Page 115 - CIWA Water Data Revolution Overview Report

These differences highlight the uncertainty across climate models, with GFDL-ESM4

suggesting a drying trend and MPI-ESM1-2-HR suggesting a more optimistic outlook for wet

season rainfall. Such variations underline the importance of ensemble analysis when

assessing future climate impacts on water availability in the region.

Figure 5.Comparison of monthly mean precipitation between baseline period (2003–2021)
for GFDL-ESM4 Model and MPI-ESM1-2-HR Model.

Table 1 provides a comparative analysis of projected seasonal and annual rainfall changes in

the Volta Basin for the 2025–2050 period relative to the baseline (2003–2021). The
projections were derived from two climate models, GFDL-ESM4 and MPI-ESM1-2-HR, and

reveal contrasting rainfall trends across the wet and dry seasons:

GFDL-ESM4 Model:
• Wet Season: Rainfall is projected to decrease by 8.47%, reducing wet-season totals
from 885.5 mm to 810.5 mm. This suggests a significant drying trend during the
primary period of water availability in the region.

• Dry Season: Rainfall is expected to increase by 11.69%, rising from 117.5 mm to 131.23
mm. While this increase could alleviate dry-season water stress, the magnitude
remains insufficient to offset wet-season declines.