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Show Hydrologic and Sedimentation Research Basic research in hydrology and sedimentation is essen- tial to full interpretation and utilization of data, and to further improve standards for programing, collecting and processing of basic data. There is a definite need for a more intensive program to improve the accuracy of many phases of collection of hydrologic and sedimenta- tion data and, if possible, to reduce the unit cost of this collection. Basic research in hydrology and sedimentation may be defined as study or investigation directed toward a more nearly complete understanding of the physical, chemical, and biological phenomena involved in the entire hydrologic cycle. Basic research involves intensive study in many sciences and is being undertaken by many agencies, usually with reference to their special problems. Integration of such research, however, is urgently needed. Projects proposals necessarily must contain factors of probabilities because sampling can never be perfect or complete. The logical way to meet this situation is (1) to reduce the uncertainties through hydrologic research and (2) to evaluate the remaining unknowns through statistical research. Therefore, such reports should pre- sent data on the probabilities of deviations from estimated benefit-cost ratios and the means by which economic losses from underdesign and the waste of overdesign may be minimized. Applied research is the application of the results of basic research in the solution of a specific problem. Major development projects justify the employment of specialists who apply the results of basic research to each project. Minor projects, on the other hand, cannot separately sup- port such personnel. Consequently there is a definite need for applied research in hydrology and sedimentation di- rected toward supplying concise presentations of signifi- cant results of basic research for use by designers. In the aggregate, investments for minor projects may ap- proach the total investment in major projects and there- fore the research needs of such projects warrant careful consideration. A distinction should be made between applied research as defined above and processing of observed data. Re- search is involved in developing the techniques of proc- essing, but the routine application of such techniques is not research. Processing consists of the reduction of the observed data to appropriate forms of presentation. Processed data should be published promptly. With these definitions clearly in mind, deficiencies in basic hydrologic and sedimentation research can be dis- cussed. In 1940 the Special Advisory Committee on Hydrologic Data of the National Resources Planning Board pointed out that "Understanding of the basic proc- esses by which water circulates on the earth and in the atmosphere is far from complete." * Despite the excellent studies which have been conducted in the interim, this statement is equally true today, partly because we have reached a more mature conception of the complexities of the hydrologic processes and partly because the growtfi in population and industry require more precise informa- 1 Deficiencies in Hydrologic Research. Keport of the Special Advisory Committee on Hydrologic Data, National Resources Planning Board (Washington : 1940). tion to insure the maximum utilization of available water resources. It is noteworthy that sedimentation, given scant notice in the 1940 report, is now regarded as a major field of research. A few of the major problems in which basic research is needed to improve our knowledge are as follows: 1. Frequency, intensity, and areal distribution of pre- cipitation and orographic influences on precipitation. 2. Evaporation from free water surfaces. 3. Evapo-transpiration from land surfaces with vari- ous types of vegetation and soil depth. 4. Solubility of minerals and rock materials. 5. Effect of vegetal cover and land use on peak rates and distribution of total amounts of runoff, and on sedi- ment loads for large as well as small streams. 6. Long-term fluctuations in annual and seasonal pre- cipitation, runoff, ground-water levels, and sediment movement. 7. Sources and processes of recharge to and discharge from water-bearing formations. 8. Significant physical, chemical, bacteriological, and other biological criteria covering concentration of pol- lutants in relation to each important water use. 9. Bed and suspended load transportation, including aggradation and degradation. 10. Techniques of estimating sediment production of watersheds from their physical characteristics. 11. Determination of density and rates of compaction and consolidation of sedimentation in bodies of water. 12. Flocculation of sediments. This list is merely representative of the wide range of problems in basic research in which intensive studies are urgently needed. Although much research is under way, some of the problems significant to water resource devel- opment have been scarcely touched. Positive provision should be made for interchange of information on basic research. The 1940 report on Defi- ciencies in Hydrologic Research recommended the estab- lishment of a "clearinghouse" on hydrologic research, but that recommendation has never been fully imple- mented. The annual publication of a bulletin giving concise information on the objectives, work in progress, accomplishments, and reports for individual research projects would stimulate hydrologic and sedimentation research and be helpful to all agencies engaged in water resource development. Reports on basic research should be prepared and pub- lished as promptly as usable increments of data become available. Such reports should be systematically circu- lated to all agencies, both public and private, interested in hydrologic and sedimentation research. Analysis and study of interrelation in basic hydrologic data should be a continuing effort so that deficiencies in the current collection and processing of data may be more quickly recognized, and accumulations of unprocessed data may be avoided. One of the most important research needs is the avail- ability of techniques for extrapolating research experience from the environment of small, controlled research areas to large operational areas such as river basins. Until such techniques are available, quantitative application of re- search results from small areas to the solution of specific problems is exceedingly difficult and results may at times be misleading. 911609-5C 351 |