The maximum depth of the pit is mainly related to the inflow angle, unit discharge and the perviousness of the dike etc. with the maximum impact from the Unit discharge.
Inflows of foreign workers into America, for instance, have been in decline since the introduction of anti-immigration policies by President Donald Trump.
With the currency allowed to float within a range of HK$7.75-7.85 per US dollar, inflows have regularly tested the strong side of the band in recent years.