BNPP/ASB Functional Value of Biodiversity Project – Phase II
VIC (Variable Infiltration Capacity)
(complete metadata: sources, definitions, dates, resolution, etc)
| study area (domain) |
The primary focus is the Mekong basin itself,
as derived explicitly from the GTOPO30 digital elevation model (DEM). |
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| land cover (including classes distinguished) |
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| DEM
(see Table 1) |
Topographic
data were taken from 30-arcsecond GTOPO30 Digital Elevation Model
(DEM), obtained from the U.S. Geological Survey, from their web site http://edcdaac.usgs.gov/gtopo30/gtopo30.html
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| stream network |
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| soils |
Two
sources of soil type data are used, to obtain the dominant soil type
in each grid cell: (see Table
1 for detailed information) -
Soils#1: 5-minute FAO/UNESCO digital soil map of the world (FAO,
1995). - Soils#2: 1:50k high resolution data from the MRC.
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| streamflow data | See Table 1 | |||||||||||||||
| dams | NA |
| variables | See Table 1 | |||||||||
| sources (real or simulated?) | See Table 1 | |||||||||
| spatiotemporal resolution, original and interpolated |
Time step = daily, spatial scale = 1 km, 8 km, and 25 km. |
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| time series | See Table 1 | |||||||||
| other |
|
Variable Infiltration Capacity (VIC) model.
VIC
(Liang et al, 1994) is a physically based model, which nonetheless
parameterizes small scale processes to allow application to large river
basins, which typically are resolved at spatial resolutions from 1/8
degree latitude by longitude (e.g., where the resolution of the
precipitation, temperature, radiative, and other surface forcings are
available or can be derived) to coarser resolutions such as the 2 degree
global application described by Nijssen et al (2002). Previous
applications of VIC include such large continental river basins as the
Columbia (Nijssen et al., 1997), the Arkansas-Red (Abdulla et al., 1996),
and the Upper Mississippi (Cherkauer and Lettenmaier, 1999), among other
rivers. VIC has also been applied to the entire area of China (Su and Xie,
2003).
A detailed description of the VIC model can be found in Liang et al. (1994, 1996 and 1998). Briefly, the model has parameterizations to represent the vertical exchange of moisture and energy between the vegetation canopy and the atmosphere, similar in many respects to other Soil-Vegetation-Atmosphere Transfer Schemes (SVATS). Its main distinction from other SVATS is its representation of the effects of spatial variability in soil, topography, and vegetation, and their effects on runoff generation, which is assumed to occur dominantly via the saturation excess mechanism (which is usually a defensible assumption in humid environments). The model also represents a “slow”, or baseflow, runoff response via a nonlinear deep soil drainage parameterization. The VIC model is coupled to a streamflow routing scheme that transports the runoff generated within each grid cell through a specified channel network. The routing model does not account for channel losses, extractions, diversions and reservoir operations (the latter are represented in the water management model). The routing model is described in detail in Lohmann et al. (1996; 1998).
| The
standard climatology for the VIC is our 20-year climate record, with
accompanying discharge. To examine the overall model and data
trade-offs, and to establish the most robust (and hence trustworthy)
product, we will conduct a set of model runs which will move
progressively though the assumptions inherent in model scaling and
data sets. From these results, we will determine the “best”
combination of parameters to do the scenarios (Activity
2.4) with. |
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| Other
than simple aggregation tasks, the primary work remaining is is
developing the time series landcover data set, and agree on scenario
datasets. It should be noted here that the primary rationale for the
scenarios in the context here is to examine landuse change
consequences; it is not necessary to work with the “most likely”
scenarios. |
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(including
paramaterization, validation
| validation |
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Reporting of direct hydrological flows
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Notes,
Comments
NA
MODELLING THE IMPACT OF LANDCOVER/MANAGEMENT CHANGE AND CLIMATE VARIABILITY ON THE PEAK FLOWS OF LARGE RIVER BASINS: Application to the Mekong Basin. Presented at the American Meteorological Society (AMS) 84th Annual Meeting, Seattle, January 11-15, 2004. Jeffrey E. Richey, Mariza Costa-Cabral, Gopalakrishna Goteti, Riyadh Al Soufi, Dennis P. Lettenmaier, Sarah D. Rodda, S.S.Im, and A. Snidvongs.
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Last updated: 03 March, 2004 ©2003 ASB. All rights reserved.