The development of Universitas Muhammadiyah Purwokerto has its
consequence,it decreased open area as well as water absorption area due to
increasing of buildings establishment to support academic activity. Thus causes an
increase the volume of rainfall runoff in campus I of the universitas
Muhammadiyah Purwokerto. This research aimed to determine out the volume of
runoff at campus I of Universitas Muhammadiyah Purwokerto based on the
intensity of rain cycling period of 2, 5 and 10 years. This research was conducted
using Rational method based on the intensity of rainfall cycling period of 2, 5 and
10. The result of research analysis of runoff at campus I of Universitas
Muhammadiyah Purwokerto using rational method based on the intensity of
rainfall return period of 2, 5 and 10 years is 0.29146 m³ / sec, 0.36970
m³ / sec and 0.42138 m³ / sec.