In this paper, scientists developed new equations to better understand how stormwater management systems work. These equations consider water flowing not just down into the ground, but also sideways. By using these new equations, they found that the way rainwater is stored in these systems can affect how well they work. They tested their equations on a type of stormwater system called an infiltration trench and found that their results matched up with more complicated computer simulations. This means that these new equations can help make designing and planning stormwater systems easier and more efficient.