The rehabiltation prospects of Hora-arsedi lake catchment with microbasins and cordia Africana (LAM.) in Debre Zeit, Ethiopia

Hora-Arsedi Lake catchment, in the town of Debre Zeit, has faced severe degradation due to irrational exploitation of the natural vegetation. This has subsequently caused runoff, siltation and displacement of the lake. Methodologies for rehabilitation of the degraded area are being looked into with the participation of concerned stakeholders. Therefore, microbasins where the soils are shallow and with low moisture holding capacity, were tested for successful rehabilitation. Thus, Cordia africana seedlings were planted using soil and stone microbasins as main plots and 5, 15 and 30% slope as sub-plots. The trial was conducted in three replications during the 1999 season. The control was normal planting with a 30 cm width hole prepared without any physical soil and water conservation structure. For all the treatments, the planting depth was 30 cm. The results revealed within one growing season that stone and soil microbasins enabled the accumulation of significantly higher (P less than or equal to 0.05) 1.82 cm and 1.58 cm high soil silt, respectively, than average loss of 0.37 cm deep soil using the control. Although stone and soil microbasins did not significantly improve the diameter and height growth during one season, they significantly (P less than or equal to 0.05) improved seedling survival with 25 and 12.5%, respectively. Height and diameter growth of seedlings, however, significantly decreased with increasing slope irrespective of microbasins used, which is due to the corresponding decrease in soil depth. Soil moisture content at 5 cm depth one month after the end of the rains, i.e. end of November was significantly higher (P less than or equal to 0.05) in soil microbasins than that of the stone and the control. Hence, microbasins are vital for soil and water conservation and good performance of indigenous tree seedlings in the rehabilitation of degraded catchments of Hora-Arsedi Lake Catchment. Thus, further studies regarding promising species, effective dimension and types of microbasins, and subsequent environmental and socio-economic applications need to be conducted with the participation of concerned stakeholders.