Estimating Pollutant Loads Caroni River Bolivar, Venezuela Global Applications of GIS Technology Lee Sherman

Location Rio Caroni is in Southeast Venezuela in the State of Bolivar. Focus is the segment which flows between Guri Lake and the Orinoco River.

Objectives Three main objectives: Estimate pollutant loads (sediment and nutrients) to the river segment in question. Incorporate load estimations into a Water Quality Model (WASP) to predict water quality downstream. Recommend improvements. The idea is to predict the impact of the Lower Caroni Development program on water quality. My focus is on estimating pollutant loads – the rest will be done by Miguel Acevedo at UNT.

Interesting aspects of this project Exploring the versatility and limitations of GIS technology Is GIS only as useful as the quality of data we are working with? LIDAR vs. GTOPO30 Working with global data is exciting: What kinds of global data are available? How useful are they?

Approach: Delineate watersheds for streams contributing to the river segment Define hydrologic properties for each watershed (area, time of concentration, runoff coefficient or curve number) Obtain precipitation data for region and compute runoff flow Assign Expected Mean Concentrations based on land use Compute mean annual loads W = Q*C

Data received from Dr. Acevedo includes: Hydrography Land Use Soils Vegetation Water Body Extents Population Roads, Other

Challenges immediately evident: No elevation data! Watershed delineation? Dataset complete for only one segment! Files and Attributes in Spanish! No hablo español! Unknown Coordinate System! How will I project?

GTOPO30 Data 1-KM DEM LZW Licensing? Converted to grid with Arcinfo using Imagegrid command Overlayed countries layer from HW 3 (geographic coordinates) Trial and error projecting

HYDRO1K Data Result of processing global DEM Hydrography & Basins – more available Used Arctoolbox to import these interchange (.eoo) files: Conversion Tools/ Import to Coverage Projected to match data Resolution is too low for objectives Back to the drawing board…

Next steps Use hydrography and GIS to estimate watershed areas (or obtain other source of elevation data i.e. topographic maps) Assign hydrologic properties to areas Obtain precipitation data and compute flows Use land use data to assign expected mean concentrations Estimate average loads

Conclusions Working with limited data is extremely challenging Global data is very useful for large-scale applications – but was too coarse for my needs. GIS will still be a useful tool in terms of computing hydrologic parameters, areas, EMC’s, etc.

Questions?