The Samburu National Reserve lies along the winding bends of the river Ewaso Ngiro, that means "brown river" or "muddy river" and that demarcates the Southern border of the reserve itself.
The river divides the Samburu National Reserve from the Buffalo Springs National Reserve, that can be reached by crossing the only bridge present on the Ewaso Ngiro in this area.
The flow of the river can vary a lot during the day and especially during the year, usually the months of January and February are those recording the minimum flow rate and, in very dry years, in some spots, the river dries up completely forming some puddles; exceptionally, the river has dried up completely due to the occurrence of a particularly long period of drought, the animals on that occasion came out of the Samburu National Reserve and went into the Buffalo Springs National Reserve where is the Isiolo River, another permanent river in the region.
In the months of April, May and November instead the maximum flow rate is detected, in particularly rainy years the river bursts its banks flooding the surrounding areas and creating some inconvenience to the lodges and tented camps; in the remaining months, the river presents a water level that allows animals to cross it easily.
The game drives are concentrated in this area because here you are experiencing most of the sightings, especially during the dry season because the river is the only permanent source of water of the reserve even in times of drought; its waters are in fact not only the result of seasonal rains, but it also collects the water generated by the melting of the glaciers of Mount Kenya.
Here it is easy to spot herds of elephants, that are present in large numbers in the park, going to the river for drinking or to cool off, while the hippos spend the hottest hours of the day immersed in water; the river is also home to many Nile crocodiles that can be spotted on the sandy shores.
As well gazelles, antelopes, reticulated giraffes and impalas usually travel to this area for the water and feed on vegetation that here is lusher than in other areas of the park; near the banks of the river, up to 200 meters away, there are bushes, Riviera acacia forests, fig and palm trees.
Where there is a high concentration of herbivorous, predators usually are not lacking: the elusive leopards often hidden in the bushes found on the river bank to scrutinize the situation, even the lions and hyenas are present here to take every opportunity to capture a prey.
Moving away from the river, the land becomes barren with little vegetation and from North to South there are some ridges, the largest of which is represented by the Koitogor, that has the shape of a knife; further North is the scenic plateau of Ol Olokwe, a rock formation similar to those found in Monument Valley in the United States of America.