Flight Crew Air Transport Pilot (ATP)
Situational Awareness; Workload
Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter CFTT / CFIT
Flight Crew Became Reoriented; Flight Crew FLC complied w / Automation / Advisory
Human Factors; Procedure
On approach into ZZZ we were given the visual approach to runway 24. The First Officer was PF (Pilot Flying) at the time and I briefed  him on the terrain that surrounds the airport and how we should be configured and slowed in order to be able to maneuver in the valley to set up for landing. We entered a downwind at 220kts and 8000ft MSL while still on autopilot control. The FO (First Officer) began a slow descent while trying to slow the aircraft to configure flaps. We continued on downwind and selected flaps 8 and 20 and began a base turn around 9 miles from the airport. The autopilot was selected off at this time and we continued descent on the base leg. I instructed the FO to begin turning final and he put the aircraft in about a 15 degree banks without adding power. This increased our descent rate. Around this time we received a CAUTION TERRAIN message from EGWPS. Immediately after that came a single TERRAIN TERRAIN PULL UP warning message. I took control of the aircraft; increased power; leveled the descent and increased bank to 30 degrees which stopped the EGPWS warnings after a single message. I aligned the aircraft on a 6 miles final on glide path and returned controls to the first officer; who completed a stabilized approach by 1000 ft AGL and a normal landing. We both became task saturated trying to maneuver the aircraft in the valley while configuring the aircraft for landing. I diverted my attention away from the terrain and altitude to look at the airport and instruct the First Officer on lining up the plane on final.  In future landings at this airport; I will be requesting vectors for the ILS approach which will ensure all terrain separation. In times where a visual approach is being made I will be better at scanning inside and outside the cockpit to ensure the safe operation of the aircraft at all times.
Air Carrier Captain reported that the First Officer failed to add power while initiating a turn onto final resulting in a EGPWS warning.