Sagehen Creek Field Station

08 Aug, 11 AM - 19 Aug, 11 AM

This project is a part of US Forest Service Sierra Nevada Meadows Hydrology Assessment Research project supervised by Barry Hill, Regional Hydrologist. Our goal is to conduct water balances for 12 meadows in the national forest. These water budgets will be used to evaluate the role of meadows in regulating groundwater discharge from hillslope and bedrock flow systems for discrete time periods within growing seasons. Information needed for each of these 12 meadows includes:  Representative values for specific yield  Representative values for hydraulic conductivity  Hydraulic head or soil moisture data adequate to determine extent of saturation throughout meadow alluvium and to determine directions of groundwater flow during the monitoring period  Streamflow entering and exiting meadows during the monitoring period  Evapotranspiration and rainfall during the monitoring period For meadows that lack the requisite information, data will be collected as described below. Data will be collected using standard methods such as those used by the U.S. Environmental Protection Agency, U.S. Geological Survey, USDA Forest Service, ASTM methods, or in commonly used references such as Black and others (1965). Groundwater monitoring networks consisting of groups of one well and 2 or 3 piezometers will be installed to measure water table elevations and hydraulic heads. Wells will be installed to bedrock, or as deep as possible. Piezometers will be installed at various depths, with one piezometer in each group installed to bedrock or as deep as possible. Within groups, wells and piezometers will be installed near enough to each other to allow determinations of vertical hydraulic gradients. Groundwater monitoring networks will include an adequate number of wells and piezometers to allow estimation of the water table elevations throughout the meadow and for determination of groundwater flow directions and gradients at meadow margins and along or near gullies and alluvium-bedrock contacts. A combined total of 9 to 18 wells and piezometers will be adequate for most meadows. Water-level measurements will be made periodically in all wells and piezometers at intervals adequate to define seasonal patterns of water-table fluctuations. At least one well and adjacent piezometer per meadow will have submersible pressure transducers and data loggers installed to record diurnal fluctuations. Streamflow measurements will be made at the upstream and downstream ends of each of the 12 meadows to allow periodic determinations of surface-water inflows and outflows. Stage recorders will be installed at the upstream and downstream ends of each meadow, as appropriate. Rainfall, if any, will be measured with simple non-recording covered collection cans (for example, standard National Weather Service 8-inch collection cans). Evapotranspiration will be estimated from available published values for meadows in the Sierra Nevada and will be independently evaluated based on diurnal fluctuations in water-table elevations during and after the growing season. Water budgets for all or parts of the growing season will be used to estimate the volume of water passing from hillslope-bedrock flow systems through meadows and into streams as follows: ΣGWB = Σ(QO ? QI) + Σ(ET ? RF) - ΔSA Where: ΣGWB is the total volume of groundwater contributed to streamflow at the downstream end of the meadow by hillslope and bedrock groundwater flow systems; Σ(QO ? QI) is total volume of water represented by the difference between surface-water inflows and outflows during the monitoring period, as determined by periodic streamflow measurements and stage records; Σ(ET ? RF) is the total volume of water represented by the difference between evapotranspiration and rainfall during the monitoring period; and ΔSA is the decrease in groundwater stored in meadow alluvium during the monitoring period (values will be negative for increases in storage) Groundwater losses to deep percolation in meadows are considered negligible in this water-budget model. This assumption is based on current understanding of meadows as groundwater discharge zones. Hydraulic head data will either verify this assumption or indicate a need to revise it. Deep percolation losses, if any, would increase values of ΔSA, resulting in underestimation of ΣGWB.

Visit #25414 @Sagehen Creek Field Station

Approved

Under Project # 23813 | Research

US Forest Service Sierra Nevada Meadows Hydrology Assessment Research project

research_assistant - University of California, Merced

Reservation Members(s)

Group of 2 Research Assistant (non-student/faculty/postdoc) Aug 8 - 19, 2011 (12 days)
Reza Namdar Ghanbari Aug 8 - 19, 2011 (12 days)

Reserve Resources(s) | Create Invoice

East Cabin (Lower Camp) 3 Aug 8 - 19, 2011
Sagehen Data 3 Aug 8 - 19, 2011