Learn Russian: Здесь у реки сильное течение.

In Russian, when describing a permanent characteristic or an attribute (like a river's current) using the у + [Genitive] construction, the verb есть is typically omitted. You only use есть to emphasize existence or possession. Here, we are describing what kind of current the river has, not whether a current exists at all.

Could we use the verb иметь and say река имеет сильное течение?

Yes, grammatically you can say река имеет сильное течение. However, иметь sounds much more formal, academic, or bureaucratic. In everyday speech, Russians overwhelmingly prefer the у + [Genitive] construction to express this kind of possession.

Why does the sentence start with the locations (Здесь у реки) rather than the subject (сильное течение)?

Russian word order places the known setting information at the beginning, and the new or most important information at the end of the sentence. The focus here is to warn or inform someone about the strong current. By placing сильное течение at the end, it receives the natural sentence stress.

How does the word течение relate to other Russian vocabulary?

Течение (current, flow) is a neuter noun formed from the verb течь (to flow). While it literally means a current in a body of water, it is also used metaphorically for a trend or movement in art, politics, or time.