Influence of diurnal variations in stream temperature on streamflow loss and groundwater recharge

Abstract

We demonstrate that for losing reaches with significant diurnal variations in stream temperature, the effect of stream temperature on streambed seepage is a major factor contributing to reduced afternoon streamflows. An explanation is based on the effect of stream temperature on the hydraulic conductivity of the streambed, which can be expected to double in the 0 ø to 25øC temperature range. Results are presented for field experiments in which stream discharge and temperature were continuously measured for several days over losing reaches at St. Kevin Gulch, Colorado, and Tijeras Arroyo, New Mexico. At St. Kevin Gulch in July 1991, the diurnal stream temperature in the 160-m study reach ranged from about 4 ø to 18øC, discharges ranged from 10 to 18 L/s, and streamflow loss in the study reach ranged from 2.7 to 3.7 L/s. On the basis of measured stream temperature variations, the predicted change in conductivity was about 38%; the measured change in stream loss was about 26%, suggesting that streambed temperature varied less than the stream temperature. At Tijeras Arroyo in May 1992, diurnal stream temperature in the 655-m study reach ranged from about 10 ø to 25øC and discharge ranged from 25 to 55 L/s. Streamflow loss was converted to infiltration rates by factoring in the changing stream reach surface area and streamflow losses due to evaporation rates as measured in a hemispherical evaporation chamber. Infiltration rates ranged from about 0.7 to 2.0 m/d, depending on time and location. Based on measured stream temperature variations, the predicted change in conductivity was 29%; the measured change in infiltration was also about 27%. This suggests that high infiltration rates cause rapid convection of heat to the streambed. Evapotranspiration losses were estimated for the reach and adjacent flood plain within the arroyo. On the basis of these estimates, only about 5% of flow loss was consumed via stream evaporation and stream-side evapotranspiration, indicating that 95% of the loss within the study reach represented groundwater recharge.

High‐frequency monitoring of catchment nutrient exports reveals highly variable storm event responses and dynamic source zone activation

“…Such DOC concentrations are akin to those reported for a similar sized agricultural catchment in northern France [Morel et al, 2009] but relatively high when compared to values reported from many mixed-use catchments in both Europe and North America [Raymond and Oh, 2007;Monteith et al, 2007]. Base flow NO 3 -N concentrations of around 6.5 mg/L were similar to those reported previously for agricultural catchments [Lloyd et al, 2016b;Thomas et al, 2016] and were likely driven by current fertilizer application and legacy fertilizer At diurnal scales, streamflow exhibited minor fluctuations during base flow conditions, most likely driven by contrasts in evapotranspiration demand between day and night but also potentially due to temperaturedriven changes in water viscosity and associated changes in bed sediment hydraulic conductivity [Schwab et al, 2016;Constantz et al, 1994]. Observed daily cycles in NO 3 -N and DOC concentrations during base flow-dominated periods are likely to reflect a combination of minor dilution effects (in relation to diurnal changes in streamflow) and in-stream assimilatory uptake by microbial communities, which Rode et al…”

Field study and simulation of diurnal temperature effects on infiltration and variably saturated flow beneath an ephemeral stream

“…He found that when temperature of the infiltrating water is controlled by daily heating and cooling, the infiltration rate can show a marked diurnal variation, with maximum infiltration occurring during the day and minimum infiltration occurring at night. Constantz et al [1994] used diurnal variations in stream temperature to explain diurnal variations in streamflow measured in two streams, one in Colorado and one in New Mexico.…”

Evaluation of the streambed leakage concept in analytical models using data from three pumping tests

“…However, few studies of stream-aquifer interactions studied the effect of temperature on the kinematic viscosity of the water and, thus, the hydraulic conductivity. Constantz et al (1994) discussed diurnal temperature effects on seepage rates. That study demonstrated qualitatively that the effect of temperature was the main reason for the variability in daily streamflow losses.…”