**3. Environmental problems in the coast of Ceará State, Northeast of Brazil**

#### **3.1 Natural settings of the study area**

Ceará is one of the states of the Brazilian equatorial northeastern region. Its coastal area spans between the latitudes of 2o 47′S and 4o 50′S for 573 km and is characterized by long and gently sloping sandy beaches, irregularly interrupted by headlands, small estuaries with mangroves, sea cliffs, and beach rocks, with large dunes and small barrier islands [1–2] (**Figure 1**).

The headlands are characterized, with few exceptions, by the occurrence of sea cliffs with heights varying from 2.7 to 20 m. Tertiary rocks are present, named Barreiras Formation, and create a low-lying tabular surface with less than 40 m in elevation, which extends from the shoreline up to 60 km inland. It outcrops as sea cliffs 3 to 15 m high [e.g., 3] (**Figure 1**).

*Environmental Problems and Coastal Mitigation in South America: Examples from Northeast… DOI: http://dx.doi.org/10.5772/intechopen.87959*

**Figure 1.** *Location and geological/geomorphological settings of Ceará state coastal area, northeast Brazil.*

The mobile dunes orient E to W and are mostly barchans and transverse dune ridges [4–7]. The rate of dune migration ranges from 9 m/y to 22 m/y, with an average of approximately 11 m/y [4–7]. Frequently, the dunes bypass across the headlands, nourishing the beaches downdrift. This process is an important element of the sedimentological budget of this coastal area, considering that it counterbalances the downdrift erosion resulting from the impoundment of the longshore sand by the headlands.

Climatic conditions are controlled by the ITCZ [8]. During fall, the ITCZ is at its southernmost position, resulting in the rainy season. After April, the ITCZ shifts northward, leading to the dry season [9]. The climate is tropical subhumid, with average precipitation between 1000 mm and 1420 mm/y [3]. Temperatures remain largely constant throughout the year, with monthly averages ranging between 25.5° and 27.5°C [10].

The trade winds dominate the area and present a similar pattern to that of precipitation but with an opposite trend: As the precipitation rate decreases, the wind speed increases; during the wet season, the average wind speed is approximately half of that in the dry season. On average, maximum wind speed is around 8 m/s in the dry season. A particular characteristic of the wind condition is its constant easterly direction, coming from southeast or northeast [10].

The predominant wave direction is 90°, with heights ranging from 1.0 to 1.5 m [4, 11]. The waves are mainly of the sea type, with occasional occurrence of NE swell [12]. The area is characteristic of a semidiurnal mesotidal regime with a spring tidal range of approximately 3.1 m [13]. The most referenced Holocene sea level curve [14] indicates +5 m at 5.1 Ky BP, followed by two rises and falls until the present level.

A unique aspect of this stretch of coastal area is that it is not influenced by storminduced surge and extreme wave conditions. Instead, extremely persistent unidirectional wind and wave forcing dominate, creating a strong and persistent longshore forcing that induces a large net rate of longshore sediment transport [15].

The mean sea level rose 14 cm in the last 73 years, as seen in Fortaleza (for location, see **Figure 1**). The data was obtained by the analysis of the nautical maps of 1945 and 2018 of Fortaleza coast, taking into account the level of the sea in both years in each map [16]. It indicates that a rising of sea level is an important element of the present dynamics in the area.

The rising of sea level, with inadequate and inappropriate uses, occupation, and development of the coast and of the shoreline, is producing large degradation of this coastal area, destroying ecosystems, construction, and equipment, thus causing economic, social, and environmental problems. The situation will be analyzed in two segments of the state coastal area, which are Mucuripe harbor headland, in Fortaleza city, and Canoa Quebrada beach, on the east coast (for location, see **Figure 1**).
