Valley bottom farming systems for climate change adaptation based on evidence from a focused review

Abstract Climate change-induced rainfall variability, recurrent droughts, and flooding increasingly threaten agricultural sustainability across sub-Saharan Africa. This systematic review evaluates the effectiveness of intensive valley-bottom farming systems as a climate adaptation strategy in vulnerable agro-ecological zones. Following PRISMA guidelines, 544 records were screened, of which 23 peer-reviewed studies published between 2015 and 2024 met predefined inclusion criteria based on study design, relevance to valley-bottom systems, and reported adaptation outcomes. Evidence from Tanzania, Kenya, Uganda, Senegal, and Mali was synthesized using a thematic analytical framework, while complementary studies from Nigeria informed broader assessments of climate vulnerability. Four dominant themes emerged: agricultural productivity, water-use efficiency, food security, and socio-economic outcomes. Across drought-prone and flood-affected environments, valley-bottom farming systems were consistently associated with 15–40% higher crop yields, improved water management, and enhanced livelihood diversification. Studies from West and East Africa, including Nigeria, further demonstrate increasing climate-induced agricultural vulnerability, underscoring the urgency of resilient land- and water-management strategies. Despite these benefits, adoption remains constrained by high initial infrastructure costs, limited technical capacity, and insecure land tenure, disproportionately affecting resource-poor farmers. Priority short-term actions include targeted investment in small-scale irrigation and water-harvesting infrastructure, farmer training in soil and water management, and policy reforms to strengthen equitable access to land and water resources. By synthesising evidence published between 2015 and 2024, a period marked by accelerating climate variability and adaptation responses, this review demonstrates the timeliness and policy relevance of intensive valley-bottom farming systems. The findings highlight their potential as a scalable climate adaptation pathway, contingent on addressing key socio-institutional barriers through integrated and context-specific policies.