Randolf Rausch

Palaeozoic glacial depositional environments of SW Saudi Arabia: process and product

Abstract Saudi Arabia is one of the few places in Gondwana where deposits of two Palaeozoic glaciations are well preserved. They were formed under similar conditions in a tectonically stable shelf setting. We studied the sedimentary facies and architectural geometries of Upper Ordovician and Permo-Carboniferous glaciogenic deposits in the Wajid Sandstone and developed a genetic model for both units. Common features and of both glacial episodes are (a) incision of glacial (tunnel?) valleys, (b) subsequent valley fill by proglacial deposits in front of an oscillating, polythermal ice shield; (c) intra-formational erosional events through repeated ice advance, (d) widespread and large-scale soft deformation due to glacial surge during deglaciation, and (e) marine transgression most probably due to eustatic sea-level rise following deglaciation. The general patterns and observations fit well with recently published observations on Upper Ordovician deposits in northern Africa, pointing to closely coupled glaciological processes of the North African–Arabian ice shield. Although the same general patterns apply for the Permo-Carboniferous glaciation, sedimentary styles and petrographical properties differ, probably due to a more heterogeneous ice-flow pattern controlled by a more pronounced topography after the Hercynian tectonic event.

The Riddle of the Springs of Dilmun—Does the Gilgamesh Epic Tell the Truth?

Introduction About 5200 years ago, the Dilmun culture (3200 to 330 B.C.) developed on the island of Bahrain in the Persian Gulf (Figure 1) (Bibby 1996). The name Dilmun appears on some of the earliest written documents in the world; these are clay tablets inscribed with an experimental version of cuneiform which was to become the dominant script of the ancient Middle East from about 3000 B.C. (Crawford 1998). Dilmun was considered to be a pure and sacred place by the ancient Sumerians, a kind of earthly paradise where gods and heroes enjoyed immortality (Crawford and Rice 2000). In the Gilgamesh epic Dilmun is described as a heavenly land, a place of the everlasting youth; a holy place without illness and death. In ancient times Dilmun was mainly known for the trading activities that were taking place in the region. The Epic of Gilgamesh, which dates from the 3rd Millennium B.C. (Sandars 1972), is one of the finest surviving epic poems in world literature. The existence of the Epic has been known to the modern world for only the last 120 years, since shortly after the decipherment of cuneiform writing (Kovacs 1989). In its complete state the Epic comprises about 2900 lines written on 11 clay tablets. George (1999) mentions that it was miraculously preserved on clay tablets dating back as far as 4000 years. The Epic relates the story of Gilgamesh’s—King of Uruk—adventures with the wild man Enkidu and of his arduous journey to the ends of the earth in quest of the Babylonian Noah and the secret of immortality. Jackson (1997) in his translation of Gilgamesh Epic refers to Dilmun as a “paradise regained;

Methods to Countermeasure the Intrusion of Seawater into Coastal Aquifer Systems

Seawater intrusion is a widely occurring environmental problem, which concerns the majority of the coastal aquifers in the world, having large negative impacts – from an economic, developmental, environmental as well as social point of view – on the coastal local communities. The fact that almost 40% of the world’s population lives within a distance of 80 km from the coastline gives rise to the significance of the aforementioned problem and emphasises the necessity for its prevention. This chapter analyses the engineering, managerial as well as techno-economical aspects with respect to the prevention of seawater encroachment into freshwater coastal aquifers and presents some state-of-the-art methods that are currently applied worldwide. It provides a critical review of the application of different type of coastal barriers (either by hydraulic, biological or construction means), management of aquifer recharge (through the application of underground or surface artificial recharge techniques), control of groundwater abstraction and exploitation scheme (by means of suggesting the optimal allocation of abstraction areas for minimising the risk of further intrusion) and other methods of prevention. Finally, this chapter investigates the current enacted legislation as well as adopted policy – mainly developed at a European level – with respect to the prevention of seawater intrusion, together with all the observed gaps and problems which create difficulties for its enforcement.

The scarp lands of Saudi Arabia

In central Saudi Arabia, the combination of rock types and sedimentary bedding created a unique scarp landscape. The escarpments were formed during Late Miocene through Early Quaternary times. At present, cuesta formation and migration are restricted to the actual escarpments as a consequence of negligible sediment removal. The plains between the escarpments are sealed through periodically active fluvial processes and through eolian sedimentation. In this publication, the major escarpments of central Saudi Arabia are described. The interactions between tectonics, climate, and morphogenesis which created this unique landscape are reviewed.

