The Lotus Effect

All physical fluids tend to have some amount of surface tension (meaning 'resistance to curvature'). $$ If a fluid makes surface contact, the little peaks/spikes as presented in 'Surface B' create points of surface tension in between every two close-by peaks. The fluid will continue to fill the gap in between the peaks anyway. Eventually, surface tension stops the fluid from increasing curvature by expanding into the valley between two peaks and therefore not make full contact with the valley. (This argument is independent of positive or negative tension. The argument still holds for a fluid curving outwards anyway.)

Due to less contact area, less adherent force can be applied, letting the fluid more easily pass by, just like with lotus leaves.

For visual representation check out the comments. Thanks for correcting "coherent" to "adherent", of course different surfaces are meant.

The lotus isn't the only species that makes itself hydrophobic with a high surface area coating. Lots of small insects have bodies covered in little hairs to increase their surface area. Creatures with small mass and volume often need to be hydrophobic to prevent them from being absorbed into a drop of water and drowning. Perhaps you've seen a clump of ants floating on a puddle. The water strider bug has legs covered in tiny hairs. It's kind of neat, although I suppose not all that surprising, that species with vastly different evolutionary trajectories (such as the lotus and the ant) develop the same solution to the same problem.

Surface area in contact must be least

Just correlate

If you put a balloon on one sharp pin it bursts,but on many pins the balloon doesn't burst, like wise the water has surface tension, on normal surfaces the density of irregularity is less so surface tension cannot keep up, while on lotus leaves the density of irregularity is high so the surface tension resits the water to stick with the leaves