Upstream Source Areas Research Articles

Analysis of spatio-temporal patterns of vegetation carbon use efficiency in watershed ecosystem and construction of ecological network: a case study of the Yangtze River Basin

ABSTRACT Watershed ecosystems play a crucial role in the global carbon cycle, and the feedback effects of carbon cycling will have significant implications for future climate change. Therefore, this study utilizes MODIS data to estimate the vegetation carbon use efficiency (CUE) of the Yangtze River Basin (hereafter referred to as the YRB) aiming to explore its spatiotemporal patterns. Additionally, partial correlation analysis is employed to investigate the driving forces of climate and ecosystem types on vegetation CUE. Furthermore, an ecological network is constructed to examine the impact of CUE changes on the stability of the ecosystems.The results indicate that the CUE values in the vegetation ecosystems of the YRB exceed the threshold of 0.5, a constant CUE value commonly used in numerous ecological models. However, even within the same geographical region, different ecosystem types exhibit distinct CUE values, underscoring the complexity of the ecological landscape.Over the past 15 years, there has been an observable declining trend in CUE for the vegetation ecosystems within the YRB. Moreover, future projections suggest a continued decrease in CUE at the pixel scale, with land use changes possibly serving as a primary contributing factor. Interestingly, within the same ecosystem, higher temperatures and reduced precipitation appear to enhance CUE, implying that under adverse environmental conditions, plants may enhance their efficiency in converting atmospheric carbon into terrestrial biomass.Ultimately, an ecological network is established to investigate the influence of CUE changes on the stability of the ecosystems. Notably, alterations in CUE within the upstream ecological source areas of the Yangtze River exhibit a particularly pronounced impact on the overall ecosystem stability.These research findings hold paramount significance, deepening our understanding of carbon cycling variations in the YRB, while also providing valuable insights for safeguarding the ecological environment and formulating strategies to address the challenges posed by climate change.

Quantifying the contribution of local drivers to observed weakening of spring dust storm frequency over northern China (1982–2017)

Recent studies have suggested that spring dust storm (SDS) events in northern China (NC) have exhibited substantial decline over the past 30 years. However, it is unclear which local factors are most responsible for the decline in SDS events, and the contribution of each dominant factor remains to be determined. This study utilized high-density DS records and collocated homogenized surface meteorological observations from 1982 to 2017, in conjunction with land surface products, to examine the local drivers that influence the long-term variation in SDS frequency (SDSF) over the entire NC area and its three dust-source areas: northwestern China (NWC), north-central China (NCC), and northeastern China (NEC). Results indicated that the observed SDSF averaged over NC, NWC, NCC, and NEC has decreased by 144.4 %, 109.3 %, 166.4 %, and 92.2 %, respectively, during 1982–2017. The variation in SDSF is largely explained by variation in wind speed (WS), precipitation, volumetric soil moisture, and surface bareness. A multivariable linear regression model incorporating these local drivers accounted for 81.0 %, 74.0 %, and 46.9 % of the variance in SDSF in NWC, NCC, and NEC, respectively. Statistical analyses on the local drivers suggested that weakening of WS was the dominant factor in the reduction in SDSF over recent decades, contributing 76.9 %, 54.7 %, and 33.6 % of the variation in NWC, NCC, and NEC, respectively. More importantly, we revealed that the interannual variation in regional SDSF was not only controlled by local drivers, but also influenced by cross-regional transport of dust aerosols emitted from upstream source areas.

Dominant source areas shift seasonally from longitudinal to lateral contributions in a montane headwater stream

