Veerle - Over the past few years, Rocky Flats Environmental Technology Site (RFETS) in Colorado has performed a similar study as part of the Actinide Migration Evaluation (AME). They are concerned about actinides (plutonium and americium) being eroded from surface soils and inpacting surface waters. The ability to predict sedimentation is a function of many items, not just the number and placement of samples. Also important are the number of rainfall events per year, how early in the spring the occur, their intensity, duration, and spacing, the particle size fractions in the soils, soil type, hydraulic conductivity, vegetation cover, rill and interrill hillslope flow, and the presence of unpaved roadways, just to name a few. We used a four-fold modeling system to estimate actinide concentrations in surface runoff: Geostatistical, GIS, Hillslope erosion, and Stream Channel sediment transport. As a result of the AME, we were able to produce maps showing areas of erosion and sedimentation across the site.
I'm afraid there isn't a real simple answer to your question. For example, certain storm events will cause more sedimentation in some locations than in others. Small storms may cause sedimentation to occur in some areas that will lateer be eroded by a larger storm event. The number of samples will also be related to the complexity of the topography and the complexity of the stream network. The AME report was available electonically before September 11, 2001, but the RFETS website where it was located has been down since that time. If it comes back up, I will let you know. Jeff Myers Fellow Engineer Westinghouse Safety Management Solutions 2131 S. Centennial Ave., SE Aiken, SC 29803 803.502.9747 (direct) 803.502.9767 (main) 803.502.2747 (fax) 803.221.1141 (cell) email: [EMAIL PROTECTED] website: http://www.gemdqos.com -----Original Message----- From: Veerle Huvenne [mailto:[EMAIL PROTECTED]] Sent: Tuesday, February 12, 2002 9:51 AM To: [EMAIL PROTECTED]; [EMAIL PROTECTED] Subject: AI-GEOSTATS: sampling strategy Hello Ai-geostats list members, A collegue of mine has the following question concerning sampling strategy : Given : a test site at which the effect of sedimentation/erosion has to be checked regularly (say every year). To start off with, the topography of the area is known. The first year the elevation is measured in a set of discrete points (say some 10 to 15 locations). From this one can gather already some information as to where there has been sedimentation and erosion. The following years, measurements are planned at the same locations. However, now comes the question : is there any rule of thumb, theory, calculation,... which allows to decide if more or less samples/measurements are necessary to achieve a certain precision in the mapping of erosion/sedimentation, given the information which can be derived from the measurements taken in the first year? If it is needed to plan more sample points, where should they be placed? In the areas of highest sedimentation/erosion? Or is it better to just choose a denser sampling grid? Has anybody any information on this? I know it's always difficult to plan a sampling design because one does not know what one will find in the test site, but this time there is some preliminary information already due to the measurements made during the first year. It seems to me this might change the way of looking at the problem. Or not? Looking forward to your answers, and thanks for your help Veerle -- Veerle Huvenne Renard Centre of Marine Geology University of Ghent Krijgslaan 281, S8 9000 Gent, Belgium +32/9/264.45.84 -- * To post a message to the list, send it to [EMAIL PROTECTED] * As a general service to the users, please remember to post a summary of any useful responses to your questions. * To unsubscribe, send an email to [EMAIL PROTECTED] with no subject and "unsubscribe ai-geostats" followed by "end" on the next line in the message body. DO NOT SEND Subscribe/Unsubscribe requests to the list * Support to the list is provided at http://www.ai-geostats.org -- * To post a message to the list, send it to [EMAIL PROTECTED] * As a general service to the users, please remember to post a summary of any useful responses to your questions. * To unsubscribe, send an email to [EMAIL PROTECTED] with no subject and "unsubscribe ai-geostats" followed by "end" on the next line in the message body. DO NOT SEND Subscribe/Unsubscribe requests to the list * Support to the list is provided at http://www.ai-geostats.org
