**4.6 Runoff depth**

The runoff depth values for the IRL ranges from 2.51 to 141.48 cm. The monthly runoff depth was calculated for 2011, the year of the super algal bloom in the IRL, to serve as potential explanation for the contribution of high surface runoff to locations of the algal blooms (**Figures 3** and **4**). The average runoff per sub-basin (**Figures 3** and **4**) was compared to the chlorophyll *a* concentrations quantified from European Space Agency's Medium Resolution Imaging Spectrometer (MERIS) for 2011 [29] (**Figures 5** and **6**). The maps were all assigned the same symbology to aid easier depictions of changes in quantities, and for comparison between months.
