Geology topics

Research about Sleepers River watershed

Source-linked reports with geographic coverage including Sleepers River watershed.

5 recordsLinked to original sources

USGS2025

Long-term trends of streamwater chemistry in an agricultural watershed: Effects of anthropogenic and climatic factors

The chemistry of headwater streams is a key indicator of the health of riparian zones and surrounding terrestrial ecosystems. This chemistry is shaped by biogeochemical processes, including chemical weathering, and anthropogenic activities that interact with one another and are sensitive to climate. Elucidating trends in streamwater chemistry and the drivers that underpin them is essential for informing land-management decisions and anticipating water-quality issues that may affect downstream waters. In this work, we investigated the effects of anthropogenic and climatic factors on long-term variations in the chemistry of a first-order stream draining an agricultural catchment nested within the Sleepers River Research Watershed in Vermont, USA. We observed statistically significant increases in alkalinity and the concentrations of calcium and magnesium over a 31-year period for which 17 years of measurements were available. Through the application of generalized linear models, we found that the upward trends in alkalinity and calcium were associated with rising air temperatures, while a response to historical acid deposition played a minor role. We hypothesize that increased production of biogenic carbon dioxide and organic acids in soil and groundwater may lead to increases in chemical weathering rates under warmer climate conditions. This study emphasizes the important role of rising temperatures in the long-term increase in streamwater alkaline solutes, potentially overshadowing other influences like acidification recovery and agricultural practices. It also highlights the importance of comprehensive, long-term research to understand climate impacts on chemical weathering and inland water chemistry, which is critical for managing water quality and understanding regional and global carbon cycles.

Vermont↗

USGS2024

Illuminating the “invisible”: Substantial deep respiration and lateral export of dissolved carbon from beneath soil

Dissolved organic and inorganic carbon (DOC and DIC) influence water quality, ecosystem health, and carbon cycling. Dissolved carbon species are produced by biogeochemical reactions and laterally exported to streams via distinct shallow and deep subsurface flow paths. These processes are arduous to measure and challenge the quantification of global carbon cycles. Here we ask: when, where, and how much is dissolved carbon produced in and laterally exported from the subsurface to streams? We used a catchment-scale reactive transport model, BioRT-HBV, with hydrometeorology and stream carbon data to illuminate the “invisible” subsurface processes at Sleepers River, a carbonate-based catchment in Vermont, United States. Results depict a conceptual model where DOC is produced mostly in shallow soils (3.7 ± 0.6 g/m 2 /yr) and in summer at peak root and microbial respiration. DOC is flushed from soils to the stream (1.0 ± 0.2 g/m 2 /yr) especially during snowmelt and storms. A large fraction of DOC (2.5 ± 0.2 g/m 2 /yr) percolates to the deeper subsurface, fueling deep respiration to generate DIC. DIC is exported predominantly from the deeper subsurface (7.1 ± 0.4 g/m 2 /yr, compared to 1.3 ± 0.3 g/m 2 /yr from shallow soils). Deep respiration reduces DOC and increases DIC concentrations at depth, leading to commonly observed DOC flushing (increasing concentrations with discharge) and DIC dilution patterns (decreasing concentrations with discharge). Surprisingly, respiration processes generate more DIC than weathering in this carbonate-based catchment. These findings underscore the importance of vertical connectivity between the shallow and deep subsurface, highlighting the overlooked role of deep carbon processing and export.

Vermont↗

USGS2022

Controls on decadal, annual, and seasonal concentration-discharge relationships in the Sleepers River Research Watershed, Vermont, northeastern United States

