Soil erosion decreases soil fertility of the uplands and causes siltation of lakes and reservoirs; the lakes and reservoirs in tropical monsoonal African highlands are especially affected by sedimentation. Efforts in reducing loads by designing management practices are hampered by lack of quantitative data on the relationship of erosion in the watersheds and sediment accumulation on flood plains, lakes and reservoirs. The objective of this study is to develop a prototype quantitative method for estimating sediment budget for tropical monsoon lakes with limited observational data. Four watersheds in the Lake Tana basin were selected for this study. The Parameter Efficient Distributed (PED) model that has shown to perform well in the Ethiopian highlands is used to overcome the data limitations and recreate the missing sediment fluxes. PED model parameters are calibrated using daily discharge data and the occasionally collected sediment concentration when establishing the sediment rating curves for the major rivers. The calibrated model parameters are then used to predict the sediment budget for the 1994–2009 period. Sediment retained in the lake is determined from two bathymetric surveys taken 20 years apart whereas the sediment leaving the lake is calculated based on measured discharge and observed sediment concentrations. Results show that annually on average 34 t/ha/year of sediment is removed from the gauged part of the Lake Tana watersheds. Depending on the up-scaling method from the gauged to the ungauged part, 21 to 32 t/ha/year (equivalent to 24–38 Mt/year) is transported from the upland watersheds of which 46% to 65% is retained in the flood plains and 93% to 96% is trapped on the flood plains and in the lake. Thus, only 4–7% of all sediment produced in the watersheds leaves the Lake Tana Basin.
Materials of Hypogastruridae, Odontellidae, Neanuridae, Onychiuridae and Isotomidae from East Africa were studied. Several new species are described: Acherontiella kowalskiorum sp. n., Furculanurida grandcolasorum sp. n., Stachorutes dallaii sp, n., and Paleonura cassagnaui sp, n. Friesea vrorovi Tshelnokov, 1977 and Tullbergia kilimanjarica (Delamare Deboutteville, 1953) are redescribed. Stachorutes arlei (Thibaud & Massoud, 1980) is a new combination. Identification keys for Friesea Dalla Torre, 1895 with 2 + 2 eyes and Stachorutes Dallai, 1973 are given.
We describe two new species of white-toothed shrews from south-western and central Ethiopia, based on recent collections and an application of morphological and genetic methods, Crocidura similiturba sp. nov. and Crocidura makeda sp. nov. Comparisons are provided with other Crocidura species known to occur in the country. Both new species are currently known only from the Ethiopian Highlands. Furthermore, we provide new geographical records and discuss biogeographical patterns in the country. New molecular data, even if based primarily on mitochondrial cytochrome b, suggests substantial divergence within afrotropical Suncus megalura, suggesting that the East African lineage might be considered separated at the species level – Suncus sorella (Thomas, 1897), stat. nov. Molecular data support a monophyly of the clade, grouping most Crocidura species endemic to Ethiopia (the East African subclade of the Old World clade), but also indicates additional colonisations of Ethiopian Plateau from East and Central Africa in the past. The remarkable number of endemics shows that Ethiopia is an important centre for the Crocidura radiation, as is the case for other groups of non-flying terrestrial vertebrates.