46870 Ontinyent, Valencia.
JUL to AUG online booking required.
|Karst Spring Dry Valley Polje
Pou Clar, Paratge Serra l'Ombria-Pou Clar, Ontinyent (Valencia), 46870, Tel: +34-96-066-21-60.
Ajuntament d'Ontinyent, Plaça Major 1, 46870 Ontinyent, Tel: +34-96-291-82-00, Fax: +34-96-291-82-02.
|As far as we know this information was accurate when it was published (see years in brackets), but may have changed since then.
Please check rates and details directly with the companies in question if you need more recent info.
|end of use for drinking water.
El Pou Clar (Clear Well) or Pou de la Reixa (Spring of Reixa) is a karst spring of a special type. It is actually located in the riverbed, in other words the river is water filled below and dry above, reactivated seasonal. While such a situation is not very common, it is nevertheless found in numerous karst area and actually quite typical. It is a river with underwater springs, also called subfluvital spring
The drainage started above ground, rivulets meeting, forming rivers, slowly cutting into the rock forming valleys. At some point the area was lifted and the water started to flow through cracks in the rock, and a small part of the water was drained underground. This water dissolved the limestone along the crack, widening it and forming caves. The amount of water flowing underground continually increased, the amount of water flowing above ground decreased. Finally, the valley became dry, the area was drained underground, the dry valley are relics of a different era. At the beginning the river bed is reactivated during times of high flow, when the caves are not able to swallow all and the excess flows on the surface. But when the caves grow further, this will end too.
But here it is a little more complicated, the water table has a slope, which is always required for water to flow gravitationally. But the slope of the water table and the valle may differ, and where the water table raches the surfe a spring occurs and the groundwater starts to flow on the surface. That's what happens here, the upper part of the valley is above the groundwater, the point where it reaches the surface is the Pou Clar. There are two basic reasons for this, first the change in slope, and second a change in the permeability of the underground. The spring is located where the limestone hills end and a river plane covered by impermeable clay-rich sediments starts. The straight edge also suggests that there is a tectonic fault line, so there are different rocks on the different sides. As a result the groundwater is forced to the surface. This happens actually in every polje on earth. The valley of Ontinyent is not a polje, but it has similar characteristics.
The Pou Clar is part of the Serra de l'Umbria-Pou Clar Municipal Natural Park and is the main source of water for the Clariano River. It was used as a source of drinking water for the city Ontinyent, but this was stopped in the 1960s. But the water is still used for irrigation.
The tourists which flood this place do not know much about the geology, this is a very popular bathing spot. During summer on weekends it is crowded, but even during the week it is full. That's the reason why actually anything is prohibited around the spring, especially picknicks or barbeques. The site is not accessible by vehicle, it is necessary to park at the Ontinyent indoor swimming pool or the Ontinyent University Campus. Its a 2 km/30 minutes walk to the spring. On weekends in July and August there is a free bus shuttle from Poliesportiu to Pou Clar. Also, the restrictions change, in general they are intensified.