The Thirika River catchment
The Thiririka River catchment in Kenya is located in the Eastern slopes of the Aberdare Mountains, approximately 30 km south of the city of Nairobi. The river enters the Ruiru River and is therefore a left tributary of the Athi River.
The Thiririka River drains a basin of around 120 km². The basin is tubular and on average only 2 km wide.
The lower areas are relatively dense settled, while the upper parts in the Aberdare Mountains are covered with a high diversity forest, which is used for agro forestry. The middle altitudes are intensively used for mixed farming and cash-crop-plantations. The annual amount of rainfall ranges from less than 700 mm up to 1800 mm.
Due to distinct land-cover and land-use, various problems occur. In the forest areas, there is a lot of logging for charcoal production and farming purposes. In the present agricultural areas soil erosion and landslides are common. Water extraction for cash-crop and cut flower production is a serious probleme in the lower areas of the catchment.
Social problems are related to rural exodus, a lack of prospects and conflicts.