Burkina Faso is a flat country. The difference between the highest and lowest levels is less than 600 meters. Almost half of the country is between 250 and 350 meters above sea level. Two large areas can initially be distinguished: a hull area and a sandstone massif.
The trunk area extends over three quarters of the country. The mostly monotonous relief is a succession of soft knolls and curving valleys. In places one encounters single hills or a group of hills that rise to a few dozen meters above the plateau (central plateau or “Mossiplateau”). The low and flat parts are made of granite and gneiss. The isolated rocky masses that have survived the erosion present themselves in the most varied of forms.
A sandstone massif occupies the southwest in the hilly region of the country around Orodara. At 749 meters, the Ténakourou represents the highest elevation in the country. The sedimentary crest of primary sandstone dominates the base, which is surrounded by impressive steep slopes. Between Bobo-Dioulasso and Banfora there is an approx. 150 meter high wall, the “Falaise de Banfora” or “Chaîne de Banfora”. It stretches in an exceptionally straight line from northeast to southwest. In the south-east of the country there is also a small massif (the massif of Gobnangou, Chaîne de Gobnangou) on the border with Togo and Benin. This also ends in a vertical rock wall with a height of up to 100 meters.
(Source: Atlas du Burkina, Jeune Afrique)
According to aristmarketing, although Burkina Faso is flat and has little rainfall, it has a relatively well-developed hydrographic network, especially in the southern part. The watercourses flow through three main basins: the Volta, Comoé and Niger basins.
The Volta Basin is the most important of all three basins. It extends to the center and the west of the country and has an area of 178,000 km². That is over 60% of the total area of the country. It is formed by three main sub-basins: the basins of the Mouhoun, Nakambé and Pendjari Rivers. The tributaries of these three basins meet in the center of Ghana, where they form Lake Volta.
The river Mouhoun (formerly Black Volta) is the only continually water-bearing river in the country with a catchment area of 92,000 km². The main tributary of the Mouhoun is the Sourou with a catchment area of 15,200 km². Since 1984, the control and diversion structures installed in the upper reaches of the tributary with the Mouhoun have made it possible to store 250 million m³ of water.
The river Nakambé (formerly White Volta) rises east of Ouahigouya, in a region with an annual rainfall between 500 and 600 mm. It has a catchment area of 50,000 km². The Nazinon (formerly Roter Volta) drains the southwestern part of the central plateau. Its catchment area is 20,000 km². His regime is very similar to that of the Nakambé. The Pendjari River forms part of the southeastern border of Burkina Faso with Benin. It has three tributaries on the right bank (Doudodo, Singou and Kompienga), the catchment area of which reaches around 21,600 km². The Comoé river, in the southwest of the country, has a catchment area of approx. 18,000 km². It rises in the cliffs of Banfora. The relatively high amount of precipitation in these regions gives this river strong currents in the period from June to September, which can reach 500 m³ / s.
In the Niger Basin, which has an area of approx. 72,000 km², the rivers are predominantly endorheic (ie they usually do not reach the main Niger River in this dry area of the country; they flow into so-called end lakes, seep into the basin floor or evaporate). These are, for example, the Béli, the Gorouol, the Goudébo and the Dargol. They can sometimes trigger large floods. In addition to these three river basins, there are also self-contained basins in the northeast of the country that provide water to large and small natural lakes (e.g. the lakes of Tingrela, Bam and Dem, the pools of Oursi, Béli, Markoye, etc.) to lead.
A website set up by the relevant ministry, Portail du secteur de l’eau au Burkina Faso, provides detailed information about water and water policy in the country.
In terms of vegetation and flora, the transition from a Sahelian area in the north to a Sudanese area in the south can be observed in Burkina Faso. The transition zone is again classified into two sub-areas.
The Sahelian area consists of the actual Sahelian vegetation area in the extreme north around Gorom Gorom and a Sudano-Sahelian vegetation area at the level of the central plateau between Ouahigouya and Fada N’Gourma. The vegetation there is dominated by grasses, shrubs, thorn bushes and thorn trees. The main tree species in the Sahel zone is the acacia, which adapts to different locations and is therefore of great importance for humans and animals (fodder, fertilizer). Vachellia (= Acacia) tortilis is found almost everywhere in the Burkinabe Sahel in front. To the south of the Sahel zone there is an approximately 100 km wide belt defined by bushes, which can be assigned to the Sudanese region and which, through increasing forest cover, introduces a Sudano-Guinean vegetation area in the south of the country. While the shea tree and the baobab determine the landscape in the transition zones, the mango tree and other fruit trees are increasingly determining elements in the south.
The south offers a variety of shrubs and other plants. A comprehensive atlas of biodiversity in Burkina Faso was published by BIOTA in English and French with the support of Goethe University Frankfurt.