A method for estimation of hydrologycal sensibility applied in Golfo San Jorge basin. Province of Chubut. Argentina

Abstract

A method developed and used in an area of Chubut Province is described. The object of the method is to determine the underground andsurficial hydrological sensitivity in order to select the site of petroleum facilities with the least possible environmental hydric risk. It isbased on the conjunction of the GOD method used to assess the intrinsic aquifer vulnerability (original version) and the proposed La PlataMethod (MLP) for the surficial hydrological sensitivity. The latter method assigns numerical values based on landforms (positive and negative),slope percent and seasonality of the water regime, using a complexive range scale from zero to one. The Surficial Sensitivity factorresults from the average of the three indicators and includes five categories, from low to extreme values. For a global coverage in theunderground and surficial terrestrial arches (geoenvironmental map) it is proposed to compare the GOD values with those of the MLPmethod using a GIS, through the mathematical overlapping of two raster layers (map algebra) in each map pixel. In addition to the cartographicdisplay, attribute tables can be used to estimate the environmental pollution in soils and waters, existing infrastructure and locationof new facilities and drillings. The ArcMap 9.1 program was used due to its capacity for a permanent and quasi-automatic updatingof thematic mapping. The map corresponding to Cerro for the initial position 2007 is presented as an example.