Evaluating spatiotemporal variation in water chemistry of the upper Colorado River using longitudinal profiling

摘要: Stream water chemistry is traditionally measured as variation over time at fixed sites, with sparse sites providing a crude understanding of spatial heterogeneity. An alternative Lagrangian reference frame measures changes respect to both space and travels through network. Here, we collected sensor‐based measurements high resolution along nearly 500 km the Upper Colorado River. Our objective was understand sources spatiotemporal heterogeneity across different solutes determine whether longitudinal change manifests smooth gradients suggested by River Continuum Concept (RCC) or abrupt Serial Discontinuity (SDC). results demonstrate that sampling integrates variation, profiles reflect processes vary in scales. Over each day sampling, temperature (T) dissolved oxygen (DO) varied strongly response diel solar cycles, most driven rather than location. Equilibration T DO atmosphere limited small scale heterogeneity, entire profile regional climate gradients. As such, more closely approximated RCC (though including temporal artefacts). Conversely, specific conductance nitrate (NO₃‐N) largely patterns lateral inflows such tributaries groundwater. This resulted discrete shifts downstream discontinuities, appearing expected SDC. The concatenation produces observed presents interpretive challenges but also augments our where, how, critically why it moves river networks.