Estimating Pollutant Loads Caroni River

Bolivar, Venezuela

Global Applications of GIS Technology

Lee Sherman

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

ObjectivesThree 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 projectExploring the versatility and limitations of GIS technologyIs GIS only as useful as the quality of data we are working with?

LIDAR vs. GTOPO30Working 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 segmentDefine hydrologic properties for each watershed (area, time of concentration, runoff coefficient or curve number)Obtain precipitation data for region and compute runoff flowAssign Expected Mean Concentrations based on land useCompute mean annual loads W = Q*C

Data received from Dr. Acevedo includes:

HydrographyLand UseSoilsVegetationWater Body ExtentsPopulationRoads, 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 Data1-KM DEM

LZW Licensing?Converted to grid with Arcinfo using Imagegrid commandOverlayed countries layer from HW 3 (geographic coordinates)Trial and error projecting

HYDRO1K DataResult of processing global DEMHydrography & Basins – more available

Used Arctoolbox to import these interchange (.eoo) files: Conversion Tools/ Import to Coverage

Projected to match dataResolution is too low for objectivesBack to the drawing board…

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

ConclusionsWorking with limited data is extremely challengingGlobal 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?