Recharge of Phreatic Aquifers in (Semi-)Arid Areas, ,

Groundwater use is of fundamental importance to meet the rapidly expanding urban, industrial and agricultural water requirements in (semi) arid areas. Quantifying the current rate of groundwater recharge and define its variability in space and time are thus prerequesites for efficient groundwater resource managment in these regions, where such resources are often the key to economic development. Attention focuses on recharge of phreatic aquifers, often the most readily-available and affordable source of water in (semi) arid regions. These aquifers are also the most susceptible to contamination, with the recharge rate determining their level of vulnerability. (Semi) arid zone recharge can be highly variable, the greater the aridity, the smaller and potentially more variable the natural flux. Its determination is an iterative process, involving progressive data collection and resource evaluation; there is also a need to use more than one technique to verify results. Direct, localised and indirect recharge mechanisms from a spectrum of known sources are addressed in the framework of recharge from precipitation, intermittant flow and permanent water bodies. The approach taken for each of these reflects the nature and current understanding of the processes involved. The volume also reviews current recharge estimation challenges, outlines recent developments and offers guidance for potential solutions.

Transport and variability of fecal bacteria in carbonate conglomerate aquifers, , Goeppert N. , Goldscheider N.

Clastic sedimentary rocks are generally considered non-karstifiable and thus less vulnerable to pathogen contamination than karst aquifers. However, dissolution phenomena have been observed in clastic carbonate conglomerates of the Subalpine Molasse zone of the northern Alps and other regions of Europe, indicating karstification and high vulnerability, which is currently not considered for source protection zoning. Therefore, a research program was established at the Hochgrat site (Austria/Germany), as a demonstration that karst-like characteristics, flow behavior and high vulnerability to microbial contamination are possible in this type of aquifer. The study included geomorphologic mapping, comparative multi-tracer tests with fluorescent dyes and bacteria-sized fluorescent microspheres, and analyses of fecal indicator bacteria (FIB) in spring waters during different seasons. Results demonstrate that (i) flow velocities in carbonate conglomerates are similar as in typical karst aquifers, often exceeding 100 m/h; (ii) microbial contaminants are rapidly transported towards springs; and (iii) the magnitude and seasonal pattern of FIB variability depends on the land use in the spring catchment and its altitude. Different ground water protection strategies than currently applied are consequently required in regions formed by karstified carbonatic clastic rocks, taking into account their high degree of heterogeneity and vulnerability.

style=

Irish Limestone Regions and Caves, 1948, Coleman J. C.

A new method for the study of limestone regions, 1956, Corbel J.

Cave Animals and Their Environment, 1962, Richards, Aola M.

Caves can be divided into three distinct regions - the twilight zone, the transitional zone and the troglic zone. The main physical characters of caves - light, air currents, temperature and humidity - are discussed in relation to their effect on cave fauna. Various classifications of cave animals are mentioned, and those of Schiner and Jeannel discussed in detail. The paucity of food in caves, and its effect on the animal population is considered. Mention is made of the loss of secondary sexual characters and seasonal periodicity of breeding among true troglobites. Cave animals have undergone many adaptations to their environment, the most interesting of these being blindness and loss of pigment. Hyper-development of tactile, gustatory, olfactory and auditory organs and general slenderness of body, are correlated with eye degeneration. Several theories on the origin of cave fauna are discussed, and the importance of isolation on the development of cave fauna considered.

Karst-hydrological researches in Hungarian caves., 1965, Kessler Hubert

Although Hungary does not belong to the large Karst countries, extensive speleologic and karst-hydrologic investigations are carried out. On the one hand, Hungary owns one of the largest stalactite caves in the world, on the other hand the majority of raw materials and the connected industries are linked with Karst regions which pose particular water supply problems. The largest water supplying caves are in the North of Hungary. The best known cave is the Aggtelek cave with a length of 22 km, but there are numerous other, recently disclosed caves of a length of 1-5 km, which were discovered by way of artificial means and on the basis of many years of hydrologic observations. Of particular interest are the active thermal caves with waters of 30°C. In one of these latter a diver discovered and measured a siphon of a length of 300 m. By way of experiment, speleotherapic treatments were applied in some of these caves. By calculation of decades of series of measures an applicable formula was established for the calculation of the percent of seepage in the Karst regions. In several of these caves the influence of precipitation on the intensity of stalactite formation was measured. The indication of the so-called ,,year-rings" in the stalactites furnishes data concerning precipitation of bygone millenaries, which are also valuable for the investigation of periods. In several caves the changes in ion concentration of the water currents was measured and the correlation with the cross section of the caves was determined. On the basis of complex measurements in Karst sources the possibility of disclosing hitherto unknown cave systems arises. In this manner, recently several caves were artificially discovered.

