The recent rains have worsened the drainage problem.
2 weaken, deteriorate, decline, degenerate, decay, slip, sink, slide, fail, disintegrate, take a turn for the worse, get worse, go from bad to worse, Colloq go downhill:
Her condition continues to worsen.
Advanced English Dictionary
+verb to become or make sth worse than it was before: [V] The political situation is steadily worsening. + Her health has worsened considerably since we last saw her. +[VN] Staff shortages were worsened by the flu epidemic. worsening noun [sing.]: The result could be a worsening of the international debt crisis. worsening adjective: worsening weather conditions