AUTOMATION OF IRRIGATION Electronic computers, automatic border takeout gates, and automatic water delivery device Developments in the automation of irrigation are underway. With automation the farmers' problems will still be the same: to determine when to irrigate, how much to apply each irrigation, and the best Imethod to use. Optimum use of water supply to achieve top crop production will require that these factors be integrated to consider the crop, stage of growth, root zone depth, waterholding capacity of the soil, soil moisture stress level, and weather. Electronic computers are needed to evaluate these factors and such instruments are under development. Current developments in this field involve use of automatically operated border takeout gates, an automatic device that travels the farm lateral introducing water into individual fields, and a self-propelled irrigation machine that traverses and sprayirrigates a field. Continued efforts should be aimed toward reducing the farmer's costs and making his irrigations more efficient in terms of water use, crop yield, and quality. NEW HERBICIDES NEEDED Development of new herbicides to reduce the number of cultural operations are also needed. These herbicides contribute to more efficient water use by reducing compaction caused by runoff and by eliminating nonbeneficial consumptive use by weeds. 1. Subsurface drains DRAINAGE (a) Mole channel lining. Mole drainage has little application in the work of the Bureau of Reclamation in the arid west. Due to present depth limitations, mole drains will not permit the control of water tables and salinity necessary under irrigation. (b) Dug-ditch subsurface drains.-Improved techniques and procedures for subsurface drainage have been developed by the Bureau. Efficient pipe-drain systems can be designed for long life, but such drains are expensive. The Bureau is working on changes in design, the use and suitability of better and cheaper materials, and more efficient installation procedures which will permit satisfactory drains at lower cost. Vitrified clay and concrete: The most commonly used materials for drainpipe are vitrified clay and concrete. These have adequate strength, are resistant to aggressive waters, and are now the least_expensive. With the cooperation and assistance of industry, the Bureau has been considering other materials such as plastic, asbestos cement, or Fiberglas, any one of which may be equally satisfactory, and may be installed at lower cost. Most drains in irrigated areas are laid in a gravel envelope. As gravel is quite expensive in some localities, the Bureau has been considering ways of eliminating it as well as searching for a less expensive but equally satisfactory material to replace it. Machines to dig trenches and to lay draintile: Machines have been built for digging trenches, holding the cut open, and for placing the gravel envelope and pipe. These machines have been basic factory equipment shop modified for specific work by individual contractors. Recognizing that efficiency of installation was essential to economic drain construction, the Bureau has worked closely with manufacturers on the requirements and design of a machine to lay draintile in a continuous operation. One such machine is now being built commercially. Development of better factory-made machines to handle improved or cheaper materials in a continuous operation should go hand in hand with the development and proved application of new materials or procedures. (c) Drainage by pumped wells.-The efficiency and economic practicability of large capacity drainage wells require that they be carefully designed to suit specific aquifer conditions. This requires that representative samples of the strata encountered be taken for examination, particularly of those considered as aquifers. The samples obtained with equipment now available are usually composed of fragments of the natural materials mixed with small particles. Significant fractions may be missing from the recovered drilling fluid. The Bureau has been working with drilling contractors on development and testing of improved sampling equipment and techniques which produce more reliable data on subsurface strata. All ferrous alloys in turbine pumps: Standard vertical turbine pumps for irrigation and drainage service are usually made with their component parts of dissimilar metals and alloys. Bronze impellers, bearings, and wear rings are commonly used in conjunction with stainless steel pump shafts, cast-iron pump bowls, mild-steel column pipe, and mild-steel drive shafts. Bureau experience, however, showed that such pumps were subject to severe electrolytic corrosion when installed in the aggressive ground waters found on pumped drainage projects. Working closely with the major pump manufacturers, the Bureau prepared specifications for pumps manufactured from all ferrous alloys. In this way, bimetallic junctions and attendant electrolytic corrosion were eliminated. Plastics and ceramics to resist agressive water: To combat other types of corrosion, the Bureau is considering the use of plastics and ceramics which are relatively inexpensive and inert to aggressive waters, but few components of such materials are available and little is yet known of their strength and suitability for such use. A promising application of plastics would be as bearing supports and column pipe for water-lubricated turbine pumps. Anaerobic bacteria and effect on well and pumps: Recent experience in drainage by pumped wells has brought to light serious corrosion, deterioration, and plugging of pumps, well casing, and well screens due to the action of anaerobic bacteria. Ground water, being deficient in oxygen, offers a favorable environment for such organisms. Two types of bacteria appear to be involved, the genus Crenothryx (iron-depositing bacteria) of which six varieties have been identified, and the sulfate-reducing bacteria of the genus Spiro vibrio desulfuricans. As only general methods of controlling these organisms are known, and as serious