LAND USE AND OCCUPATION AND WATER QUALITY OF THE MEIA PONTE RIVER

Purpose: The present study aimed to study the catchment basin of the Meia Ponte River, analyzing land use and occupation, verifying whether permanent preservation areas are being preserved and which activities predominate in the region. Theoretical framework: Inadequate land use and the release of effluents can harm the quality and quantity of water available for use. Therefore, the sustainable exploitation of natural resources is necessary, combining economic development and environmental preservation. Methods : Physicochemical analyzes were carried out, evaluating the following parameters: pH, turbidity, color, temperature, biochemical oxygen demand (COD) and total phosphorus. The location chosen to carry out the collections was the water collection point for public supply from the Meia Ponte River. In addition to data obtained by the mapbiomas program using QGIS software. To delimit the basin, data from the Goiás geographic information system (SIEG) was used. Results and conclusion: The results showed that more than 60% of the basin area studied was pasture area, showing that there is degradation in the basin and satellite images showed that there are also areas of APP that are not properly preserved. Furthermore, water collections during the rainy season showed a high turbidity value, indicating that solids are being transported into the water body. Research implications: The main contributions are related to the eutrophication process and the environmental impacts caused by human actions. Originality/value: Verification of the impacts of human actions on land use and occupation on water quality in the Meia Ponte river region.


INTRODUCTION
Brazil is a country with a predominantly tropical climate and has a high availability of fresh water.Despite the great availability, the country suffers from poor distribution, since 70% of Brazil's surface water resources are concentrated in the Amazon region.However, the northern region is the least populated in the national territory, meaning that most of the water is located where there is the least amount of people.On the other hand, the hydrographic region of Paraná contributes 6% of the national water resources and has 32% of the Brazilian population (ANA, 2002).
A river basin district is a group of river basins that have similar environmental and economic characteristics.A river basin is the territorial unit for the implementation of the National Water Resources Policy.More clearly, it is the drainage region of a main river and its tributaries.Brazil has 12 hydrographic regions composed of several basins (ANA, 2002).
The volume of water in river basins depends directly on the meteorological and environmental conditions of the location of the basin.It is therefore important that there are management plans for the basin so that the activities that depend on it are not adversely affected (SANTOS, et al., 2015).
Brazil's economic development is directly linked to agriculture, according to the National Supply Company (CONAB) Brazilian grain production in 2015/2016 was 210.5 million tons, although agriculture can cause several impacts to bodies of water.The great development of agriculture and of the industries is jeopardizing the sources of fresh water in Brazil.Deforestation, irrigation and chemical pollution of rivers are examples of activities that put at risk the availability of Brazilian water (MACHADO, 2003).
According to Pereira et al. (2016) the use and occupation of Brazilian soil is intensely marked by the exploitation of natural resources and removal of native vegetation.This exploitation is a result of the expansion of urban and agricultural areas.Unplanned exploration of sites near water bodies can cause various environmental problems, including reduced water supply (silting), and reduced water quality due to sediment from areas without vegetation cover.
The analysis of land use and occupation are also relevant in understanding changes in productive structures, since they relate to activities, resulting from modernization and the ever greater integration between industry and agriculture, thus conditioning urban-rural dynamics (MATOS et al., 2020).
Thus, the sustainable exploitation of natural resources was made necessary, combining economic development and environmental preservation.To this end, public policies were implemented with the aim of limiting the exploitation of natural resources, among them it is worth highlighting the Brazilian Forestry Code, created on September 15, 1965, through Law No. 4,771, which instituted the concept of Permanent Preservation Area (PEREIRA, MACIEL, et al., 2016).
According to BRAZIL (2012) Permanent Preservation Area (APP) is a protected area that aims to conserve water resources and biodiversity, as well as ensure the well-being of the population and the conservation of the soil.
In order to monitor and analyze the use and occupation of the soil in river basins, several scientists and researchers use the geoprocessing tool, also known as Geographic Information Systems (GIS).For Oliveira et al. (2013) the GIS is an important tool for environmental monitoring, because it allows a wider view of the site under study.Furthermore, geoprocessing makes it possible to analyze large areas without high costs for activities in the field.
Regarding the process of systematizing the evolution of urban occupations, which has always been limited by the scarcity of spacetime data, it was made possible by technological advances of GIS and remote sensing (SILVA et al., 2023).
Riparian vegetation, areas of permanent preservation, are of great importance for the conservation of the sources of public supply, according to Silva et al. (2008) "The original covering of the vegetation avoids countless environmental disturbances, as is the case of erosion and silting of river beds".Therefore, monitoring APPs and land use and occupation in public supply sources is fundamental to environmental planning with the aim of avoiding contamination.
The Meia Ponte River is an important river in the state of Goiás, responsible for the supply of several cities and used by several rural producers for animal desedation and irrigation of pastures and diverse crops.Due to these activities, the deforestation of waterside forests and the large population growth, contributes to the increase of contamination of the water body, as well as silting and eutrophication due to erosive processes (OAK and SIQUEIRA, 2011).
In order to identify the eutrophication state of water bodies, the researchers developed an indicator called the trophic state index.According to the Companhia Ambiental do Estado de São Paulo (CETESB, 2018), the "Trophic State Index aims to classify bodies of water in different degrees of trophy, that is, it assesses the quality of water as to enrichment by nutrients and its effect related to the excessive growth of algae and cyanobacteria".
The present study aimed to evaluate spatially and seasonally the limnological characteristics of the Meia Ponte river, through the determination of the Trophic State Index (TEI) in order to determine the degree of trophy of this aquatic environment and thus verify if the permanent preservation areas are being respected, and which predominant activities can alter the water quality of the basin.

