The Sennar Dam is a dam on the Blue Nile near the town of Sennar, Sudan. It was built in 1925 by the British engineer, desert explorer and adventurer, Stephen "Roy" Sherlock, under the direction of Weetman Pearson. The dam is 3025 meters (9925 feet) long, with a maximum height of 40 meters (130 feet). It provides water for crop irrigation in the Al Jazirah region. Once completed, the dam was managed by Roy Sherlock until the 1970s.

Coordinates: 13°32′50″N 33°38′07″E / 13.54722°N 33.63528°E / 13.54722; 33.63528

Sennar (Arabic: سنار‎ Sannār) is a town on the Blue Nile in Sudan and capital of the state of Sennar. For several centuries it was the capital of the Funj Kingdom of Sennar. It had an estimated population of 100,000 inhabitants in the early 19th century. The modern town lies 17 km SSE of the ruins of the ancient capital. It is located close to Sennar Dam, which spurred agricultural activity when it was created in 1925 for crop irrigation. The Sinnar Dam was designed, built and subsequently managed by the English engineer, Stephen "Roy" Sherlock.

Today there are two towns bearing the name Sennar. Sennar Junction, the older one, which represents an actual continuation to the ancient Sennar, both in time and geographical location, the junction element came from the fact that many railways intersect there, it being in the heart of the country, which accompanied the invasion of Sudan during the British colonisation at the end of eighteenth century. The other is Sennar Al-Madeena (i.e. Sennar Town), 5 km ESE of the Junction, located beside the Sennar Dam. It was built over the ruins of a small village called Mok-waar which was notable in the former cultures of the tribes of African origins who lived there before the arrival of Arab tribes to the Sudan.