| dc.description.abstract | The rapid growth of urban centers and the increase in deforested areas and agricultural
activities, coupled with a lack of proper management of water resources has generated large
amounts of waste carried to water bodies, usually beyond their capacity of assimilation. So, to
assist the efforts of monitoring, control, supervision and development of territorial planning
for environmental management body, one of the main tools used is the map of environmental
fragility. However, it is necessary to assess how much uncertainty is implicit in applying this
type of method. In this context, the objective of this study is to analyze the consistency of the
methodological approach applied in the project FRAG-RIO, related for the contamination of
water for the basin under study. For this, was compared the hierarchy of river reaches in a
map of environmental fragilities of water contamination, with the hierarchy of river reaches
based on the sampling stations for water quality of FEPAM/RS. The study area is the river
basin Santa Maria, located on the southwestern border of Rio Grande do Sul, a predominantly
rural watershed, characterized by extensive livestock and rice fields. For the development of
methodology, in the stations of quality of FEPAM/RS were obtained observed data for
concentration of the following parameters: fecal coliform, BOD, COD, ortho phosphate, total
phosphorus, manganese, total Kjeldahl nitrogen and total solids. These data were transformed
into loads, and then ranked. To construct the map of fragilities were considered three
variables: the population organic load remaining, organic load of breeding and agriculture
index. The final map of fragilities varies from 0 to 255, where smaller values indicate low
fragility, while higher values represent the greatest fragility. The fragilities were analyzed in
relation to the quality stations of FEPAM/RS in two ways: considering all contributing
drainage area to the station, and considering only the incremental area of the station. The
results of these tests were ranked and compared with the ranking of each parameter of quality
stations. For this, the correlation between the hierarchies was analyzed using the Spearman
test. The main result, it was observed that the analysis of environmental fragility relating to
the aspect of water contamination is presented as a useful tool to support decision making in
basins with a lack of data, particularly when considering the quality parameters of BOD and
nitrogen. These parameters had the highest correlations with the hierarchy generated by the
sum of the fragilities of all contributing drainage area to the quality station , with a
determination coefficient of 59%. | |