damage to Bureau installations has occurred, the Bureau is studying methods of combating the problem. This includes evaluation of different metals and alloys, plastics, various plastic and epoxy coatings, and cathodic protection. Study is being given to methods of detecting the presence of these bacteria in ground water at well sites before construction of the well. Drainage investigations Need for portable depth-measuring device. For accurate inplace permeability tests, a control valve is needed to maintain constant water level within a 31⁄2-inch hole while delivering up to 12 gallons per minute under a 5-foot head. The Bureau formerly fabricated a control for this purpose from used automobile carburetors, but has recently worked with another agency and industry in developing a commercial control more suitable for this and other test purposes. A portable depth-measuring device is needed to determine without drilling a hole the depth to the saturated zone from the surface. 2. Surface drains Transpiration losses.-Transpirational losses could be reduced by use of herbicide materials produced by industry for control of phreatophytes. However, there would be problems of applying and maintaining the film in flowing water. The Bureau has been active in this field, but neither equipment nor procedures have been perfected. RUNOFF CONTROL Utilizing plastics, fiber, asphalt, and mulches There is considerable potential in the development of materials and techniques for the control and reduction of surface runoff, either through the application of chemical soil stabilizers or inert materials such as plastic, fiber, asphalt, and mulches. The purpose of these techniques would be to increase infiltration opportunity with resultant increase in soil moisture content and possibly increased percolation to ground water aquifers. At the same time, rates of surface water runoff would be reduced with consequent reduction in soil erosion and potential flood damage. Chemical soil stabilizers Various chemical soil stabilizers have been developed in recent years that are quite effective in improving soil aggregation, thereby greatly increasing the noncapillary pore space in the soil and the opportunity for infiltration. Such chemical soil stabilizers have been used only in special situations on small areas in fields where the use could be economically justified. There has been no indication that this approach could be economically applied on a watershed basis. Use of inert materials The use of various inert materials such as plastics, fibers, and net covers, either to increase surface runoff in some instances, or in others to reduce surface runoff and increase infiltration, have been tested on experimental plats and found to be quite effective. There are indications that plastic covers might be used effectively on small watersheds to provide increased runoff for stockwater, industrial plants, or for small community supplies. It is quite evident at this time, however, that such practices would not be justified on a large drainage area basis. The utilization of various types of artificial mulches to facilitate infiltration and thereby revegetate a watershed has been found feasible on an experimental basis but not economically justified on major drainages. There is opportunity for research in the development of suitable materials at very low cost to accomplish these purposes. LANNING, DESIGN, CONSTRUCTION, OPERATION, AND MAINTENANCE OF CONTROL STRUCTURES FOR IRRIGATION, FLOOD CONTROL, MUNICIPAL WATER SUPPLY, NAVIGATION, POWER, AND RIVER REGULATION SITE INVESTIGATIONS ems suggested for research and development The Bureau of Reclamation is using photogrammetry and autoatic data processing in site investigations. Research and the perrmance of photogrammetric work are largely dependent upon comercial firms. Items which are suggested for research and developent include: Profile meters and sounding devices.-Improvement in profile meters nd sounding devices to achieve greater accuracies under difficult field onditions. Aerial triangulation and automatic computer compilation for toporaphic mapping. Improvements producing greater accuracy at wer cost in aerial triangulation and automatic computer compilation rocedures for large-scale topographic mapping by photogrammetry, articularly in areas of difficult or forbidden access. Stero cross-sectional and profile data.-Improved processes of comilation by stero means of cross-sectional and profile data for autonatic processing to quantity estimates. Ultraviolet or infrared light radioactive isotopes, etc., for identifying naterials, for geologic mapping.-Development of devices utilizing altraviolet or infrared light; sound; light and electronic wave propagaion and reflection; radioactive isotopes; and other physical and chemical methods for identification of materials and their physical properties for geologic mapping and earth materials evaluation. In-situ rock properties measurements. Recent scientific meetings have revealed that the study and testing of foundations and in-situ ock properties measurements have not kept pace with engineering design ability, and that additional research is greatly needed. Improvements in design practice and standards used for major engineering structures such as dams, bridges, tunnels, and canals are closely tied to improvements in the means of study and subsurface conditions, and engineering data on the character of foundations on which such works will be built. Development of subsurface investigation techniques Effective application of such improved design practice and the more economical use of concrete, steel, and other new or standard construction materials require more accurate determination of the geologic and petrographic characteristics of foundations. The Bureau of Reclamation is studying and developing the potential uses of subsurface investigation techniques as follows: (a)_Geophysical (seismic) determination of the modulus of elasticity and Poisson's ratio of foundation rock by on-site tests.-Equations |