<?xml version="1.0" encoding="UTF-8"?><!DOCTYPE article  PUBLIC "-//NLM//DTD Journal Publishing DTD v3.0 20080202//EN" "http://dtd.nlm.nih.gov/publishing/3.0/journalpublishing3.dtd"><article xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink" dtd-version="3.0" xml:lang="en" article-type="research article"><front><journal-meta><journal-id journal-id-type="publisher-id">JGIS</journal-id><journal-title-group><journal-title>Journal of Geographic Information System</journal-title></journal-title-group><issn pub-type="epub">2151-1950</issn><publisher><publisher-name>Scientific Research Publishing</publisher-name></publisher></journal-meta><article-meta><article-id pub-id-type="doi">10.4236/jgis.2019.115031</article-id><article-id pub-id-type="publisher-id">JGIS-95616</article-id><article-categories><subj-group subj-group-type="heading"><subject>Articles</subject></subj-group><subj-group subj-group-type="Discipline-v2"><subject>Earth&amp;Environmental Sciences</subject></subj-group></article-categories><title-group><article-title>
 
 
  Remote Sensing Applied to the Evaluation of Spatial and Temporal Variation of Water Quality in a Coastal Environment, Southeast Brazil
 
</article-title></title-group><contrib-group><contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Pedro</surname><given-names>Bettencourt</given-names></name><xref ref-type="aff" rid="aff1"><sup>1</sup></xref></contrib><contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Julio</surname><given-names>Cesar Wasserman</given-names></name><xref ref-type="aff" rid="aff2"><sup>2</sup></xref><xref ref-type="corresp" rid="cor1"><sup>*</sup></xref></contrib><contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Fábio</surname><given-names>Ferreira Dias</given-names></name><xref ref-type="aff" rid="aff3"><sup>3</sup></xref></contrib><contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Paulo</surname><given-names>Roberto Alves</given-names></name><xref ref-type="aff" rid="aff3"><sup>3</sup></xref></contrib><contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Dandara</surname><given-names>Bernardino Bezerra</given-names></name><xref ref-type="aff" rid="aff4"><sup>4</sup></xref></contrib><contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Camila</surname><given-names>Américo Santos</given-names></name><xref ref-type="aff" rid="aff5"><sup>5</sup></xref></contrib><contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Luis</surname><given-names>Perez Zotes</given-names></name><xref ref-type="aff" rid="aff1"><sup>1</sup></xref></contrib><contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Sérgio</surname><given-names>Ricardo Barros</given-names></name><xref ref-type="aff" rid="aff1"><sup>1</sup></xref></contrib></contrib-group><aff id="aff2"><addr-line>Post-Graduate Program in Geochemistry, UFF, Niterói, Brazil</addr-line></aff><aff id="aff5"><addr-line>Pós gradua&amp;amp;#231;&amp;amp;#227;o em Engenharia de Biossistemas, UFF, Niterói, Brazil</addr-line></aff><aff id="aff3"><addr-line>Department of Geoenvironmental Analysis, UFF, Niterói, Brazil</addr-line></aff><aff id="aff1"><addr-line>Post-Graduate Program in Sustainable Systems Management, UFF, Niterói, Brazil</addr-line></aff><aff id="aff4"><addr-line>Pós gradua&amp;amp;#231;&amp;amp;#227;o em Biologia Marinha e Ambientes Costeiros, UFF, Niterói, Brazil</addr-line></aff><pub-date pub-type="epub"><day>27</day><month>09</month><year>2019</year></pub-date><volume>11</volume><issue>05</issue><fpage>500</fpage><lpage>521</lpage><history><date date-type="received"><day>19,</day>	<month>August</month>	<year>2019</year></date><date date-type="rev-recd"><day>8,</day>	<month>October</month>	<year>2019</year>	</date><date date-type="accepted"><day>11,</day>	<month>October</month>	<year>2019</year></date></history><permissions><copyright-statement>&#169; Copyright  2014 by authors and Scientific Research Publishing Inc. </copyright-statement><copyright-year>2014</copyright-year><license><license-p>This work is licensed under the Creative Commons Attribution International License (CC BY). http://creativecommons.org/licenses/by/4.0/</license-p></license></permissions><abstract><p>
 
 
  The monitoring of water quality in large coastal regions demands great analytical efforts through the collection of many samples, over long periods. Remote sensing is a reliable tool that can provide valuable information on the spatial and temporal variations of environmental parameters, particularly turbidity and chlorophyll a. The aim of the present research was to evaluate the spatial and temporal distribution of water quality from 2005 to 2017 along the north coast of S
  &amp;#227;o Paulo and its responses to the implementation of industrial developments and to variations in rainfall. Fifty-two MODIS images were used, showing concentrations of chlorophyll a and turbidity, in the dry season and wet season, from 2005 to 2017. The results showed that dilution processes (due to rainfall) control chlorophyll a concentrations. However, a notable increase in concentrations could be identified after the installation of some of the developments in the region, particularly roads and ports. Turbidity was also shown to be affected by dilution processes, and during the wet season this parameter presented lower values. No effect in the results of turbidity could be identified from the installation of roads or ports, showing that vegetation cover exerts an important control on the erosional processes.