Phreatobiological researches II., 1965, Motas Constantin, Serban Eugène

The present note calls into question the opinion of different authors concerning the presence or lack of adult Niphargus near the phreatic table (superior layer of phreatic water) in zones prospected by Karaman-Chappuis method. Our investigations have proved the reason for which Niphargus adults were less frequent in the superior layer of the phreatic water is rather concerned with our investigation means; which are very approximate -, than with the ecological or ethological requirements of these animals. The assertion that the phreatic fauna performs downward migrations during the floods must be considered as doubtful. During floods it is impossible to dig into the alluvial deposits immediately near the stream, these being completely flooded; so, we are obliged to dig in regions more distant from the riverside, which are not flooded. It is well known that in this zone the biocoenosis contains always a greater number of phreatobius elements. One of the authors (C. Motas) introduce the terms: rithrobios; for the fauna inhabiting the epigean streams, phreatobios; for that inhabiting the phreatic water, and geobios; for the terrestrial world.

Present-Day Cave Beetle Fauna in Australia A Pointer to Past Climatic Change, 1965, Moore, B. P.

Beetles form an important element of life in caves, where they provide some of the most spectacular examples of adaptation to the environment. The troglobic forms are of greatest interest from the zoogeographical point of view and their present distributions, which are largely limited to the temperate regions of the world, appear to have been determined by the glaciations and later climatic changes of the Quaternary. Troglophiles, which are much more widespread, show little adaptation and are almost certainly recently evolved cavernicoles.

Hydrology of carbonate rock terranes -- A review , : With special reference to the United States, 1969, Stringfield V. T. , Legrand H. E. ,

Limestone and other carbonate rocks are characterized by many unusual features and extreme conditions, either involving the hydrologic system within them or wrought by hydrologic conditions on them or through them. Perhaps there could be little agreement as to what is typical or average for the many features of carbonate rocks, as indicated by the following conditions: bare rock and thin soils are common, but so are thick soils; very highly permeable limestones are common, but so are poorly permeable ones; and rugged karst topographic features with underlying solution caverns are common, but so are flat, nearly featureless topographic conditions. Some conditions of carbonate terranes are suitable to man's needs and interests, such as the use of some permeable aquifers for water supply and the exploitation of caves for tourist attractions. On the other hand, many problems may exist, including: permeability too low for adequate water supply or so high that the aquifer retains too little water for use during periods of fair weather, soils too thin for growing of crops and for adequate filtration of wastes near the ground surface, instability of the ground for buildings and foundations in sinkhole areas, and unusually rugged topography. Some of the many variable conditions are readily observable, but others can be determined only by careful geologic and hydrologic studies.The need for knowing the specific geologic and hydrologic conditions at various places in limestone terranes, as well as the variations in hydrologic conditions with changing conditions and time, has resulted in many published reports on local areas and on special topical problems of limestone hydrology. Many of these reports have been used to advantage by the present writers in preparing this paper.The concept that secondary permeability is developed by circulation of water through openings with the accompanying enlargement of these openings by solution is now universally accepted in limestone terranes. Emphasis is placed on the hydrogeologic framework, or structural setting, in relation to the ease or difficulty of water to move from a source of recharge, through a part of the limestone, to a discharge area. Parts of the limestone favored by circulating ground water tend to develop solution openings, commonly in the upper part of the zone of saturation; as base level is lowered (sea level or perennial stream level), the related water table lowers in the limestone leaving air-filled caverns above the present zone of saturation in sinkhole areas. Reconstruction of the geologic and hydrologic history of a limestone area aids in determining the extent of development and the positions of fossil and present permeability. References are made to the hydrology of many limestone regions, especially those of the United States

Seminar on Karst Denudation - Comparative morphogenetical study of Karst Regions in the Tropical and Temperate Zones, 1972, Balazs D.

Karst. Important Karst Regions of the Northern Hemisphere. M. Herak and V. T. Stringfield, Eds. Elsevier, New York, 1972. xiv, 552 pp., illus. $35, 1972, White William B. ,

Trouble-Making Terrains, 1972, White William B. ,

Karst of Yugoslavia, 1972, Herak M.

Historical review of hydrogeologic concepts, 1972, Herak M. , Stringfield V. T.

Historical review of morphological concepts, 1972, Roglic J.