  Orthorhombic CuMnAs has been proposed as an antiferromagnetic semimetal
hosting nodal line and Dirac points around the Fermi level. We investigate
relations between the topological bands and transport phenomena, i.e. spin Hall
effect and anomalous Hall effect, in orthorhombic CuMnAs with first-principles
calculations combined with symmetry analysis of magnetic structures and of
(spin) Berry curvature. We show the nodal line gapped with spin-orbit coupling
in CuMnAs dominantly generates large spin Hall conductivity in the ground
state. Although the magnetic symmetry in the ground state of CuMnAs forbids the
finite anomalous Hall effect, applied magnetic fields produce a significant
anomalous component of the Hall conductivity with the magnetic symmetry
breaking. We identify that the dominant contribution to anomalous Hall
components comes from further lifting of band degeneracy under external
magnetic fields for the Bloch states generated with splitting of nodal lines by
spin-orbit coupling near Fermi energy.