 
</p></abstract><kwd-group><kwd>Water Quality</kwd><kwd> Chlorophyll a</kwd><kwd> Turbidity</kwd><kwd> MODIS</kwd><kwd> Remote Sensing</kwd></kwd-group></article-meta></front><body><sec id="s1"><title>1. Introduction</title><p>Long-term monitoring programs can provide information on water-quality changes caused by population growth, large infrastructure projects, and increased industrial activity [<xref ref-type="bibr" rid="scirp.95616-ref1">1</xref>] [<xref ref-type="bibr" rid="scirp.95616-ref2">2</xref>] . These anthropogenic activities may surpass the loading capacity of a system, resulting in environmental degradation. Yet, in order to be effective, monitoring programs need to be carefully designed and thorough. Simply drawing samples from a system does not always take spatial variations into account, and interpolation frequently fails to give a realistic or comprehensive picture of the spatial processes [<xref ref-type="bibr" rid="scirp.95616-ref3">3</xref>] . To overcome these pitfalls, remote sensing techniques have proved useful, to fill in the gaps between sampling sites [<xref ref-type="bibr" rid="scirp.95616-ref4">4</xref>] .</p><p>The application of remote sensing to evaluate water quality began in the early 1970s, and was based on the concept that light backscattering changes as a function of the presence of different substances in the water [<xref ref-type="bibr" rid="scirp.95616-ref5">5</xref>] [<xref ref-type="bibr" rid="scirp.95616-ref6">6</xref>] . Later, Miller, Cruise [<xref ref-type="bibr" rid="scirp.95616-ref4">4</xref>] showed that the application of algorithms to the strength of the remote sensor signals, pixel by pixel, would allow the quantification of the amount of suspended particulate matter in the water. In their work, they were able to calibrate the values with simultaneous measurements, using oceanographic procedures. Following on their work, international cooperation efforts like the Ocean Color European Archive Network (the OCEAN project) [<xref ref-type="bibr" rid="scirp.95616-ref7">7</xref>] were shown to be useful in the identification of relationships between water components and remote sensor signals.</p><p>The validation of remote sensing data has been the subject of various research programs (e.g.: Hakvoort, de Haan [<xref ref-type="bibr" rid="scirp.95616-ref8">8</xref>] ), showing that in many situations, concentrations of phytoplankton pigments and turbidity could be adequately estimated from multi-band satellite images. Many different satellite sensors have been used for the purpose of estimating water quality; for example, various versions of the Landsat satellite system have been applied [<xref ref-type="bibr" rid="scirp.95616-ref9">9</xref>] [<xref ref-type="bibr" rid="scirp.95616-ref10">10</xref>] [<xref ref-type="bibr" rid="scirp.95616-ref11">11</xref>] . But the most commonly used sensor is MODIS (Moderate Resolution Imaging Spectroradiometer), installed aboard the Terra and Aqua satellites; it is capable of obtaining enough images to cover the entire surface of the earth every one or two days [<xref ref-type="bibr" rid="scirp.95616-ref12">12</xref>] [<xref ref-type="bibr" rid="scirp.95616-ref13">13</xref>] . The main limitation of MODIS is its resolution (images consist of 250-m pixels), which, although suitable for many large-scale applications [<xref ref-type="bibr" rid="scirp.95616-ref14">14</xref>] , is not always sufficient for more detailed studies. Recently, however, Fu, Xu [<xref ref-type="bibr" rid="scirp.95616-ref15">15</xref>] showed that, depending on the needed scale, MODIS images can be spatially downscaled with Landsat 8 images.</p><p>Yet, aside from the importance of producing extended series of temporal and spatial data, what matters most is the interpretation of these various images of water quality. The relationship between anthropogenic inputs and water quality is not as direct as one might expect. Local water currents and rainfall patterns can significantly affect the behavior of the plumes of rivers draining populated areas [<xref ref-type="bibr" rid="scirp.95616-ref16">16</xref>] . There are only a few works that consider these spatio-temporal evolutions of the water quality considering rainfall [<xref ref-type="bibr" rid="scirp.95616-ref12">12</xref>] [<xref ref-type="bibr" rid="scirp.95616-ref17">17</xref>] [<xref ref-type="bibr" rid="scirp.95616-ref18">18</xref>] and we could not identify any work relating water quality, rainfall and large dimension developments in the drainage basin altogether.