Why is it difficult to derive an analytical solution for an aquifer pumping test in an unconfined aquifer?

Question

Answer

Because the aquifer compressibility and hence specific storage (Ss) changes as the pumping test progresses.

Answer

Because the aquifer saturated thickness changes as the pumping test progresses.

Answer

Because the specific yield is hard to measure and has a high uncertainty.

Answer

Because such aquifers are usually deep and inaccessible.

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