 2002, D.E. Myers, Space-time correlation models and contaminant
plumes.
*Environmetrics*13, 535-554 (papers from the Fourth Int. Conference on Envi ronmetrics and Chemometrics, Las Vegas, NV Sept. 2000) - 2002, S. De Iaco, D.E. Myers and D. Posa, Nonseparable space-time
covariance models:some parametric families.
*Mathematical Geology*34, 23-42 - 2002,
D.E. Myers, S. De Iaco, D. Posa and L. De Cesare, Space-Time
Radial Basis Functions, in a special
issue of
*Computers and Math. Applications*34, 539-549

- 2000, L. De Cesare, D.E. Myers and D. Posa,
FORTRAN Programs for Space-Time\ Modeling.ACM
citation
*Computers & Geosciences*28, 205-212 - 2001,
S. De Iaco, D.E. Myers and D. Posa,Space-time
analysis using a general product-sum model.
*Statistics and Probability Letters*52, 1, 21-28. - 2001,
L. De Cesare, D.E. Myers and D. Posa,
Estimating and Modeling Space-Time Correlation Structures,
*Statistics and Probability Letters*51/1, 9-14 - 2000, L. De Cesare, D.E. Myers and D. Posa, Product-sum
covariance for space-time modeling: an environmental application.
*Environmetrics*12, 11-23 - 1997, L. De Cesare, D. E. Myers and D. Posa, Spatial Temporal
Modeling
of SO2 in the Milan District. in
*Geostatistics Wollong '96*, E.Y. Baafi and N.A. Schofield (eds), Kluwer academic Publishers, 1031-1042

Donald E. Myers

Noemi Barabas wrote:Dear Oscar, It sounds like you need kriging in a single dimension. If so, I think what you need to do is a kind of coordinate transformation, for example using river mile as your distance vector. You would also need to pay attention to the dates of the samples. Variation in time might obscure spatial trends along the river's course if you just have a few sampling events at different times for the stations. If you have data in space as well as time, there are several methods for space-time interpolation. Constructing correlograms for data vs time on paired stations could give you an idea of what constitutes a data pair for kriging purposes in terms of the time lag between them. Methods will differ depending on whether it is the time or space dimension that is more densely sampled. References on techniques include the following: For straightening rivers (which might be more involved than you need): Barabas, N., Goovaerts, P. and P. Adriaens. 2001. Geostatistical assessment and validation of uncertainty for three-dimensional dioxin data from sediments in an estuarine river. Environmental Science & Technology, 35(16): 3294-3301. For space-time data: Pebesma and de Kwaadsteniet (1997) Mapping spatial and temporal variation of groundwater quality in the Netherlands. In GeoENVI - Geostatistics for Environmental Applications, eds., Soares et al, pp. 139-151. Kluwer Academic Publishers, Netherlands. Kyriakidis and Journel (1999) Geostatistical space-time models: A review. Mathematical Geology (not sure which volume etc.) Heuvelink et al (1996) Spatio-temporal kriging of soil water content. In Geostatistics Wollongong '96, eds Baafi and Schofield. pp. 1020-1030. Kluwer Academic Publishers,Netherlands. Noémi -----Original Message----- From: oscar garcia [mailto:osgarcia@...] Sent: Thursday, February 24, 2005 11:56 AM To: ai-geostats@... Subject: [ai-geostats] Kriging along streams Dear list members, I want to perform kriging of water quality indicators measured in stations along a river course, so Can you help me with references about kriging along streams in a river basin?? is there software to perform this kind of analysis??? Thanks in advance for your help, Oscar Javier García-Cabrejo Master in Hydrosystems, Civil Engineering Department Pontificia Universidad Javeriana Bogota, Colombia South America _________________________________________________________ Do You Yahoo!? La mejor conexión a internet y 25MB extra a tu correo por $100 al mes. http://net.yahoo.com.mx

* By using the ai-geostats mailing list you agree to follow its rules ( see http://www.ai-geostats.org/help_ai-geostats.htm ) * To unsubscribe to ai-geostats, send the following in the subject or in the body (plain text format) of an email message to sympa@... Signoff ai-geostats- Edzer,

You are right about river networks.

