Flood and erosion potential of the municipal natural park of Jacarenema , Vila Velha-Es

In the present work, the level of vulnerability within the Jacarenema Municipal Natural Park, Vila Velha / ES was assessed. This vulnerability is in regards to erosion and flood, caused by sea level rise. Sea level rise prediction was retrieved from the Intergovernmental Panel on Climate change. The results indicate a loss of land equivalent to 40.24 ha (11.62% of the total), mainly in the areas of swamp, restinga and mangrove. This can lead to several impacts to the region. Such as salinization of fresh water, loss of habitat, recreational and tourist areas within the Park. Also, generating conflicts of occupation by residents in the surroundings of the conservation unit (CU).


Introduction
Coastal regions are naturally vulnerable to erosion and / or flooding due to their low altimetry and proximity to coastal hydro-dynamics.They present high variability as a result of the mutual adjustment between the oceanographic and continental agents, in relation to the transport / deposition of sediments and consequent modification of the morphology.
The coastal zone may still be threatened with environmental, social and economic damage due to climate change and the possible rise of the Medium Sea Level (NMM).The IPCC (Intergovernmental Pannel of Climate Changes) scenarios indicate that in the next 100 years the NMM can reach 1 meter of the current level (IPCC, 2014).In Portugal, Antunes (2010), using modern radar and pressure tides in the city of Cascais, monitored NMM variation, and estimated the current rate of sea rise relative to the Portuguese coast at 2.6 mm / year .
The strips of coastal land are densely populated and extremely valuable for their logistic resources and services.A relatively small rise in the level of the oceans could cause catastrophic effects such as: the contamination of salt-water tables, the flooding of coastal plains, the destruction of human settlements, as well as leaving millions of people homeless.
A number of studies have been carried out in the last few years revealing the impacts caused by coastal erosion due to climate change and anthropogenic interventions (Maia et al., 1998;Albino et al., 2006;Macedo et al., 2012;Manca et al., 2013).Erosion, on the other hand, is the process of removing sediments from one environment to another by air, land or water transport (Muehe, 1996).In Brazil, the coastal zone may have a process of accelerated erosion by anthropic intervention in coastal zones and / or anthropic pressure of socioeconomic character (Albino et al., 2006;Souza, 2009).
In the city of Caiçara, Rio Grande do Norte, the sea has advanced more than 50 meters in the last decade.Consequently, more than 80 houses were destroyed and their residents forced to abandon their homes (Trabanco et al., 2001).Another example is the Maracaípe beach, in Pernambuco, where urban expansion accelerated the economic development of the region, resulting in an irregular occupation of the coastal zone, triggering erosive problems at the coastline (Macedo et al., 2012).
The understanding of the processes responsible for the morphodynamics of coastal environments, and the formation and migration of sandy banks, is necessary, considering that such processes play an important role in shaping, stabilizing the coastal environment and identifying coastal risks (Albunquerque et al., 2009).Mendoza and Jiménez (2006) studied the impact of storms on the coast of Catalonia, classifying them according to their potential for beach erosion.The beach profiles were simulated in models that indicated the coastal response from the duration and intensity of the storm.In later studies, Alvaro-Aguilar and Jiménez (2009) mapped the coastal response to flood risk by coastal storms in the Delta of the Ebro, Spain.
One of the techniques currently used to investigate and predict environmental impacts in a given area is the making of vulnerability maps.Nascimento and Dominguez (2009) mapped the environmental vulnerability of the municipalities of Belmonte and Canavieiras, located on the southern coast of the state of Bahia.In the research, vulnerability indexes were generated from the integration of geological characteristics, soils, declivity, land use and vegetation.For each different feature, weights were assigned from 1 (least vulnerable) to 5 (most vulnerable).According to the results, the most vulnerable environments were the mangroves, the fluviallagoon lowlands and the coastline, while the less vulnerable were the Tableland (Barreiras Group).Vulnerability analyses, therefore, allow the understanding of different degrees of fragility in an area of study, and can be used as an instrument for coastal management and urban planning.The creation of protected areas is one of the most widely used instruments in the world to find alternative ways to curb environmental degradation, preserve and protect areas of high ecological interest (Santos, 2009).In Brazil, these areas have been designated as Conservation Units.
The history of the creation of Conservation Units occurs around conflicts and interests between society, environmentalists, public and private companies, and government (Vivacqua and Vieira, 2005, Martins, 2012and Souza, 2014).According to Brito (2008), these conflicts require a theoretical and technical understanding, since only with this knowledge is it possible to delineate actions and interventions capable of minimizing the environmental and social degradation of these areas.In Fortaleza / CE, the vulnerability of the Sabiaguaba Conservation Units was studied by Crispim et al. (2008).The authors diagnosed the potentialities and limitations regarding their use and occupation, defining the morphodynamic agents and how it acts, in an integrated way, for the composition of the coastal landscape inserted in the area.As a result, Crispim et al. (2008) stated that coastal CUs have the following functions: 1) protect the surrounding environments, and absorb the effect of tides and waves; (2) sediment suppliers for estuarine and morphodynamic hydrodynamics; (3) protect the high biodiversity; (4) serve as freshwater reserve, among others.
According to data from the IEMA (2016), Espírito Santo has 112 CUs, distributed among federal, state, municipal and private reserves.They have been presented as important legal instruments for the preservation of threatened natural environments.However, CUs present in the territory of the state of Espírito Santo have been the target of management problems as a result of its small size (less than 1,000 ha on average).In addition, the bodies responsible for their management and supervision, lack suitable operational, financial and technical conditions.
The objective of the present work was to map the flood and erosion potential of the Jacarenema Municipal Natural Park (PNMJ), Vila Velha / ES, based on a scenario of average sea level rise based on IPCC forecasts.In this sense will be presented: a) the natural vulnerability of the park, considering the sedimentary composition and altimetry of the land and b) considering the increase of the water level and the consequent floods and erosions in the park, the changes in the use of the area will be quantified.Such information allowed evaluation of ecosystems in greater threat and contributed to the conservation and management of the park.