MILESTONE
In urban regions, population growth can have several negative impacts on the environment, especially water resources.Inadequate land use and effluent discharges may impair the quality and quantity of water available for use (SANTOS, 2019).Therefore, studies that analyze the use and occupation of the land in urban regions are necessary, to get to know the real situation of the basin in question and, if necessary, to think about ways of mitigating the environmental impacts in the basin.
Anthropic action on the water sources is related to the three sectors of the economy (primary, secondary and tertiary sectors); indicators that represent the development of a region.Based on the principle of concern, agricultural anthropolized areas have an impact on surface water quality.
In relation to the cause and consequence, plowing and grating are perceived as sedimentation factors in the beds; fertilization as a source of nutrients related to eutrophication of bodies of water; manure and urine as disseminators of metals, nutrients, pathogens and pharmaceutical products; irrigation causing salinization and favoring surface runoff similar to leaching; cutting of the riparian forest favoring erosion and alteration of the hydrological regime; and agro-toxins that impair the quality of water and contaminate its biota, leading to dysfunction of the ecological system through the loss of predators, growth inhibition, reproductive compromise and bioaccumulative action (FAO, 2011).
In order to classify a water body as to its trophy state, Carlson (2014) developed the Trophic State Index -IET in the study of lakes in temperate regions.This study was modified for applicability in rivers and reservoirs of subtropical regions by Toledo et al. (1983) in Brazil and for adaptation to other trophy categories arising from the variation of time and space with the use and occupation of the soil (TOLEDO et al., 1990).In 2004, Lamparelli carried out alterations at the EIT, adapting the results obtained to express the reality of both the lentic environment and the lotic environment in the state of São Paulo, emphasizing its particularities and considering this to be a lowland region.
To determine the trophic state of the water body it is important to determine phosphorus, chlorophyll-a and transparency (BRAZIL, 2009).Phosphorus participates in fundamental processes of biota metabolism, such as energy storage and cell membrane structuring.In this way, it can be a limiting factor of productivity and responsible for the artificial eutrophication of aquatic environments (BRAZIL, 2014).
The Meia Ponte River is responsible for supplying several neighborhoods of Goiânia, capital of the state of Goiás.For it to be possible to supply the city, the river needs a minimum flow to attend to the population, without jeopardizing the course of the river.The volume of water in river basins depends directly on the meteorological and environmental conditions of the location of the basin.It is therefore important that there are management plans for the basin so that the activities that depend on it are not adversely affected (SANTOS et al., 2015).
Accordingly, the present study aimed to evaluate the limnological characteristics of the Meia Ponte river, with the aim of determining the degree of trophy of this aquatic environment and thus verify if the permanent preservation areas are being respected, and which predominant activities can alter the water quality of the basin.

Location of the Study Area
The Meia Ponte river rises in Serra dos Brandão, between the limits of Itauçu and Taquaral de Goiás, 60 km from Goiânia, and runs for an extension of 471.6 km until it flows into the Paranaíba River.The basin covers an area of approximately 12,180 km², that is, about 4% of the area of the state of Goiás, being the main source that supplies Goiânia (CALIL et al., 2012).In Figure 1 it is possible to observe the municipalities that the studied basin covers, as well as to have an overview of the basin.

