Arid Lands Colloquia (1959-1960, 1960-1961)
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Arid Lands Colloquia (1959-1960, 1960-1961) Publisher University of Arizona (Tucson, AZ) Download date 02/10/2021 22:09:48 Link to Item http://hdl.handle.net/10150/303144 THE UNIVERSITY OF ARIZONA ARID LANDS COLLOOt1IA 1959 -1960 1960 -1961 THE UNIVERSITY OF ARIZONA ARID LANDS COLLOQUI 1959 -1960 1960 -1961 CONTENTS Page Foreword William G. McGinnies . 1 1959-1960 COLLOQUIA PAPERS Some Considerations of the Problem of Recording Data A. Richard Kassander, Jr. 2 Origin of the Drainage and Geomorphic History of Southeastern Arizona Mark A. Melton . 8 Prehistoric Agriculture in East - central Arizona Richard B. Woodbury . 17 Natural History of the Saguaro Stanley M. Alcorn . 23 Precipitation and Saguaro Growth James Rodney Hastings . 30 Chemical Constituents of the Saguaro James W. Berry and Cornelius Steelink . 39 1960 -1961 COLLOQUIA PAPERS Economic Alternatives for Native Peoples in Arid Lands Robert A. Hackenberg . 46 Changes in the Properties of Water Due to the Interaction of Soil and Water Duwayne M. Anderson . 58 Economic Evaluation of Water Conservation Practices Sol Resnick . 65 Status of Cenozoic Geochronology in the Southwest Terah L. Smiley . 69 FOREWORD William G. McGinnies Coordinator, Arid Lands Program This second volume of colloquia proceedings includes copies of six papers presented in the eight meetings held during the school year 1959 -1960, and four papers presented in 1960 -1961.Written papers were not prepared for two of the talks presented in 1959 -1960 and for four in 1960 -1961. The purpose of processing these papers is to make them available to the members of the University faculty and their associates. As the results presented are often preliminary and the treatment of the material is informal, it is not intended that this report be considered as publication. Citation of any of this material should only be made after personal communication with the author. The Arid Lands Colloquia were oriented toward promoting the "interdiscipli- nary approach ". The programs were designed to keep the participants in the Arid Lands Program up to date in each field. Speakers were requested to keep this in mind in preparing material and to bring out points of special interest to workers in other fields.Ample time was also provided for questions and dis- cussion and this gave an opportunity to bring out interrelationships. The papers presented during the second year were mostly progress reports of research under way in the Arid Lands Program. The 1959 -1960 series was intro- duced by a general paper on the recording of data, followed by reports on some geologic and prehistoric aspects of the Arid Lands Program.The last three meet- ings were devoted to various aspects of research on the saguaro including its life history, the relation of growth to precipitation and some of its chemical characteristics. During the 1960 -1961 school year the program included general information papers as well as reports on specific phases of arid land research. As in the previous Colloquia as many different phases of the arid land program as possible were included.The aim in the third year was to round out the three year colloquia program, by covering various aspects that had not been included in the first two years. 2 SCME CONSIDERATIONS OF THE PROBLEM OF RECORDING DATA A. Richard Kassander, Jr. Director, Institute of Atmospheric Physics The University of Arizona To understand the fundamental biological and physical mechanisms of the various processes at work in an arid land, one rather quickly proceeds from the purely descriptive phase of investigation to a phase involving the measurement and recording of the variables thought to be influential. This rapid procession has taken place in several of the arid lands projects, emphasizing further that one of the desirable features of an interdisciplinary program is the ability to call on the techniques of one investigation to be applied to a new one in a different field. Although most modern laboratories and many field investigations are well equipped with recording apparatus of many different types, the problem of in- strumenting a new measurement is sometimes very subtle and perhaps more involved than is suggested by a first look at an instrumentation catalogue. Even when the recorder appears to be working satisfactorily, the results may cover the whole spectrum from inadequacy to deception.Thus,it is worth while to look at some of the basic concepts involved in recording. A complete recording system may be thought to contain five basic elements. These are: 1. The Sensor 2. The Interpreter 3. The Recorder 4+. The Analyzer 5. The Computer The sensor is that element which, when acted on by the variable of inter- est, converts the energy of the variable into some form which is more effici- ently recorded. Typically, the sensor converts temperature, pressure, moisture, displacement, light intensity, or any