Bongani Ncube, Manuel Magombeyi, Walter Mupangwa, Paiva Manguambe, David Love

PRESENTATION Introduction Rainwater harvesting studies under PN17 Proposed approach of assessing up-stream/down stream interactions

INTRODUCTION Water scarcity in the Limpopo basin FFBAR studies on rainwater harvesting (RWH) Phase 2 – rainwater management Propose approaches of assessing up-stream/down stream interactions

Rain Water Harvesting RWH is the process of concentrating rainfall as runoff from a larger/small area for use in smaller target area (Botha et al, 2003). In-field rainwater harvesting Tillage and other in situ soil water management / conservation agriculture strategies Basins (Zambia, Zimbabwe), Zai (Mozambique, Mali and Burkina Faso), Chololo (Tanzania), Trus system in Sudan, and the Tassa system in Niger – differ in size and spacing Ex-field water management practices and runoff capture Runoff catchments (check dams, rock outcrops), roof catchment, dams, weirs and natural streams

RWH Technologies: PN17 Zimbabwe Mzingwane Catchment (Conservation Farming, basins) Mozambique Chokwe (Zai Pits) Use of plastic material South Africa Olifants Basin - Chololo Pits Supplemental irrigation – water collected from a weir

Conservation Farming- Zimbabwe

Benefits of basins promote infiltration of rainwater minimize soil, water and nutrient losses from the field reduce siltation and pollution (by agrochemicals) downstream of the fields groundwater recharge as soil water is lost through deep drainage especially on sandy soils BUT Water logging occurs in high rainfall seasons

Zai Pits - Mozambique Results Maize and cowpea yields increased under Zai Pits compared to conventional methods 21% of farmers in the study area adopted the pits Which crops do we use under RWH? Need to think of a model to assess the potential payoffs of RWH?

Use of plastic material- Mozambique Increase area for in-field rainwater harvesting Possibility of increasing yield by increasing water availability during the growing season System costly, is there a possibility to use local material?

Chololo Pits – South Africa

WorcesterEnable Chololo pitsConventionalRidgesConventional Rainfall (mm) Maize grain yield (kg/ha) Grain yield/crop evapotranspiration (kg/mm) Person days Cost (ZAR/ha)

Chololo Pits – South Africa Higher yield obtained under Chololo pits compared to ridges Ridges performed better than the conventional practice

Proposed Methodology

Concluding Remarks RWH techniques have been tried at field scale Out-scaling and up-scaling approaches of successful RWH technologies is in the future Socio-economic analysis of the RWH technologies needed

THANK YOU