Makanya Catchment Research Articles

Water productivity analysis for smallholder rainfed systems: A case study of Makanya catchment, Tanzania

Decreasing food security as a result of ever-increasing population, less water availability and soil degradation is common in countries in sub-Saharan Africa. While most of the developed fresh water resources are heavily committed to irrigation, about 90% of sub-Saharan populations rely solely on rainfed agriculture for their livelihoods. The majority of the population is therefore not directly benefiting from developed water resources but are, in fact, subsistence rainfed farmers. Thus, in sub-Saharan Africa, techniques which help to improve water productivity (WP) can assist in alleviating the impacts of water scarcity especially for crop production purposes. A study was conducted in the semi-arid Makanya catchment in northern Tanzania where farmers depend on rainfed subsistence farming for their livelihoods. The objective of the study was to assess the effect of improved conservation agriculture techniques on WP of a maize crop. An assessment of the current WP in rainfed and partially supplementary irrigated agriculture was made. The crop water requirement for maize in the study area was found to be 508 mm/season by using the CROPWAT model compared to total received rainfall of up to 383.86 mm per study plot during the same period. An attempt was made to separate transpiration from evapotranspiration using a transpiration meter. Results indicate that, currently, WP for maize in the catchment is low (0.18–1.33 kg m −3). Introduction of improved techniques increased WP by between 90% and 110%. Infiltration rates also increased from 6 to 26 cm/h. The conclusion from the research is that, from a purely scientific view, there is room to significantly improve the water use techniques being applied for crop productivity through improving current smallholder farming practices A clear understanding and quantification of the water partitioning processes is required to maximise productive water use by the plant as transpiration and this is directly related to biomass production.

Indigenous knowledge as decision support tool in rainwater harvesting

Rainfall patterns in semi-arid areas are typically highly variable, both spatially and temporally. As a result, people who rely completely on rainwater for their survival have over the centuries developed indigenous knowledge/techniques to harvest rainwater. These traditional water-harvesting systems have been sustainable for centuries. The reason for this is that they are compatible with local lifestyles, local institutional patterns and local social systems. In order to develop sustainable strategies, it is therefore important to take into account of, and learn from, what local people already know and do, and to build on this. This paper explores how indigenous knowledge is used by farmers in the Makanya catchment, Kilimanjaro region, Tanzania to identify potential sites for rainwater harvesting (RWH). The paper draws on participatory research methods including focus group discussions, key informant interviews, field visits and participatory workshops. Initial findings indicate that farmers do hold a substantial amount of knowledge about the resources around them. As there are spatially typical aspects to indigenous knowledge, it could be extrapolated over a wider geographic extent. From the preliminary findings, it is being recommended that geographic information system (GIS) could be an important tool to collect and upscale the utility of diverse indigenous knowledge in the decision-making process.