</p><p>An earlier study [<xref ref-type="bibr" rid="scirp.95616-ref19">19</xref>] evaluated variations in the water quality of a small drainage basin in Southeast Brazil, and observed the extreme influence of one rainfall event, but hourly sampling showed that early in the morning, when local inhabitants had not yet begun their daily activities, human inputs were insignificant. Later in the day, human-induced inputs increased. Then, at night, water quality improved again. These authors showed that the rapid response of the water system to human activities was attributable to the small size of the drainage basin (a few square kilometers), where heavy rains promote immediate increase in discharge rates. It is also interesting to note that, in addition to drainage basin size, drainage network structure, spatial distribution of land use, basin storage capacity in urban and rural soils, and storm-water retention ponds also influence the discharge rates [<xref ref-type="bibr" rid="scirp.95616-ref20">20</xref>] , which in turn affect the water quality of the ocean just off the coast. Nevertheless, the amount of rain in a drainage basin always exerts a heavy influence on water quality, and graphs of monthly or weekly rainfall patterns are extremely useful for supplementing water-quality data from remote sensing images.</p><p>In the present research, the evolution of the water quality along the northern coast of S&#227;o Paulo State, Brazil, was evaluated based on satellite (Acqua) images (MODIS) from 2005 to 2017, taking into account the additional influence of large infrastructure projects recently constructed in the region (since 2005), population increases, and rainfall events. The association of these parameters as explaining elements for the water quality determined by satellite images is a new approach for a better understanding of the factors that control concentrations of chlorophyll a and turbidity. Regardless the fact that images provide 35 spectral bands that are capable of displaying a number of water quality parameters, these two elements were chosen as indicators, because they are good indicators and, because they are reliably mapped from satellite images.</p></sec><sec id="s2"><title>2. Materials and Methods</title><sec id="s2_1"><title>2.1. The Study Area</title><p>The north coast of S&#227;o Paulo State is located some 170 km ESE from the city of S&#227;o Paulo and comprises the municipalities of S&#227;o Sebasti&#227;o, Ilhabela, Caraguatatuba and Ubatuba (<xref ref-type="fig" rid="fig1">Figure 1</xref>). The main geomorphologic feature of the region is the Sea Range, a mountain chain that stretches west to east, close to the coast, restricting drainage basins to a few kilometers in length. Near the ocean, the narrow coastal flats comprise urban areas, while the steep inland hills are densely covered with Atlantic Forest vegetation. The geology of the whole region was described by Suguio and Martin [<xref ref-type="bibr" rid="scirp.95616-ref21">21</xref>] , characterizing the Sea Range as Precambrian and Cretacean crystalline intrusive rocks. The coastal plain, whose elevation does not exceed 70 meters, is filled with sand and mud originating in the Marine Holocene and Pleistocene. Mangrove and recent wetland sediments are associated with fluvio-lagoon and embayment sands and muds.</p><p>Because of access limitations, human occupation of the north coast of S&#227;o Paulo was not prioritized during the nineteenth or twentieth centuries. However, near the end of the 1960s, the construction of the maritime terminal Tebar in the city of S&#227;o Sebasti&#227;o led to fast-paced industrial development in that city. In the early 1980s the SP-55 road (presently BR-101) was constructed, creating easy land transportation access to the area [<xref ref-type="bibr" rid="scirp.95616-ref22">22</xref>] . The well-preserved forest and attractive recessed beaches drew tourism activity, and the area began to be significantly developed for recreation, mainly in Ilhabela and Ubatuba [<xref ref-type="bibr" rid="scirp.95616-ref23">23</xref>] , causing conflicts with the industries and petroleum facilities that had recently been installed.