Chemical tracing techniques for evaluating rill hydraulics

ABSTRACT:

Development of water erosion and surface water quality control practices requires information concerning the hydraulic characteristics of upland areas. The relatively small flow rates normally found within rills make measurement of bydraulic parameters difficult. Chemical tracing procedures, originally developed for stream and river systems, have been successfully used to measure rill flow properties. A chemical tracer of known concentration is added to the rill and by knowing the degree of dilution at a downstream sampling point, flow rate can be calculated. Rill flow velocity can be measured by determining the time required for a slug of tracer material to travel a designated distance. Measurements of flow rate and velocity can be used to calculate other hydraulic variables. The ability to understand and properly model rill flow will improve as additional information.