I'm trying to figure out the unit of impedance in the hydraulic analogy of electronic networks. Assuming

$$Z=\frac{P}{Q},$$ 

with $P$ as pressure difference, $Q$ as volumetric flow rate and $Z$ as impedance, the unit would be

$$\rm \frac{Pa}{m^3/s} = \frac{N/m^2}{m^3/s} = \frac{kg/m\cdot s^2}{m^3/s} = \frac{kg}{m^4\cdot s}$$

Intuitively, this unit doesn't make sense. Did I get some part of the unit conversion wrong? If not, could someone help me understand the unit?