سَيْلٌ مُفْعَمٌ
A flood described as “filled” or full to overflowing.
The underlying event can be expressed as أَفْعَمَ السَّيْلُ الْوَادِيَ: the flood filled the valley. The flood is the agent of filling, while the valley is what gets filled. In the compact description, a passive-participle type of quality is applied to the flood itself.
The example shows the reverse direction from the preceding case: an action's agent receives an expression typically connected with the patient. The crucial task is to recover the proper semantic relation.