In arid and semiarid zones, groundwater plays a key role in the ecology and availability of freshwater. Coastal lagoons in arid zones have great importance as a refuge for species of flora and fauna, as a source of freshwater, and for recreational purposes for local communities and tourism. In addition, as environments under natural stress, they are suffering pressure from anthropogenic activities and climate change, especially in zones with intense touristic development as in the case of the Baja California Peninsula in northwest Mexico. In this paper, we analyze the future of a coastal lagoon impacted by climate change and anthropogenic pressures. We constructed a groundwater MODFLOW-SWI2 model to predict changes in freshwater–saltwater inputs and correlated them with the geospatial analysis of the distribution and evolution of the water body and surrounding vegetation. The methodology was applied to the San Jose lagoon, one of the most important wetlands in the Baja California peninsula, which had been affected by anthropogenic activities and endangered by climate change. According to our water balance, the deficit of the San Jose aquifer will increase by 2040 as a result of climate change. The water table north of the lagoon will drop, affecting the amount of freshwater inflow. This reduction, together with an increase of evapotranspiration and the sea-level rise, will favor an increase of mineralization, reducing the surface water and groundwater quality and in consequence affecting the vegetation cover. Without proper management and adequate measures to mitigate these impacts, the lagoon may disappear as a freshwater ecosystem. Results of this research indicate that the use of a groundwater flow model, together with a geospatial analysis provide effective tools to predict scenarios for the future of coastal lagoons, and serve as a basis for land planning, nature conservation, and sustainable management of these ecosystems.

Floods are amongst the most frequent and destructive type of disaster, causing significant damage to communities. Globally, there is an increasing trend in the damage caused by floods generated by several factors. Flooding is characterized by the overflow of water onto dry land. Tropical cyclones generate floods due to excess water in rivers and streams and storm surges; however, the hazard of both phenomena is presented separately. In this research we present a methodology for the estimation of flood hazards related to tropical cyclones, integrating runoff and storm surge floods. As a case study, we selected the south-western suburbs of the city of La Paz, the capital of the state of Baja California Sur in northwest Mexico. The city has experienced in recent years an expansion of the urban area. In addition, there is an infrastructure of great importance such as the transpeninsular highway that connects the capital with the north of the state, as well as the international airport. Our results indicate that urban areas, agricultural lands, as well as the air force base, airport, and portions of the transpeninsular highway are in hazardous flood areas, making necessary to reduce the exposure and vulnerability to these tropical cyclone-related events. A resulting map was effective in defining those areas that would be exposed to flooding in the face of the impact of tropical cyclones and considering climate change scenarios, which represents an invaluable source of information for society and decision-makers for comprehensive risk management and disaster prevention.

The Las Cruces intrusive suite is located at the southern extent of the Baja California Peninsula in northwestern Mexico. The suite constitutes the northern part of the Los Cabos Batholitic Complex. It is correlated with extensive Cretaceous magmatic activity extending across California and the Baja Peninsula, known as the Peninsular Ranges Batholith. Despite its significance for understanding the regional tectonic and magmatic evolution, detailed information to fully support this correlation remains limited. This work provides new cartographic and structural data of the units comprising the intrusive suite and the temporal relationships between lithological units, supported by U-Pb zircon geochronology. The suite consists of granite in its central part, tonalite displaying magmatic foliation at its NW and SE margins, and two gabbro apophyses along the western edge. The host rocks consist of intercalations of hornblende and biotite schists, forming screens and roof pendants. Late magmatic felsic dikes, derived from the granite, intrude into the suite units. Five new U-Pb zircon age determinations indicate that the suite has a normal crystallization history with ages from 103.5 ± 1.2 to 97.6 ± 0.8 Ma for the tonalite and from 93.6 ± 0.7 to 95.0 ± 0.9 Ma for the granite. The gabbro is the oldest intrusive unit, with previous U-Pb zircon ages reported near 109 ± 2.3 and 102.3 ± 2.9 Ma. Structural analysis indicates that the gabbro and tonalite were emplaced during an E–W synmagmatic compressional event, evidenced by N–S oriented magmatic foliation, aligning subparallel to the granite and metasedimentary screens contacts. Later, the granite was emplaced during a compressional stress relaxation phase, causing the tonalite dissection and forming the current suite margins. The calculated U-Pb ages for the Las Cruces intrusive suite and reported geochemical and geophysical data from the northern Baja California Peninsula support its correlation with the Peninsular Ranges batholith.