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.