The Erms () is a river of the karstified Swabian Alb range in Baden-Württemberg, Germany. It flows into the Neckar in Neckartenzlingen. On its way from the Karst spring to the next large municipality Bad Urach, a former Erms sedimented, especially during floods, no less than eight valley cataracts, where chemically precipitated travertine repeatedly drops .
Geography
The Ermstal valley is one of the largest valley systems that have cut into the layer of the Swabian Alb from the northwest. The nearby large waters of the river system of the Rhine lie much deeper than the Danube on the south-eastern side of the Alb, so that regressive erosion of the Rhenish waters is gradually shifting back the European watershed at the expense of the Danube basin. Due to the Neckar river, which runs here particularly close to the Alb's eaves, and the great difference in altitude between them, the Erms possessed sufficient erosive power to form one of the most striking valleys of the Alb's eaves. The valley is rich in karst phenomena. The longitudinal profile, stepped by limestone sinter deposits, was once more conspicuous than today due to several natural reservoirs and favoured the industrial development along the river because of the easily usable water power.
Spring
The spring known as "Ermsursprung" is located just under southeast of the village Seeburg in the Mühltal. The average flow rate of the karst spring is between and (this corresponds to 20.1 m³ or 22.8 m³ per minute). Depending on the weather, the source discharge fluctuates between .
Course
Coming from the Fischburg valley, the much longer Fischbach flows into Seeburg. Its valley is part of the western border of the former Münsingen military training area. Mühltal, Fischburgtal and the Seetal, which flows in from the south, form here a three-part Talspinne.
Between Seeburg and Bad Urach the river Erms flows through the upper Ermstal, which here forms the Border of the villages Wittlingen and Sirchingen. The valley section is characterized by the closely opposite, wooded slopes of the Albtrauf, crowned by limestone rocks. Until the 19th century, several natural lakes existed, dammed by Kalktuffbarren. Since the limestone tuff (precipitated lime) is a good building material that is easy to extract, the lakes gradually disappeared.
In the area of the old town of Urach lies the centre of another valley spider. Here, from the east, the multi-branched valley system of the Elsach, whose sources lie in the Falkensteiner Höhle and in the Elsachbröller, flows out. From the southwest, from the Maisental, where the Uracher Wasserfall and the Gütersteiner Wasserfall lie, the Brühlbach flows into the Elsachbröller. Below Urach, the Stufenrandtal valley, eroded by the Erms river, widens. Down the valley there are more and more traces of the early use of the Erms' water power during industrialisation. In Dettingen there is still a paper mill.
The Glemsbach flows into Neuhausen. Here as in Metzingen, vineyards accompany the course of the river. The Erms leaves the valley of the Jura mountains and flows into the Albvorland. Below Riederich the Riederichbach, which was previously called Stetterbach for a long time, flows out. After the river has passed Bempflingen, it flows into the Neckar at Neckartenzlingen, whose waters reach the North Sea via the Rhine.
Catchment area
The river Erms drains an area of about , mainly in the middle Swabian Alb and its foreland. Its upper part belongs to the Mittleren Kuppenalb, the lower part almost entirely to the foothills of the central Swabian Alb, where it passes successively through the Neuffen-Vorberge and the Erms-Steinach-Albvorland. Finally, a gusset close to the mouth of the river counts towards the subspace Nürtinger-Esslinger Neckartal of the Fildern.
The highest point in the area reaches about above sea level in the area of the Römerstein on the Alb plateau.
Tributaries
Tributaries from the source to the estuary. With length and partial catchment area. Other sources are noted.
Selection, usually without side channels.
Ermsursprung in Mühltal less than one kilometre before Seeburg.