Montane ecoregions are important vehicles for downstream hydrologic function, but their dynamics are relatively understudied compared to alpine and subalpine catchments in the western United States. Montane catchments experience shifts in precipitation inputs seasonally, which results in spatiotemporal differences in source area contributions to the stream. We collected hydrometric and geochemical data between 2018 and 2021 from a 2.65 km2 semi-arid headwater catchment in the Front Range of Colorado, USA. Using a combined approach of hydrometric monitoring, geochemical characterization, and end-member mixing analysis (EMMA), we assess hydrologic connectivity between areas with high upslope accumulation and the stream. Within our study area, high upslope accumulation area corresponded to alluvial/ colluvial fans wherein we focused instrumentation and water sample collection. Using observed rainfall, and multiyear measurements of groundwater levels, soil moisture, and streamflow, we observed distinct hydrologic seasons within our catchment characterized by snowmelt during the spring, rainstorms during the summer, and a return to baseflow during the fall. Within this framework, we found that source areas to streamflow shift with longitudinal distance downstream, and among hydrologic seasons. Notably, our EMMA results indicate that contributions from upstream source areas become less important than lateral inputs from spring snowmelt into the fall return to baseflow. This was most pronounced at the upper catchment where upstream contributions to streamflow decreased up to 33.3% between spring and fall. These results suggest that streamflow is maintained by local source areas contributing laterally and vertically. Our results reflect dynamic shifts in hydrologic connectivity in space and in time, which are increasingly important to land and water resource management given rapid climate changes within the western United States.

Compositional dynamics of suspended sediment in the Rhine River: sources and controls

PurposeInformation on the geochemical composition of suspended sediments in rivers is crucial to identify sediment source type or area. In large river basins, however, the relation between sediment composition and its controlling factors is often obscured. This study aims to assess and improve the conceptual understanding on the factors and mechanisms that control the composition of suspended sediments in the River Rhine, one of the large European rivers, and to identify the dominant source types of elements.Materials and methodsWe performed log-linear regression analysis and principal component analysis (PCA) on bi-weekly monitoring data of suspended sediment composition, supplemented with daily measurements of suspended sediment concentrations (SSC) and discharge at the Lobith monitoring station near the German-Dutch border for the period 2011–2016.Results and discussionThe statistical analyses show a consistent grouping of elements that display contrasting temporal variation or different responses to increased discharge. The contrasting behaviour also becomes manifest in the results from the PCA. A first component that explains about the half of the total variance in the entire dataset reflects the variation in clay content in the suspended sediment. A second component reflects anthropogenic pollution and explains about a quarter of the total variance. A third component probably reflects variation in sediment provenance.ConclusionsThe majority of the temporal variation in suspended sediment composition can be attributed to variations in grain size (clay content), organic matter content, and anthropogenic pollution. Only a minority of the variation can be attributed to variations in the contributions from different upstream source areas. This variation represented by the third and higher components from the PCA can potentially be used for sediment provenance analysis.

Paired geochemical tracing and load monitoring analysis for identifying sediment sources in a large catchment draining into the Great Barrier Reef Lagoon

While sediment tracing has been typically applied to identify sediment sources that are difficult to measure by gauging (monitoring), it can also be useful in estimating relative sediment yields from gauged river catchments. The major and trace element composition of river sediments from eleven locations in the 130000km2 Burdekin River catchment, northeastern Australia was analysed to examine relative contributions from upstream source areas in the 2011/12 water year. Sediment tracing results are compared against estimates derived from sediment load monitoring at three locations. Comparisons show that there is good agreement between tracing results and monitoring data at one of the tributary confluences. At the second site, notable contrasts were found between the load estimates from the monitoring and tracing data. At this site a large impoundment occurs between the upstream sampling/gauging sites for source sediments and the downstream sampling/gauging sites for target sediments. The contrast is likely caused by temporal variations in particle size distributions of suspended sediment from each river and differential trapping efficiencies in the impoundment for sediment derived from the different tributaries. In the absence of the detailed particle size data and trapping efficiency estimates, sediment tracing provides the unique opportunity to elucidate source contributions of the finer fractions of suspended sediment. At a third site, where there were recognised measurement gaps in the monitoring data during large discharge events, the relative load estimates from the tracing data provided a means of constraining the recognized uncertainty of monitored load estimates. We conclude that sediment tracing can be used as a valuable adjunct to monitoring data particularly in remote, large and data-sparse catchments. Both tracing results and monitoring data show that the Upper Burdekin River and Bowen-Bogie Rivers were the dominant source of the <10μm sediments being delivered to the GBR lagoon from the Burdekin River catchment in the 2011/12 water year. More substantial contribution from the Belyando-Suttor Rivers indicated by the tracing results than the monitoring data is attributed to preferential delivery of the 1–10μm sediments through the impoundment and has uncovered a knowledge gap in sediment budgets in the catchment.

