Short, tight plant canopies use less water

Plants with a short, tight canopy (e.g., a closely mown sward of turf) have less evapotranspiration than plants with a tall, open canopy.  It may harmful in other ways to mow the turf too closely, but actual research studies have shown that that reduces the evaporanspiration.  This is because a tighter canopy has higher turbulent resistance.