The deluge was caused by breaches in the floodwall and the overflowing Yom River north of the flood barrier.
Links:
[1] http://admin.indiaenvironmentportal.org.in/news/sukhothai-hit-2nd-flood
[2] http://admin.indiaenvironmentportal.org.in/category/newspaper/bangkok-post
[3] http://admin.indiaenvironmentportal.org.in/category/thesaurus/thailand
[4] http://admin.indiaenvironmentportal.org.in/category/thesaurus/natural-disasters
[5] http://admin.indiaenvironmentportal.org.in/category/thesaurus/floods