Characterization of the area
The study area, in the case of Jacarenema Municipal Natural Park (PNMJ), is located in the coastal zone of the municipality of Vila Velha, Espírito Santo state (Figure 1).The CU in question covers an area of 346.27ha (SEMMA, 2010), comprising the Morro da Concha, the estuary of the Jucu river and the surrounding mangrove swamp, the areas of vegetation of restinga adjacent to the Rodovia do Sol, and other ecosystems present in the CU (Pinheiro, 2011).In the vicinity of the PNMJ there was great pressure on real estate, highlighting: to the south, an already consolidated urbanization, with the presence of restaurants, berth area, summer residences and tourist attractions.
The PNMJ area is characterized by the outcrops of pre-Cambrian crystalline rocks in contact with the quaternary deposits interspersed by the outcrops of the Barreiras Formation preceded by the beach.The coastline is very severely cut, being observed salient stretches without conditions of deposition of sands and stretches with significant development of the coastal plains.The PNMJ presents important morphostructural characteristics, since it stands out to the residual elevation of the granite formation near the coast line, denominated Morro da Concha.It should be noted that in this sector of the state of Espírito Santo, according to Vale (2004), the occurrence of tertiary deposits is less pronounced, appearing occasionally in the form of hills.The fluvial-marine plain already includes a number of flooded and floodable areas around the Park.

