6. One paragraph description of your model (e.g. abstract from report or paper); The Simultaneous Heat and Water (SHAW) Model is a one-dimensional model originally developed to simulate soil freezing and thawing. The SHAW model simulates a one-dimensional vertical profile extending from the top of a plant canopy or the snow, residue or soil surface to a specified depth within the soil. The system is represented by integrating detailed physics of vegetative cover, snow, residue and soil into one simultaneous solution. The model is sufficiently flexible to represent a broad range of conditions and the system may or may not include a vegetative canopy, snow, or a residue layer. Interrelated heat, water and solute fluxes are computed throughout the system and include the effects of soil freezing and thawing. Daily or hourly predictions include a surface energy balance, evaporation, transpiration, soil frost depth, snow depth, runoff and soil profiles of temperature, water, ice and solutes. Within the model, a complete energy balance of a multi-layered snowpack is computed on a daily or hourly time step. Energy terms include solar and long-wave radiation exchange, sensible and latent heat transfer at the surface, and vapor transfer within the snowpack. Absorbed solar radiation, corrected for local slope, is based on measured incoming solar radiation, with albedo estimated from grain size, which in turn is estimated from snow density. Long-wave radiation emitted by the atmosphere is estimated from the Stefan-Boltzmann law and adjusted for cloud cover (estimated from measured solar radiation). Surface sensible and latent heat transfers are estimated using a bulk aerodynamic approach with stability corrections. The SHAW model additionally includes the effect of vegetation and a detailed energy balance of residue and soil beneath the snow cover. Liquid water is routed through the snowpack using attenuation and lag coefficients, and the influence of metamorphic changes of compaction, settling, and grain size on density and albedo are considered. Snowmelt simulation with the SHAW model was tested by applying the model to two years of data at three sites ranging from shallow (<0.1 m) snow cover on a west-facing slope to a deep (2m) snow drift on a north-facing slope. Snow depth, density, and the magnitude and timing of snow cover outflow were accurately simulated for all sites. [This paragraph is taken from Flerchinger, G.N. and K.R. Cooley, 1998: Snowmelt simulation with the simultaneous heat and water (SHAW) model, EOS, Transactions, American Geophysical Union, Fall Meeting, Supplement, Vol. 79, No. 45, page F272.] 50. Please provide references relevant to the model description and use. Flerchinger, G.N. 1991. Sensitivity of soil freezing simulated by the SHAW Model. Trans. of ASAE 34(6):2381-2389. Flerchinger, G.N., J.M. Baker and E.J.A. Spaans. 1996. A test of the radiative energy balance of the SHAW model for snowcover. Hydrol. Proc. 10:1359-1367. Flerchinger, G.N., K.R. Cooley, and Y. Deng. 1994. Impacts of spatially and temporally varying snowmelt on subsurface flow in a mountainous watershed: 1. Snowmelt simulation. Hydrologic Sci. J., 39(5):507-520. Flerchinger, G.N., R.F. Cullum, C.L. Hanson and K.E. Saxton. 1990. Soil freezing and thawing simulation with the SHAW model. pp. 77-86. In: K.R. Cooley (ed.). Frozen Soil Impacts on Agricultural, Range, and Forest Lands, Proceedings of the International Symposium. CRREL Special Report 90-1. U.S. Army Cold Regions Research and Engineering Laboratory, Hanover, NH. 318p. Flerchinger, G.N. and C.L. Hanson. 1989. Modeling soil freezing and thawing on a rangeland watershed. Trans. Amer. Soc. of Agric. Engr., 32(5):1551-1554. Flerchinger, G.N., C.L. Hanson and J.R. Wight. 1996. Modeling evapotranspiration and surface energy budgets across a watershed. Water Resour. Res. 32(8):2539-2548. Flerchinger, G.N. and F.B. Pierson. 1991. Modeling plant canopy effects on variability of soil temperature and water. Agricultural and Forest Meteorology, 56:227-246. Flerchinger, G.N. and F.B. Pierson. 1997. Modeling plant canopy effects on variability of soil temperature and water: Model calibration and validation. J. Arid Environ. (In press) Flerchinger, G.N. and K.E. Saxton. 1989. Simultaneous heat and water model of a freezing snow-residue-soil system I. Theory and development. Trans. of ASAE 32(2):565-571. Flerchinger, G.N. and K.E. Saxton. 1989. Simultaneous heat and water model of a freezing snow-residue-soil system II. Field verification. Trans of ASAE 32(2):573-578. Flerchinger, G.N. and M.S. Seyfried. 1997. Modeling Soil Freezing and Thawing and Frozen Soil Runoff with the SHAW Model. In: Proceedings of the International Symposium on Physics, Chemistry, and Ecology of Seasonally Frozen Soils, Fairbanks, AK, June 10-12, 1997. (In press) Flerchinger, G.N. and K.R. Cooley, 1998: Snowmelt simulation with the simultaneous heat and water (SHAW) model, EOS, Transactions, American Geophysical Union, Fall Meeting, Supplement, Vol. 79, No. 45, page F272. Hayhoe, H.N. 1994. Field testing of simulated soil freezing and thawing by the SHAW model. Can. Agric. Engin., 36(4):279-285. Pierson, F.B., G.N. Flerchinger and J.R. Wight. 1992. Simulating near-surface soil temperature and water on sagebrush rangelands: A comparison of models. Trans. of ASAE. 35(5):1449-1455. Xu, X., J.L. Nieber, J.M. Baker and D.E. Newcomb. 1991. Field testing of a model for water flow and heat transport in variably saturated, variably frozen soil. p 300-308 In: Transportation Research Record No. 1307, Transp. Res. Board, Nat. Res. Council, Washington D.C. ------------------------------------------------------------------ Gerald N. Flerchinger Phone: 208-422-0716 Research Hydraulic Engineer Fax : 208-334-1502 USDA - ARS gflerchi@nwrc.ars.pn.usbr.gov 800 Park Blvd., Ste 105 http://ars-boi.ars.pn.usbr.gov/ Boise, ID 83712 http://ars-boi.ars.pn.usbr.gov/nwrc/gflerchi/shaw.html http://ars-boi.ars.pn.usbr.gov/nwrc/gflerchi/MyhomePage.html ------------------------------------------------------------------