EOS- Amazon Hydrological Models
We are continually analyzing rainfall data, trying to build the best
interpolated rainfall surface for the basin. For the most part, we assemble
monthly files from our daily and monthly raw files. Interpolated surfaces are
built from those stations for which we have data for that month.
In January, 1986, for example, 387 stations (marked with x's) of 600 have data.
The rainfall is clipped to the the Amazon and Tocantins Basins.
We are also investigating the use of rainfall at a daily timestep with
Thiessen polygons.
For daily data, spatial interpolation may not be appropriate, because
storms can be smeared out between rainfall stations. We therefore assume that
the rainfall at any given point is equal to the rainfall at the nearest gauge.
The polygons shown are based on the 366 stations which have 10 or more good
months of data in the period from 9/85 through 8/89. The large image (click
on it) shows the centroids in green, other daily stations in red, and monthly
stations in black. Hydrologic analysis of a portion of the basin will be
based on the Thiessen polygons rather than on grid cells. Each polygon will
have a continuous daily record, once data holes are filled with
the data of the nearest neighbor.
The locations of 164 discharge stations were used to as a basis for
digitizing 164 basins. For each basin, the mean depth of discharge is
simply the volume of water discharged through the mouth of the basin
(minus upstream discharge) divided by the basin area (minus upstream basins).
Runoff is discharge minus storage. Over the course of a year, the change
in storage can be assumed to be zero.
Details
Another approach is to work on a vertical water balance model. At each point
on a grid (we are currently comparing the results of 0.0625, 0.2, and 0.5
degree grids), we use the best available data for precipitation, evaporation,
surface roughness, net downward radiation, net longwave radiation, temperature,
and soil properties to model the movement of water through vegetation and the
soil, predicting evapotranspiration. Data includes point source information
for rainfall and temperature, and processed satellite data from
the
GSFC Data Assimilation Office Multi-Year Assimilation.
We have massaged our database for the Purus basin to generate 1805 nodes with
many attributes to feed a streamflow routing model. The routing model is
coupled with a land-surface water balance model, and is also coupled with our
GIS and statistical packages.
Baçia Grande do Manaus is the name we give to four basins near the city of
Manaus: the Cuieiras, the Tarumã Mirim, Tarumã Açu, and Puraquequara.
River channel networks were digitized from 1:50000 and 1:100000 scale maps
and used for routing of streamflow.
Note: the landcover shown does not represent our current land-classification
algorithm.
Our GIS river network is based on the the digital chart of the World, with
some corrections. The map on the left was created by gridding the DCW rivers
onto .01° cells, correcting continuity problems, and calculating the distance
down to the river and down to the mouth. The river system actually displayed
on the large version (click on the map) is a simpler version.
This is an older image, and does not represent the most accurate representation
possible from our database. In fact, we will soon be using much more
accurate data from IBGE as our river database.
Curator:Harvey Greenberg
Last revised:21 April 95 (H. Greenberg)
Interpolated rainfall
Rainfall Thiessen polygons
Depth of Runoff
A basin-wide water balance model
The Rio Purus basin
A large-scale vector-raster model
A totally raster river model
River Network and River "travel" Distance