Abstract:
The main aim of this thesis is to study the current and future water availability and
allocation under changing climate condition in Lower Nyabarongo river catchment in the
developing country, where demands are growing and the supply seems to be constant.
Assessment of impact of climate change on water resources in river catchment requires a
proper estimation of availability of water and that can only be achieved by hydrologica
modeling of the catchment. In this study a catchment simulation model (HEC-HMS) has
been calibrated and validated for Lower Nyabarongo catchment for forecast of its
hydrologic response. The future stream flow forecasted in the catchment were simulated
by the dynamically downscaled RCP 4.5 (Representative Concentration Pathways
scenarios has been adopted from CORDEX archive and bias correction were done by
using power transformation equation before using in Hydrologic Engineering Cente
Hydrologic Modeling system (HEC-HMS model). The annually result of current and
future water availability from 1983-2010 and 2011 to 2040 in the catchment was found to
be 7482.14Million Cubic Meter (MCM) and 5951.67Million Cubic Meter (MCM
respectively.
Water Evaluation and Planning System (WEAP) model is used for the study for wate
allocation of the river water based on the existing water requirement and user priority
setting situation. The water resources availability assessment and the allocations are
performed for two scenarios; Scenario I: The current (1983-2010) water use rate. This
scenario holds the overall existing water supply in Kigali, Muhanga, Gicumbi and
Rwamagana city. Also two irrigation scheme and industry demand takes into account
The overall irrigable area in this scenario is around 864.93ha. Scenario II: The presen
water use rate plus various schemes under Planed. In this scenario the total irrigable area
under this scenario is 5,000 ha. According to future scenario period the Kajevuba and
Kanyenyomba irrigation projects shows increasing monthly water demand from 3.83
Million Cubic Meter to 64.57 Million Cubic Meter due to extension of the irrigation
scheme. The Annually water demand and supplied for the current period found to be
78.49MCM while the demand rises to 244.10 MCM for the future scenario with unme
demand of 165.61 Million Cubic Meter (67.87%)
