A well-known hydrologist, doctor of geographical sciences, a member of the dissertation council of the Institute of Geography named after academician G.A. Aliyev, Rena Mirtagi gizi Gashgay, has passed away. R. M. Gashgai was born in Baku in 1938. In 1960 she graduated from the Faculty of Geology and Geography of the Baku State University with a degree in Geography. Since 1959 she worked as a laboratory assistant, junior researcher, senior researcher department employee. In 1966 she defended her Ph.D. thesis "Water balance of the Greater Caucasus (within Azerbaijan)" in Moscow, and in 2009 “Geographical aspects of the formation, passage and use of the rivers of Azerbaijan”. She was awarded the medal "Progress" of the Republic of Azerbaijan, the honorary title "Honored Worker of Science" of the Republic of Azerbaijan. The main scientific activity was devoted to the flow of Azerbaijani rivers. She studied the formation of rivers and their constant fluctuations, established the patterns of power sources (underground, surface) of rivers, as a result of their interactions, carried out hydrographic zoning on the territory of the republic and identified individual altitudinal belts, natural regions, economic regions, made a calculation of water resources. She developed a method for determining groundwater involved in the formation of river waters. R. Gashgay is the author of three monographs and more than 60 scientific articles. Among them, "Water Balance of the Azerbaijan SSR” (co-author, 1979), “Water Resources of the Azerbaijan SSR” (co-author, 1989), etc. She is one of the main authors of the monograph “Constructive Geography” prepared at the Institute (3 volumes), as well as "Natural conditions and natural resources of Azerbaijan". She is the author of the sections "inland waters" in the monographs "Physical geography of the Republic of Azerbaijan" (2015), "Physical geography of the Nakhchivan Autonomous Republic" (2018), "Physical geography of the Turkic world" (2019). R. Gashgai was a member of the Dissertation Council of the Institute of Geography, Scientific and Technical Council of the Institute of Geography and the Institute of Water Problems. Rest in peace!