# Long-Term Analysis of Wave Climate and Shoreline Change along the Gulf of California
## 2 Study Area  
The study area is the Gulf of California, also known as the Sea of Cortes or Sea of Bermejo. It is located in the northwestern part of Mexico (Figure 1a) and is bordered by the states of Sonora and Sinaloa in mainland northwest Mexico, as well as the Baja California Peninsula (Figure 1b). It is one of the most productive and diverse marine ecosystems in the world [20]. Currently, it is mostly in a relatively good state of conservation, but it has started to be threatened by increasing human pressure [21] (see Figure 1b). The length of its west coast (Baja California Peninsula) is 1640 km, and the length of its east coast (Sonora and Sinaloa states) is estimated to be 1731 km; the mean cross-shore distance from the west to east coast varies from 110 to 220 km.  
Due to its geographical location (within the transition zone between tropical and subtropical climate regimes), the GC is exposed to multi-year processes, such as the El Nino-Southern Oscillation (ENSO) and the Pacific Decadal Oscillation (PDO) [22], and other phenomena such as the North American Monsoon (NAM) (also known as the Southwest Monsoon) and cold fronts. The Southwest Monsoon usually covers the period from July to September and is related to the onset of rainfall, tropical cyclones (hurricanes and depressions), the formation of a low-pressure center and the change of northwesterly winter winds to winds from the south or even the southeast [23; 24; 25; 26]. The cold fronts last from September to March, with northwesterly winds blowing over the GC [27; 28].  
On the west coast, the beaches are characterized by coarse sands (0.50-1.00 mm), and the mean beach slope is 7\({}^{\circ}\). The river network is non-perennial, so the contribution of new sediment to these beaches only occurs after storms or heavy rains. On the east coast, the beach sands are mainly medium in size (0.25-0.50 mm), and the mean beach slope is 4\({}^{\circ}\). The river network there is almost perennial, but most of the rivers are dammed, which can reduce the transport of sediment to the coast during the dry season. Rivers that are not dammed have some small impoundments for irrigation but still largely freely run towards the sea [29]. An important aspect of the coastal profile of the GC is that the beach and continental shelf on the west coast are narrower than the ones on the east coast, and in some stretches (mainly in the state of Baja California Sur), the beach is absent [30]. Figure 2 shows some images of the GC coast.  
The astronomical tide is predominantly of a mixed type, with trends towards the semidiurnal type in the northern upper Gulf and towards the diurnal type in the middle Gulf, especially on the east coast [31]. The mean tidal range shows an upward trend from the lower to the upper Gulf, ranging from less than 1.0 m in the lower Gulf up to approximately 3.5 m in the upper Gulf [32]. Regarding the waves, these are of low height (\(\sim\)0.30 m) in the upper Gulf, while in the middle Gulf, 0.60 to 0.90 m waves are found, and in the lower Gulf, heights from 1.50 to 1.80 m have been reported [29].