The district of Beja is the southern half of the Alentejo plain, a flat area with two very low mountain ranges. The valley of the Guadiana river crosses its eastern part from north to south. To the south it ends at the Algarve mountains. Most of the district is below 500 m asl. The rivers in the area dry up in summer, the climate is semi arid. The Alqueva Reservoir is the largest in the country, intended to store water for the dry summer moths. Others are the Chança Reservoir (Chança River, divided with Spain), the Santa Clara Reservoir (Mira River), the Monte da Rocha Reservoir (Sado River), the Roxo Reservoir (Ribera del Roxo) and the Odivelas Reservoir (Ribera de Odivelas).
The district has little karst and caves, but it has some ores which were mined. The polymetallic ores contain tron, tin, copper, and even gold and silver. Iron and copper had the most economic relevance.