Paul Mecia was found facedown in the shallows on the morning of October 27 last year - having hit his head on a concrete plinth during the 12-foot fall.
Divorced father-of-two Paul appeared before magistrates multiple times for alcohol-related matters over the years.
An inquest into his death heard how Paul was found with a severe head injury in the stream near the site of the former Lidl on Chatsworth Road - a bottle of sherry was found floating nearby.
CCTV footage taken from the Crafty Dog pub across the road from the wall showed “alcoholic” Paul “drooping” as though falling asleep and falling backwards off the wall.
He was discovered by friend Paul Newton - who had been drinking with him the previous day in the hours leading up to his fall.
Paramedics found the former Coventry man in the river with trauma, blood and swelling to his face.
Derbyshire Police’s Detective Constable Danni Matthewman said in her evidence hitting the concrete would have rendered Paul unconscious - drowning him if not “killing him outright”.
Mental health nurse Sarah Sammans said in her evidence Paul would roam “aimlessly” around Chesterfield - having forgotten where he lived despite being housed during the pandemic.
He was jailed “many times” for breaching a restraining order not to contact his wife and two sons after leaving the family home in 2010.
Speaking about concerns Paul should have been better-supported by mental health services Coroner Miss Evans found the 58-year-old had been assessed on “a number of occasions”.
He was admitted to Chesterfield Royal Hospital’s emergency department nearly 40 times between 2019 and 2020.
During a mental state examination specialist lead nurse David Henstock described Paul as a “jolly, slightly overweight” man who was “very proud”.
Although Paul showed signs of short-term memory loss linked to alcohol-related brain injury he was assessed as having the capacity to make decisions.
Miss Evans concluded “on the balance of probability” that Paul - who was known to use synthetic drug Mamba - died as a result of a “severe head injury while in the water”.