Abstract:
Effective utilization of rainfall in semi-arid areas is very much dependent on land characteristics,
land use, and management practices. Important land characteristics include soil type, soil hydraulic
properties down the profile, soil variation along the catena, slope and vegetation cover. In
most semi-arid areas of Tanzania, three soil types dominate the catena. The top of the catena is
normally occupied by Lithisols. The middle part is usually, subjected to erosion and is occupied by
a complex of soils but usually Cambisols/ Arenosols/ Ferrosols. Soils with vertic properties commonly
Vertisols are found at the bottom of the catena. The relative proportions of the three sections
in a given catena, how they are used and managed, determine the amount of runoff, erosion
and the potential for rainwater harvesting (RWH). These factors also have a very important influence
on the ability of the soil to receive, store, redistribute and release rainwater. This paper presents
case studies from sites in Mwanga, Same, Morogoro and Maswa Districts, Tanzania to
elaborate the role of these factors in RWH. It is concluded that the landscape is an important factor
in determining yield, control and management of runoff, and hence potential for RWH. The
catena is a natural set-up for rainwater harvesting where the top section acts as natural generator
of runoff and the bottom section as natural receiver.