Complex shoreline changes happened at Añasco beach from 1936 to 1993. Two main areas were defined based on net shoreline changes. These were: 1) net accretion from stations 7 to 13; and 2) a net erosion to the south close to the Rio Grande de Añasco mouth. Shifts between erosion and accretion were observed between the two sections. These were major shoreline changes close to the river mouth (Figure 13). Changes were related to variation in magnitude and occurrence of flood events in the Rio Grande de Añasco Valley.
Figure 13. Shoreline change at Añasco.
Accretion occurred in the northward beach from stations 5 to 12 during 1936 to 1950. Moderate erosion rates were measured from 1950 to 1964. An increase in erosion rates was observed in all stations during 1964-1971. The severe erosion rates were related to both storms and flooding which occurred during this period. Human activities, such as the construction of the Yahuecas and Guayo water reservoirs during 1956, were also responsible for the reduction in the local sediment supply to the beach.