Sample Collection
The samples were collected in plastic bottles of 100 milliliters, and conditioned at a temperature of 4º C until the moment of the analyzes.The analyzes were carried out at the Sanitation laboratory of the School of Civil and Environmental Engineering, EECA-UFG, with the exception of the phosphorus samples that were analyzed in a private laboratory.Three sampling points were defined for the sampling.
The method for dividing the points was a distance of approximately 50m from the capture.The first point 50m above the pick-up point, the second 50m below, and the third 50m from the second point.Collections were carried out in the rainy season, on days 11/12 and 19/12/2019.
The present study was carried out in the catchment basin for public supply of Goiânia, as shown in Figure 2. Therefore, the exutorium of the considered basin was the location of the supply company, located between the coordinates 16° 34.171' S and 49° 19.745' O.The basin has a total area of 163,164,320 hectares.
The data was obtained by the website of the mapbiomas program using the free character software called QGIS.Data from the Goiás Geographical Information System (SGEI) was used for the delimitation of the basin.

Physico-chemical Analyzes
The main physical-chemical parameters of water quality were evaluated: turbidity, color, temperature, pH and biochemical oxygen demand (BOD) following the Standard Methods (APHA, 2012).

Trophic Status Index
The trophic state index used was the index in Appendix D of the Environmental Company of the State of São Paulo (CETESB), which uses the following formula: EIT (PT) = 10x (6-((0.42-0.36x(ln PT)) / ln 2)) -20 (equation 1) Where: PT: total phosphorus concentration measured at the water surface, µg.L-1 ln: natural logarithm.
The results obtained were compared with table 1:

RESULTS AND DISCUSSION
Looking at Figure 3, and Table 2, it was found that there is a large predominance of pasture / agriculture in the catchment area, and these activities are still present in areas of permanent preservation.
According to Ferreira & Dias (2004), "the presence of riparian vegetation significantly reduces the possibility of contamination of the watercourses by sediments, residues of fertilizers and agro-chemicals, driven by the surface runoff of the water on the land".
Therefore, it is necessary to carry out projects for the recovery of these areas of waterside vegetation that have been deforested with the objetive of improving the quality of the water in the watercourse, since the conservation and sustainable management of the watersheds directly affects the quality of the water.Observing the data of color and turbidity in tables 3 and 4, it was noted high values of turbidity and color on 11/02, 136 uT and 1.120 uC, respectively, this due, possibly, to the rainy period, and due to the absence of riparian forests the rain water is responsible for the transport of sediments to the river.By 19/02, after a few days of drought, the values of turbidity had already decreased, 71 evidencing the presence of erosive processes in the basin.In addition, one type of soil that is present in the basin and presents high vulnerability to erosive processes is the Cambisol, therefore it is necessary to recover degraded areas in this type of soil (CALIL et al., 2012).
By observing the total phosphorus values in table 4, it is possible to conclude that the region analyzed is within the values allowed by Conama 357 / 2005, which states that for rivers (lotic environments) of class 2 the maximum total phosphorus concentration allowed is 0.1 mg/L P. In table 4, only the first point showed above the allowed, and when analyzing the mean it is possible to see that it is within the resolution standards.In relation to the EIT, all the points analyzed are, according to table 1, in the ultra-oligotrophic state, that is, the Meia Ponte River is not eutrophicated, analyzing by the total phosphorus parameter and in the specific region evaluated.In the present study, the DBO parameter was analyzed in the day 19/02 collection available in table 04, the mean value was 4.97.Conama 357 indicates that the BOD for class 2 rivers should have a maximum value of 5 mg/L.Therefore, there are no indications of possible organic pollution in the studied stretch of the basin.

CONCLUSIONS
Analyzing the satellite images, one can conclude that pasture is the predominant activity in the basin area studied, and that some permanent preservation areas are not respected.This is reflected in the quality of the water, since in the analyzes carried out in rainy periods there is a presence of solids suspended in the water, evidencing erosive processes.
Therefore, actions to recover these areas of permanent preservation are necessary, betting on the partnership of the farmers with the responsible bodies, producing more in-depth studies on the tributaries of the Meia Ponte river indicating the critical areas and ways of recovering these areas.

Figure 1 .
Figure 1.Location Map of the Meia Ponte River Basin Source: Veiga et al. (2013)

Table 2 .
Land Use and Land Cover Areas Table