Hydrology And Water Chemistry Of Shallow Aquifers Along The Upper Clark Fork Western Montana

Author : Richard G. Hopson
Publisher :
ISBN 13 :
Total Pages : 382 pages
Book Rating : 4.:/5 (392 download)

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Download or read book Shallow Aquifer Characteristics Adjacent to the Upper Middle Fork John Day River, Eastern Oregon written by Richard G. Hopson and published by . This book was released on 1997 with total page 382 pages. Available in PDF, EPUB and Kindle. Book excerpt: Subsurface inputs into lotic systems are a primary mechanism for cooling streams with high ambient water temperatures. Objectives of this study include: 1) to determine the effectiveness of Forward Looking Infrared (FLIR) thermal imagery to detect shallow aquifers, 2) to characterize certain physical, spatial, and temporal characteristics of the fluvial, floodplain, and subsurface environments, and 3) to determine if hyporheic water can be distinguished from true groundwater using water quality characteristics. Primary variables include free water surface elevation, temperature, and specific conductivity. Study sites were located within three effluent reaches of the unconstrained, fourth order upper Middle Fork John Day River in eastern Oregon. A significant association was observed between relative ground surface temperature and depth-to-groundwater at the three well fields. In addition, the ability of FLIR to predict shallow aquifers decreased as depth-to-groundwater increased. However, a high degree of variability was observed. Spatial aquifer water surface patterns varied between sites and appear to be influenced by hydrologic origin, including various groundwater, hyporheic water, and irrigation water sources. The net hydrologic flux into the river per meter depth at Well Field 3 was estimated at 4.2E-03 m3/s-m. Diurnal water surface elevation varied among wells and between wells and staff gages. Annual mean aquifer recharge was greatest during fall months while mean discharge occurred only during spring months. Mean annual aquifer temperature varied according to degree of connectivity between surface/subsurface environments. Subsurface aquifer temperature and specific conductivity patterns were not always correlated to water surface gradients. However, these variables may represent subsurface fluxes not apparent using water surface contours. An irrigation effect on aquifer temperature and specific conductivity may have influenced these variables. Mean percent saturation of dissolved oxygen was low in the wells and saturated in the Middle Fork. pH values were generally neutral in the aquifer and slightly alkaline in the Middle Fork. Water surface gradient provided the most reliable indicator of hyporheic water, followed by subsurface temperature and specific conductivity. Boundaries between groundwater, hyporheic water, and irrigation water appeared to exist as a gradient rather than an abrupt edge. However, environmental factors may also have influenced this relationship.