4.2.1 Turbidity
Analysing the turbidity data, suspended solids, phosphorus and dissolved
organic carbon (Figures: 3 - A, B, C, and D), it ensures that the data
from treatment T2 are more uniform or stable than in T1 for these
indicators. When analysing Figures 3A and 3B, related to water
turbidity, in previous years the implementation of the study (T1) and
after the implementation of the study (T2), it observes that, on
average, water turbidity was lower in the months of February and
December when we compare (T2) with the situation before the
implementation of the study (T1). For the T1 treatment, the values were
higher than the CONAMA standard (Conama, 1986), which is 100 NUT (Figure
3A), in the average of February and December. In T2 treatment, the
average values were 102 NUT, except for February 2009, 2014, 2017 and
2018; October 2009, 2012 and 2018; December 2009 and 2015 (Figure 3B).
This difference seen in T2 can be explained by the decrease in the
supply of sediments in the watercourse. It happened because of the
effects of the change in soil management with the adoption of
conservationist practices and erosion control through the implementation
of technical projects at the 196 properties that were recovered with
conservationist agriculture, through the work performed (Figures 3B, 3D,
3E, 3G, 3I, 3K, 3M and 3O). A similar result was found by Souza &
Gastaldini (2014), who observed that land use significantly influenced
the water quality parameters. In areas considered to have a higher
percentage of agriculture and with problems related to erosion, the
situation of the area before the implementation of constructions, the
parameters of turbidity, suspended solids are higher. This land use,
without adopting conservationist practices, can be considered as having
the biggest potential for erosion.