Assessment of the Current and Future Available Water Resources Under Different Climate Scenarios in the Lake Bunyonyi Catchment, Uganda

The report evaluates the hydrological impact of climate change on the Lake Bunyonyi catchment within the Ruhezamyenda catchment in southwestern Uganda. Using the COSERO hydrological model and CMIP5 global climate model ensembles under RCP4.5 and RCP8.5 scenarios, the study projects increases in temperature, precipitation, and evapotranspiration for the mid-term (20412070) and far future (20712100). While runoff trends show significant uncertainty, there is a general trend toward increasing runoff, particularly in the far future under RCP8.5. The report identifies 'no-regrets' adaptation options focusing on governance, land management, and data collection to address risks such as soil erosion, landslides, and wetland degradation.

• The Ruhezamyenda catchment is identified as one of 15 hotspot catchments in Uganda threatened by water scarcity, deforestation, soil erosion, loss of wetlands, and population pressure.
• Between 1987 and 2014, the Lake Bunyonyi catchment experienced significant land-use changes, primarily the conversion of tropical high forests to small-scale farmland and woodlots, and a 3.8 per cent decline in wetland areas.
• All climate simulations project an increase in mean annual temperature for the Ruhezamyenda catchment. For RCP4.5, the median increase is approximately 1.5C to 2.0C by 2100, while for RCP8.5, the median increase is approximately 2.5C to 4.0C.
• Mean annual precipitation is generally simulated to increase for both future periods. Under RCP4.5, increases range from approximately 0 to 50 per cent, and under RCP8.5, changes range from -25 to +75 per cent compared to the 19712000 period.
• Increased air temperatures are projected to lead to higher potential evapotranspiration (PET) and actual evapotranspiration (AET). In the RCP8.5 far future scenario, the median GCM indicates PET will be higher by about 12 mm/month and AET will increase by approximately 8 mm/month.
• Runoff simulations for the future periods 20412070 and 20712100 show a slight trend toward increasing runoff compared to 19712000, though results contain large uncertainties. The increasing trend is stronger under the far future RCP8.5 scenario, with simulated increases up to 200 mm/yr.
• The risk of significant water availability shortcomings for 20412100 is considered low, unless there is a significant increase in domestic water demands or the implementation of large-scale dam construction and irrigation schemes.
• The study recommends 'no-regrets' adaptation options, including the implementation of terraces and bund systems to manage soil erosion, stopping the conversion of wetlands to farmland or eucalyptus woodlots, and establishing a continuous hydro-meteorological observation network.

APA

Mehdi, B., Herrnegger, M., Dekens, J., Crerar, S., & Schulz, K. (2019). Assessment of the Current and Future Available Water Resources Under Different Climate Scenarios in the Lake Bunyonyi Catchment, Uganda. NAP Global Network. https://napglobalnetwork.org/wp-content/uploads/2019/10/napgn-en-2019-assessment-of-the-current-and-future-available-water-resources-under-different-climate-scenarios-in-the-lake-bunyonyi-catchment-uganda.pdf

Chicago

Mehdi, Bano, Mathew Herrnegger, Julie Dekens, Steve Crerar, and Karsten Schulz. Assessment of the Current and Future Available Water Resources Under Different Climate Scenarios in the Lake Bunyonyi Catchment, Uganda. NAP Global Network, 2019. https://napglobalnetwork.org/wp-content/uploads/2019/10/napgn-en-2019-assessment-of-the-current-and-future-available-water-resources-under-different-climate-scenarios-in-the-lake-bunyonyi-catchment-uganda.pdf.

Wikipedia

{{cite report |last1=Mehdi |first1=Bano |last2=Herrnegger |first2=Mathew |last3=Dekens |first3=Julie |last4=Crerar |first4=Steve |last5=Schulz |first5=Karsten |title=Assessment of the Current and Future Available Water Resources Under Different Climate Scenarios in the Lake Bunyonyi Catchment, Uganda |publisher=NAP Global Network |date=February 2019 |url=https://napglobalnetwork.org/wp-content/uploads/2019/10/napgn-en-2019-assessment-of-the-current-and-future-available-water-resources-under-different-climate-scenarios-in-the-lake-bunyonyi-catchment-uganda.pdf |access-date=23 October 2026 |via=Climate Insights Directory}}

BibTeX

@techreport{mehdi2019assessment, author = {Mehdi, Bano and Herrnegger, Mathew and Dekens, Julie and Crerar, Steve and Schulz, Karsten}, title = {{Assessment of the Current and Future Available Water Resources Under Different Climate Scenarios in the Lake Bunyonyi Catchment, Uganda}}, institution = {NAP Global Network}, year = {2019}, month = feb, url = {https://napglobalnetwork.org/wp-content/uploads/2019/10/napgn-en-2019-assessment-of-the-current-and-future-available-water-resources-under-different-climate-scenarios-in-the-lake-bunyonyi-catchment-uganda.pdf}, urldate = {2026-10-23}, note = {Indexed by Climate Insights Directory} }