Past studies on concentration-discharge ( C-Q ) relationships have focused on short-term or low-temporal resolution data. While advancing understanding of catchment processes, these studies provided limited insight on catchment response over time or to climate change. Using 15 solutes from 1992 to 2015 at Sleepers River Research Watershed, Vermont, we compared C-Q relationships over decades, years, and seasons to elucidate controls on stream chemical variation. We applied end-member mixing analysis (EMMA) to identify solute sources and flow path routing. EMMA identified three end-members: near-surface runoff (NSR), riparian groundwater, and hillslope hollow groundwater. Shifting mixing proportions of these end-members accounted for the temporal variability of conservative (no chemical reaction en route from source to stream) solutes in streamflow. For example, an increase in NSR fraction, typical of high flow, caused flushing (increased concentrations) of NO 3 − , DOC, Al, and Fe, which were greatest in NSR, dilution of specific conductance and base cation, SO 4 2− , Si, Sr, Ba, and Mn concentrations, which were greatest in the two groundwater end-members. This behaviour is reflected in the b -coefficient of the C-Q relation ( C = aQ b ), which indicates the strength of dilution ( b < −0.1) and flushing ( b > 0.1) effects. For conservative solutes, the b -coefficient decreased significantly ( p < 0.01) with an increase in the groundwater to NSR concentration ratio. Solutes that are conservative and have relatively constant concentrations in end-members over time showed consistent annual C-Q patterns over years and decades. Furthermore, the strength of dilution or flushing was stronger during the snowmelt period, when the NSR fraction peaked, than during the dormant and growing seasons. With shorter snowmelt periods and snow to rain shifts, the flushing or dilution power of snowmelt runoff will weaken and alter catchment response to climate change. These insights provide more tools for the interpretation of catchment processes and responses to climate change.

Vermont↗

USGS2022

Streams as mirrors: Reading subsurface water chemistry from stream chemistry

The shallow and deep hypothesis suggests that stream concentration-discharge (CQ) relationships are shaped by distinct source waters from different depths. Under this hypothesis, baseflows are typically dominated by groundwater and mostly reflect groundwater chemistry, whereas high flows are typically dominated by shallow soil water and mostly reflect soil water chemistry. Aspects of this hypothesis draw on applications like end member mixing analyses and hydrograph separation, yet direct data support for the hypothesis remains scarce. This work tests the shallow and deep hypothesis using co-located measurements of soil water, groundwater, and streamwater chemistry at two intensively monitored sites, the W-9 catchment at Sleepers River (Vermont, United States) and the Hafren catchment at Plynlimon (Wales). At both sites, depth profiles of subsurface water chemistry and stream CQ relationships for the 10 solutes analyzed are broadly consistent with the hypothesis. Solutes that are more abundant at depth (e.g., calcium) exhibit dilution patterns (concentration decreases with increasing discharge). Conversely, solutes enriched in shallow soils (e.g., nitrate) generally exhibit flushing patterns (concentration increases with increasing discharge). The hypothesis may hold broadly true for catchments that share such biogeochemical stratifications in the subsurface. Soil water and groundwater chemistries were estimated from high- and low-flow stream chemistries with average relative errors ranging from 24% to 82%. This indicates that streams mirror subsurface waters: stream chemistry can be used to infer scarcely measured subsurface water chemistry, especially where there are distinct shallow and deep end members.

Vermont↗

USGS2014

Water's Way at Sleepers River watershed – revisiting flow generation in a post-glacial landscape, Vermont USA

The Sleepers River Research Watershed (SRRW) in Vermont, USA, has been the site of active hydrologic research since 1959 and was the setting where Dunne and Black demonstrated the importance and controls of saturation-excess overland flow (SOF) on streamflow generation. Here, we review the early studies from the SRRW and show how they guided our conceptual approach to hydrologic research at the SRRW during the most recent 25 years. In so doing, we chronicle a shift in the field from early studies that relied exclusively on hydrometric measurements to today's studies that include chemical and isotopic approaches to further elucidate streamflow generation mechanisms. Highlights of this evolution in hydrologic understanding include the following: (i) confirmation of the importance of SOF to streamflow generation, and at larger scales than first imagined; (ii) stored catchment water dominates stream response, except under unusual conditions such as deep frozen ground; (iii) hydrometric, chemical and isotopic approaches to hydrograph separation yield consistent and complementary results; (iv) nitrate and sulfate isotopic compositions specific to atmospheric inputs constrain new water contributions to streamflow; and (v) convergent areas, or ‘hillslope hollows’, contribute disproportionately to event hydrographs. We conclude by summarizing some remaining challenges that lead us to a vision for the future of research at the SRRW to address fundamental questions in the catchment sciences.

Vermont↗