Managing Water Resource Challenges in the Congo River Basin

Abstract:

Water resources in the tropical regions are under pressure from human appropriation and climate change. Current understanding of interactions between hydrology and climate in the tropical regions is inadequate. This is particularly true for the Congo River Basin (CRB), which also lacks hydroclimate data. Global climate models (GCM) show limited skills in simulating CRB’s climate, and their future projections vary widely. Yet, GCMs provide the most credible scenarios of future climate, based upon which changes in water resources can be predicted with coupled hydrological models.

The objectives of my work are to i) elucidate the spatial and temporal variability of water resources by developing a spatially explicit hydrological model suitable for describing key processes and fluxes, ii) evaluate the performance of GCMs in simulating precipitation and temperature and iii) develop a set of climate change scenarios for the basin. In addition, I also quantify the risks and reliabilities in smallholder rain-fed agriculture and demonstrates how available water resources can be utilized to increase crop yields.

Key processes and fluxes of CRB’s hydrological cycle are amply characterized by the hydrology model. Climate change projections are evaluated using a multi-model ensemble approach under different greenhouse gas emission scenarios. The near-term projections of climate and hydrological fluxes are not affected by emission scenarios. However, towards the mid-21st century, projections are emission scenario dependent. Available freshwater resources are projected to increase in the CRB, except in the semiarid southeast. These increases present new opportunities and challenges for augmenting human appropriation of water resources.

By evaluating agricultural water requirements, and timing and availability of precipitation, I challenge the conventional wisdom that low agriculture productivities in the CRB are primarily attributable to nutrient limitation. Results show that doubling crop yields cannot be achieved without reallocation of available water resources.

The findings have wider implications for climate change assessment and water resource management, because the region, with high population growth and limited capacity to adapt, are the primary targets of land and water grabs.