Aabach is a 14 km long river in Germany, which was formerly called Große Aa, flowing into the river Afte . It rises in eastern North Rhine-Westphalia nearby the border with Hesse between Bad Wünnenberg and Marsberg . Its source is where the regions Briloner Hoehen and Sindfeld meet, in Brilon -Madfeld . From there it flows north between up to 503 m high mountains through a wonderful forested landscape, partly in the natural park Diemelsee . Already after a few kilometers it flows into the artificial lake Aabachstausee . It flows to the north and empties only about 3.5 km further north after Bad Wuennenberg, where it flows into the Afte. The drainage area of the Aabachs lies on Rhine River Watershed : The Aabach, which flows to the north over the Afte, Alme and Lippe River drains into the Rhine, while the small rivers that rise on the southern side of the ridge drain into the Weser through the Hoppecke and Diemel .