Die Erdfälle von Layla und Al-Kharj - Einblicke in die Karst-Hydrogeologie des oberen Jura von Saudi-Arabien

ZusammenfassungDie Erdfallseen von Layla und Al-Kharj bildeten bis Ende des 20. Jahrhunderts Oasen im Zentrum Saudi-Arabiens. Sie wurden durch aufsteigendes Grundwasser aus den verkarsteten oberjurassischen Anhydriten der Arab- und Hith-Formation gespeist. Sowohl morphologische Merkmale einer Höhle bei Al-Kharj als auch Grundwasserspiegelhöhen in Brunnen der Region Layla zeigen, dass die Verkarstung der Anhydrite hypogen war. Die Verkarstung führte entlang des Streichens zu Zonen der Subrosion, in denen die hangenden Kreidesedimente verstürzt sind. Durch die Überbeanspruchung der Grundwasserressourcen des unterliegenden Aquifers trockneten die Erdfallseen aus. Dabei wurden an den Wänden der Erdfälle weltweit einmalige sublakustrine Gipstuffe sichtbar, die zusammen mit großflächigen Gipskrusten in der Umgebung vom Aufstieg des sulfatreichen Grundwassers zeugen.AbstractUntil the end of the 20th century, the sinkhole-lakes of Layla and Al-Kharj formed oases in central Saudi Arabia. They were fed by ascending groundwater from the karstified Upper Jurassic anhydrites of the Arab and Hith formations. Morphologic features of a cave near Al-Kharj and hydraulic heads in wells of the Layla region show that the karstification of the anhydrites was hypogene. The karstification led to zones of collapse in the overlying Cretaceous sediments. Because of the exploitation of the underlying aquifer, the sinkhole-lakes dried up, exposing world-wide singular sublacustrine gypsum tufas on their walls. The gypsum tufas and widespread gypsum crusts in the vicinity of the sinkholes reflect the former ascent of the sulphate-enriched groundwater.

Hydrogeology of arid and semiarid environments

Many of our society’s future challenges will be linked to geosciences. In particular, the limited availability of georesources, like water, soils, fossil and renewable energies are of great concern. This has been emphasized by the “geocommission” of the German Research Foundation in their recently published strategic paper on the future challenges of geosciences. Water is an essential resource. It is widely predicted that global water consumption will double, from the consumption levels of the 1960’s to that predicted in 2025. Already in many arid and semiarid environments water resources are dramatically overexploited, and it has to be admitted that a sustainable use of these resources is difficult or even unrealistic. Smart and efficient concepts are needed to manage water resources with the greatest possible benefit for our society. This requires a fundamental understanding of local and regional hydrogeology, hydrochemistry and hydrody-

New Tools for Coherent Information Base for IWRM in Arid Regions: The Upper Mega Aquifer System on the Arabian Peninsula

In arid regions like the Arabian Peninsula, available water resources are essentially restricted to groundwater, requiring a detailed understanding of the local and regional hydrogeological conditions and water budgets. In the framework of the IWAS initiative, the 1.8 × 106 km2 large sedimentary Upper Mega Aquifer of the Arabian Peninsula was chosen as a model region to develop concepts and methodologies to quantify water fluxes in such an arid environment. Field and laboratory studies were conducted to analyse (i) precipitation patterns, (ii) groundwater recharge, (iii) the hydrochemical evolution of groundwater and (iv) evaporation particularly from Sabkhas in detail. Results were used as input parameters for a 3D groundwater model for the central part of the Peninsula, which was later extended to the full dimension of the Upper Mega Aquifer. It could be shown that in such a region different components of the water cycle have to be quantified with great care and several methods should be applied to reduce data uncertainty. It was not possible to make use out of satellite products to receive reliable actual precipitation patterns for the peninsula. It was observable; recharge estimations based on average annual precipitation are not applicable but should be based on singular precipitation events. A threshold of 6 mm/event was derived, below of which no recharge in sand seas occurs. The loss of water from UMA, due to sabkha evaporation reaches about 40 mm/a under the given recent climatic conditions.

Zu wenig Wasser oder zu wenig Zuversicht

Betrachtet man heute die Medien, stößt man täglich auf neue Schreckensmeldungen zum Thema Wasser. Es gibt Warnungen zu einer lebensbedrohenden weltweiten Wasserkrise. Berichte von Dürren, Kriegen um Wasser, vergiftetem Wasser und dem Ende unserer Wasserressourcen schüren Ängste bald verdursten zu müssen oder kein Trinkwasser mehr zu haben. Diese Meldungen entsprechen der Denkweise vieler Medien „What bleeds leads“. Sie mögen wohl die Auflage der Zeitschriften bzw. die Einschaltquoten der TV-Sender erhöhen, tragen aber nichts zu einer seriösen Information bei, noch helfen sie bei der Lösung der Probleme. Als Experten wissen wir, dass die Situation tatsächlich ernst ist und nicht auf die leichte Schulter genommen werden kann. Wir wissen aber auch, dass wir nicht resignieren müssen. In vielen Fällen besitzen wir schon heute Antwor-

Advances in understanding the relation between reservoir properties and facies distribution in the Paleozoic Wajid Sandstone, Saudi Arabia

The Wajid Sandstone is one of the most important groundwater reservoirs in the Kingdom of Saudi Arabia. The knowledge of the dimensions and the distribution of its sedimentary facies are essential for high quality reservoir interpretation. Hitherto, the facies and their dimensions are only roughly known from extrapolation of subcrop data and geophysical surveys.