**Abstract**

This chapter presents a collection of studies performed in the Amazon region that includes thematic products portraying its fluvial sensitivity to oil spills. The research addresses the intense Amazonian seasonal dynamics, as well as the environmental peculiarities of this singular ecosystem. Periodic changes caused by natural phenomena have a significant impact on not only flooded alluvial plains and riverine habitats but also on petroleum exploration, production, and transportation activities. Therefore, the implementation of tools to assess the potential impact of oil spills in the Amazonian rivers must be adjusted to the local conditions. The main deliverables of the research are (1) fluvial oil spill sensitivity index maps contemplating each phase of the hydrological cycle (low water, high water, receding water, and rising water), (2) a computational method to represent fluctuations of the seasonal inundation, and (3) a risk analysis method using linguistic rules for the construction of a risk matrix.

**Keywords:** Amazon region, fluvial sensitivity to oil spills, computational modeling, linguistic rules, risk matrix

## **1. Introduction**

The Amazon is a region characterized by ecologically complex environments subjected to constant and rapid seasonal changes. The environmental patterns that make up the Amazonian scenario are determined by the changes that occur in the different phases of its hydrological cycle. The seasonal dynamic is evidenced by the average annual variation of the waters between maximum drought and flood conditions, which is on the order of 10–12 meters and is associated with rainfall in the headwaters of the rivers of the region and the annual thaw of the Andean summer [1].

A significant quantity of sediments from the Andes slopes, as well as a high concentration of nutrients, is transported during the flood period. This is the

main contributor responsible for the productivity of Amazonian floodplains, in terrestrial and aquatic systems alike [2]. The resulting annual deposition of such sediments defines the fauna and flora, the geomorphology of the floodplain, biogeography, and patterns of human occupation [1].

The discovery and exploitation of oil and gas in the Central Amazon rainforest is a major challenge for sustainable development. Hydrocarbon transportation is an industrial enterprise that involves various potential environmental impacts, thus requiring interdisciplinary studies for risk assessment [3, 4].

The study area includes the flow route of crude oil, liquefied petroleum gas (LPG), and natural gas produced by Petrobras in the Petroleum Province of Urucu. Three pipelines are used to bring crude oil, LPG, and natural gas from Urucu to a terminal located in Coari. From there, crude oil and LPG are transported to Manaus by river, while natural gas is taken via a terrestrial gas pipeline. Thus, this region is susceptible to possible damages due to oil activities, which are a potential threat to environmental conservation in the areas under its influence [5, 6].

The major oil companies have intensified their programs of excellence in environmental management and operational safety in order to reduce the risk of accidents in the operations of exploration, production, and transportation of petroleum and its derivatives. Nevertheless, these accidents can occur in rivers or at sea, due to product spills during procedures of oil tanker reservoir cleaning or loading in terminals, which require standardized response procedures for such emergencies [7].

Thus, given that the Amazon region presents considerable environmental sensitivity to oil spills, there is a need to respond proactively to possible accidents. In order to do this, it was necessary to examine the list of features of its rivers and lakes and their corresponding sensitivity in more detail, in order to hierarchize them in terms of potential impacts [8]. As a result, Araújo et al. [9] defined the fluvial sensitivity index to oil spills, adapted to the corresponding features and consistent with the typical Amazonian seasonality.

Among the factors that influence the sensitivity of habitats to oil spills, the most important are (1) the degree to which affected areas are exposed to processes of natural removal, (2) biological productivity and recovering capability after oil impacts, (3) existing land-use practices, and (4) ease of oil spill cleaning [10]. The overall sensitivity of natural habitats to oil spillage is ranked according to the aforementioned factors in the context of the environmental sensitivity index (ESI). The use of ESI is fundamental for oil spill contingency planning.

The most sensitive habitats in the Amazon region are flooded forests. In fact, inundation causes seasonal differences in the water level and changes the landscape, which creates the need for production of a specific sensitivity index map for each season: low water, high water, receding water, and rising water. The areas occupied by flooded forests change with time, such that continuous monitoring is required through the collection, processing, and analysis of remote sensing data. These areas were first systematically studied in the last decade using LHH SAR images based on the multi-seasonal coverage of the JERS-1 satellite [11].

The global weather-independent coverage provided by the synthetic aperture radar (SAR) system onboard the JERS-1 satellite allowed end users to monitor the rapidly changing conditions in cloud-covered rainforest regions. This L-band, HH polarization system is best suited for flood mapping in rainforest-covered areas due to its capability to penetrate dense vegetation [12].

The JERS-1 satellite orbital arrangement favors the continuous monitoring of the Amazonian hydrological cycle. To do so, contiguous orbits on consecutive days are used. Such a procedure allows temporally homogeneous images to be acquired on a continental scale [13]. Consequently, JERS-1 SAR data were instrumental in mapping inundation variation in space and time over large forested floodplain regions [14–18].

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**Table 2.**

*Fonte: Petrobras [21].*

*Overview of Hydrological Dynamics and Geomorphological Aspects of the Amazon Region…*

stretch that covers Urucu, Coari, and Manaus, will be presented.

**Fluvial channel features River plain features**

2. Beaches along the banks 2. Dense flooded forest

**Transitional features between channel and river plain components**

4 Scarps/high banks in unconsolidated sediment

10b Scrub-shrub wetlands (swampland, lowland, bushland, field, etc.)

 Exposed beaches and sand/gravel bars Sheltered beaches and sand/gravel bars Exposed mud beaches and bars Sheltered mud beaches and bars River and lake confluence zones 10a Aquatic macrophyte bars

*Fluvial sensitivity index to oil spills of the Amazon region.*

3. Waterfalls 3. Bushland (lower-density forest)

well as the ease of operational implementation [8].

**Riverine features of the Amazon region**

precise characteristics) and islands

1. Holes 2. Lake outlets *Fonte: Petrobras [21].*

*Amazon region riverine features.*

**Table 1.**

1. River banks (large class subdivided into more

4. Riverine sand bars—beaches formed in the middle of the river, isolated from the shores

**Index Characteristic or feature** Man-made structure Rocky shoals Rapids/waterfalls

**2. Determination of the fluvial sensitivity index in the Amazon**

Since the beginning of the 1990s, Petrobras has verified that the methodology of drawing up maps of environmental sensitivity to oil spills, adopted by the National Oceanic and Atmospheric Administration (NOAA), adequately adapts to the Brazilian reality, due to its great acceptance and utilization in many countries, as

1. Exposed lake/plain

4. Herb or grass macrophyte bank/exposed plain, depending on the period, functions as a filter

In this chapter, a brief summary will be presented on how the main Amazon features were identified and hierarchized, with relevance to the determination of the environmental sensitivity to oil production and transportation activities. Next, the three approaches used in mapping the fluvial sensitivity index to oil spills, in the

*DOI: http://dx.doi.org/10.5772/intechopen.86592*

*Overview of Hydrological Dynamics and Geomorphological Aspects of the Amazon Region… DOI: http://dx.doi.org/10.5772/intechopen.86592*

In this chapter, a brief summary will be presented on how the main Amazon features were identified and hierarchized, with relevance to the determination of the environmental sensitivity to oil production and transportation activities. Next, the three approaches used in mapping the fluvial sensitivity index to oil spills, in the stretch that covers Urucu, Coari, and Manaus, will be presented.
