This research aims to estimate the impermeable area and identifyits relationship with the dwelling density in the Cadena watershed in SantaMaria – RS. For establishing this relation, images from Ikonos satellite were automatically and visually classified. Sidewalks, pavement streets,building, parking and concrete covering were considered as impermeableareas. The impermeable areas were bigger than the permeable ones in thestudied area and it favors the negative impacts. The tendency curve betweenpopulation density and impermeable area may be acceptable although itpresents a little slope shift due to urban vertical growth in downtownneighborhood. The automatic and visual classification showed differentoutcomes as the impermeable areas. However, the relation obtained betweendwelling density and impermeable area by satellite images still constitutesin the more suitable methodology to the identification of impermeable areas.
