[en] The processes in the water-unsaturated zone have in the past received too little attention from hydrogeologists and their study by pedologists has been patchy. It is only recently that studies have been published, with for some part very diverse scientific approaches, which consider the water-unsaturated zone and the soil as a whole. There are small-scale and large-scale hydraulic approaches, hydraulic and first tracer-hydrological approaches. This poses the problem of how to transfer results obtained locally to larger spaces. Moreover, the homogeneity of substrates has been found to be such that hydraulic and tracer-hydrological approaches are unproblematic at the large scale, while at the small scale their results can only be interpreted with certain reservations. For example, this has led to findings of steady groundwater recharge at a large scale which contrast with findings at a smaller scale of a separation into highly variable matrix and bypass flows or into groundwater recharge and intermediate outflows. Studies at different levels of scale consequently bear different implications for material transport within and material export from specific landscape sections to underground or aboveground neighbouring compartments. The purpose of the present workshop on seepage water movement is to contribute to the establishment of facts on this issue, identify deficits, and stimulate future cooperation

[en] It is reported about tracing investigations carried out at present in order to detect the passages of waste waters in the Karst of the Southern Frankish Alb. Tracings of karstic waters in the area of karstic watersheds can be performed successfully if the volume of the karstic ground waters equals the small quantities existing in the area between Altmuehl and Anlauter. In this region the karstic watershed is shifted by a strip of about 1 km width. This shift depends on the recharge and volume of the groundwater. All tracings between Altmuehl and Danube, carried out in the area of the karstic water shed, led to negative results, because in this region the volume of the karstic water is particularly large and since consequently the fluorescent tracers are extremely diluted in the waster masses. The amount of tracer material to be recovered ranges below 10%, if the ''most frequent distance velocity'' is below approximately 500 m/d. With higher distance velocities it is sometimes possible to recover more than 50% and even up to 100% of the dyes. (orig.)

[en] This study reports about ₁₄C model ages of woods coming from the Alm and from the Quaternary filling in the valleys of Isar and Loisach. The results are briefly compared and contrasted with the previous theories about the formation of Quaternary sediments. For the Loisach valley for example, sedimentation rates of more than approximately 2 mm/a are derived. (orig.)

[en] The propagation of Escherichia Coli (ATCC 11229, Gelsenkirchen) is compared with that of conservative tracers in groundwater. The experiments were performed with injection quantities of 10₇, 10₈, 10₁₀ and 10₁₁ of Escherichia Coli. Both, bacteria and conservative tracers pass their maximum at the same instant in the observation gauges. With injection quantities of more than 10₈, the propagation of the Escherichia Coli sets in at the same time as it begins with the dyes. When the quantities range below 10₈, the propagation begins after that of conservative tracers, because Coli bacteria were measured with a lower degree of detecting sensitivity than the tracers. With Coli injection quantities ranging above 10₁₀, an increased filtering of these bacteria can be observed. Coli bacteria propagate more laterally than conservative tracers, however it could not be proved that this lateral propagation depends on the bacteria concentration. (orig.)

[en] Stable isotope methods (δ¹⁸O and δ²H) have been used investigate the importance of bypass flow in the unsaturated zone which leads to unproductive water loss during flood irrigation. Field experiments have been carried out in Jordan and Pakistan in order to determine the occurrence of bypass flow, its amount and its velocity compared to piston flow. Results show that there is not only an advective component of flow (bypass flow) but a diffusive tracer exchange between piston and bypass flow. Infiltration calculations and analysis of tracer distributions are used to show that at the research sites, bypass flow amounts to about 25% of water recharged during winter. This estimate is important as it provides an assessment of the amount of water that passes the root zone and directly recharges groundwater. (author)

[en] Groundwater tracings require a particularly thorough preparation in order to ensure a useful performance. It shall be possible to verify the interpretation of the test results by means of other investigation results, because then logic solutions can be found for the existing problems. - Several case studies are given, illustrating that the investigation on the content of environmental isotopes of the groundwaters and the dilution method applied for determining the filtering velocity help to solve hydrologic problems. (orig.)

[en] The numerical flow and transport models are used to calculate the streamline distribution in the aquifer and the tracer concentration in the outflow from the system for the groundwater aquifer consists of parallel layers with different hydraulic conductivity. Infiltration takes place through the whole aquifer surface and the aquifer is drainaged by the river (constant head). Using the streamline distribution calculated using numerical model of water flow, the distribution of the transit time of water particle through the aquifer is constructed. These distribution functions calculated for different imagine aquifers are compared with the well known distribution functions of Black-Box-Model (BBM) approach. In that way it was found which of BBM functions approximates the real hydrological situation with the best accuracy. It was also found the relation of the mean transit time of water to the aquifer parameters. Additionally, the numerical transport model was applied for the continuous injection of ideal tracer through the aquifer surface and the calculated weighted concentrations found for the outflow (river) were taken into BBM modeling. It was found which BBM model can be calibrated to the observed output concentrations and what is the value of the mean transit time of water through the aquifer. The aquifer parameters obtained by applying distribution functions to the numerical modeling of water flow and by applying BBM to the transport modeling, are compared with the real parameters of the aquifers being considered. (author)

[en] To document the impact of evaporation on percolation water, detailed stable isotope analyses were performed over a 24 month period at four experimental sites with different types of sediment and land use. The test sites were situated within 5-12 km of each other with almost identical climate conditions. 4 refs, 3 figs

No abstract available

[en] The immediate availability of groundwater recharge decreases significantly with depth. Mathematical modelling showed, that as an average more than 85% of the groundwater recharge of a landscape is turned over in the upper decametres of aquifer systems (active recharge zone) and less than 15% penetrates the great depth (passive recharge zone). The passive recharge zone occurs above connate waters that did not return to the biosphere since these waters have been included in the sediment during sedimentation. As a rule, groundwater of the active recharge zone has low turn-over times (< 50 years), is tritiated and contaminants have easy access; contrary, groundwater from the passive recharge zone has high turn-over times, a significant dilution, chemical and microbial reaction potential, is free of tritium and has Argon 39 and Carbon 14 contents lower than initial concentrations. The active recharge zone reaches a thickness of a few meters to 100m according to the amount of groundwater recharge and the hydraulic properties of the aquifer system; the passive recharge zone reaches several hundred meters in thickness. All these modelling results have been confirmed by isotope related, hydrochemical and hydraulic field research in humid, tropical and semiarid climates