Get light attenuation parameter Kd from Secchi depth
Secchi_to_Kd.RdCalculates the light attenuation coefficient in water via: $$\begin{array}[ccc] K_d(PAR) &=& 1.584 × SDD^{-0.894} \end{array}$$ where SDD is the Secchi disk depth. Equation is adapted from Zhang, Y., Liu, X., Yin, Y., Wang, M., & Qin, B. (2012). Predicting the light attenuation coefficient through Secchi disk depth and beam attenuation coefficient in a large, shallow, freshwater lake. Hydrobiologia, 693(1), 29–37. https://doi.org/10.1007/s10750-012-1084-2.