New use for random encounters

[Lich]

Already randoms was used in these ways
1-curious locations
2-enemy
3-out of fuel in car

I want make game more realistic so include needs of water and food
-40% chance to thirsty on desert
-40% chance to hungry on mountains

But how make it? (only ideas got about option3)

 

[Per]

Only way I can think of is to up the overall random encounter frequency by 40% (however that is calculated), then insert a large-probability (60% maybe) encounter in every table depending on terrain:

Mountain: You starve. Deduct 1 Iguana-on-a-stick or die.
Desert: You thirst. Deduct 1 Vault 13 Water Flask or Vic dies.
City: You thought you saw a rat. Carry on.
Coast: A fish nips your ankle. Lose 1 health point, stupid tribal.