402 brown. EFFECTS OF SOIL CONSERVATION [Ch. 22 



value of maintaining water-storage capacity in many western water- 

 sheds indicates, however, that the cost of reducing sediment production 

 by some 50 percent, on an average, through watershed-treatment 

 measures, may be justified. 



RESEARCH AND PLANNING NEEDS 



In few fields is such a wide variety of research and planning needed 

 as in the conservation of the soil and water resources of the nation. 

 Needed studies fall within the scope of soil science (particularly soil 

 physics and soil chemistry) , agronomy, ecology, biology, forestry, hy- 

 drology, geology (particularly geomorphology, sedimentation, and 

 ground water), engineering (particularly hydraulic, structural, and ag- 

 ricultural), economics, and law. 



Soil- and water-conservation research can be grouped functionally 

 under the following headings: 



Studies of basic forces and resistances. These include, for example, 

 studies of the forces involved in raindrop impact; the fluid dynamics 

 of thin overland flows of water; the mechanics of sediment entrainment, 

 transportation, and deposition in open-channel flow; aerodynamic 

 forces causing soil movement; and the resistances afforded by the 

 character of the soil, degree, length and aspect of slope, and various 

 types of vegetal cover. 



Studies of the areal distribution and frequency of occurrence of forces 

 and resistances. This research involves analysis of the geographic 

 distribution in terms of amounts, intensities, and duration of precipita- 

 tion, wind action, runoff, sediment transportation, soil erodibility, veg- 

 etal cover, and watershed characteristics such as drainage density and 

 relief. 



Development, testing, and improvement of measures and practices 

 for the control of water erosion and moisture conservation on the land 

 surface. 



Development of methods for controlling water and sediment move- 

 ment and conveyance in channels, conduits, etc. 



Development of methods for water conservation and utilization in 

 the soil and underground storage. 



Development of measures and practices for wind-erosion control. 



Studies of conservation economics affecting the operation and in- 

 come of farms and other private land holdings, of drainage enterprises, 

 of irrigation enterprises, and of public interests in flood and sediment 

 control. 



