6o 3 



WATERSHEDS AND HOW TO CARE FOR THEM 



GEORGE W. CRADDOCK, CHARLES R. HURSH 



A watershed is a concave or trough- 

 shaped land area in which the runoff 

 from rain and snow drains toward a 

 single channel. A watershed may cover 

 less than an acre, or it may be a com- 

 plex of many watersheds. Our entire 

 land surface is made up of watershed 

 units. On them we depend for our 

 supply of water. 



Never before has our interest been 

 greater than now in water for irriga- 

 tion, power, industry, navigation, do- 

 mestic use, and recreation. Most of the 

 water for those purposes has its source 

 on the forest and range lands, which 

 comprise two-thirds of the land area in 

 the United States. Stream flow is a 

 natural product of most of those lands, 

 but the usefulness of the runoff from 

 them hinges on their management. 



Watershed management is a system 

 of handling land resources within a 

 drainage primarily to achieve usable 

 runoff. This generally involves the 

 same methods of husbandry that are 

 employed in good forest and range 

 management, but the objectives go be- 

 yond the attainment of sustained tim- 

 ber and forage production. Watershed 

 management aims to keep the land in 

 such condition that there will be maxi- 

 mum yields of high-quality water. 



Because watersheds have been inex- 

 pertly handled, the water problems are 

 critical in all parts of the country. In 

 the past 100 years, while population 

 increased from 17 million to 140 mil- 

 lion, the demands for water increased 

 manyfold. Industrial development and 

 municipal expansion are now restricted 

 in many places because of insufficient 

 water. The extent of destructive floods 

 is increasing. Sediment eroded from 

 the land is filling reservoirs, stream 

 channels, and harbors. Those problems 

 will become more serious as our popu- 

 lations and business expand. 



Through research on watersheds we 

 are finding out how different types of 



land use affect runoff and water qual- 

 ity, how to avoid past mistakes, and 

 how to restore and maintain our water 

 resources in the future. Some 40 years 

 ago two experimental watersheds near 

 Wagon Wheel Gap in Colorado were 

 equipped to measure the effect of clear 

 cutting of timber on stream flow. A 

 few years later, a pair of range water- 

 sheds near Ephraim, Utah, were simi- 

 larly equipped to determine the effects 

 of grazing herbaceous plant cover on 

 summer storm flow and erosion. More 

 recently, additional forest and range 

 watershed laboratories have been es- 

 tablished in the Rocky Mountains of 

 Colorado and in the mountains of 

 Idaho, Utah, Arizona, and California. 

 The Forest Service has developed an 

 outdoor hydrologic laboratory on the 

 Coweeta Experimental Forest in west- 

 ern North Carolina. Research on run- 

 off and erosion problems of farm lands 

 also has expanded greatly. 



EVERY ACRE of land in a drainage 

 basin receives and disposes of precipi- 

 tation and thus functions as an integral 

 part of a whole watershed. On each 

 acre, the plant cover and soil mantle 

 control the reception and disposition 

 of precipitation. The control varies 

 from place to place, resulting in differ- 

 ent degrees of balance between the 

 destructive forces of the weather and 

 the developmental processes of soil 

 formation and plant succession. 



Before man started to move soil 

 around, the developmental processes of 

 soil formation and plant succession 

 were stronger than the forces of deg- 

 radation on much of the forest and 

 range lands. That is, soil had been 

 formed on most of those lands faster 

 than it had eroded. The naturally ad- 

 justed balances between land and 

 weather that had been in the process 

 of development for thousands of years, 

 however, were disrupted by land clear- 



