Complex sentence: The outreach of the system caused heavy rainfall in Karachi, Pakistan up to 122 mm on August 30,2017 where at least 11 deaths were reported, mainly due to electrocution.
Split into simpler sentences: The outreach of the system caused heavy rainfall in Karachi, Pakistan where up to 122 mm fell on August 30. At least 11 deaths were reported there, mainly due to electrocution.