Diagnosis of Extreme Precipitation Events in the Yucatan Peninsula.

Given the impacts of human-induced global warming on the water cycle, it is relevant to pay attention to those impacts on water security as it is one of the UN's SDGs (sustainable development goals).

Many studies on future climate projections agree on a positive trend of extreme precipitation in various regions of the world. However, the process and causes of those events are not always clear and can change depending on local scales.

On the one hand, there is a dynamic mechanism due to atmospheric circulation, and on the other, there are local and thermodynamic effects from surface variables. In addition, the characteristics of the vegetation cover can influence the distribution and conservation of water in the system.

The Yucatan Peninsula - located in the southeastern part of Mexico- has a particular climate due to its morphological and hydrological characteristics (scarce orography and absence of rivers). Therefore, in this region, the recharge of the aquifer depends entirely on rainfall.

In this study, we first characterised the trend of precipitation in the last 30 years. Then we analysed the region's contribution to total annual precipitation by different hydrometeorological phenomena (e.g. tropical cyclones and cold fronts). Finally, simulations with RegCM4 were analysed to understand local mechanisms that favour the occurrence of extreme rainfall related to changes in vegetation and land use due to urbanization.

In general, the results show that the accumulated total annual precipitation has a negative trend, while the contribution of extreme events to total precipitation has increased. Moreover, under urban land use, precipitation would increase, especially in the spring months, and it would decrease during the summer.

Keywords: precipitation, extreme events, land use change, Yucatan, RegCM, urbanization.