An unconfined aquifer covering an area of 50 ha has a hydraulic conductivity of $20 \mathrm{~m}$ day $^{-1}$ and specific yield of $12 \%$. After a significant rainfall event, the water table rises from $17 \mathrm{~m}$ to $14.5 \mathrm{~m}$ below the ground level. Assuming no abstraction and outflow of groundwater during the recharge period, the amount of groundwater recharge contributed by the rainfall in $\mathrm{m}^{3}$ is______________
An unconfined aquifer covering an area of 50 ha has a hydraulic conductivity of $20 \mathrm{~m}$ day $^{-1}$ and specific yield of $12 \%$. After a significant rainfall event, the water table rises from $17 \mathrm{~m}$ to $14.5 \mathrm{~m}$ below the ground level. Assuming no abstraction and outflow of groundwater during the recharge period, the amount of groundwater recharge contributed by the rainfall in $\mathrm{m}^{3}$ is______________