HyTests: A
set of numerical models for hydrogeologic parameter estimation
Gonzalo Pulido and Thomas P. Ballestero
University of New Hampshire. Durham, NH
Bedrock Bioremediation Center
Output results consist of
modeled drawdowns at each monitoring well.
These are statistically and
graphically compared with the measured drawdowns. The input parameter data can then be modified until a
satisfactory fit between computed and observed data is achieved.
+ q
(1)
Main Features:
üHydraulic parameter
estimation for heterogeneous formations
üVariable
flowrate pumping test analyses
üHydraulic
tests starting in non-equilibrium conditions
üSlug
test analyses for tested well and monitoring wells
üNon-Linear
Losses can be included
üDrawdown
cone and Reynolds Number assessment
Input data are
incorporated into three windows, which allow specifying:
•the general character of the
model,
•the field data, and
•the assumed hydraulic parameters
During Processing, drawdown cone and Reynolds Number are shown in real time, and can be saved for post-processing analyses
Example HyTests application for hydraulic parameter estimation using a slug test conducted in an isolated interval of a well completed in a fractured bedrock formation. A homogeneous model fails to reproduce the measured data. A radial heterogeneous model, consisting of two concentric zones, fit the field data with a Measured Percent Error MPE = 1.52 +/- 1.47 % relative to the maximum drawdown. [Inner zone radius 6.56 ft, T=2.17 m2/day; outer zone T = 14.5 m2/day]
Pumping Test analysis by HyTests in well BBC4 completed in a fractured bedrock formation
HyTests models solve the respective (1-D, 2-D, 3-D) transient,
saturated groundwater flow equation:
Where: s is drawdown [m], T is the
Transmissivity (T [m2/s]), t is elapsed time since initiation of the hydraulic test, S is the dimensionless Storage Coefficient of the formation, and q [m/s] is the inflow per unit area.
HyTests is a JAVA
application used for the interpretation of Hydraulic Test (HT) field data.
It is meant to assist identifying
formation: hydrogeologic units,
hydraulic parameters, and
boundary conditions. Two HyTests numerical models are presented: a 1D Finite–Difference radial-flow model (homogeneous formations or radial heterogeneous formations - Rushton and Redshaw, 1979), and a 2D Finite–Element model for horizontally–heterogeneous formations (Istok, 1989).
The radial flow model was
successfully validated against synthetic and field HT data. HyTests assisted in the
hydrogeologic characterization of a
fractured bedrock formation (Pulido et.al, 2003). It can be
downloaded FREE at
http://www.unh.edu/erg/bbc/
References
•Istok J (1989) Groundwater modeling by the finite element method, 1st edition.
American Geophysical Union,
Water Resources Monograph 13, Washington, DC, 495 pp •Pulido G, Ballestero TP, Barrera MI, Marbet HJ and Kinner NE (2003) Developing a conceptual hydrogeological model for a fractured bedrock formation. Oral presentation in the International Conference on Groundwater in Fractured Rocks, Prague.
•Ruston KR and Redshaw SC (1979) Seepage and groundwater flow, 1st edition. John Wiley & Sons,
Norwich, 339 pp
Acknowledgment
This
research was performed under US EPA contract
CR
827878-01-0
