China
Africa
Explore chapters and articles related to this topic
Natural tracers – Indicators of the origin of the water of the Vrana Lake on Cres Island, Croatia
Published in A. Kranjc, Tracer Hydrology 97, 2020
Božidar Biondić, Sanja Kapelj, Saša Mesić
Taking into account sediment analyses, one may reconstruct the succession of events up to the formation of the lake as it currently exists. The depression, 7 km long, 3 km wide and almost 400 m deep, was formed by very heavy tectonic movements occurring from the Palaeogene till the beginning of the Quaternary and still active. The depression wan formed in the Pliocene, when numerous lakes within the Dinaric karst were formed. During the Pleistocene, the depression was still a karst polje, confirmed by the finds of fluvial sediments. In that time, sea-water level was some 100 m under its present elevation (Šegota, 1983) and the whole northern Adriatic region up to Dugi otok (Long Island), thus including the Cres island area, was land, i.e. the river Po mouth. During the glacial stage, almost desert conditions occurred in the area. There was no surface water and sand storms deposited sandy sediments on the edges of river mouth terraces. The remnants of those deposits can still be found on the slopes of the hills on surrounding islands. The rise of sea level of the Pleistocene resulted in the rise of fresh water in the karst underground and creates the present hydrological features of that space: a relatively shallow sea and numerous islands. The depression filled with fresh water. The present lake relief, with an open doline-type depression where surface water used to sink before the sea-water rise, makes possible a hydraulic connection between the lake water and a deep karst underground.
Agriculturally induced impacts
Published in David Drew, Heinz Hötzl, Karst Hydrogeology and Human Activities, 2017
Many Dinaric Karst poljes have been subjected to drainage schemes because of their importance as flat, fertile lands within a barren karst landscape. The flooding regime of the poljes, which can involve either ponding up of surface water or inflow of groundwater (Mijatovic 1984b), has been altered by various means, with varying degrees of success. An attempt to prevent flooding in Fatnicko Polje by constructing a concrete plug in the ponor led to the water rising at new locations, causing localised seismic shocks (Milanovic 1984). Schemes involving tunnel construction have been more successful, although Bonacci (1985) warns that the decrease in water level and shorter duration of flooding in a polje drained by this method can lead to a worsening of the water regime in downstream and upstream poljes. The multipurpose nature of polje water regulation schemes is stressed by Habic (1987), with schemes being designed for summer irrigation and winter flood relief together with non-agricultural purposes (hydro-electric power generation, water supply and recreation). In some instances, occasionally flooding poljes are transformed into permanent storage basins, which alter the water table in the surrounding karst aquifer, resulting in reactivation of springs or creation of new springs in higher level poljes (Bonacci 1985).
Tracers
Published in Werner Käss, Tracing Technique in Geohydrology, 2018
Uranine will always be the first choice for groundwater tracer investigations. Due to its low detection limit, the modest interaction with the aquifer, and its favourable price, uranine has more advantages on its side than all the other tracers used in water investigations. Especially in cases with long distances and a wide range of possible reemergence sites, uranine is the best choice and when needed the injected amount can be increased. The largest recorded amount injected was 160 kg in a karst water tracing test in Dalmatian, in the Popovo-Polje north of Dubrovnik (Milanovic 1976).
Health risk assessment of potentially toxic elements in Maros karst groundwater: a Monte Carlo simulation approach
Published in Geomatics, Natural Hazards and Risk, 2022
Anwar Mallongi, Annisa Utami Rauf, Anwar Daud, Muhammad Hatta, Wesam Al-Madhoun, Ridwan Amiruddin, Stang Stang, Atjo Wahyu, Ratna Dwi Puji Astuti
The Maros karst landscape covers an area of 450 km2 between 4°7′S and 5°1′S (Huntley et al. 2021). The karst hills complex has a high topography and some steep hillsides called Polje. The elevation of Maros karst hills ranges from 100 to 1000 meters. Moreover, plain karst with flat topography covers 30.29% of the total karst area and is utilized as agricultural land (Setiadi et al. 2021). The karst hills were enriched by alluvial plain, silica sand/quartz, basalt, coal, propylite, calcite, marble, clay and slate (Astuti et al. 2021a). These rocks are often associated with the mineralization process. Fault and fold form the geological structure of this area. Faults play a crucial role in the recharge and discharge of water into and from the aquifers (Rahmani et al. 2019). A previous study detected a fold around Leang-Leang village (Setiadi et al. 2021). If the rock layer experienced horizontal pressure, peaks and valleys would be formed. Meanwhile, the fault is widely distributed around the study area, particularly Mattoangin, Kalabbirang, Mengeloreng, Tukamasea and Baruga villages. The tensile stress from the fault results in more open fractures and is a groundwater exploration area. The rock weathering due to the presence of faults in the karst region is higher because the material is more susceptible than other rocks. This geochemical weathering of parent rocks are the natural sources of PTEs in groundwater. Water–rock interaction is the main factor in the accumulation of PTEs around karst aquifers (Ma et al. 2020).