</p><p>The petroleum industry in the region is mainly associated with offshore pre-salt exploration and may generate significant impacts on this very ecologically sensitive territory—similar to what occurred in the region of Maca&#233; (North of Rio de Janeiro State), where degradation of the socio-environmental structure was reported by Binsztok and colleagues [<xref ref-type="bibr" rid="scirp.95616-ref24">24</xref>] [<xref ref-type="bibr" rid="scirp.95616-ref25">25</xref>] . These activities, together with the development of maritime terminals and ports and transportation improvements (since 2005) are reported in <xref ref-type="table" rid="table1">Table 1</xref>. The activities reported here are not the only ones that have impacted the region, but were selected for this study based on two criteria: 1) the activities are located along the coastline, or significantly impact the coastal areas; and 2) financial investment has exceeded 250 million dollars. For every development depicted in <xref ref-type="table" rid="table1">Table 1</xref>, a relevant impact</p><table-wrap id="table1" ><label><xref ref-type="table" rid="table1">Table 1</xref></label><caption><title> Large new developments installed along the north coast of S&#227;o Paulo (since 2005) that have significantly impacted the area. The developments are divided into petroleum facilities (onshore and offshore), terminals and ports, and transportation facilities</title></caption><table><tbody><thead><tr><th align="center" valign="middle" >Development</th><th align="center" valign="middle" >Description</th><th align="center" valign="middle" >Commencement of activity</th></tr></thead><tr><td align="center" valign="middle" >Platform and underwater pipeline from Mexilh&#227;o Field</td><td align="center" valign="middle" >Offshore—Gas and condensed gas production from Mexilh&#227;o field, Santos Basin</td><td align="center" valign="middle" >February 2007</td></tr><tr><td align="center" valign="middle" >TLDs Guar&#225;</td><td align="center" valign="middle" >Offshore—Long-term testing in the offshore petroleum fields of Guar&#225;, Carioca, Tupi and Iracema, Santos Basin</td><td align="center" valign="middle" >September 2009</td></tr><tr><td align="center" valign="middle" >Pilot production test in the field of Tupi/Lula</td><td align="center" valign="middle" >Offshore—Pilot production and outflow of petroleum and gas from the field of Tupi, Santos Basin.</td><td align="center" valign="middle" >September 2008</td></tr><tr><td align="center" valign="middle" >Exploration and development projects of the pre-salt in the Santos Basin</td><td align="center" valign="middle" >Offshore/onshore—integrated projects of production and outflow of petroleum and natural gas from the pre-salt</td><td align="center" valign="middle" >November 2011</td></tr><tr><td align="center" valign="middle" >UTGCA</td><td align="center" valign="middle" >Onshore—Caraguatatuba gas treatment unit</td><td align="center" valign="middle" >April 2006</td></tr><tr><td align="center" valign="middle" >GASTAU</td><td align="center" valign="middle" >Onshore—Gas pipeline Caraguatatuba-Taubat&#233;</td><td align="center" valign="middle" >April 2006</td></tr><tr><td align="center" valign="middle" >New pier—TEBAR</td><td align="center" valign="middle" >Terminals and ports—Enlargement of a petroleum pier in the terminal of S&#227;o Sebasti&#227;o</td><td align="center" valign="middle" >September 2011</td></tr><tr><td align="center" valign="middle" >Enlargement of the S&#227;o Sebasti&#227;o Port</td><td align="center" valign="middle" >Terminals and ports—Enlargement of the S&#227;o Sebasti&#227;o Port and its integration with the city</td><td align="center" valign="middle" >October 2009</td></tr><tr><td align="center" valign="middle" >Nova Tamoios Highway sub-track upland</td><td align="center" valign="middle" >Transportation facilities—duplication of the Tamoios Highway in the upland region</td><td align="center" valign="middle" >August 2011</td></tr><tr><td align="center" valign="middle" >Nova Tamoios: sub-track southern contours</td><td align="center" valign="middle" >Transportation facilities—Construction of the southern contours of the Tamoios Highway linking Caraguatatuba and S&#227;o Sebasti&#227;o</td><td align="center" valign="middle" >February 2010</td></tr><tr><td align="center" valign="middle" >Nova Tamoios: sub-track northern contours</td><td align="center" valign="middle" >Transportation facilities—Construction of the northern contours of the Tamoios Highway north of Caraguatatuba</td><td align="center" valign="middle" >December 2011</td></tr></tbody></table></table-wrap><p>might be expected. Regional population growth was significant in the decades of the 1990s and 2000s, reaching 44% in the former period and 22% in the second [<xref ref-type="bibr" rid="scirp.95616-ref26">26</xref>] .