As indicated by the inquiry,
Normal dislodging by an individual = 0.04 m3
Normal uprooting by 500 people = 500 × 0.04 = 20 m3
Subsequently, the volume of water brought up in lake = 20 m3
It is likewise given that,
Length of lake, l = 80 m
Expansiveness of lake, b = 50 m
Stature = h
Volume of water brought up in lake = 80(50)(h)
20 m3 = 4000h
h = 0.005 m = 0.5 cm
Subsequently, raise in the tallness of water = 0.5 cm.