Rainwater Harvesting for Climate-resilient Agriculture: A Critical Appraisal of Field-scale Gains, Catchment-scale Trade-offs and Institutional Constraints

Abstract

Rainfed cropping supports the majority of the world's cultivated land and a large share of global crop production, yet it remains acutely exposed to intra-seasonal dry spells and to the shifting rainfall regimes associated with a warming climate. Rainwater harvesting, understood as the deliberate capture of precipitation or of locally generated runoff for productive agricultural use, has therefore acquired a central position in adaptation policy and in dryland development programmes. The present article offers a critical narrative review of the evidence linking rainwater harvesting to climate-resilient agriculture, drawing on peer-reviewed literature published between 2000 and June 2026 and identified through openly accessible bibliographic databases and scholarly indexes, supplemented by citation tracing and verification against digital object identifier records. Four analytical themes structure the synthesis: the agronomic performance of in-situ and ex-situ systems, the hydrological consequences of aggregating many small structures within a catchment, the methodological adequacy of siting and design studies, and the socio-institutional determinants of sustained use. The evidence indicates that field-scale yield and water-productivity gains are real but strongly conditional, being largest in low-rainfall seasons, on responsive soils, and where water capture is combined with nutrient inputs. Confidence in catchment-scale conclusions is considerably weaker. Modelling studies disagree about whether extensive adoption redistributes water benignly or depletes downstream flows, and the disagreement is traceable to differences in model structure, calibration data and the treatment of evapotranspiration rather than to settled physical understanding. Siting frameworks remain dominated by geospatial multi-criteria procedures that are seldom validated against observed structure performance. Adoption evidence reveals substantial disadoption and uneven distribution of benefits, which conventional biophysical potential assessments do not capture. Rainwater harvesting is best interpreted as a conditional risk-management technology whose net contribution to resilience depends on placement, complementary inputs and institutional arrangements rather than on the practice itself.