</p></sec><sec id="s2_2"><title>2.2. Pluviometric Survey</title><p>Rainfall data were obtained from various meteorological stations within the region (stars in <xref ref-type="fig" rid="fig1">Figure 1</xref>) reported in the National Agency of Waters (ANA-Hidroweb), enabling the construction of an isohyet map of rainfall distribution. Three meteorological stations (black circles in <xref ref-type="fig" rid="fig1">Figure 1</xref>) were selected to analyze the variations during the period 2005-2017. No station in the municipality of Ilhabella was included because they were all located very close to the S&#227;o Francisco Station in the Municipality of S&#227;o Sebasti&#227;o. Rainfall was displayed in monthly line graphs to give a better overview of the variations within this period.</p></sec><sec id="s2_3"><title>2.3. Chlorophyll a and Turbidity from Satellite Imagery</title><p>Satellite images were obtained every year, from 2005 until 2018, in the summer (December-March; wet season) and in the winter (June-September; dry season) from the sensor MODIS (Moderate Resolution Imaging Spectroradiometer), installed in the satellite Aqua (originally known as EOS PM-1). The acquired images provide 35 spectral bands that can be treated to evaluate many aspects of the surface of the water, including concentrations of chlorophyll a and water turbidity. These images were obtained from the site “Ocean Color Browse” (https://oceancolor.gsfc.nasa.gov/cgi/browse.pl?sen=am). Images displaying chlorophyll a concentrations and water turbidity in a day with little cloud cover were chosen for each period, downloaded and analyzed using the software “SeaDAS7.4”. The final maps were prepared in the environment “ArcMap” using the software “ARCGIS 10.2”. In the summers of 2007 and 2012, the images were inadequate (due to cloud cover) and could not be used.</p></sec></sec><sec id="s3"><title>3. Results and Discussion</title><sec id="s3_1"><title>3.1. Climatic Conditions during the Study</title><p>De Souza Rolim, Paes de Camargo [<xref ref-type="bibr" rid="scirp.95616-ref27">27</xref>] showed that the climate in the north coast area of S&#227;o Paulo is tropical, with extremely wet summers and dry winters (type Am, after the classification of K&#246;ppen). The average rainfall over 70 years of measurements at the S&#227;o Francisco Station (S&#227;o Sebasti&#227;o; black circle in <xref ref-type="fig" rid="fig1">Figure 1</xref>) was 1197.1 mm, while at the CEEPAM station (Caraguatatuba; black circle in <xref ref-type="fig" rid="fig1">Figure 1</xref>), the value was 2027.9 mm and in Ubatuba (black circle in <xref ref-type="fig" rid="fig1">Figure 1</xref>), it was 2253.6. This significant southwest-to-northeast rainfall gradient is represented in the isohyet map (<xref ref-type="fig" rid="fig2">Figure 2</xref>). These differences are probably associated with orographic processes, because the elevated areas in the northeast are steeper than those in the southeast. It has to be emphasized that vegetation cover in the north is denser, and higher pluviosity should not result in higher concentrations of suspended matter (turbidity), as will be discussed further here.</p><p>The results of monthly rainfall data from 2005 to 2017 are represented in the graphs of <xref ref-type="fig" rid="fig3">Figure 3</xref>, for the stations S&#227;o Francisco (S&#227;o Sebasti&#227;o), CEEPAM (Caraguatatuba) and Ubatuba (Ubatuba). It is possible to identify periods of very</p><p>strong rainfall activity during the summers of 2011 and 2013 in the stations CEEPAM (Caraguatatuba) and Ubatuba. During the spring of 2009 and the summer of 2011 very high values were registered in Ubatuba. High values were also observed in CEEPAM (Caraguatatuba) in October 2008. The highest monthly values for the municipalities of Caraguatatuba and Ubatuba reached 500 mm, while in S&#227;o Sebasti&#227;o, the highest values never exceeded 400 mm. The years 2009, 2010, 2011 and 2013 also registered excessive rainfall in other areas of southeast Brazil; these were probably associated with more intense El Ni&#241;o phenomena [<xref ref-type="bibr" rid="scirp.95616-ref28">28</xref>] .</p></sec><sec id="s3_2"><title>3.2. Chlorophyll a and Turbidity in the North Coast Area of S&#227;o Paulo</title><p>In the present work 26 images (dry and wet seasons from 2005 to 2017 inclusive) were prepared, displaying the parameter chlorophyll a, with another 26 images displaying the parameter turbidity. A complementary sample set of images is presented in the appendix A (A1 to A9).