5. Future Study
Given the existence of only flux tower in the East River basin, more towers and data are needed to draw firm conclusions about ET values across the rest of the basin. The data from both the Niwot Ridge and Valles Caldera flux towers give us some insight into estimates of ET at other locations throughout the East River. The East River ET values likely represent the lower-bound estimates of ET given missing data (especially during the months of August and September) at various times in water years 2017, 2018, and 2019. We would expect the ET values at the East River to increase at both the seasonal and annual time scales probably surpassing ET values at Niwot Ridge, as seen in Section 4 when ET is gap-filled. The Niwot Ridge site is useful in helping to quantify ET at higher elevations in the east River basin during the summer months. These high-elevation locations are often marked by evergreen needleleaf land cover, greater wind speeds, lower temperatures, and lower soil moisture. We hypothesize that ET is lower at higher elevations in the East River basin—more closely resembling values from Niwot Ridge—than the riparian area where the flux tower currently sits. While we would expect ET to be similar to the Valles Caldera values at lower elevations with greater radiation; the location of the East River eddy flux tower sits at one of the most saturated and lowest elevations locations within the East River basin. Therefore, we expect the rest of the basin ET to be less than or equal to the measured East River ET flux values.
This site comparison helps constrain ET not only across the East River basin leading to a better understanding of water availability, but also across the rest of the Rocky Mountains. The East River flux tower offers useful information at a highly heterogeneous, yet vital, headwaters region about energy and water fluxes that differs from the only two currently operational AmeriFlux and/or FLUXNET sites in the Rocky Mountains, Valles Caldera and Niwot Ridge. By adding the flux tower at the East River site, we increase the number of eddy covariance towers in the Rocky Mountains by 50%. Understanding the high, end-member ET values allow for estimations to be made across the rest of the basin and Rocky Mountains leading to better understanding of water availability in historically underrepresented, complex locations. These flux tower comparisons also highlight the need for more flux towers in these heterogeneous mountain environments. End-member analysis is useful for constraining the higher end of ET in the East River basin; however, a larger number of flux towers at diverse locations across the basin—and the rest of the Rocky Mountains—would ensure better water and energy availability estimations useful for downstream planning.