Mae llifogydd wedi bod yn broblem yn Rhisga ers blynyddoedd lawer. Cafodd y rhan fwyaf o’r amddiffynfeydd eu hadeiladu yn yr 1980au a gwelwyd gwendidau ynddynt wrth iddynt gael eu hasesu. Mae argloddiau newydd ar gyfer amddiffyn rhag llifogydd wedi’u hadeiladu ac mae’r amddiffynfeydd presennol wedi’u codi a’u sefydlogi.
There is a history of flooding in Risca. The majority of the defences were built in the 1980s and analysis of these identified areas of weakness. As part of the works new flood defence embankments have been constructed and existing defences have been raised and stabilised.