relating the elastic properties of foundation rock in place and the speed of travel of seismic waves through rock have been available for many years. The Bureau has applied field data to the equations since 1954, and has improved the techniques since that time.

(b) Electrical logging of canals to detect seepage. Electrical logging of drill holes has been adapted to the problem of finding stretches of canal that are leaking. The method was first tested by the Bureau in 1958. The electric log provides a continuous record on a strip chart of the electrical resistance and the natural electrical voltage of the canal bottom material and variations therein. A canal can be logged at a speed of 2 to 4 miles per hour.

(c) Improvements in correlation and use of subsurface geologic data.— Development of better correlation and understanding of the results. of subsurface investigations secured by standard techniques (drilling shafts and tunnels and sampling) and by new techniques (forms of bore hole logging and geophysical measurements) is essential to provide basic data for design.

(d) Subaudible rock noise listening devices.-Microscale movements of mineral grains against each other in tunnel wall rock develop squeaks and creaking noises which are not detectable by ear, but which can be heard with electronic instruments. A rock stethoscope can be inserted in a small-diameter bore hole in a tunnel wall. Subaudible noise increases with increased internal stress in a rock mass, thus giving advance warning of possible rock falls or bursts and impending landslides in deep cuts. Field testing is needed to develop the full potential of this type of instrument as related to safety and engineering geology of structure sites.

(e) Continuous vibration procedures for probing foundation rock to detect flaws. Continuous vibration testing is applied to concrete specimens and large metal castings to locate imperfections. Applying similar vibration to locate flaws or faults in abutments has a background from tests of mine roof stability and should be applicable to testing abutment quality.

(f) Drill behavior monitoring device.-A device for attachment to standard small-diameter core drills used in foundation exploration to register rate of drill advance, rotation of the bit, bit pressure, and variation in drilling fluid loss would reflect subsurface conditions that may escape attention.

(g) Study of drill holes by photographic and TV cameras.-Bore hole cameras and recently developed bore hole television give the geologist the opportunity to figuratively put his eye down a drill hole to study jointing, faulting, the attitude of bedding, and other rock characteristics not always clear from examination of a core.

(h) Bore hole stress-strain meter.-In planning the reinforcement schedule for tunnels, a knowledge of stresses in tunnel wall rock is imperative. There is need for an in-hole stress-strain meter for smalldiameter exploration holes. Certain instruments suitable for measurement of strain at points in a bore hole are available, and adaptation to drill holes may be possible.

(i) Improvement of standard geologic and geophysical techniques.The techniques used to conduct surface and subsurface geological investigations are field mapping, core drilling, exploration drifts, trenching, sampling, and geophysical testing. Improvement in the techniques of interpretation and extent of use are needed.

Vane shear instrument, soil samplers, electric resistivity, inductance, eismic velocity and nuclear energy sources. In the investigation of oils, undisturbed samples are indispensable. Testing for in-place haracteristics of soils must also be done. The in-place vane shear nstrument has been developed for evaluation of shear strength. Among soil samples are the thin-wall drive, fixed piston, and Denison louble tube samplers. Sampling research has brought into promience the use of heavy drilling mud and chemical additives to support he sides of drill holes, thus eliminating casing. Techniques for testing he bahavior of natural soils include:

Electrical resistivity.
Inductance.

Seismic velocity.

Nuclear energy sources.

Permeability, pore-water pressure, and shear strength.-Permeability tests using bore hole, tracer, and pumping techniques could be refined, along with tests to determine the in-situ state of stress in soils. Improved equipment and measurements of pore-water pressure and shear strength are desirable. Also the development of dynamic porepressure gages for field use and dynamic in-place loading devices could yield valuable data on strength of soils for the condition of rapidly applied forces.

Machinery to evaluate pozzolan aggregate and pozzolan sources

Evaluations of possible aggregate and pozzolan sources for use in concrete require excavations in depth to obtain samples. The excavations and samples yield information on the quality and quantity of materials present. Various types of power equipment are being used to replace manual methods. Machines designed for other uses such as draglines and backhoes, have been adapted to this work. Equipment to sample at depths greater than 20 feet, possibly under water, should be designed to retain fine materials normally lost. It would also be advantageous to sample strata containing large-size aggregate fractions.

Basic data

HYDROLOGY

Improved equipment and techniques are needed for recording and processing basic data. Some of the items which could be included in this category are the development of acoustical and electromagnetic principles for water velocity measurements; neutron-type soil moisture meters that would facilitate the continuous measurement and recording of soil moisture amount and movement; equipment and techniques for sediment analyses, particularly for observing variation in sediment concentration and distribution of particle sizes; techniques and instrumentation for estimating water-use requirements under various soil and vegetative complexes, including the amount of water salvage that may be realized by the eradication of nonbeneficial vegetation; and new techniques for estimating the relationships between crop yields and water shortages under differing crop, soil, and climatic conditions.

Planning

There are three basic categories of hydrologic problems that must be resolved in the process of water resources planning. These include problems relating to the evaluation of water resources and their utili

zation; the magnitude and occurrence of floods and their control; and sediment transport, deposition, and accompanying problems in channel aggradation and degradation. Improved and more abundant basic data would provide one means of obtaining more accurate solutions to these problems. The use of electronic data processing equipment also offers opportunity for more thorough and accurate analyses of these data and for investigating alterant solutions. Development of procedures by which long-range changes in climate, particularly precipitation, can be reliably predicted would be of tremendous significance in the planning process.

Design

Most of the items mentioned above under planning will also be directly applicable to the design of all types of structures involved in water resource development. Of immediate concern are those techniques of analysis which will permit prediction of the magnitude, duration, and frequency characteristics of all types of hydrologic events. One item of particular concern is the obtaining of all essential basic data and development of techniques for predicting the magnitude and frequency of flood flows from relatively small drainage areas such as are encountered adjacent to canals and laterals. In estimating maximum probable flood from large drainage areas, there is need for the development of new techniques and procedures to evaluate individual basin characteristics and relate them to the unitgraph; to improve the derivation of hydrographs of snowmelt runoff; to evaluate lag times from watersheds having different physical characteristics; and to provide isohyetal maps representing critical rainfall duration relations for maximum probable and standard project storm conditions. Limnological studies to establish procedures for prediction of daily, seasonal, and annual changes in temperature and water quality distribution within various types of reservoirs are essential to the proper design of outlets and outlet structures. Better basic data and analytical procedures are needed for estimating channel degradation below dams and for formation and distribution of sediment deposits in reservoirs, both immediately above the dam and at the reservoir inlet.

Operation

A wide variety of information is needed to improve the efficiency and effectiveness of operating water resources projects and installations. Long-range forecasts of climatic changes would be of great value in planning future project operations. Also, more accurate techniques for forecasting floodflows and seasonal runoff are essential to dependable and efficient project operation. Better procedures are needed for accurate estimating of water requirements for various crop, soil, and climatic complexes, and for predicting the magnitude and manner of occurrence of irrigation return flows and changes in water quality. Chemical and other methods may be developed whereby the deposition of sediment in reservoirs could be controlled or the sediments could be caused to move through the reservoirs. Simple and reliable instrumentation for following the movement of water through project facilities, including the distribution of soil moisture in irrigated areas, would greatly facilitate project operations.