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The mission of the Hydrology and Remote Sensing Laboratory is to conduct nationally orientated basic and applied research on water resources and remote sensing concerns related to the production of food and fiber and the conservation of natural resources.
The Hydrology and Remote Sensing Laboratory is one of 14 laboratories in the Animal and Natural Resources Institute at the Beltsville Agricultural Research Center. The Hydrology and Remote Sensing Laboratory was established in 1961. There are currently 7 research scientists and 4 support scientists who are involved in one or more of the following major research areas:
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Quantifying Environmental Hydrology to Mitigate Detrimental Chemical FluxesThe overall objective is to develop and evaluate methods for quantifying atmospheric, surface, and subsurface fluxes of water, nutrients, and pesticides at field, watershed, and regional scales and to develop and evaluate methods for identifying water and chemical source areas within a watershed and design and evaluate management recommendations and practices for mitigating environmental degradation. |
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Spectral and spatial measurements and modeling to improve nutrient management and environmental qualityThe overall objective is to exploit the spectral, spatial, temporal, and bidirectional domains of remotely sensed data for the extraction of quantitative physical and physiological information about vegetation and soils. |
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Integrating Remote Sensing, Climate and Hydrology for Evaluating Water, Energy and Carbon CyclesThe overall objective is to develop process-based land surface algorithms and models using remote sensing technology and evaluate their utility for mapping surface states (i.e., soil moisture, surface temperature, vegetation cover, landscape roughness, soil erosion distribution, etc.) and water, energy and carbon fluxes from field and farm to watershed, regional and ultimately global scales. |
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Development and evaluation of new remote sensing technologies to assess food and fiber productionThe overall objective is to develop and integrate new methods for the retrieval of soil and crop information using remote sensing and complementary technologies. |
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Soil Hydraulic PropertiesPreferential movement of surface applied chemicals to the groundwater has resulted in a need to physically model the movement of water into and through the soil. Knowledge of the matrix and macropore soil hydraulic properties is critical to describing these field scale processes. Methods were developed using fractal principles to describe macropores. The Marshall saturated hydraulic conductivity equation was modified to predict the hydraulic conductivity based on soil properties. This development enables the use of domain concept for modeling both macropores and matrix flow in soils; thus, allowing the identification of potential pollutant paths and the evaluation of agricultural practices on these pathsWalter Rawls: wrawls@hydrolab.arsusda.gov Rawls, W.J., D.L. Brakensiek, and S.D. Logsdon. 1996. Estimation of macropore properties for no till soils. Transactions ASAE. 39(1): 91-95. |
Tilled Field |
Top View |
No-till Field |
Volatilization and leaching losses of agricultural chemicals are not only an economic loss to the farmer but pose a threat to water quality. If truly sustainable production systems are to be developed, methods for accurately quantifying the effect of various production practices on chemical behavior must be developed. Recently, complex photographic techniques and image analysis of a soluble dye were linked to bromide tracer and pesticide leachate concentrations so that the effect of tillage on spatial flow patterns could be determined and visualized. Visual observations and chemical breakthrough curves showed that preferential chemical transport was common under both tillage regimes. However unlike the flow pathways observed in the tilled field, no-tillage flow pathways were associated with bio-pores. The bio-pores were not only effective in transporting the applied chemical but gave evidence of enhanced microbial activity. As a result, linkage of preferential flow pathways and microbial activity will not only be paramount to the development of production systems but also for modeling efforts that attempt to accurately simulate the impact of agricultural chemicals in the field.
Tim Gish: tgish@hydrolab.arsusda.gov
T.J. Gish, A. Shirmohammadi, R. Vyravipillai, and B.J. Wienhold. 1995. Herbicide leaching under tilled and no-tillage fields. Soil Sci. Soc. Am J. 59:895-901.