Flood potential and erosion
The mapping and analysis of flood potential classes was based on the proposal of Nascimento & Dominguez (2009), based on the rereading and interpretation of mapping criteria (Table 1) prepared by Pinheiro (2011).We then developed a routine for converting vector data from contour curves and geomorphology into raster formats with cell size of 1 m, both files were provided by PMVV (2016) and later edited, with the purpose of refining and adapting the information to the scale of the study area.The choice of flood potential and erosion was based on the methodology proposed by the U.S. Geological Survey -USGS (Thieler and Hammar-Klose, 1999), also used by Nascimento and Dominguez (2009).For this, 5 classes of natural fragility were determined, namely: I -Very Low, II -Low III -Medium, IV -High and V -Very High.Later, in a GIS environment, Fuzzy logic was used, which according to Moura (1993) is a mathematical system created to manipulate imprecise descriptions.Against binary relations, of the yes or no, the interpretation of reality as a set in which the members have degrees of pertinence is proposed.These degrees are given by arbitrary values that depend on different points of view of the context.In this way, an algebraic operation was performed with coefficients to assign importance for each variable between 0 and 10, where weight was given 4 for Geomorphology and 6 for Altimetry.The geomorphological classes were defined by the form and materials that constitute it and can offer greater or less resistance to erosion and flooding.The altimetry received a higher value because it controls the degree of exposure of the geomorphology.
In this regard, the potential for flooding and erosion was calculated from the sum of the variables.Each one of these was multiplied by its relevance coefficient, and later divided by the number of these variables (Geomorphology * 4 + Altimetry * 6) / (2).

Rise of sea level
According to forecasts by the International Panel on Climate Change (IPCC) in 2014, the worst case scenario indicates a sea level rise of 1 meter by the year 2100 (Figure 2).According to this scenario, a simulation based on Brunn (1962) was carried out in order to identify and quantify coastal areas affected by maximum sea level rise.The loss of land was determined by the equation: Hallermieier (1981), R represents the retreat of the coastline in plan, S the elevation of the sea level, L the distance to the closing depth D and H the height of the active profile (Figure 3).In the field, the height of the active profile was raised by means of GPS / GLONASS, and later the depth of closure and the distance to the same were verified, by means of the vectorization and interpolation of the nautical chart.As a complement, we performed the simulation of the elevation in 1 meter of the Jucu River as a response to the sea level variation, aiming to quantify the loss of interior areas by the overflow of the river, based on the altimetric dimensions.

Vulnerability to flood and erosion
According to Vale (2004), the marine plain has unconsolidated, sandy, porous permeable sediments, with shallow or outcrop water table, susceptible to movement as well as the Flúvio-Marinha plains.The Fluvial Plain is represented by sandy and clayey, non-solid sediments, permeable with shallow and often outcrop water table.The coastal trays, in turn, consist of consolidated, stable, porous, permeable sediments with soils slightly susceptible to erosion.
Along the Capixaba coast, the sea terraces are distributed in large scale, formed mainly of the union of old coastal strings, partly reworked by the rivers.In Vila Velha, there is the narrowing of the coastal plain and consequently the same occurs with sandy cords, these are intensely exploited and account for most of the sand supplied to the industrial and population poles.Pleistocene marine terraces are flat reliefs and with cohesive sediments, guaranteeing a certain geotechnical stability to the region, being this target of occupation (CPRM, 2015).Finally the rock crystal has the least potential due to the high stability of the erosion terrain (Figure 4).
Altimetry is the most important factor in relation to flood potential.Regions with higher elevations are less susceptible to flooding by an eventual elevation of the river level.Given that flooding is a phenomenon occurring in a sea level rise, it has been established that the 1 meter altimetry is represented by the highest flood potential class.On the other hand, land with altimetry above 5 meters represents the class with reduced flood potential (Figure 5).
In summary, Table 2 shows the classes defined for each variable analyzed for the mapping of flood potential and erosion.From the cross-referencing of the data represented in Table 2, we have the map of flood potential and erosion (Figure 6), demonstrating which areas are most vulnerable from the altimetric and geomorphological points of view.
Analyzing the generated map, it can be seen that areas with very high potential are not only concentrated in the vicinity of the river, but extend to interior regions, associated mainly with the fluvial-marine, fluvial and marine plains, but also in areas close to the mouth of the Jucu River.There is a concentration of less vulnerable areas to the west of the Rodovia do Sol, which crosses the park, related to crystalline outcrops, Tableland and marine terraces.Areas with presence of covered marine terraces, found adjacent to the highway, are related to medium and high potentials, as well as the coastal cordon in the marine plain.In this way, it can be said that although altimetry plays a major role, geomorphology also contributes to the determination of the terrain and flood mobility potential, given the characteristics of the sedimentary packages that make up each feature.

