HR: 16:55h
AN: H12I-04 INVITED     [PDF]
TI: Atmospheric and land surface measurements in a prototype hydrologic observatory
AU: * Scanlon, B
EM: bridget.scanlon@beg.utexas.edu
AF: U of Texas, Bureau of Economic Geology, Austin, TX 78713 United States
AU: Krajewski, W
EM: vitold-krajewski@uiowa.edu
AF: U of Iowa, Civil and Environ. Eng., Iowa City, IA 52242 United States
AU: Famiglietti, J
EM: jfamigli@uci.edu
AF: U of California, Earth System Science, Irvine, CA 92697 United States
AU: Duffy, C
AF: Pennsylvania State U, Civil Eng, Univ Park, 16802
AB: Quantifying spatial and temporal variability in fluxes across interfaces and storage within reservoirs is critical for understanding the water cycle. The interfaces being considered in this presentation on the Neuse basin prototype hydrologic observatory (HO) include the land surface - atmosphere and land surface - groundwater. Critical fluxes include precipitation, infiltration, evapotranspiration and energy balance, and groundwater recharge; soil water storage in the unsaturated zone is an important determinant of flux partitioning at either interface. A companion presentation in this session (Genereux et al.) focuses on fluxes of water and solutes related to groundwater-surface water interfaces and surface water flow. The proposed measurement approach combines remote sensing and in-situ measurements to cover a wide range in spatial (1 m2 - 10,000 km2) scales. High-resolution precipitation maps will be provided by a combination of NEXRAD data and an enhanced ground-based network of rain gauges, disdrometers, and profilers. Evapotranspiration and energy balance fluxes will be monitored at several locations to characterize spatial patterns and process controls. Measurements of water content and matric potential will be co-located in the unsaturated zone to develop in situ water retention functions and to test existing pedotransfer functions for translating basic soils data to hydraulic parameters for modeling. Subsurface water fluxes in the unsaturated zone will also be estimated using newly developed fluxmeters. Co-located unsaturated and saturated zone instrumentation will be used to measure vertical and horizontal gradients to determine flux direction and to quantify fluxes using modeling. Fluxes in the unsaturated zone below the root zone may be equated to groundwater recharge. In addition, environmental tracers (tritium/helium and chlorofluorocarbons) will be measured in groundwater to estimate recharge rates. Ground-based measurements will be located in different microclimate, vegetation, land use, and soils regions to assess the relative importance of these parameters as controls on fluxes and to provide baseline data for predicting potential impacts of future climate and land use change on these fluxes. Critical parameters for hydrological modeling will be included in the measurement design. Although this prototype HO focuses on a porous media system in a humid environment, many of the design aspects are generic and should apply to HOs in other settings (fractured media, arid settings). Another goal of the program is to locate ground-based measurement stations to provide ground referencing for satellite systems. An example application is the use of satellite data (LandSat TM, AVHRR, and MODIS) to estimate ET with comparison to ground-based systems (Eddy Covariance/Bowen Ratio) and scintillometers. The use of Advanced Microwave Scanning Radiometer (AMSR-E) for monitoring soil moisture will also be evaluated using ground-based water content monitoring and field campaigns. Precipitation gauge clusters will be optimally located to evaluate NEXRAD and satellite precipitation data. Understanding the correlation between satellite and ground-based data is essential because spaceborne observations provide spatially and temporally distributed measurements and a framework for scaling local measurements to regional areas. The HO networks will provide valuable information on many aspects of the water cycle to advance our understanding on controls on spatial and temporal variability in fluxes across interfaces.
DE: 1836 Hydrologic budget (1655)
DE: 1848 Networks
SC: Hydrology [H]
MN: 2003 Fall Meeting