Fig. 3.

Temporal analysis of climate impacts of four hypothetical irrigated water management classes. Each water management regime is represented by a fixed water index and range of flood events_{>3 d} and is presented relative to a fixed “base case” (continuous flooding, water index = 500, flood events_{>3 d} = 6; represented by the red line). The ratios of cumulative radiative forcing relative to the base case are shown on the y axis, and continuous flooding regimes (red band; water index = 500, flood event 5–8) are compared with mild (blue band; water index = −100, flood events 2–6), medium (green band; water index = −600, flood events 0–5), and intense (purple band; water index = −1,200, flood events 0–3) intermittent regimes in A–C, respectively. The ratio of cumulative radiative forcing values below 1 (red line) represent climate benefit relative to the fixed base case with the width of the shaded regions reflecting the variability in climate impacts for a given water index depending on the number of flood events. The lowest number of flood events are at the lower band edge, and the highest number of flood events at the top edge, because the less flood events_{>3 d} cause net lower GWP (Eqs. 1 and 2). These ratios of cumulative radiative forcings change with time on x axis. Intense intermittent regimes cross over and have more cumulative climate impact than our base case within 60–100 y. Medium intermittent regimes with many flood events_{>3 d} could cross over as early as 40 y. However, medium intermittent scenarios with very few flood events_{>3 d} or mild intermittent scenarios might never have more climate impact than the chosen base case.