The Southwest Indian Ocean islands are characterized by strong orographic gradients, generating risks of intense rainfall. The study of precipitations over mountainous tropical islands is essential to get a better understanding of tropical rainfalls formation mechanisms, spatial and temporal variability, and statistical properties at local scales. As part of the INTERREG V programs in the Réunion region, the ESPOIRS project (Study of Precipitation Systems in the Indian Ocean by Radar and Satellites) focuses on the study of the internal (dynamic, microphysical) and external (interactions with the relief) processes driving the formation and life cycle of extreme meteorological rain events in the South West Indian Ocean basin. Within this project, the Atmosphere and Cyclone Laboratory (LACy) has acquired a transportable dual-polarization Doppler X-band radar. This radar was installed in Saint Joseph, in the south of La Reunion late September 2021. During its first months of use, it was thus possible to observe the passage of two cyclones near the island: Batsirai, 3 February 2022 at ~ 200 km for over 24h. In this contribution, we will first briefly present the characteristics, operability and installation of the radar in Saint Joseph. We will then discuss its missions within the ESPOIRS project. Finally, we will present the first results of the analysis of the passage of the various cyclones and more particularly of the interactions between the generated rains and the marked reliefs of the island and their corresponding hydrological impacts.