No abstract

No abstract

No abstract

Sustainability of rainwater harvesting in enhancing water productivity in various biophysical and socioeconomic conditions of SSA is a key in large scale livelihood improvement. A study was undertaken in Makanya catchment of rural Tanzania to assess sustainability of storage type of rainwater harvesting systems including microdam, dug out pond, sub-surface runoff harvesting tank and rooftop rainwater harvesting system. The increasing population in upstream areas of the catchment has forced use of RWH systems for streams and river water abstraction. The agricultural intensification in hillslopes has affected the water availability for downstream uses. Rainfall variability, runoff quality and quantity, local skills and investment capacity, labour availability and institutional support influence sustainability of rainwater harvesting systems.

Concern about food security has increased because of a changing climate, which poses a great threat to food crop productivity. Climate change projections from the Coupled Model Inter-comparison Project phase 5 (CMIP5) and crop models were used to investigate the impacts of climate change on rain-fed cereal production. Calibrated and evaluated crop models simulated maize and sorghum yields over time periods and scenarios across central zone Tanzania with and without adaptation. Simulation outputs without adaptation showed predominant decrease and increase in maize and sorghum yields, respectively. The results showed that maize yields were predicted to decline between 1% and 25% across periods, representative concentration pathways (RCPs) and global circulation models (GCMs). However, sorghum yields were on average predicted to increase between 5% and 21%. Overall when adaptation is incorporated toward mid-century, yields are projected to increase for both crops. The yield projections variation between cereal crops highlights the importance of location and crop specific climate change impact assessments. Despite the uncertainties in predicting the impacts of climate change on rainfed crops, especially on cereals (maize and sorghum) which are important staple food crops in semi-arid Tanzania, the findings of this study enable policy makers to develop plans aimed at sustainable food security. In conclusion, the results demonstrate the presumption that sorghum productivity stands a better chance than maize under prospects of negative impacts from climate change in central zone Tanzania.