> For the complete documentation index, see [llms.txt](https://swatplus.gitbook.io/io-docs/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://swatplus.gitbook.io/io-docs/theoretical-documentation/section-2-hydrology/chapter-2-4-groundwater/2-4.2-shallow-aquifer/2-4.2.2-partitioning-of-recharge-between-shallow-and-deep-aquifer.md).

# 2:4.2.2 Partitioning of Recharge Between Shallow and Deep Aquifer

A fraction of the total daily recharge can be routed to the deep aquifer. The amount of water than will be diverted from the shallow aquifer due to percolation to the deep aquifer on a given day is:

$$w\_{deep}=\beta\_{deep}\*w\_{rchrg}$$                                                                                                                                        2:4.2.4

where $$w\_{deep}$$ is the amount of water moving into the deep aquifer on day $$i$$ (mm H$$*2$$O), $$\beta*{deep}$$ is the aquifer percolation coefficient, and $$w\_{rchrg}$$ is the amount of recharge entering both aquifers on day $$i$$ (mm H$$\_2$$O). The amount of recharge to the shallow aquifer is:

 $$w\_{rchrg,sh}=.w\_{rchrg}-w\_{deep}$$                                                                                                                              2:4.2.5

where $$w\_{rchrg,sh}$$ is the amount of recharge entering the shallow aquifer on day $$i$$ (mm H$$\_2$$O).