How do storm characteristics influence concentration-discharge hysteresis in a high-elevation tropical ecosystem?

Spatially distributed tracer‐aided modelling to explore DOC dynamics, hot spots and hot moments in a tropical mountain catchment

“…A simple comparison of simulated versus observed concentration–discharge relationships showed a lower simulated increase in DOC with discharge (Figure 9). This difference is more pronounced under low flow conditions, where the DOC response to flow is faster and more linear compared to simulated data, where it remains consistent under most conditions, similar to Peña et al (2023). It is possible that including various parameters that allow to capture the mechanism of a low‐capacity compartment with a very rapid response and recharged DOC throughout the soil profile, under specific conditions of discharge, could address this issue (Figure 9).…”

“…Wen et al (2020), for instance, observed that under low discharge conditions the system was influenced by inputs of DOC from groundwater and especially preferential organic rich flow pathways originating in the valleys. In a previous study conducted at Zhurucay, a variety of DOC sources in the stream were identified, particularly during low‐flow events, displaying hysteresis loops resembling a figure‐eight shape (Peña et al, 2023). Interestingly, in the previous mentioned study the authors present the same concentration–discharge pattern as the one resolved in this study, whereas the discharge during the event decreases, different DOC sources become activated which leads to the mobilization or dilution of DOC even during similar discharge conditions (Figures 4 and 9).…”

“…Moreover, although temperature has not been a relevant factor in simulating DOC production due to its current relative stability throughout the year (Córdova et al, 2016), it is generally reported that an uniform increase in temperature could also lead to a notable rise in carbon release (Wen et al, 2020). Consequently, a release of other elements such as metals that are strongly associated to DOC in the humid páramo could be expected in a warmer climate, posing serious concerns for future water quality (Arízaga‐Idrovo et al, 2022; Mosquera et al, 2023; Peña et al, 2023; Sánchez‐Murillo et al, 2019; Wu et al, 2022).…”

“…The parameters of the DOC production equation depend on the TWI to identify whether there is a differentiation between DOC production (kDOC) on the hillslopes (Andosols) and in valley bottom areas (Histosol), as found by Pesántez et al (2023). These landscape units may present differences in carbon production due to their different soil type, depth, organic matter content and land vegetation cover, which determines their ability to store and transport water (Peña et al, 2023; Pesántez et al, 2018). Similar to Birkel et al (2017), we assumed linear DOC losses in the fast and slow storage using different calibrated parameters for each hydrological unit (Histosols and Andosols).…”

“…and are distinguished by hillslopes with volcanic Andosols soils vegetated with tussock grass and valley bottoms with organic‐rich Histosols and wetlands. Soil moisture and land cover have been identified as the most important controls on DOC concentrations in páramo soil water and streams (Peña et al, 2023; Pesántez et al, 2018). Identifying hot spots of DOC production within páramo catchments is an important next step for understanding the timing and mechanisms that relate carbon export peaks to the hydrologic flow regime.…”