Premium
Considerations for measuring pressure head and water content in inclined boreholes
Author(s) -
Hinnell A. C.,
Ferré T. P. A.
Publication year - 2008
Publication title -
water resources research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.863
H-Index - 217
eISSN - 1944-7973
pISSN - 0043-1397
DOI - 10.1029/2008wr007122
Subject(s) - borehole , casing , hydraulic head , geology , pressure head , head (geology) , geotechnical engineering , vadose zone , soil science , water content , water flow , pore water pressure , pressure gradient , flow (mathematics) , hydrology (agriculture) , soil water , petroleum engineering , mechanics , geomorphology , engineering , mechanical engineering , oceanography , physics
Angled boreholes have been proposed to improve water content and pressure head monitoring in deep vadose zones by reducing the impact of the borehole on measurements by placing sensors below undisturbed soil. However, the borehole casing distorts the flow field, which may impact measurements made with sensors placed on or in the boreholes. We examined a wide range of soil types, background fluxes, and casing radii and angles of inclination to predict the error in water content and pressure head measurements that arise due to this flow disruption under unit gradient flow. We found that placing pressure head and water content sensors 110° and 120° from the top of the borehole, respectively, minimizes the effects of flow perturbation. Under some conditions, it may be possible to use the perturbation of the flow field caused by the casing to estimate hydraulic parameter values.