3- Sustainability – Long Term Goal of African Water Use

In our preceding blog entry, we delved into the current landscape of land irrigation within Africa, emphasizing its significant role. And basically came to the conclusion: small-scale irrigation has considerable prospects in Africa. Recognizing that irrigation is inherently reliant on the availability of water, the focus of this blog will shift towards the utilization and extraction of water resources. This includes an examination of various water collection methodologies, with a particular emphasis on their sustainability. Additionally, the stability of freshwater resources, a critical factor for the success of any irrigation strategy, will be thoroughly explored.

Rainwater Harvesting: A Strategic Approach

Rainwater harvesting from a rooftop

Large-scale rainwater harvesting in South Africa

Rainwater harvesting encompasses the collection and storage of rainwater, typically via roofing systems. This stored rainwater, when required for consumption, can be released for various uses, providing a source of clean freshwater. Some scholars claims the method could be used to increase agricultural output.

An illustrative example of this practice is demonstrated in the accompanying video, showcasing the efforts of the Aquascape Foundation in Uganda. 

This initiative predominantly focuses on domestic water usage, where collected rainwater undergoes purification before being stored in tanks for community and school use. However, the potential applications of these systems extend beyond domestic use. Given the predominantly small-scale nature of agricultural production in Africa, rainwater harvesting facilities can be efficiently adapted for irrigation purposes. Their design does not necessitate large-scale construction and investment, thereby facilitating quicker and more widespread implementation. Some scholars pointed out that investment in small-scale water harvesting systems by large institutions like the African Development Bank and the World Bank can offer substantial returns in terms of development and resilience. Combined with my last post, this method is especially suitable for small-scale farmers, and there are already examples in Ethiopia where farmers perceive the technology positively and adhere to local norms and regulations that govern water use.

Subsurface Dams: An Innovative Approach to Groundwater Management

sub-surface dam structure

A subsurface dam represents a specialized type of dam, engineered specifically for the interception and retention of groundwater resources. Contrary to traditional dams, a subsurface dam is not discernible at ground level, often leading to a misconception about its water-holding capabilities due to the arid appearance of the surface above. 

Sub-surface dam looks dry, but it doesn't mean there is no water.

The accompanying diagram offers a simplified representation of a subsurface dam's structure. These underground barriers effectively capture and store groundwater. This capacity becomes particularly crucial in periods following seasons of reduced rainfall, thereby ensuring a more stable and reliable water supply.

Why sustainability is important?

The imperative of sustainability is particularly pronounced in Africa, where rapid population growth is exacerbating food security challenges. As projected by the World Bank and the United Nations, the continent's population is set to reach 2.5 billion by 2050. The drought in East Africa from 2020 to 2023 further confirmed the vulnerability of food security. Notably, in the Sub-Saharan region, 80% of rural communities rely on boreholes and wells, underscoring the need for sustainable water sources to enhance stability. Recognizing this, international bodies like the United Nations have prioritized 'sustainable water resources' as a key theme for AFRI CONVERSE 2023. Nevertheless, enhanced regional and local cooperation is essential, as broader participation from various national governments is anticipated and encouraged in the near future.