The word « Trächelchen » is the nick-name of the word « Tra­ch » mean­ing water­ing place in Luxembourgish.

At this loca­tion numer­ous sources have their ori­gins. The dif­fer­ent springs flow togeth­er to become the Aal­bach (or Sen­ninger-Bach), cross­ing the vil­lage of Sen­nin­gen before flow­ing into the riv­er Syre. Because of the huge water amount and the steep­ness of its way, many mills were sit­u­at­ed on the banks of the Sen­ninger­bach. Because of its paper mills, Sen­nin­gen was famous, even beyond the nation­al bor­ders, as an impor­tant cen­tre of paper production.

The origins of the sources.

The dif­fer­ent spring waters are com­ing togeth­er to form the brook of Senningerbach.

The springs at the “Trächelchen” erupt on the edge of the Lux­em­bourg Sand­stone lay­er. The sur­face of this lay­er is sub­ject of an intense ero­sion and crum­ble away into loose sands.

Because of its porous and per­me­able sur­face the Lux­em­bourg Sand­stone lay­er is a per­fect water car­ri­er, facil­i­tat­ing the infil­tra­tion of rain waters to be led to the undergrounds.

At the con­tact point of the sand­stone lay­er with the imper­vi­ous clay lay­ers of Psilono­tis (li1), the water infil­tra­tion is blocked and at the sur­face the springs are erupt­ing, just as at the “Trächelchen”.

The Luxembourg Sandstone Layer as a drinking water reservoir.

The spread­ing of the Lux­em­bourg Sand­stone layer

Lux­em­bourg has an aver­age rain­fall rate of 2 bil­lion cube meters per year. Near­ly 55% of these waters are direct­ly evap­o­rat­ing at the ground, 41% flow out on sur­face and only 4% can pen­e­trate into the grounds to sup­ply the phreat­ic water sheet.

The major part of the rain runoffs (60 – 65 mil­lions of cube meters) are pen­e­trat­ing the Lux­em­bourg Sand­stone Lay­er, spread­ing over a sur­face of 493 square km. But only 300 square km of this sur­face are per­me­able, the oth­ers are cov­ered by imper­vi­ous clay and lime layers.

Spring waters drawn off at the water­ing place.

The water, com­ing from the phreat­ic water sheet of the sand­stone lay­er is cov­er­ing 90% of the nation­al drink­ing water sup­ply (2/3 of our drink­ing water comes from the phreat­ic water sheet and 1/3 from sur­face waters.)
The waters are cap­tured in the sand­stone lay­er for only a peri­od of 6 to 12 months, so that a con­stant renew­ing of the phreat­ic water sheet is possible.