Evaluating the impact of agricultural abandonment on flood mitigation functions.

The flood mitigation functions of agricultural ecosystems are crucial in Ecosystem-based Disaster Risk Reduction (Eco-DRR). However, agricultural ecosystems, particularly in developed countries, face increasing abandonment in recent years. This study examined how agricultural abandonment affects Eco-DRR functions in central Japan. In paddy fields, water retention is key for flood mitigation, while in dry farmlands, water infiltration is vital. We analyzed the relationship between abandonment ratios and flood frequency across 132 municipalities in Japan. Results indicated that abandonment had little or no impact on Eco-DRR functions both paddy fields and dry farmlands. For paddy fields, this may be due to high levels of modernization or a low abandonment rate, which can enhance Eco-DRR functions. In dry farmlands, abandonment likely does not affect flood mitigation because it does not impair infiltration functions. Thus, conserving agricultural land is beneficial for Eco-DRR, even if abandoned. Land managers should avoid converting abandoned areas into residential zones or installing artificial structures.