The Czech won all six competitive stages on Saturday to finish three minutes 12.8 seconds clear of closest rival Delecour.
The penultimate stage, the second running of Santa Max, was made a liaison after Kopecky, Francois Delecour and Toshi Araidue raised safety concerns with organisers in the extreme weather.
Skoda Fabia Super 2000 driver Kopecky was boosted on Friday when Bryan Bouffier retired while leading and Delecour broke his shock absorbers and his engine overheated.
The Frenchman suffered another broken shock absorber – on the front right - on his Peugeot 207 Super 2000 on Saturday’s third stage, the first running of the Santa Max (SS10) which put him more than a minute off the pace at that point.
“I’m really happy we got this opportunity from ŠKODA to be here and take my second win on gravel,” said Kopecky.
“It was a really tough event: the hot weather was not such a problem but there were a lot of rocks and loose stones on the stages and you had to use your head to decide when and where to push.
“I was enjoying a big battle with Bryan and Francois until they had problems but this is motorsport and this can happen.”
Kopecky now leads the drivers' standings by 71 points having won four rallies in 2013, with Bouffier, Jari Ketomaa and Freddy Loix having won one apiece.
Home driver Edwin Keleti’s hopes of a podium were dashed when his Mitsubishi Lancer Evolution X stopped on SS12 while fourth overall, an incident which also slowed Delecour.
“He was parked on the right, a mechanical I problem I think,” Delecour told ERC Rally Radio. “I went slowly because I want to be at the finish.”
With Keleti out, Arai - who is suffering from a stomach upset – finished third overall.
Arai was affected by dust inhalation on SS10 and co-driver Anthony McLoughlin had to drive the subsequent road section back to service in Sibiu to allow the Japanese to rest.