XA04N0930 AN INTERIOR SEAWAY FOR NORTHERN AFRICA J. B. F. Champ1in* Westinghouse Electric Corporation Environmental Systems J. W. Poston, J. A. Lake Georgia Institute of Technology FOREWORD One of the difficulties confronted in,advancing explosives-engineering is that experimentation is both hazardous and expensive. This is particularly true of engineering experiments employing nuclear explosives, because there is a possibility that personnel located many miles from the center of the atomic blast may suffer from fallout or the migration of radioactivity through ground- water to public sources of drinking water. As a consequence, in order to establish courses of instruction in nuclear explosives engineering, it is necessary to use the special technique of deep consideration of a problem as a substitute for a laboratory exercise. This paper represents a summary of one such exercise in which students were assigned the task of performing the pre- liminary engineering on a project which could, if implemented, have considerable beneficial effect on a rather large area of the world. The possibilities of this project coming into being are quite remote in our time, largely due to the political ramifications and the current tendency to overemphasize the hazards of anything pertaining to nuclear explosions. But, as a classroom device, the use of the Project Analysis as a teaching tool has proved invalu- able in training the students to think of the whole system involved rather than a part of it. This paper, primarily a summary of a report submitted by a student team in the course of Engineering with Nuclear Explosives at Georgia Tech in the summer of 1968, speaks for itself in its inventiveness and its expression of deliberate concern for the betterment of mankind. A minimal amount of additional material was added by the senior author to draw attention to recent related events and publications. The students named the study "Project Pecos Bill" after an American folk- lore character, a mythical super cowboy who invented roping and other cowboy skills. During a very dry spell, Pecos Bill is said to have used a pointed stick to dig the Rio Grande River and bring water from the Gulf of Mexico. The poignant results of his work can be seen in the agricultural splendor that is the Rio Grande Valley. The parallel to this present study is obvious. Formerly at Georgia Institute of Technology. 1643 INTRODUCTION After the U. S. Atomic Energy Commission established the Plowshare Program in 1957 to investigate and develop peaceful uses for nuclear explosives, several possible applications were considered that were primarily large scale excavations of a magnitude greater than was economically feasible with conventional explosives. To date, these peaceful applications of atomic energy have been restricted to experimental blasts in several different media and depths, two of the more recent being the gas-sands shot at Rulison, Colorado and the deep blast in the igneous rock of the Aleutian Islands. Until early in 1969 it was hoped that it might be possible to make a real excavation for a harbor on the west coast of Australia to aid in the shipping of newly proven deposits of iron ore. Unfortunately, that development was postponed rather indefinitely. Nonetheless, many regions of the world could greatly benefit from applica- tions of nuclear explosives. In spite of the emotional and political deterrents involved in the use of nuclear explosives, the prime reason for their use is economy. This is true even in this day of rapidly developing social conscience about contamination of the atmosphere and hydrosphere. There is no less expen- sive source of large quantities of energy and no less expensive way to move large quantities of earth than with nuclear explosives. Man now possesses the ability to control this explosive energy and from it derive enormous benefit. Through such studies as this, it may be shown that nuclear explosive engineering can be far less contaminating to the environment than the conventional alterna- tive methods for doing the same job. To determine and examine the criteria for such a task can be sufficient justification in itself. This report is such a study. The area chosen for this study was the chott region in central Tunisia and Algeria, North Africa, Figure 1. This region is characterized by the series of so-called dry lakes or "chotts" which stretch across a considerable section of the northern Sahara desert region from the Gulf of Gabes in Tunisia on the east to the eastern borderlands of Morocco on the West. The sections in Tunisia and Algeria appear on the geographic maps to have been parts of a bay- like extension or arm of the Mediterranian Sea which recently (geologically speaking) have been cut off by the intrusion of sand bars and sand dunes. Con- struction of a canal by nuclear excavation would open this area to the sea. The immediate benefits of such an excavation are several: 1) A plentiful water supply could turn this arid land into a more useful agricultural area. New developments in arid-agriculture in Israel have shown that the problematic sand dunes can be a blessing in disguise when combined with irrigation from salt water sources such as seawater. 