Using Heat to Characterize Streambed Water Flux Variability in Four Stream Reaches

Abstract

Estimates of streambed water flux are needed for the interpretation of streambed chemistry and reactions. Continuous temperature and head monitoring in stream reaches within four agricultural watersheds (Leary Weber Ditch, IN; Maple Creek, NE; DR2 Drain, WA; and Merced River, CA) allowed heat to be used as a tracer to study the temporal and spatial variability of fluxes through the streambed. Synoptic methods (seepage meter and differential discharge measurements) were compared with estimates obtained by using heat as a tracer. Water flux was estimated by modeling one‐dimensional vertical flow of water and heat using the model VS2DH. Flux was influenced by physical heterogeneity of the stream channel and temporal variability in stream and ground‐water levels. During most of the study period (April–December 2004), flux was upward through the streambeds. At the IN, NE, and CA sites, high‐stage events resulted in rapid reversal of flow direction inducing short‐term surface‐water flow into the streambed. During late summer at the IN site, regional ground‐water levels dropped, leading to surface‐water loss to ground water that resulted in drying of the ditch. Synoptic measurements of flux generally supported the model flux estimates. Water flow through the streambed was roughly an order of magnitude larger in the humid basins (IN and NE) than in the arid basins (WA and CA). Downward flux, in response to sudden high streamflows, and seasonal variability in flux was most pronounced in the humid basins and in high conductivity zones in the streambed.

Statistical and numerical analyses of the influence of climate variability on aquifer water levels and groundwater temperatures: The impacts of climate change on aquifer thermal regimes

“…The VS2DH numerical code (Healy and Ronan, 1996) that was used in this study can simulate heat transport under unsteady, nonuniform water movement (by accounting for time-discrete recharge periods and heterogeneous aquifer conditions) and with variable boundary conditions (Su et al, 2004;Essaid et al, 2008;Duque et al, 2010). The governing equation for subsurface temperature distribution can be written as:…”

“…Under these circumstances, numerical codes such as the Codeon Multiflo for transient and steady-state well simulation (MULTIFLO from Lichtner et al, 2000, with application in Ferguson andWoodbury, 2005;Majorowicz et al, 2006) and VS2DH (Healy and Ronan, 1996, with application in Su et al, 2004;Essaid et al, 2008;Duque et al, 2010) facilitate the simulations of heat transport in the subsurface layer under variable boundary conditions. Previously, there have been no studies that have estimated the climate change impacts on aquifer thermal regimes by considering the dynamic nature of the boundary conditions and unsteady groundwater flow.…”

Using subsurface temperatures to derive the spatial extent of the land use change effect

“…The VS2DH numerical code (Healy and Ronan, 1996) used in this study can simulate heat transport under unsteady, non-uniform water movement and with variable boundary conditions (Su et al, 2004;Essaid et al, 2008;Duque et al, 2010). The governing equation for subsurface temperature distribution can be written as follows:…”

Using multiple environmental methods to estimate groundwater discharge into an arid lake (Dakebo Lake, Inner Mongolia, China)

“…Currently, three main methods are used to estimate hydrodynamic exchanges between groundwater and surface water: the hydrodynamic method (Kalbus et al 2006), environmental isotope tracing method (Carey and Quinton 2005;Yin et al 2011;Oyarzún et al 2014), and thermal tracing method (Hatch et al 2006;Essaid et al 2008;Rau et al 2014). Isotopes of 18 O and 2 H are widely used because their isotopic compositions differ markedly between water sources and they are not influenced by other factors during the mixing process (Marimuthu et al 2005).…”