</p><p>Among the parameters that may control intensity of chlorophyll a production, the provision of nutrients is relevant and associated with wet-season (summer) tourism activity in the region [<xref ref-type="bibr" rid="scirp.95616-ref29">29</xref>] . Sunlight incidence is also important for primary chlorophyll a production and is expected to be more intense in the wet season (summer). On the other hand, the transparency of the water is very important because less turbid water allows more light to penetrate, increasing water primary production [<xref ref-type="bibr" rid="scirp.95616-ref30">30</xref>] , so that in the dry season (winter), although lower nutrient concentrations are expected, higher primary production may result from water transparency. Finally, higher volumes of water entering the system (as in the wet season) may dilute concentrations of chlorophyll a [<xref ref-type="bibr" rid="scirp.95616-ref19">19</xref>] .</p><p>For chlorophyll a, the analysis of the whole image sequence (since 2005) indicates that in the wet season primary production is less intense than in the dry season (<xref ref-type="fig" rid="fig4">Figure 4</xref> shows the dry and wet seasons for the year 2010). This behavior indicates that although the provision of nutrients and the intensity of sunlight are expected to be higher during the wet season (summer), it is probable that strong water dilution hinders primary production. In <xref ref-type="fig" rid="fig3">Figure 3</xref>, for all stations, it can be observed that the dry-period (from May to September) rainfall is about one third that of the wet-period amounts. However, <xref ref-type="fig" rid="fig5">Figure 5</xref> shows that</p><p>the results of turbidity (also for the year 2010) did not show the expected higher values during the wet season, indicating that dilution from higher rainfall is more important than other influences. This trend was similar for all the other years.</p><p>For a temporal evolution of the concentrations of chlorophyll a and turbidity (2005-2017), besides rainfall, we considered the major development projects in the region and their impacts. <xref ref-type="table" rid="table2">Table 2</xref> depicts the impact of each development and the estimated intensity at the qualitative scale (irrelevant, light, mild, strong and very strong). From <xref ref-type="table" rid="table2">Table 2</xref>, it is possible to identify the period between 2009 and 2011 as the beginning of the most impacting development. It must be emphasized that the development did not stop in 2011, because the roads and harbors have continued to produce suspended matter (from removed vegetation) and nutrient elements (from population increase). The intensification of the</p><table-wrap id="table2" ><label><xref ref-type="table" rid="table2">Table 2</xref></label><caption><title> Main impacts of development projects, their intensities and the periods when the activity began</title></caption><table><tbody><thead><tr><th align="center" valign="middle" >Development</th><th align="center" valign="middle" >Aspects/Impacts [<xref ref-type="bibr" rid="scirp.95616-ref33">33</xref>]</th><th align="center" valign="middle" >Intensity of impact</th><th align="center" valign="middle" >Commencement of activity</th></tr></thead><tr><td align="center" valign="middle" >Platform and underwater pipeline from Mexilh&#227;o Field</td><td align="center" valign="middle" >Dredging and underwater movements/offshore resuspension of sediments</td><td align="center" valign="middle" >Irrelevant</td><td align="center" valign="middle" >February 2007</td></tr><tr><td align="center" valign="middle" >Long-Term Testing Guar&#225;</td><td align="center" valign="middle" >Dredging and underwater movements/offshore resuspension of sediments</td><td align="center" valign="middle" >Irrelevant</td><td align="center" valign="middle" >September 2009</td></tr><tr><td align="center" valign="middle" >Pilot production test in the field of Tupi/Lula</td><td align="center" valign="middle" >Dredging and underwater movements/offshore resuspension of sediments; intensification of naval activity along the coast</td><td align="center" valign="middle" >Light</td><td align="center" valign="middle" >September 2008</td></tr><tr><td align="center" valign="middle" >Exploration and development projects of the pre-salt in the Santos Basin</td><td align="center" valign="middle" >Dredging and underwater movements/offshore resuspension of sediments</td><td