Final answer:
A perched lake remains permanent if the input water matches or exceeds the loss, considering evaporation, collection, and dam capabilities.
Step-by-step explanation:
A perched lake may remain permanent if the inflow of water is at least equal to the loss of water. The permanence of a perched lake is influenced by various factors such as evaporation, seepage, and the inflow of water. For a perched lake to maintain its water level, the inflow must balance or exceed the water that is evaporated and lifted to high altitudes, typically around 5 km.
Additionally, factors such as the collection of rainwater, terrain height, and dammable locations affect the water balance.
For instance, if 30% of the water falls on land where collection is possible and only 20% of the water makes it to dammable locations, factoring in the remaining height available for the dam, which is only 50 m out of the average land height of 800 m, these constraints would need to be considered for the lake's water management.