following year. The stream channel is expected to he stable during this 

 period . 



Establishing Bench Marks 



Establish a bench mark at or near your study area. The bench mark is a point 

 that will not be disturbed or moved. A nail driven into the base of a tree, a 

 fixed spot on a bridge abutment and a survey stake driven into the ground are 

 examples of bench marks. Designating one of the cross-sectional headstakes 

 within a study area as the bench mark is an acceptable practice. Bench marks 

 should be well marked and described in your field notebook so they can be 

 easily located during return trips. All channel and water surface elevations 

 are established relative to the bench mark, which is assigned an elevation of 

 100.0(1 or 10.00 ft. Use 10.00 ft whenever possible. 



For streams having "heavy" vegetative cover, the use of a single bench mark 

 may not be practical. In this case, the individual headstakes can be used as 

 bench marks. For example, the headstake for cross-section #1 could serve as 

 the bench mark for cross-sections #1 and 2, while the headstake for 

 cross-section #3 could serve as the bench mark for cross-sections #3, 4 and 5. 

 F.ach headstake could also serve as the bench mark for that individual 

 cross-section. While this is not the best surveying technique, certain stream 

 reaches may require its use. Be sure to carefully record in your notebook 

 which headstakes are used as bench marks to avoid confusion and errors on 

 return trips. 



Remember, channel and water surface elevations for all cross-sections within a 

 study area do not have to be tied to a single bench mark for the WETP program 

 to run properly. However, the use of a single bench mark enhances your field 

 technique. 



Surveying Techniqu es 



The reader is referred to Spence (1075) and Bovee and Milhous (1978) for a 

 discussion of the surveying techniques used to measure cross-sectional 

 profiles and water surface elevations. Both papers should be read by those 

 unfamiliar with the mechanics of surveying. All investigators must receive 

 field training before attempting any measurements. 



It is Important to be consistent and to use good technique when collecting and 

 recording data. Record all data in your notebook and complete all 

 calculations while in the field, so that any surveying errors can be detected 

 and corrected. Remember, your field notebooks may be examined in court or 

 hearing proceedings. Good quality equipment such as an automatic level is 

 also an asset. 



5-3 



