Champion Irish trainer Willie Mullins dominated on a truncated Punchestown card run in gruelling conditions.
Heavy rain, mixed with strong winds, forced the two chases to be scrapped on the day, including the feature Gold Cup, but that did not stop the County Carlow handler claiming four winners on an all-hurdles and bumper card which totalled five races.
Loch Ard got the ball rolling for the Mullins team as he ran out a convincing winner of the Louis Fitzgerald Hotel Hurdle.
Wrekin Rock made a brave bid to lead all the way but he was headed by Walsh on Mullins' charge before the final flight, where he came down.
That left the 6-4 favourite to bound clear and score by 33 lengths from Un Beau Matin with Dysios third.
"We'll try to find another race for him if the weather stays like this but he's on the team for France and will probably go for the four-year-old hurdle at Auteuil next," said Mullins.
Walsh said: "Loch Ard travelled well, jumped well and found plenty in. He's a fairish horse and he did it well.
"The ground isn't too bad - the water is lying on top but it's all surface water. There's a good bottom to it and it is perfectly safe."
Patrick Mullins, successful earlier on Champagne Fever, doubled up, and made it four for his father (also successful with Marasonnien), as Flash Of Genius (11-4 favourite) proved aptly named for the pair in the At The Races INH Flat Race, this time in the Gigginstown House Stud colours.
Shamiran got the better of British raider Weekend Millionair in a gruelling opening race as Punchestown's depleted all hurdles and bumper card got under way in difficult conditions.
The two principals were always to the fore as no other horse really got into the Martinstown Opportunity Series Final Handicap Hurdle over two and a half miles.
Tom Bellamy tried to make all the running on the David Pipe-trained Weekend Millionair, but he was accompanied all the way by Shamiran (12-1) in the hands of Ian McCarthy.
Shamiran took it up just before the final flight and pulled away to score by two and three-quarter lengths for County Kildare trainer Stephen Nolan. Streets Of Newyork was third just ahead of Beau Michael.
"I think conditions are perfectly safe. The horses are getting through it," McCarthy told At The Races.
"Six or seven of us lined up to make it. My lad took a bit of a tug going to the first and I jumped to the front. I was able to steady it up everywhere I need to and suit myself.
"He's a tough little horse. We were going into the unknown up to two and a half and in these conditions.
"In fairness he battled and galloped all the way to the line.
"There are a few puddles here and there, but they are getting through it and my horse came fresh enough out of it."