you can also use SCS-CN ...
Published by Emna Gargouri-Ellouze, Assistant professor at National School of Engineers of Tunis
you can also use SCS-CN (Soil Conservation Service Curve Number) .
You can use monthly rainfall P (mm)
Q = (P-0.2S)2/(P + 0.8S) P³ 0.2S
CN = 1000/(10 + S)
Q = direct runoff , and P = total rainfall
SCS-CN depends on the different land-uses of the catchment area. SCS-CN is tabulated and easy to find (i.e. https://www.hec.usace.army.mil/confluence/hmsdocs/hmstrm/cn-tables
To find direct runoff in m3
1mm corresponds to 10m3 per ha, so if you have your area, you should just multiply Q by A and adapt yours units