The Mordovski Reserve's terrain reflects the retreating glaciers of the Moksha River plain: belts of sandy soils, terraces, moraines, and scattered sinkholes (some of which reach a diameter of 30 meters). The reserve is crossed by a network of small rivers. The Moksha River, a tributary of the Oka River, flows from east to west along the southern border of the reserve. The Satis River flows from north to south along the northern border to meet the Moksha. To the south of the territory is the transition to the steppe zone.