Freshwater ecosystem services supporting humans: Pivoting from water crisis to water solutions

A new global scale water indicator, the freshwater provisioning index for humans (FPIh), maps the capacity of upstream source areas to provide water for human populations downstream. The freshwater provisioning index for humans combined with estimates of threats to water source areas assesses the compounded impacts on freshwater provisions at their point-of-service and the humans they support downstream. Nearly the entire world is serviced by freshwater sources compromised to a moderate extent through human activities, with 82% of the world’s population served by upstream areas exposed to high levels of threat. Globally, 75% of the world’s population benefits from engineered remediation of highly impaired source areas. Despite these gains, more than 80% of the global population still experiences moderate levels of threat impacting their freshwater provisions. Industrialized nations greatly limit their exposure to threats via infrastructure investments whereas regions in the developing world with moderate threat and little means of mitigation are viewed as the most vulnerable. Populations served by water source areas in industrialized countries receive highest threat reductions overall (50–70%) while those served by provision areas in the least developed countries receive <20% threat decrease. Better management of upstream source areas in poorer countries represents an opportunity to reduce threat lessening reliance on costly engineering solutions. Viewing the world in terms of the threats imposed on freshwater provisions combined with regional capacity to abate these impairments through infrastructure investments yields a spatial typology of freshwater resource development states reflecting region-specific challenges with unique management implications. Global mapping of threat development states provides a synoptic-scale diagnosis of key water resource challenges we link with state-specific water service management strategies including service area conservation, threat reduction, and green and gray infrastructure investments to more sustainably manage upstream freshwater provisions. This study provides a functional architecture to assess potential investment strategies to sustainably protect and manage critical upstream freshwater provisions addressing unique challenges faced by different regions of the world.

Factors controlling the abundance of rainbow trout in the Colorado River in Grand Canyon in a reach utilized by endangered humpback chub

We estimated the abundance, survival, movement, and recruitment of non-native rainbow trout (Oncorhynchus mykiss) in the Colorado River in Grand Canyon to determine what controls their abundance near the Little Colorado River (LCR) confluence where endangered humpback chub (Gila cypha) rear. Over a 3-year period, we tagged more than 70 000 trout and recovered over 8200 tagged fish. Trout density was highest (10 000–25 000 fish·km–1) in the reach closest to Glen Canyon Dam, where the majority of trout recruitment occurs, and was 30- to 50-fold lower (200–800 fish·km–1) in reaches near the LCR confluence ∼100 km downstream. The extent of rainbow trout movement was limited with less than 1% of recaptures making movements greater than 20 km. However, because of high trout densities in upstream source areas, this small dispersal rate was sufficient to explain the threefold increase in the relatively small population near the LCR. Reducing dispersal rates of trout from upstream sources is the most feasible solution to maintain low densities near the LCR to minimize negative effects of competition and predation on humpback chub.

Identifying and controlling critical sources of farm phosphorus imbalances for Vermont dairy farms

Lake Champlain, located between Vermont, New York, and Quebec exhibits eutrophication mainly due to continuing phosphorus (P) losses from upstream nonpoint source areas. Several state and local agencies have initiated efforts aimed at assessing and identifying critical sources areas for P loss. To augment these efforts, accounting of farm P inputs (in purchased animal feed and fertilizers) and P outputs (in milk, meat, or off-farm sales of harvested crops or other products) is needed as a means of determining potential P build-up in farm soils. When farm P inputs exceed P outputs, P surplus occurs on the farm. This leads to potential soil-P accumulations and risk of P loss in runoff, negatively impacting the quality of receiving water bodies. In this study, a combination of farm record data and a model-based approach, using the Integrated Farming System Model (IFSM), was used to estimate farm P inputs and outputs, identify root causes of farm P imbalances, and explore viable P balancing strategies. Three Vermont dairy farms with varying farm systems (grass-based organic farm, fully confined farm, and a mixed system farm with high-producing confined dairy cows and grazing heifers) were studied. These farms were found to have P surpluses ranging from 5.5 kg/ha to 18.7 kg/ha on annual basis. This study also identified critical causes of P imbalances for each farm and suggested farm specific alternative strategies needed to address the P imbalances. By balancing farm P inputs and outputs, potential accumulation of soil-P can be prevented. As a result, maximum benefits can be obtained from land treatment measures implemented to control off-field P loss without the additional concern of continuing P build-up that could reduce their effectiveness.