align="center" valign="middle" >Irrelevant</td><td align="center" valign="middle" >November 2011</td></tr><tr><td align="center" valign="middle" >UTGCA—Gas treatment unit</td><td align="center" valign="middle" >Vegetation removal, landfilling, population increase/degradation of the landscape</td><td align="center" valign="middle" >Mild</td><td align="center" valign="middle" >April 2006</td></tr><tr><td align="center" valign="middle" >GASTAU—Gas pipeline</td><td align="center" valign="middle" >Vegetation removal, landfilling, population increase/degradation of the landscape</td><td align="center" valign="middle" >Mild</td><td align="center" valign="middle" >April 2006</td></tr><tr><td align="center" valign="middle" >New pier—TEBAR</td><td align="center" valign="middle" >Dredging and underwater movements; intensification of naval activity along the coast, population increase/sediment resuspension, noise, emissions, degradation of water quality</td><td align="center" valign="middle" >Mild</td><td align="center" valign="middle" >September 2011</td></tr><tr><td align="center" valign="middle" >Enlargement of the S&#227;o Sebasti&#227;o Port</td><td align="center" valign="middle" >Dredging and underwater movements; intensification of naval activity along the coast, population increase/sediment resuspension, noise, emissions, degradation of water quality</td><td align="center" valign="middle" >Strong</td><td align="center" valign="middle" >October 2009</td></tr><tr><td align="center" valign="middle" >Nova Tamoios Highway sub-track upland</td><td align="center" valign="middle" >Vegetation removal, landfilling, population increase (distant from the coast)/degradation of the landscape; degradation of the water quality.</td><td align="center" valign="middle" >Strong</td><td align="center" valign="middle" >August 2011</td></tr><tr><td align="center" valign="middle" >Nova Tamoios: sub-track Southern Contours</td><td align="center" valign="middle" >Vegetation removal, landfilling, population increase (near the coast)/degradation of the landscape; degradation of water quality.</td><td align="center" valign="middle" >Very strong</td><td align="center" valign="middle" >February 2010</td></tr><tr><td align="center" valign="middle" >Nova Tamoios: sub-track Northern Contours</td><td align="center" valign="middle" >Vegetation removal, landfilling, population increase (near the coast)/degradation of the landscape; degradation of water quality.</td><td align="center" valign="middle" >Very strong</td><td align="center" valign="middle" >December 2011</td></tr></tbody></table></table-wrap><p>production of chlorophyll a is clearly verifiable from the images in the dry seasons of 2007 and 2012 (<xref ref-type="fig" rid="fig6">Figure 6</xref>), indicating a population increase as the source of increased inputs of nutrients. Observations from all the years, sampled in the Supplementary Material, clearly corroborate this trend. However, the year 2017 was an exception, when the concentrations significantly decreased. Based on the parameters we considered in this article, it is not possible to explain this phenomenon environmental improvement. Considering that the images are instantaneous pictures of the different situation, it is possible that other factors like exceptional oceanic currents (not considered in the present article) influenced water quality in the year 2017. Although there is no indications of the presence of oceanic waters in the study area, Paloczy, Brink [<xref ref-type="bibr" rid="scirp.95616-ref31">31</xref>] observed the intrusion of the South Atlantic Central Water (SACW) om the continental shelf of the Espirito Santo Basin, farther North of the study area.</p><p>Turbidity did not show the same trends as chlorophyll a; there was no significant evolution in the concentrations, with the development along the north coast of S&#227;o Paulo. Some years, such as 2005, presented high turbidity during the dry season, but in the dry season of 2013 (<xref ref-type="fig" rid="fig7">Figure 7</xref>), after the installation of some of</p><p>the most impacting development, the turbidity was low. It is probable that, regardless of whether the most impacting development promoted the resuspension of sediments and the intensification of erosion in the continent, the region presented a well-preserved vegetation cover, particularly in the eastern portion [<xref ref-type="bibr" rid="scirp.95616-ref32">32</xref>] . This vegetation cover hinders any long-term increase in turbidity in the region.