*2.1. Study Area*

This study's area of interest (AOI) belongs to the TCP, a tropical lowland on the Gulf of Mexico, in Tabasco State, southeastern Mexico (Figure 1). It is part of the Mexican physiographic province called the Southern Coastal Plain of the Gulf of Mexico [47]. It was formed by alluvial sediments brought by rivers from the mountains of Chiapas (Mexico) and Guatemala; the rivers cross the state to flow into the Gulf of Mexico. The land is largely covered with lakes, lagoons, and wetlands (floodable areas), one of the most important in Mexico. About 80% of the TCP surface is composed of marsh, alluvial, coastal, and lake deposits from the Quaternary period; corresponding with the development of the current environments, from the Pliocene to today, and about 20% is made up of sedimentary rock from the Tertiary period [48–50]. The soils of the TCP are predominantly of alluvial and organic origin, such as Gleysols, Histosols, and Fluvisols [50,51], and are characterized by a poor drainage capacity.

**Figure 1.** Central region of Tabasco (AOI) and its main urban areas, hydrography, and topography. The background image is a shaded relief based on the INEGI elevation model (www.inegi.org.mx, accessed on 11 July 2022).

The TCP region has a tropical rainforest climate, designated as Af under the Köppen-Geiger climate classification system. This region's average annual air temperature is 26 ◦C, with average monthly temperatures ranging between 22.7 ◦C (January) and 28.9 ◦C (May). The TCP receives 1500–2000 mm of annual precipitation, mainly in the rainy season between June and November [52]. Furthermore, the region is regularly subjected to tropical storms and hurricanes from the Gulf of Mexico and the Pacific Ocean. The monthly average precipitation in the analyzed period (2018–2019) is presented in Figure 2.

Due to TCP's climatic and hydro-geologic conditions, its territory is exposed to floods annually [39]. Some floods have been catastrophic, such as those of 1980, 1995, 2007 [53], and 2020 [54]. The extensive flooding that occurred in 2020, at the end of October and early November, affected over 62% of the Tabasco state and more than 1.2 million people [54].

**Figure 2.** Monthly average precipitation (data available at [55]).

The AOI covers 596,573 ha, of which 69.76% are dedicated to economic activities, and 22.01% are covered by natural vegetation. The natural vegetation in TCP is represented by tropical rainforest and various wetland communities, including mangroves. The most important economic activities for the state of Tabasco are oil and gas production, agriculture, and livestock. Tabasco is a mainly rural state; agricultural fields and pastures cover approximately 69% of the area used for economic activities, and only 3.48% is urban (Figure 3a).

Since large-scale exploitation of hydrocarbon resources began at the end of the 1950s, oil and gas production has become Tabasco's economic mainstay. At present, Tabasco is a leader in hydrocarbon reserves and is one of Mexico's primary oil-producer states. Figure 3a shows the hydrocarbon extraction wells distribution over the AOI. Most wells have a depth ranging from 1500 to 3500 m. However, some wells reach up to 7615 m.

The study area is part of the Salina de Istmo, Pilar Reforma-Akal, and Macuspana basins (Figure 3b). The Salina de Istmo basin is Miocene-Pliocene and associated with a system of normal faults, including the Comalcalco sub-basin, associated with sediment loading and salt evacuation. The Macuspana basin is from the early Miocene-Pliocene. Sedimentary facies vary from fluviodeltaic to marine and are characterized by turbidite deposition. The Pilar Reforma-Akal Basin is the most representative of the study area where hydrocarbons are stored in limestone from the Upper Cretaceous and Upper Jurassic [56,57]. The hydrocarbon system's distribution corresponds to the Mesozoic oil fields and, to a lesser extent, to the Tertiary (Figure 3b) [57].

High volume extraction of hydrocarbons can cause LS around the producing wells. Land surface sinking due to oil and gas production depends on the geometrical shape and thickness of the reservoir, the compaction coefficient, the pressure drops in the reservoir, and the geomechanical behavior of the overburden [58]. The documented rates of LS caused by hydrocarbon extraction range from a few mm/yr [59] to up to 0.75 m/yr [60]. Even a small subsidence in plain areas could significantly increase flood vulnerability.

**Figure 3.** Physical-geographical characteristics of AOI; (**a**) land cover (INEGI [61] and distribution of hydrocarbon wells (IICNIH [62]). The area with the highest well density is located west of Villahermosa, with wells depth ranging between 1500 and 3500 m; (**b**) Lithology, geological provinces, distribution of the oil system, and its geological era [57,62].
