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Evaluation of the superficial extension of unpaved roads in Lake’s Descoberto watershed and the sediment arrives to the lake.

Congress: 2008
Author(s): Nabil J. Eid, Licia Azevedo, Sergio Koide


Keyword(s): unpaved roads, sediments, GIS
AbstractThe increasing conscience that soil losses represent declines of financial resources makes the small farmers to take measures for its protection. This is also applied to the ones on Lake’s Descoberto watershed, amongst which the most evident is the no-tillage farming system (annual cultures), and the plantation on contour farming (fruit plants and greens); by this way, in that periurban basin the majority arrives of sediments to the water bodies is represented by the contribution originated from the unpaved roads. Due to the dimensions of these roads, its quantification can be done by the land use interpretation of satellite images of high and very high spatial resolution. The main objective is to compare the results of the application of diverse algorithms for the identification of the superficial extension of unpaved roads in the lake of the Descoberto river basin (~413 km2) and, by means of the quantification of this extension, to get a model to evaluate sediment arrives to the lake of the Descoberto river. It will be used algorithms to identify the extension of unpaved roads that consider spatial filtering, as well as resources of interpretation of images oriented to objects identification. By means of GIS these superficial extensions are quantified. It is employed a bi-weekly collection of samples of water collected at the 6 flow stations for suspension solids determination. Twenty one months data availability is used for the determination of the load of sediments arrives to each station. The loads are correlated to total precipitation of the 3, 5 10 and 15 days previous collect for analysis of sediments concentration and extension of unpaved roads on each one of the monitored basins. Beyond this procedure a mathematical model was employed looking at the inclusion of the slope of each stretch of the road. With the model developed by Ramos-Scharrón (2004) the load of sediments to the 6 monitored stations is calculated. Tests are still been conduced to gather better relationships between selected variables.
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