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Show GROUP WATER INVESTIGATION LIKEWISE FINDS THE MAP INDISPENSABLE THERE IS GREAT NEED FOR A COMPLETE HYDROLOGIC MAPPING OF ALL OF THE FACTORS AFFECTING THE MANAGEMENT OF OUR WATER RESOURCES Of equal importance with its interrelated surface water component, ground water investigation likewise finds the topographic map indispensable. The combination of elevation datum points and the ground surface as delineated by contours establishes the varying surface from which all measurements for determination of underground characteristics can be made. Wells and springs are plotted on the topographic map as a base. By measuring the distance between their locations and by measurements down from the land surface, the dips of the permeable zones of rock and of water- bearing strata can be determined geometrically. With knowledge of the dip and land surface as portrayed on the map, quantitative ground- water studies can reliably be made. By observing the relative locations of streams and wells shown on the topographic map, assistance is obtained in resolving the question of recharge possibilities. Studies for quality of water are interrelated with surface and ground- water studies, and in that manner, have the same requirements for topographic maps. Upstream management of water resources is basically topographic and geologic, yet suitable maps are not available to show the characteristics of surficial deposits nor of the hard rock formations. The interrelation of these two as it affects runoff and downward percolation of precipitation on various catchment areas has not been portrayed in adequate form for headwaters management. The geologic mapping and research required for the effective development of ground- water resources throughout the country is more retarded than any phase of our mapping and basic data programs. The factual data and suitable maps are not available for programs of effective utilization of this great resource and this has retarded the development of the technique of effective management of ground- water resources. The Federal Government's ground- water program is nearly 100 percent cooperative, being tied almost completely to local and State programs. This arrangement prevents adequate study and development of the basic data required for the integration of ground- water resources into the gigantic Federal programs of reclamation, flood control, and hydroelectric power development, all based almost exclusively on surface stream runoff and control. There is great need for a complete hydrologic mapping of our drainage basins that will clearly depict all of the factors affecting the management of our water resources. This would involve an extension of the maps showing surface water in rivers, lakes, and other bodies to include the characteristics of headwaters affecting water retention and runoff and all those subsurface channels and conditions influencing water movements, storage and utilization, and all features related to erosion and destructive floods. AGRICULTURE, FORESTRY AND OTHER CROPPING ACTIVITIES All uses of the soil can proceed on a sound basis more certainly if properly interpreted in relation to the source and past and current processes affecting the accumulation of soils. Topographic, hydrologic, geologic, and soil maps are all essential for this purpose. Virtually all soils are derived from the underlying rock formations by weathering processes. The kind of soil that develops from a given kind of rock is determined regionally by climate and locally by the slope of the land surface. The amount of runoff and current soil erosion of an area is greatly influenced by the permeability of the underlying rock formations. Soil scientists have long recognized the value of geologic maps in their soil mapping work. Each type of soil is derived from a parent material; and each parent 15 " |