</p></sec></sec><sec id="s4"><title>4. Conclusions</title><p>Various parameters seem to control chlorophyll a in the water column of the north coast of S&#227;o Paulo including provision of nutrients (associated with population increase and tourism). The transparency (depending on turbidity) of the water also contributes to the primary production by increasing the intensity of sunlight incidence also depending on the season. The volume of rainwater entering the system that promotes dilution of the concentrations also seems to be important. The occurrence of higher concentrations of chlorophyll a in the dry season (winter) is unexpected, because this period has less tourism activity, less incidence of sunlight and higher turbidity. Therefore, the dilution promoted by intense rainfall during the wet season (summer) is more effective in reducing primary production than all the other parameters, along the north coast of S&#227;o Paulo.</p><p>The temporal evolution of the concentrations of chlorophyll a (2005-2017) shows that impacting developments like the construction and maintenance of roads and the installation or upgrade of ports promote population growth and increases in maritime activity. These impacting events, which were intensified after 2009, resulted in increasing chlorophyll a concentrations along the north coast of S&#227;o Paulo. To mitigate the impacts, developments like these should be accompanied by extensive sanitation works, to reduce the load of nutrients.</p><p>Images of turbidity along the north coast of S&#227;o Paulo show that dilution from heavy rainfall in the wet season (summer) also controls this parameter in the water column. Most of the images show a higher turbidity in the dry season (winter) than in the wet season (summer), except for the years 2005 and 2009. Nevertheless, no temporal trends in turbidity could be observed from 2005 to 2017. After the installation of the most impacting developments during 2009-2011 no consistent or relevant increase in turbidity could be identified. Apparently, the preservation of the vegetation cover along the north Coast of S&#227;o Paulo, and particularly in the eastern portion of the region, hinders increases in turbidity due to impacting developments like dredging and landfilling.</p><p>Finally, it is interesting to highlight some limitations of the research. First, although satellite images of the chlorophyll a and turbidity have been largely calibrated in many studies, the fact that we did not calibrate the results with real samples is a limitation, because the color response of the images may be different in distinct locations. Second, the interpretation of the results with other parameters like position of oceanic waters may be important, as discussed on the results of the year 2017. Unfortunately, the temporal behavior of oceanic currents in the southeast Brazil is poorly known and further studies are necessary. Third, it would be very helpful to compare the results of images with other biogeochemical parameters, like salinity, pH, redox potential, dissolved oxygen and freshwater discharges. Some of these parameters like salinity can also be estimated by satellite imaging, while others have to be measured in situ.</p></sec><sec id="s5"><title>Acknowledgements</title><p>The authors are grateful to Nemus Ltd. for financial support. JCW is also grateful to the Brazilian Council of Scientific and Technological Development (CNPq) for a research grant (grant # 306714/2013-2). PB is also grateful to CAPES for financial support (grant # 001). These financial supports do not imply any sort of bias in the results or their interpretation.</p></sec><sec id="s6"><title>Conflicts of Interest</title><p>The authors declare no conflicts of interest regarding the publication of this paper.</p></sec><sec id="s7"><title>Cite this paper</title><p>Bettencourt, P., Wasserman, J.C., Dias, F.F., Alves, P.R., Bezerra, D.B., Santos, C.A., Zotes, L.P. and Barros, S.R. (2019) Remote Sensing Applied to the Evaluation of Spatial and Temporal Variation of Water Quality in a Coastal Environment, Southeast Brazil. Journal of Geographic Information System, 11, 500-521. https://doi.org/10.4236/jgis.2019.115031</p></sec><sec id="s8"><title>Appendix A</title></sec></body><back><ref-list><title>References</title><ref id="scirp.95616-ref1"><label>1</label><mixed-citation publication-type="other" xlink:type="simple">Kohli, P., Siver, P.A., Marsicano, L.J., Hamer, J.S. and Coffin, A.M. 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