of the myriad of other imaginable variables into an electric variable such as voltage, current, resistance, or frequency change. This is not necessarily the case, but for the purpose of this discussion, it will be well to restrict interest to systems whose sensors produce an electri- cal "output" as a function of the variable of interest, i.e., the "input." The interpreter (a term not in general usage) is here thought of as the element of the system which renders the sensor output compatible with the re- quired recorder input for reasonable scale deflection. It may be simply an am- plifier or a battery. In more complicated systems it may be an impedance- match- ing device, a rectifier or demodulator, or an electronic device to linearize a non - linear output from the sensor. The recorder is the "memory" of the system. It must render the data into some form that can be analyzed at a convenient time after the data have been recorded. Sometimes the recorder may be, or may take the place of, a pencil and paper. More often the recorder is used to make a record of data that are changing too rapidly for manual notation, or to eliminate the requirement of con- stant human attendance on an experiment. 3 The analyzer reduces the data to such form that subsequent mathematical, statistical, or merely speculative use may be made of it. If the recorder in- volves magnetic tape, punched cards or paper tape, or some form of ink recorder using electrically conducting ink, the analyzer may be more electronic equipment for optically sensing holes in cards, detecting magnetic variations on magnetic tape, or following a conducting -ink line on the recorder. In the same sense as the interpreter was the intermediate step from sensor to recorder, the analyzer mustperform the intermediate step from recorder to the element here thought of as final in the system. The computer is the final element in the basic recording system. In prac- tice, it may be anything from a simple electric- counter to the most elaborate electronic computer. Its function is to produce the final number or numbers describing the experiment for which the system has been designed. Recording systems have an infinite number of possible variations. Every experiment has involved a system analogous to the one described, even though a graduate student may have performed every one of the five basic functions of the system. Since almost every conceivable experiment is limited by personnel, finances, or time, careful design of recorder systems to make optimum use of available resources or minimize the limitations, can pay large dividends in pro- ductive research. Just as important experiments have failed because one vari- able was omitted, so also have expensive and elaborately instrumented experi- ments failed because it proved impossible to analyze the data. Ideally, a recording system should be designed by starting from the back, or the computer element. The basic equation or relationship to be tested should be clearly established. Then the number of variables needed and the minimum acceptable accuracy required should be established. The manner in which these variables will be combined should be planned, and it should be known whether the final step will be via a graduate student with a desk calculator or the IBM 650 electronic computer. The assumption that data once recorded or on punched cards can surely be analyzed scmehow, can be a devastatingly costly mistake.When the choice of experimental objective is made and the availability of final analysis and computing facilities determined, the rest of the system falls into place fairly well, provided that sensors are available for the variables of interest. A survey of recording systems will immediately suggest that the requirements for "automation" and " datomation" have been so extensive that well -designed and, in many cases quite reasonably -priced components are available for almost any im- aginable recording operation.However, a sensor for the particular variable to be measured is sometimes a difficult thing to find, since original research, by definition, suggests that the particular measurement under the particular con- ditions of interest has never been made. A complete discussion of all types of recording systems is obviously far beyond the scope of this paper. Competent people are available, particularly in the University's Electrical Engineering Department and the Numerical Analysis Laboratory, to advise on any aspect of such systems, no matter how complex they might be. Discussions of recording problems with a number of workers in the Arid Lands Program indicate that they are not yet ready to consider complete systems involv- ing electronic digital computers as the final step.Moreover, they have found ways to measure the variables of interest, but are restricted to the use of sin- gle variables recording on meters. The next important step is to multiple - variable recordings, particularly in field work where power is not available.