Grass Hedges for Erosion ControlConcentrated flow erosion is a major concern in agricultural areas around the world. In a series of recent studies, quantitative data has been collected showing that narrow, stiff grass hedges act as a filter to slow and broaden the flow area, resulting in ponding that increases settling times for suspended material to be deposited. This causes the development of terraces that further reduce the steepness of slopes giving even larger areas for the water to spread. Narrow, stiff grass hedges should not be seen as a panacea but as another tool to control soil loss from agricultural fields. Stiff grass hedges are an alternative conservation practice for reducing soil loss and dispersing runoff from areas of concentrated flow erosion in agricultural fields.Jerry Ritchie: jritchie@hydrolab.arsusda.gov Ritchie, J.C., W.D. Kemper and J.M. Englert. 1997. Narrow stiff grass hedges for erosion control, pp.195-204. In: D.E. Walling and J.-L. Probst (eds.), Human impact on erosion and sedimentation, Intl. Assoc. Hydrological Sci. Publ. No. 245. |
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The capability to compute spatially distributed energy and water fluxes over a basin is essential for identifying sources and sinks of hydrologic, atmospheric and biogeochemical fluxes. Remote sensing information provides key spatial information which has been used in operational models for extrapolating local fluxes to whole basins. This technique has been tested at field and basin scales over agricultural and natural landscapes. For area averaged regional scale fluxes, similarity formulations for the atmospheric boundary layer have been combined with surface temperature and reflectance data collected over large areas. The models developed are the first of their kind for computing all components of the energy balance in a spatially distributed manner using primarily remote sensing technology in climate and hydrologic research. The model-derived fluxes will provide one of the few independent methods for evaluating new techniques and concepts used in prognostic hydrologic and climate models for computing spatially distributed fluxes at regional scales. |
| Bill Kustas: bkustas@hydrolab.arsusda.gov
Kustas. W.P., T.J. Schmugge and L.E. Hipps. 1996. On using mixed-layer transport parametrizations with radiometric surface temperature for computing regional scale sensible heat. Boundary-Layer Meteorology. pp. 205-221. | |
| Measurement of landscape surface properties have been made using a laser altimeter mounted in an airplane and analyzed to provide data on topography, surface roughness, stream and gully cross-sections and vegetation canopy properties. Laser measurements of vegetation cover and height were correlated to ground measurements made with line intercept methods. Measurements of topography can contribute to a better quantification of the movement of water over landscape surfaces. Airborne laser altimeters offer the potential to measure large areas quickly and easily, providing valuable data for understanding and managing natural resources at large scales. |  |
| Jerry Ritchie: jritchie@hydrolab.arsusda.gov
Ritchie, J.C. 1996. Remote sensing applications to hydrology: airborne laser altimeters. Hydrological Sci. J. 41(4):625-636. | |
 | Climate Change Effects on Water Supply |
| A hydrological model is the best tool known today to project the potential
effects of climate change on water supply. Because the majority of water in the West comes
from snowmelt, the Snowmelt Runoff Model (SRM) has been employed for such projections. In
addition to changes in temperature and precipitation which can be input directly, an algorithm
has been developed that calculates changes in basin snow cover under the new climate. It has
been discovered that many model parameters, overlooked by other investigators, will also change
in a response to the changing climate. Use of SRM under conditions of climate change has
shown that the spring runoff peak will shift by 2-4 weeks earlier in the year. The average
proportion of winter runoff/summer runoff in the Rockies will change from 13/87% to 28/72%.
Water resources management for irrigation, hydropower, and domestic supplies will have to
change to keep pace with the changes in climate.
Al Rango: alrango@hydrolab.arsusda.gov Rango, A. 1995. Effects of climate change on water supplies in mountainous snowmelt regions. World Resource Review 7(3):315-325. | |
ARS Water DatabaseThe ARS Water Database is a collection of precipitation and streamflow data from small agricultural watersheds in the United States. This national archive of variable time-series readings for precipitation and runoff contains over 16,000 station years of data. Watersheds used as study areas range from .2 hectare (0.5 acres) to 12,400 square kilometers (4,786 square miles). Raingage networks range from one station per watershed to over 200 stations. The period of record for individual watersheds vary from 1 to 50 years. Various types of ancillary data include maximum-minimum daily air temperature, land management practices, topography and soils information. These data are useful to researchers, hydrologists and engineers for climate change studies, hydrologic modeling and comparing management strategies. A CD-ROM is available with management software designed to run in a Microsoft Windows environment. Internet access is available using the URL:http://hydrolab.arsusda.gov/wdc/arswater. html. Jane Thurman: jthurman@hydrolab.arsusda.gov Thurman, J.L. and R.T. Roberts. 1996. Comparative study of distribution strategies for the ARS Water Database. ASAE 6th Intl. Conf. Of Computers and Agriculture. Proc. of Computers in Agriculture. pp. 762-768. |
 | New Antenna Technology Evaluated for Soil Moisture Applications |
| A multibeam aircraft passive microwave radiometer using new synthetic
aperture
technology
was built and installed on a NASA aircraft. Through the cooperative efforts of ARS, NASA, and
the University of Massachusetts, the performance of the prototype instrument was successfully
verified in two large-scale experiments. In Walnut Gulch, AZ, a short duration experiment
showed that soil moisture estimates had accuracies comparable with ground sampling and other
aircraft sensors. A longer duration experiment in the Little Washita watershed, OK involved
mapping over 600 sq. km at a 200m resolution every day for an eight day period. The resulting
data revealed significant spatial patterns in soil moisture that have been associated with the soil
texture distribution of the region.
Tom Jackson: tjackson@hydrolab.arsusda.gov Jackson, T.J. 1997. Soil moisture estimation using special satellite microwave/imager satellite data over a grassland region. Water Resources Research. 33(6): 1475-1484.
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Estimating Surface Temperature RemotelySurface temperature is a key remotely sensed variable for estimating the partitioning of available surface energy into heat and moisture fluxes from the surface to the atmosphere. However, the emissivity of the surface must be known in order to convert radiometric temperature measured with remotely sensed data to a physically meaningful temperature. Appropriate values of that parameter for semi-arid ecosystems are not well known. Ground-based remotely sensed data were used to estimate surface emissivity for two very typical semi-arid ecosystems (desert grasslands and shrubland).Tom Schmugge: schmugge@hydrolab.arsusda.gov Chanzy, A., T.J. Schmugge, J.-C. Calvet, Y. Kerr, P. van Oevelen, O.Grosjean, J.R. Wang. 1997. Airborne microwave radiometry on a semi-arid area during HAPEX-Sahel. Hydrology. pp. 285-309. |
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