Knowing the rate of change of storage allows us to find the rate of change of water depth in the wetland. We would have to assume that the rate of evapotranspiration was constant during the day, but evapotranspiration varies continually during the day. If we assume that daily evapotranspiration is constant, then we could find the change of depth of water over several days. No, because we do not know the length of the storm. No, because rate of rainfall was probably not constant and rate of infiltration was certainly not constant if water was ponded on the soil.
Infiltration occurs more rapidly at the beginning of a ponding event and slows down over time.
However, if we assume that the storm was 2 hours long, then we could calculate the average rate of change of percent water in the soil over the period of the storm. This may all seem very boring, but the continuity equation as shown above is the basis of nearly every lecture in this class. The challenge in this class is to quantify the terms in the equation based on measured data such as air temperature and humidity for ET and soil conductivity for drainage rate. In natural systems such as drainage and wetlands, calculation of magnitude of inputs and outputs based on soil properties and other parameters is often complicated and sometimes impossible. Many engineers and scientists have spent their careers trying to derive equations to calculate terms in the conservation of mass equation for drainage and wetlands.