How does 哇 affect the meaning of 大河向东流哇?

Question

As part of my immersion process I am studying Chinese lyrics of songs that I like. Many times I find Chinese phrases that I understand all of the words but none of the context. In this case 大河向东流哇 seems to describe a great river flows eastward. The final word threw me for a loop and so I wanted to ask whether how that word affects the overall sentence? What is the implied emphasis being added (if any) or am I misunderstanding the interpretation?

My local MacOSX dictionaries tell me that 哇 (wā) is

哇 (Simplified/Traditional)
| wā |
sound of child's crying

哇 wā
拟声模拟呕吐、哭等的声音。
哇的一声吐了出来 | 小孩子哇 哇地哭。
另见 wa。
哇 wa
助“啊（a）”受前一个字韵母u、ao、ou 的影响产生音变而采用的不同写法。
你让我找得好苦（kǔ）哇 | 这样多好（hǎo）哇 | 快走（zǒu）哇。
另见 wā。

wā
哇

Wow!; sound of child's crying; sound of vomiting
哇

BTW - This line is from the following song/artist:

歌名: 好汉歌
演唱: 刘 欢

Answer 1

It does not change the sentence meaning. 哇,啊,呀, those words are always just for emphasis.

大河向东流哇=大河向东流啊=大河向东流.

Answer 2

哇, in this case interchangeable with 啊 or 呀, does not change the meaning but can affect the intonation and atmosphere.

The way you pronounce will totally change how your utterance is perceived.

For example, with a powerful sound (as in the song). It provides a background of the rest of the song. Since the song is about history/hero/war etc. It has a sense of the flow of time and history. In Chinese, river are often used as a symbol of time and history.

On the other hand, with a soft, emotional tone like a sigh (of course the rhythm of the whole sentence should be adjusted accordingly, e.g. slower), it could be perceived as full of regret and sorrow.