Simulation of sea level rise
The result of the simulation of sea level rise shows the migration of the coastline as well as the affected areas (Figures 7 and 8).
The importance of identifying flooded compartments revolves around the assessment of loss of coastal ecosystem areas.Swampy areas present greater loss in a flood scenario according to (Table 3).According to the World Wide Fund for Nature (2016), swamps are environments that provide a series of environmental services such as: storage and cleaning of water; regulation of local climate and biogeochemical cycles; recharge of the water table and maintenance of biodiversity.
Soon afterwards there is the herbaceousshrub restinga, located mainly near the coastal strip, associated with sand dunes.According to Table 3, there will be more than half of the herbaceous-shrub restinga vegetation.In this way, the loss of this vegetation can lead to the destabilization of these dunes, compromising groundwater, besides impacting the associated fauna.
The third most impaired ecosystem was the mangrove, important regions of reproduction and maintenance of species, they function as natural nurseries, concentrating great bio-diversity.They represent an area of intense interaction between man and nature, since the local community depends on its resources to survive, through fishing and catching crabs (Pinheiro, 2011).
It is important to emphasize that anthropic areas would also be impacted by the proposed scenario, since in the fluvial-marine plains and at the edge of the Marine Terraces, near the mouth of the Jucu River, there are inhabited areas such as residences, restaurants and a boat dock of small size.
In the Fluvial Plains, 27.28 ha, present 23.22% of their flooded area.This is because, they are also areas of low altimetry, reaching a maximum of 2 meters.They would therefore have as a loss area, a part of the marshland and part of Coastal vegetation (Mata Paludosa) that represents 45.47 hectares of the area in the PNMJ (13.13%), being equivalent to an area of 1.38 hectares (0.4%).
Another flooded environment would be the edge of the Marine Terraces, which is in direct contact with the right bank of the Jucu River.In these areas, there would be loss of Coastal vegetation (Mata Paludosa) and predominantly of marsh.
In the Marine Plains, which represent 45.18 ha corresponding to a total of 69.19% of the PNMJ, the flooded area corresponds to Dry vegetation of restinga that represents 85 ha total within the PNMJ (24.55%) and that will have 19.88 ha of directly flooded area that represents 5.7% of the total area.In this geomorphological compartment, there is still the Herbaceous-Shrub Restinga with 10 hectares of area that represents 2.89% of the total of the Park.This vegetation, however, would disappear completely.

Conclusions
Based on the analysis and interpretation of the elaborated maps, it is possible to distinguish areas prone to flooding and erosion, which require greater attention on the part of those responsible for the management of the Jacarenema Municipal Natural Park and the Public Power.It was concluded that altimetry is the most important factor in the determination of this potential; however, geomorphological characteristics corroborate the determination of this classification.
On the probable simulated flood in the park, it is of fundamental importance to know the characteristics of each ecosystem, as well as the species present, in order to determine action plans in front of the flood of the area.
In summary, the maps were intended to illustrate the vulnerability of the region, but can be used as a tool for decision-making by environmental managers.

Figure 1 .
Figure 1.Location of the study area.

Figure 6 .
Figure 6.Map of Flood Potential and erosion of the PNMJ.

Figure 7 .
Figure 7. Map of flooded areas due to elevation at 1 meter of sea level.

Figure 8 .
Figure 8. Map of areas compromised due to elevation at 1 meter of sea level.

Table 1 .
Variables mapped with their criteria and consequences

Table 2 .
Classification of Flood Risk Indicators.