Some hydrological effects of peatland drainage in Alberta's boreal forest

Ninety hectares in a treed fen in north central Alberta were drained to improve growth of stagnant black spruce (Piceamariana (Mill.) B.S.P.) and tamarack (Larixlaricina (Du Roi) K. Koch) stands. Installation of 30-, 40-, 50-, and 60-m ditch spacings resulted in a lowering of the average water table by 79, 66, 56, and 73 cm, respectively. The results and the groundwater level criteria used (drainage norm, 40 cm; flood duration limit, 14 days) indicated that the 50-m ditch spacing was hydrologically the most appropriate one for this area. Given the relatively high hydraulic conductivity of the area, it is believed the 30-m spacing was too narrow and resulted in an excessively low average water table. The 60-m spacing was also overeffective, but in this case, overeffectiveness was attributed more to "edge effects" i.e., to site factors such as the proximity to uplands and the small size of upstream source areas, than to the distance between ditches. The results illustrate the importance, for ditch network design purposes, of taking into account hydrologic conditions both within and well beyond the boundaries of an area proposed to be drained. Peat subsidence after drainage appeared to be related to the average drop in water table level and amounted to about 5 cm•a−1.

Paleohydrology of pool-and-riffle pattern development: Boulder Creek, Utah

Research Article| April 01, 1986 Paleohydrology of pool-and-riffle pattern development: Boulder Creek, Utah JIM E. O'CONNOR; JIM E. O'CONNOR 1Department of Geosciences, The University of Arizona, Tucson, Arizona 85721 Search for other works by this author on: GSW Google Scholar ROBERT H. WEBB; ROBERT H. WEBB 1Department of Geosciences, The University of Arizona, Tucson, Arizona 85721 Search for other works by this author on: GSW Google Scholar VICTOR R. BAKER VICTOR R. BAKER 1Department of Geosciences, The University of Arizona, Tucson, Arizona 85721 Search for other works by this author on: GSW Google Scholar Author and Article Information JIM E. O'CONNOR 1Department of Geosciences, The University of Arizona, Tucson, Arizona 85721 ROBERT H. WEBB 1Department of Geosciences, The University of Arizona, Tucson, Arizona 85721 VICTOR R. BAKER 1Department of Geosciences, The University of Arizona, Tucson, Arizona 85721 Publisher: Geological Society of America First Online: 01 Jun 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Geological Society of America GSA Bulletin (1986) 97 (4): 410–420. https://doi.org/10.1130/0016-7606(1986)97<410:POPPDB>2.0.CO;2 Article history First Online: 01 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation JIM E. O'CONNOR, ROBERT H. WEBB, VICTOR R. BAKER; Paleohydrology of pool-and-riffle pattern development: Boulder Creek, Utah. GSA Bulletin 1986;; 97 (4): 410–420. doi: https://doi.org/10.1130/0016-7606(1986)97<410:POPPDB>2.0.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract The low-flow channel morphology of Boulder Creek is characterized by a well-developed pool-and-riffle pattern. The riffles consist of accumulations of basaltic boulders deposited from upstream source areas during extremely large flows. Paleoflood water-surface profiles defined by high-water indicators such as slack-water sediments and silt lines indicate that discharges of up to 400±50 m3/s have affected the lower reaches of this bedrock stream system. Stratigraphic relationships and archaeologic and radiometric age constraints indicate that at least four large-magnitude, low-frequency flow events have occurred within the past 500 to 1,000 radiocarbon years B.P.Step-backwater hydraulic reconstructions of these large flows suggest that the positions of the boulder-comprised riffles are controlled by spatial variations in large-flow stream power. Boulder deposition occurs where channel stream power drops below critical-power thresholds necessary for boulder transport. High-discharge stream-power minima occur in reaches immediately upstream of canyon bends and constrictions and downstream of canyon expansions. The low-flow riffles occur at these sites. Comparison of calculated stream-power values and measured boulder sizes with established coarse-particle transport relationships indicates that a 400-m3/s flow is approximately the minimum discharge competent to affect this pool-and-riffle pattern. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Urban Runoff Management Strategies

