Hydro-climatic stress, shallow groundwater wells and coping in Ghana's White Volta basin

Positive effect of a canal system and reservoir group on the spatial-temporal redistribution of water resources in a pinnate drainage pattern

The uneven spatial and temporal distribution of water resources in pinnate drainage patterns is a major problem worldwide. As scattered components of water conservancy projects, systems of canals and groups of reservoirs in a basin can redistribute water resources in time and space to solve problems. This redistribution effectively avoids the environmental impact inherent in centralized water conservancy projects. In this study, we focused on a network of 88 reservoirs and 675 km of canals in a basin with a pinnate drainage pattern. The discharge of the trunk stream in the basin was calculated in natural, present and forecasted conditions based on the hydrological frequency curve. Then, the hydrodynamics of the trunk stream were simulated by the HEC-RAS model. Furthermore, we analysed the temporal and spatial distribution of water resources in five zones in the basin by Morlet wavelet analysis to determine the balance between water supply and demand. The results demonstrated that the river catchment in the basin changed periodically over periods of 1 year, 8 years and 18 years, as affected by the reservoir groups. The canal system played a major role in water resource transport in the five zones in the basin. The joint action of the reservoir group and canal system reduced the gap between the supply and demand water balance from 27.11% to 0.89%. This study focused on the influence of decentralized water conservancy projects on the spatial and temporal distribution of water resources and provides ideas for solving the problem of water resource allocation in the studied basin.