**4. Coastal environmental problems in northern Colombia**

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

The northern Colombia coast is located along the south side of the Caribbean Sea (latitude and longitude of the west and east boundaries are 11.1 north 74.9o west and 12.2 north 72.0 west, respectively) (**Figure 13**). The meteorological and oceanographic conditions are dominated by northeast trade wind, which results in the dominating northeasterly approaching wave occurring over 95% of the time. Effectively, northeasterly approaching waves occur by far the most frequently (**Figure 14**), driving a persistent westward longshore sediment transport.

The general shoreline orientation of the study area is roughly 60 degrees, or striking WSW-ENE. The relatively straight shoreline is interrupted by two protruding headlands, Santa Marta and Cabo De La Vela. A broad shoreline orientation change occurs near Riohacha. To the west, the shoreline orientation is roughly 68°, while to the east, the orientation is roughly 52° or a change of 16° around the broad Riohacha headland. These shoreline orientation changes play a significant role in beach processes.

Rocky coast dominates at both the Cabo de la Vela and Santa Marta headlands, with pocket sandy beaches distributing in the numerous embayment areas (**Figure 15**). Sandy beaches distribute along most of the coastline except at the

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

#### **Figure 13.**

*The northern Colombia coast, located on the south side of the Caribbean Sea.*

#### **Figure 14.**

*Regional wave modeling results for NE (45°) approaching wave. Example of the area Santa Marta— Barranquilla Cienaga.*

**Figure 15.** *Example of rocky coast at Santa Marta headland.*

headlands. Numerous rivers discharge into the Caribbean Sea. Most of the sandy beaches distribute directly along the mainland. The westward longshore sand transport is illustrated in this example from Riohacha by the sand impoundment along the east updrift side of the long groin (**Figure 16**).

Several spit type barrier islands extend along this stretch of coastline, originated from westward spit growth, and are of the wave-dominated type [26]. All the tidal inlets are quite narrow with small flood and ebb deltas. This is controlled by the fact that the tidal range is mostly less than 0.3 m even during spring tides, while wave forcing is relatively strong. Therefore, beach-inlet interaction only has

**Figure 16.** *Example of sandy beach at Riohacha, accreted updrift by the help of jetties.*

localized influences on beach erosion and accretion. Wave plays a dominant role in shaping the coastline, since it is the dominating forcing, causing beach erosion or accretion. Extreme energetic conditions associated with direct hit or nearby passage of tropical storms can have significant and long-lasting impacts on coastal morphology.

The beach processes along northern Colombia coast are relatively simple, driven predominantly by westward longshore sand transport. The trend of beach erosion or accretion and the state of the beach are largely controlled by the gradients of longshore sand transport, which can be caused by both natural and artificial factors.
