New approach to hydrogeological modelling and source data collecting in a small mountainous hard rock basin – experiences from the Sudetes Mts. (SW Poland)

Abstract

We dem on strate a new re search meth od ol ogy into flow paths and ground wa ter re sources with in small hard rock bas ins, where lit tle hydrogeological data is avail able, a pic ture may be ob tained by mod el ling. Data has been col lected in the Z³oty Potok River catch ment (area 4.4 km 2 ), lo cated in the east ern Sudetes Mts. (SW Po land). The study area, as for most small hard rock bas ins in the Sudetes Mts. is char ac ter ized by: (1) steeply slop ing ter rain, (2) a com plex flow sys tem con nected to sev eral me dia, (3) poorly con strained hydrogeological pa ram e ters. In such con di tions, ground wa ter mod els are dif fi cult to im ple ment. To over come these dif fi cul ties, we ap plied a con cept of mixed flow ruled by laws of Darcy (po rous me dia) and Hagen-Poiseuille (frac tured me dia), and the con cept of three wa ter-bear ing zones, a clas sic so lu tion for scales of above several sq km, com bined with a dis crete frac ture model. Field data ap plied for mod el ling were col lected over one year, mea suring all man i fes ta tions of ground wa ter oc cur rence: (1) ef fec tive in fil tra tion (lysimeter), (2) frac ture map ping, (3) stream flow and flow dis ap pear ance. As a re sult of mod el ling, spe cific flow do mains were iden ti fied; which form a sys tem of zones, charac ter ized by dif fer ent ge om e tries and flow ve loc i ties. A new, pre vi ously un rec og nized zone of con sid er able im por tance for wa ter ex trac tion, i.e. frac tures in the river val ley axis, reach ing a deep part of the orogen (up to 300 m b.g.l.) was de fined. The re la tion ships in ves ti gated al lowed prepation of a prog no sis for deep ground wa ter in take lo ca tions in poorly de scribed mountain ous ar eas. The suc cess of the so lu tions ob tained in this typ i cal moun tain ous river ba sin sug gests that this method may be come ef fi ciently and widely used in other hard rock ar eas. The re search un der taken of fers an in no va tive, ef fi cient approach to ground wa ter re source as sess ment in hard rock.