I do think that the uni-directionality of flow is not necessarily a problem

in terms of what can inform what. Statistically, a downstream station can

inform an upstream station because what is downstream is there because of

what happened upstream, and the same for past and future. While there may

not be a *physical* link from future to past, there will still be a

*statistical* link from future to past as long as there was a statistical

link from past to future. [That is the idea in inverse modeling for example

(which are a combination of physical and statistical modeling)].

Intuitively, kriging backwards might have to be done according to a

different model than forward, but, I am open to surprises. It is worth a

try, anyway.

Noémi

-----Original Message-----

From: Edzer J. Pebesma [mailto:e.pebesma@...]

Sent: Thursday, February 24, 2005 5:19 PM

To: Noemi Barabas

Cc: oscar garcia; ai-geostats@...

Subject: Re: [ai-geostats] Kriging along streams

Noemi, the idea of transforming to a one-dimensional situation,

distance along river, was the first one I got. Then, I rejected

it because it will not work for river networks; it will for a

single sections without joints though. Space-time modelling may

be complicated by the fact that there will be a strong

correlation with future observations downstream, but not with

observations upstream because water flows down; this may call

for another translation of space-time using flow speed to get

to a space-time coordinate system where the usual models make

sense.

--

Edzer

Noemi Barabas wrote:> Dear Oscar,

what

>

> It sounds like you need kriging in a single dimension. If so, I think

> you need to do is a kind of coordinate transformation, for example using

to

> river mile as your distance vector. You would also need to pay attention

> the dates of the samples. Variation in time might obscure spatial trends

different

> along the river's course if you just have a few sampling events at

> times for the stations.

differ

>

> If you have data in space as well as time, there are several methods for

> space-time interpolation. Constructing correlograms for data vs time on

> paired stations could give you an idea of what constitutes a data pair for

> kriging purposes in terms of the time lag between them. Methods will

> depending on whether it is the time or space dimension that is more

densely

> sampled.

assessment

>

> References on techniques include the following:

>

> For straightening rivers (which might be more involved than you need):

>

> Barabas, N., Goovaerts, P. and P. Adriaens. 2001. Geostatistical

> and validation of uncertainty for three-dimensional dioxin data from

35(16):

> sediments in an estuarine river. Environmental Science & Technology,

> 3294-3301.

of

>

> For space-time data:

>

> Pebesma and de Kwaadsteniet (1997) Mapping spatial and temporal variation

> groundwater quality in the Netherlands. In GeoENVI - Geostatistics for

the body (plain text format) of an email message to sympa@...

> Environmental Applications, eds., Soares et al, pp. 139-151. Kluwer

> Academic Publishers, Netherlands.

>

> Kyriakidis and Journel (1999) Geostatistical space-time models: A review.

> Mathematical Geology (not sure which volume etc.)

>

> Heuvelink et al (1996) Spatio-temporal kriging of soil water content. In

> Geostatistics Wollongong '96, eds Baafi and Schofield. pp. 1020-1030.

> Kluwer Academic Publishers,Netherlands.

>

>

> Noémi

>

>

>

> -----Original Message-----

> From: oscar garcia [mailto:osgarcia@...]

> Sent: Thursday, February 24, 2005 11:56 AM

> To: ai-geostats@...

> Subject: [ai-geostats] Kriging along streams

>

>

> Dear list members,

>

> I want to perform kriging of water quality indicators

> measured in stations along a river course, so Can you

> help me with references about kriging along streams in

> a river basin?? is there software to perform this kind

> of analysis???

>

> Thanks in advance for your help,

>

> Oscar Javier García-Cabrejo

> Master in Hydrosystems, Civil Engineering Department

> Pontificia Universidad Javeriana

> Bogota, Colombia

> South America

>

> _________________________________________________________

> Do You Yahoo!?

> La mejor conexión a internet y 25MB extra a tu correo por $100 al mes.

> http://net.yahoo.com.mx

>

>

>

>

> ------------------------------------------------------------------------

>

> * By using the ai-geostats mailing list you agree to follow its rules

> ( see http://www.ai-geostats.org/help_ai-geostats.htm )

>

> * To unsubscribe to ai-geostats, send the following in the subject or in

>

--

> Signoff ai-geostats

Edzer