2) Tunisia has about one-third of the world's phosphate deposits. The proposed canal would provide a sea route to within 25 miles of those deposits and could conceivably make them more economical to mine and market. 1644 3) Such a canal would provide ready access to vast petroleum de- posits in east-central Algeria At present the petroleum pro- duced in this area must be moved via pipeline over the Atlas mountains to the coastal cities of northern Algeria. The impact of such a project on the entire economic structure of both Tunisia and Algeria is difficult to evaluate at this point. The very presence of the waterway and relatively large lagoons would provide excellent opportunities for recreational development. While considered fairly remote at present this area is much closer to large population centers than many of the coastal African cities now used by Europeans for recreational spots, such as Dakar, Agadir, etc. Potential changes in humidity could enhance rainfall probabilities not only in Tunisia and Algeria but possibly in other countries such as Libya and Egypt. Salt farming, for centuries the prerogative of legendary Timbuctu, could take place in various locations across north Africa with better production methods and products. Indeed, cave paintings found in the southern Sahara suggest that well established agriculture and much game (now restricted to savannah country far to the south) once existed here. Obviously, the economic potentials could be as great as there are imaginative minds and ambitious capital to bring them about. Project Pecos Bill, as it was originally conceived, would link several of the larger chotts and would terminate at the Chott Chergui. The lack of con- crete geologic and physiographic detail on the area and deeper consideration of the proposed route to Morocco made it advisable to terminate it in the Chott Djerid. While the possibility of extension of the project to full length is good, engineering planning for that extension must wait until more adequate information on the area becomes available. 1645 The Physiography of North Africa The north coast of Africa west of Libya features a rather continuous chain of mountains of moderate height. These mountains have their easternmost expression in the highlands of northern Tunisia. South of this relatively narrow mountain chain that characterizes northern Algeria and Tunisia is a series of wide basins, the centers of which are commonly below sea level. The climate in the area of the basins is predominately arid with an annual rainfall of a few hundred millimeters. Even in the highlands the rainfall passes through a "ten" year cycle and the monthly discharge of the Wadi Nabhanah varies through the year from about 0.05 cubic meters per second to as much as 25 M-Vs. The level of the fresh groundwater in the countryside surrounding the basins is strongly influenced by the degree of accumulation of runoff in the so-called dry lakes or "chotts" that occupy the central or deepest portion of the basins. Despite the physiographic appearance of the chotts that suggests a geologic history as an arm of the Mediterranean Sea, paleontologic evidence does not seem to justify this assumption. The Chott Djerid is a basin caused by tectonic movement during Cretaceous and Tertiary times and much of its present depth is attributed to the scouring effect of the desert winds. Chott Fedjadj is located between two prominent anticlines. The Tebaga Dome extends for approximately 100 kilometers (62 miles) along the entire southern boundary of the basin from Chott Djerid to the easternmost point of Chott Fedjadj where another anticline begins that extends roughly 20 kilometers (13 miles) to the Gulf of Gabes. Along the northern reaches of the chott area a system of anitclines extends approximately 250 miles from west of the Chott Djerid eastward to the Gulf of Gabes. The Djerid Range of mountains formed by these anticlines reach elevations greater than 600 meters, dropping off rapidly to the south to elevations below sea level in the chotts.^ Terraces which rise a few meters above the saline flats of the sebkhas** or more generally the haliferous stepps that surround the sebkhas, are vestiges of a series of geologic events that date from the early Quaternary geomorphic processes. These are best seen in the Cardium lagoon sequence which dates from the Villafranchian. Many of the terraces are structural and contain intercala- tions of massive beds of gypsum in the Villafranchian lagoonal facies which locally includes a gypsiferous Cardium coquina.