▁was ▁se aled , ▁and ▁the ▁water ▁di vert ed ▁away ▁from ▁the ▁tunnel . ▁ ▁The ▁hydro log ical ▁survey ▁in ▁ 2 0 1 6 ▁stated ▁that ▁" the ▁concrete ▁l ined ▁channel ▁installed ▁by ▁Victor ian ▁engine ers , ▁in ▁an ▁attempt ▁to ▁reduce ▁water ▁in flow ▁into ▁the ▁Se vern ▁T unnel , ▁is ▁reported ▁to ▁be ▁in ▁poor ▁condition ▁and ▁in effect ive ▁in ▁retain ing ▁water ▁in ▁the ▁bro ok ". ▁ ▁Local ▁historian ▁John ▁N ett les hip ▁and ▁others ▁have ▁post ulated ▁that ▁sw allow ▁holes ▁on ▁the ▁site ▁known ▁locally ▁as ▁" wh ir ly hol es " ▁created ▁a ▁si phon ▁effect , ▁and ▁could ▁have ▁generated ▁the ▁early ▁Wel sh ▁story ▁of ▁L lyn ▁L li wan , ▁mentioned ▁in ▁the ▁Historia ▁Brit ton um ▁as ▁producing ▁volumes ▁of ▁fresh ▁water ▁when ▁the ▁t ide ▁falls ▁in ▁the ▁nearby ▁Se vern ▁est u ary . ▁ ▁The ▁holes ▁were ▁blocked ▁with ▁cl ay ▁as ▁part ▁of ▁the ▁Se vern ▁T unnel ▁work . ▁ ▁References ▁ ▁Category : S ites ▁of ▁Special ▁Scient ific ▁Interest ▁in ▁Mon mouth shire ▁Category : S ites ▁of ▁Special ▁Scient ific ▁Interest ▁not ified ▁in ▁ 1 9 8 8 ▁Category : W et lands ▁of ▁Mon mouth shire ▁Category : C ald ic ot , ▁Mon mouth shire <0x0A> </s> ▁The ▁King ▁F ah d ▁Naval ▁Academy ▁() ▁is ▁the ▁main ▁naval ▁a cademy ▁of ▁the ▁Kingdom ▁of ▁Sa udi ▁Arab ia ▁for ▁the ▁Royal