A dramatic shift has occurred in the control of urban runoff over the past 10 yr to 15 yr. The conventional practice of rapid removal and delivery of urban runoff to downstream areas is being replaced by the newer concept of reduction and detention of urban runoff in upstream source areas. A successful strategy for managing urban runoff must be based on: (1)Application of proper hydrologic tools for the analysis of urban runoff under alternative land-use conditions in the watershed; (2)hydrologic and economic evaluation of the performance of alternative runoff abatement measures; and (3)projection of downstream impacts of selected abatement schemes. The purpose of this paper is to review these basic elements in urban runoff management and to comment on future directions in this evolving field.

Patterns of initial benthic recolonization of a reclaimed coal strip-mined river channel

Benthic macroinvertebrate samples were taken at sampling stations upstream of, downstream of, and within a newly opened channel of the Tongue River in Wyoming. The channel, reclaimed from coal strip-mining, contained layers of topsoil, gravel, and small to medium cobble. Benthic recolonization progressed towards maximum densities following terms of a power function. The mayflies of the genus Baetis were the primary colonizers. Colonization occurred primarily by drift of aquatic insects and algal mats in the first 14 days of channel opening. Some upstream migration, particularly by the dragonfly Ophiogomphus, was observed. Attainment of maximum diversity lagged density by 20 to 30 days. This period represented a time of dynamic adjustment within the community to match the undisturbed source area communities. The combined effects of differential drift rates and distances for aquatic insects and detrital material were responsible for the rather predictable patterns of colonization as well as the sequentially decreasing diversity values as distance from the upstream source areas increased.

Comments on letters relating to ‘Role of subsurface flow in generating surface runoff: 2, Upstream source areas’ by R. Allan Freeze

Comments on letters relating to ‘Role of subsurface flow in generating surface runoff: 2, Upstream source areas’ by R. Allan Freeze

Reply [to “Comments on ‘Role of subsurface flow in generating surface runoff: 2, Upstream source areas’ by R. Allan Freeze”

Water Resources ResearchVolume 9, Issue 4 p. 1111-1112 Letters Reply [to “Comments on ‘Role of subsurface flow in generating surface runoff: 2, Upstream source areas’ by R. Allan Freeze”] R. Allan Freeze, R. Allan FreezeSearch for more papers by this author R. Allan Freeze, R. Allan FreezeSearch for more papers by this author First published: August 1973 https://doi.org/10.1029/WR009i004p01111Citations: 3AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article.Citing Literature Volume9, Issue4August 1973Pages 1111-1112 RelatedInformation

Comments on ‘Role of subsurface flow in generating surface runoff: 2, upstream source areas’ by R. Allan Freeze

Comments on ‘Role of subsurface flow in generating surface runoff: 2, upstream source areas’ by R. Allan Freeze

Role of subsurface flow in generating surface runoff: 2. Upstream source areas

Runoff simulation for rainfall events on hypothetical upstream source areas, carried out with a deterministic mathematical model that couples channel flow and saturated‐unsaturated subsurface flow, provides theoretical support for the runoff‐generating mechanisms observed in the field by Ragan and Dunne. The simulations show that there are stringent limitations on the occurrence of subsurface storm flow as a quantitatively significant runoff component. Only on convex hillslopes that feed deeply incised channels, and then only when saturated soil conductivities are very large, is subsurface storm flow a feasible mechanism. On concave slopes with lower permeabilities, and on all convex slopes, hydrographs are dominated by direct runoff through very short overland flow paths from precipitation on transient near‐channel wetlands. On these wetlands surface saturation occurs from below because of rising water tables that are fed by vertical infiltration rather than by lateral subsurface flow. These conclusions, when coupled with field observations that show classic Hortonian overland flow to be a rare occurrence in vegetated humid environments, have implications in the planning of field instrumentation networks, and in the designing of hydrologic response models.