Data from: Multiple timescales of streambed flux variability in two perennial mountain-front streams
Data files
Abstract
Streambed fluxes are highly variable through time and space, having a range of implications for stream‐aquifer processes. This study investigated streambed fluxes over a 3‐year study period to characterize short‐ and long‐term variations and related implications for seepage recharge and hyporheic exchange. Time series of streambed fluxes were estimated through Darcy‐based methods using water level and temperature inputs from shallow (<1.5 m) nested streambed piezometers installed in two mountain‐front streams in Colorado, USA. Three predominant temporal scales of variability were characterized: sub‐daily (<1 day), daily (>1 day; <1 year), and interannual (>1 year). Temporal variability was quantified using the median absolute deviation (MAD), a statistical measure that is resistant to extreme values associated with short‐duration events. Sub‐daily variability (MADS‐D) was related to ET, temperature‐induced changes in hydraulic conductivity, and variable stream stage, and was quantified using the MAD of detrended fluxes (daily mean subtracted). Daily variability (MADD), calculated as the MAD of daily median fluxes for a given year, exceeded sub‐daily variability, and was influenced by strong seasonality at some sites. For individual sites and water years, the ratio of MADS‐D to MADD ranged from 0.03 to 0.70, with an average of 0.25. Annual median fluxes at each site varied across years, but typically remained consistent in order of magnitude and direction. Results reveal a strong linear correlation between the daily variability and the median annual flux at individual sites. Within a year, summer months characterized by stronger losing conditions showed greater overall variability. 1D numerical heat and flow modelling was performed to calibrate hydraulic parameters and to investigate temperature‐related controls for sub‐daily variations. We discuss implications of documented temporal variability for analyses of hyporheic exchange and groundwater recharge. Results provide a basis for quantifying temporal variations in streambed fluxes and highlight the extent to which fluxes vary over multiple timescales.
README: Paper: Multiple timescales of streambed flux variability in two perennial mountain-front streams
Authors: Kristen Cognac, Michael Ronayne
Description:
This README file describes the data package accompanying the above publication.
Files:
- Data folder: Includes seven text files ('.txt') containing comma-separated timeseries datasets.
- Files 'CCA.txt','CCB.txt','PCB.txt','PCC.txt','PCDS.txt', and 'PCMU.txt' correspond to piezometer nest locations with columns:
- Date_time: date and time stamp of data
- Shal_Temp_C: shallow piezometer temperature in degrees Celsius
- Deep_Temp_C: deep piezometer temperature in degrees Celsius
- Shal_Head_m: shallow piezometer water level relative to streambed in meters
- Deep_Head_m: deep piezometer water level relative to streambed in meters
- SDgrad: vertical hydraulic gradient between shallow and deep piezometer
- K: time-varying hydraulic conductivity corrected for temperature in meters per day
- The file 'Baro.txt' contains barometric pressure timeseries with columns:
- Date_time: date and time stamp of data
- BaroT: air temperature in degrees Celsius
- Corr_Baro_m: barometric pressure as meters of water.
- Files 'CCA.txt','CCB.txt','PCB.txt','PCC.txt','PCDS.txt', and 'PCMU.txt' correspond to piezometer nest locations with columns:
- Script: Example MATLAB script 'Process_PZ_Dat.m' to import datasets and generate plots and statistics from associated manuscript. Created with MATLAB version: '9.13.0.2105380 (R2022b) Update 2'.
- Metadata: Comma-separated file containing location and depth metadata for piezometers with columns:
- Site_Name: name of piezometer nest location
- Latitude: latitude coordinate of piezometer nest
- Longtidue: longitude coordinate of piezometer nest
- Shal_Depth: midpoint of shallow piezometer slotted interval as depth into streambed in meters
- Deep_Depth: midpoint of deep piezometer slotted interval as depth into streambed in meters
- Elevation: elevation of streambed at piezomter nest to the nearest meter above mean sea level
- Distance: For PC sites, distance from mountain front. For CC sites, distance of longest path from drainage divide
Methods
This dataset includes 10-minute timeseries (28-SEP-2018 to 28-SEP-2021) of temperature, groundwater level, vertical hydraulic gradient (VHG), Darcy flux (q), temperature dependent hydraulic conductivity (K), barometric pressure, and related metadata for a nested streambed piezometer network located on East Plum and Cherry Creeks in Colorado, USA.