The words bhidya and uddhyau are irregularly formed by the affix kyap , when meaning 'river'.,
Thus भिद् + क्यप् = भिद्यः 'a river that breaks its banks by the rush of its water', the name of the Bhidya river.
ऊज्झ् + क्यप् = उद्ध्य 'a river whose waters overflow the banks', name of the Uddhya river; the झ is changed into ध.
When not meaning or qualifying the river, the regular forms are used; thus भेत्ता and उज्झिता.,