| Non-perennial streams make up over half of the total global stream length. Due to their
abundance, the export of dissolved organic carbon (DOC) from these streams could influence
energy and carbon dynamics in downstream ecosystems. Our current understanding of DOC in
non-perennial streams suggests that DOC dynamics are strongly influenced by variations in
surface longitudinal connectivity (SLC), but no studies have explicitly quantified the SLC at
network scales and focused specifically on DOC export. In this thesis, we quantified DOC
concentrations in three intermittent watersheds that spanned the rain-to-snow transition in
southeastern Idaho. In one watershed, we quantified the influence of SLC on DOC export during
the seasonal rewetting period. Networks of sensors and water samples were used to quantify
DOC concentrations, discharge and the SLC. Temporal patterns of DOC at the outlet of each of
the three watersheds were distinct. Our analysis of the SLC and metrics of DOC export in one of
the watersheds suggested that the flushing of channel DOC was not a dominate process that
influenced DOC export during the rewetting period. Instead, multiple processes likely influenced
DOC export and were responsible for episodes of disproportionately high DOC yields during
rewetting. In total, this study suggests that the controls on DOC export cannot be constrained to a
single dimension in the stream network connectivity and that these controls likely vary among
watersheds.
Key Words: intermittent stream, hydrology, biogeochemistry, organic carbon, stream network
connectivity, concentration-discharge, hysteresis, double mass curve |