Gumindoga, Webster

Rientjes, T.H.M.

English

University of Twente Research Information

A decade of water resources research in the data and water limited environments of Zambezi basinWebster Gumindogaab & Tom RientjesaaFaculty ITC, University of Twente, The NetherlandsbUniversity of Zimbabwe, Civil Engineering  Department, Zimbabwe121stWaterNet/ WARFSA/ GWPSA Symposium28 October 20202Outlinea. Drylandsa. Food and water security in Zambezi Basina. Past decade research in the Zambezi Basinb. Upscaling and implications on sustainable water and food security3Drylands The UNEP defines drylands as tropical and temperate areas with an aridity index of less than 0.65. Drylands are defined by a scarcity of water. High  variability  of rainfall  amounts  and  intensities Prolonged  periods  of  drought4Zambezi River BasinOver 50 million inhabitants, largely dryland Floods and droughts Food and water security Land use and climate Largely ungauged Research policies do not often touch the communities5Rainfall estimation in the Zambezi Basin6 Zambezi basin showing gauge network Rainfall an important resource that drives all sustainable economic goals. Limitations of gauge based estimates in Zambezi basin Satellite rainfall estimates (SREs) Bias correction of SREs7 Rainfall estimation8Satellite rainfall important in water limited environments Increased use of the products at research and universities Local authories, national water authorities in past decade have adopted SRES for their operations If adequately packaged can impact on food security as well Caution is that institutions should not relax in improving gauging 9Spatio-temporal soil moisture variation along the major tributaries of Zambezi River 10Soil moisture retrieval guided by topography and river network Knowledge of soil moisture dynamics in floodplains provides: scientific insights towards understanding the functioning of floodplains & Supporting livelihoods through recession farming. Cabora Bassa11Soil moisture retrieval efforts Surface Energy Balance System (SEBS) TOPographic driven MODEL (TOPMODEL) Data loggers & Ground based gravimetric measurements An upscaling procedure to improve the comparison12Schematic illustration of soil moisture logging stations at a Zambezi tributary13Spatial variation of soil moisture important in drylandsTOPMODELSEBSDATA LOGGERS Flooding processes provide soil hydrodynamics that are favourable to longer growing seasons and with possibilities of double cropping. Spatio-temporal variation of soil moisture across floodplain ensures security of at least some harvest under extreme event environments such as flooding. Mechanisms regulating soil moisture dynamics affect agronomic & soil water management practices14Land evaluation for floodplain agriculture15 Land suitability analysis for flood recession farming Performed in a GIS environment  soil moisture maps distance from stream network vertical channel distance land use/cover datasets Soil propertiesLand suitability assessment 16Land evaluation for floodplain agriculture Suitable areas for recession farming identified Most suitable land is located close to the Zambezi River tributaries due to the effect of back flows on residual soil moisture accumulation Information crucial to farmers Ensures food security  Environmental considerations. 17Landcover & Climate change&Hydrological impact assessment Zambezi River basin18 Recent reports on the remote and inaccessible Zambezi River Basin suggest that the runoff regime has changed over the past decades. We identified the causes of the regime change by climate and land cover change. Trend analysis and statistical tests are performed to assess if climate change has affected the basin. Tests are followed by analysis of streamflow characteristics and analysis of land cover changes using Landsat satellite imagesChanges in landcover, climate change & hydrological changes 19Rainfall, runoff & land cover changes & implications on Kabompo runoff   Opposing trends in rainfall and streamflow This implies that any change in monthly and annual streamflow is caused by changes in landuse change.  Conversion of forested area and savannah woodlands in cultivated and grazing lands has implications on water balance Above have implications on water and food security in data scarce regions Similar work with hydrological models such as HBV, HEC-HMS in the other Zambezi basin showed similar results20Coping with droughts and floods in the fertile Zambezi floodplains 21 Coping mechanisms identified  Tighten adaptation measures cultivation of drought-resistant crop varieties Irrigation off-farm employment opportunities.Coping with droughts in the Zambezi floodplains 22Coping with floods in the fertile Zambezi floodplains  Coping mechanisms should involve communities Participatory GIS and earth observation approaches Impactful research that leads to positive policy and practice change in floodplains23Recommendations for future work There is much scope and linkage's with Breccia focus themes Upscaling sustainable food and water security research in drylands of sub-Saharan Africa  In data scarce drylands, earth observation techniques allows for timely retrieval of water cycle components to improve food and water security Research need to be implemented on the ground via several upscaling approaches Policy makers and communities need to be engaged at every stage of the research process24Acknowledgements The following former UZ MSc students participated in this research WaterNet that funded the above researches Department of Civil Engineering, University of Zimbabwe ITC, University of Twente, The NetherlandsThank you.

A decade of water resources research in the data and water limited environments of Zambezi basin

https://ris.utwente.nl/ws/files/288426968/Gumindoga2020decade.pdf

A decade of water resources research in the data and water limited environments of Zambezi basin

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