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Decisions on stress periods to be used in calibration of Eastern Snake Plain Aquifer Model Version 2. Technical report 20080x. ESPAM2 design document DDM-V2-0x ''Stress Periods'' Item Info

This report is a Design Document for the calibration of the Eastern Snake Plain Aquifer Model Version 2 (ESPAM 2). Its goals are similar to the goals of Design Documents for ESPAM 1.1: To provide full transparency of modeling data, decisions and calibration; and to seek input from representatives of various stakeholders so that the resulting product can be the best possible technical representation of the physical system (given constraints of time, funding and personnel). It is anticipated that for some topics, a single Design Document will serve these purposes prior to issuance of a final report. For other topics, a draft document will be followed by one or more revisions and a final "as-built" Design Document. Superseded Design Documents will be maintained in a "superseded" file folder on the project Website, and successive versions will be maintained in a "current" folder. This will provide additional documentation of project history and the development of ideas. The ESPAM 1.1 model was calibrated in 6-month stress periods over the 1980-2001 period and model results were matched to both long term and seasonal variations in aquifer head and Snake River gains and losses. All recharge and discharge events and river stage are assumed constant for the length of a stress period, although aquifer heads may be computed at more frequent time steps. In ESPAM 1.1, the stress periods were selected as May through October (higher recharge irrigation season), and November through April (lower recharge non-irrigation season). Recharge and discharge data for each stress period are assembled and processed in the GIS-Fortran based Recharge Program which will work on stress periods of different lengths. In most cases recharge and discharge data and stream stage are available at a higher frequency than semi-annual periods. During model calibration the outputs of aquifer head and river gains and losses are compared to measured or estimated values. Estimates of the aquifer properties of transmissivity (or hydraulic conductivity) and storativity are adjusted to achieve a good fit between simulated and measured values. These property estimates subsequently control model results in simulations performed to guide aquifer management and administration. A more accurate description of recharge and discharge and river stage as model input should result in a better fit to historic measured values and improved calibration of aquifer properties, ultimately generating greater reliability of management and administrative simulation results. Since recharge, discharge, and river stage must be assumed constant during a stress period, it would seem that the shorter the stress period the more accurate the representation of reality. This is true to the extent that a) data are collected at short intervals, and b) there are not unknown or unrepresented elements of storage or lag in the system.

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Title:
Decisions on stress periods to be used in calibration of Eastern Snake Plain Aquifer Model Version 2. Technical report 20080x. ESPAM2 design document DDM-V2-0x ''Stress Periods''
Authors:
Johnson, Gary S.
Date Created (ISO Standard):
2008-06
Description:
This report is a Design Document for the calibration of the Eastern Snake Plain Aquifer Model Version 2 (ESPAM 2). Its goals are similar to the goals of Design Documents for ESPAM 1.1: To provide full transparency of modeling data, decisions and calibration; and to seek input from representatives of various stakeholders so that the resulting product can be the best possible technical representation of the physical system (given constraints of time, funding and personnel). It is anticipated that for some topics, a single Design Document will serve these purposes prior to issuance of a final report. For other topics, a draft document will be followed by one or more revisions and a final "as-built" Design Document. Superseded Design Documents will be maintained in a "superseded" file folder on the project Website, and successive versions will be maintained in a "current" folder. This will provide additional documentation of project history and the development of ideas. The ESPAM 1.1 model was calibrated in 6-month stress periods over the 1980-2001 period and model results were matched to both long term and seasonal variations in aquifer head and Snake River gains and losses. All recharge and discharge events and river stage are assumed constant for the length of a stress period, although aquifer heads may be computed at more frequent time steps. In ESPAM 1.1, the stress periods were selected as May through October (higher recharge irrigation season), and November through April (lower recharge non-irrigation season). Recharge and discharge data for each stress period are assembled and processed in the GIS-Fortran based Recharge Program which will work on stress periods of different lengths. In most cases recharge and discharge data and stream stage are available at a higher frequency than semi-annual periods. During model calibration the outputs of aquifer head and river gains and losses are compared to measured or estimated values. Estimates of the aquifer properties of transmissivity (or hydraulic conductivity) and storativity are adjusted to achieve a good fit between simulated and measured values. These property estimates subsequently control model results in simulations performed to guide aquifer management and administration. A more accurate description of recharge and discharge and river stage as model input should result in a better fit to historic measured values and improved calibration of aquifer properties, ultimately generating greater reliability of management and administrative simulation results. Since recharge, discharge, and river stage must be assumed constant during a stress period, it would seem that the shorter the stress period the more accurate the representation of reality. This is true to the extent that a) data are collected at short intervals, and b) there are not unknown or unrepresented elements of storage or lag in the system.
Subjects:
Aquifers Computer models Irrigation Water stress
Location:
Eastern Snake Plain Aquifer; Southern Idaho
Latitude:
42.96
Longitude:
-115.13
Collection:
Boise Basin
Series:
ESPAM2
IWRRI number:
200807
Rights:
Rights to the digital resource are held by the University of Idaho. http://www.uidaho.edu/
Publisher:
Idaho Water Resources Research Institute; University of Idaho
Contributing Institution:
University of Idaho
Type:
Text
Format:
application/pdf
Cataloger:
KIT

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Preferred Citation:
"Decisions on stress periods to be used in calibration of Eastern Snake Plain Aquifer Model Version 2. Technical report 20080x. ESPAM2 design document DDM-V2-0x ''Stress Periods''", Idaho Waters Digital Library, University of Idaho Library Digital Collections, https://www.lib.uidaho.edu/digital/iwdl/items/iwdl-200807.html
Rights
Rights:
Rights to the digital resource are held by the University of Idaho. http://www.uidaho.edu/
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