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TitleMethodology for measuring the spatial distribution of low streamflow within watersheds
AuthorHinton, M J
SourceGeological Survey of Canada, Open File 4891, 2005, 69 pages; 1 CD-ROM, (Open Access)
PublisherNatural Resources Canada
Documentopen file
Mediapaper; CD-ROM; digital; on-line
File formatreadme
File formatpdf
Subjects12; hydrogeology; stream flow; analytical methods; discharge rates; watersheds; 27
Illustrationssketch maps; photographs
Released2005 04 01
AbstractSurveys to map the distribution of low streamflow within watersheds are useful for many purposes including groundwater and aquatic habitat studies. This report describes a detailed methodology to plan, conduct and report a low-flow survey. Low-flow surveys are a cost-effective approach to collect spatial data and develop a conceptual understanding of groundwater-surface water interactions within a watershed. Carefully collected and documented surveys also provide baseline datasets of low-flow discharge and chemistry data for future comparison. This report is intended for both the professional who plans and designs the field program and the technician who does the fieldwork. The first recommended step is to conduct a reconnaissance survey in which basic field data are collected in order to plan an efficient and effective survey. Careful planning of a survey using the reconnaissance data will yield better low-flow survey results in a more time- and cost-effective manner. Stream gauging using the current meter and volumetric methods is then described with a particular emphasis on the measurement of flow in small streams under low-flow conditions. The reporting of results includes both the calculation of stream discharge and estimation of measurement errors. The error estimation is described in detail and the various factors contributing to measurement errors are evaluated. In general, measurement error can be reduced most effectively by choosing a cross-section where water velocities exceed 0.1 m/s and by increasing the number of measurement sections (verticals) within a cross-section. Some uses of low-flow survey results are briefly presented.