Academic literature on the topic 'Hillslope zones'
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Journal articles on the topic "Hillslope zones"
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Kim, C. P., G. D. Salvucci, and D. Entekhabi. "Groundwater-surface water interaction and the climatic spatial patterns of hillslope hydrological response." Hydrology and Earth System Sciences 3, no. 3 (September 30, 1999): 375–84. http://dx.doi.org/10.5194/hess-3-375-1999.
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Abstract. A transient, mixed analytical-numerical model of hillslope hydrological behaviour is used to study the patterns of infiltration, evapotranspiration, recharge and lateral flow across hillslopes. Computational efficiency is achieved by treating infiltration and phreatic surface movement analytically. The influence of dynamic coupling of the saturated and unsaturated zones on the division of hillslopes into units of distinct hydrological behaviour is analyzed. The results indicate the importance of downhill groundwater flow on the lateral distribution of soil moisture and hydrological fluxes; unsaturated lateral flow is shown to be of relatively minor importance. For most conditions, the hillslope organizes itself into three distinct regions; an uphill recharge and a downhill discharge zone separated by a midline zone over which there is, on average, no recharge or discharge. A temporal perturbation analysis of the phreatic surface, made to quantify the deviations between the equivalent-steady water table derived by Salvucci and Entekhabi (1995) and the long-term mean water table, shows that the equivalent-steady water table effectively couples the unsaturated and saturated zone dynamics across storm and interstorm periods and divides the hillslope into distinct hydrological regions. The second order closure terms in the perturbation analysis, expressed as the gradient of water table variance, quantify the deviations and tend to make the hydrological zones relatively less distinct.
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Herron, N. F., and P. B. Hairsine. "A scheme for evaluating the effectiveness of riparian zones in reducing overland flow to streams." Soil Research 36, no. 4 (1998): 683. http://dx.doi.org/10.1071/s96098.
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Two time-independent equations are developed to assess the effectiveness of riparian zones in reducing overland flow to streams for events in which the time-scale of subsurface water redistribution exceeds that of the rainfall event. In one equation, the effectiveness of the riparian area is limited by the storage capacity of its soils, while in the other equation, the infiltration rate determines the buffer’s effectiveness. Riparian zone widths, expressed as a proportion of total hillslope length, are calculated for a number of different climate, antecedent moisture, and management scenarios for hillslopes of varying topographic convergence. A riparian zone width not exceeding 20% of total hillslope length is proposed as a practical management option in this paper. Riparian zone widths that fall within these bounds are predicted for areas where both the hillslopes and riparian areas are in good condition. Where conditions in either area are degraded, disproportionately large riparian buffer widths are predicted. The results suggest that land management initiatives need to be directed at the catchment as a whole if riparian buffers of realistic widths are to be effective.
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Martínez-Carreras, N., C. E. Wetzel, J. Frentress, L. Ector, J. J. McDonnell, L. Hoffmann, and L. Pfister. "Hydrological connectivity inferred from diatom transport through the riparian-stream system." Hydrology and Earth System Sciences 19, no. 7 (July 16, 2015): 3133–51. http://dx.doi.org/10.5194/hess-19-3133-2015.
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Abstract. Diatoms (Bacillariophyta) are one of the most common and diverse algal groups (ca. 200 000 species, ≈ 10–200 μm, unicellular, eukaryotic). Here we investigate the potential of aerial diatoms (i.e. diatoms nearly exclusively occurring outside water bodies, in wet, moist or temporarily dry places) to infer surface hydrological connectivity between hillslope-riparian-stream (HRS) landscape units during storm runoff events. We present data from the Weierbach catchment (0.45 km2, northwestern Luxembourg) that quantify the relative abundance of aerial diatom species on hillslopes and in riparian zones (i.e. surface soils, litter, bryophytes and vegetation) and within streams (i.e. stream water, epilithon and epipelon). We tested the hypothesis that different diatom species assemblages inhabit specific moisture domains of the catchment (i.e. HRS units) and, consequently, the presence of certain species assemblages in the stream during runoff events offers the potential for recording whether there was hydrological connectivity between these domains or not. We found that a higher percentage of aerial diatom species was present in samples collected from the riparian and hillslope zones than inside the stream. However, diatoms were absent on hillslopes covered by dry litter and the quantities of diatoms (in absolute numbers) were small in the rest of hillslope samples. This limits their use for inferring hillslope-riparian zone connectivity. Our results also showed that aerial diatom abundance in the stream increased systematically during all sampled events (n = 11, 2011–2012) in response to incident precipitation and increasing discharge. This transport of aerial diatoms during events suggested a rapid connectivity between the soil surface and the stream. Diatom transport data were compared to two-component hydrograph separation, and end-member mixing analysis (EMMA) using stream water chemistry and stable isotope data. Hillslope overland flow was insignificant during most sampled events. This research suggests that diatoms were likely sourced exclusively from the riparian zone, since it was not only the largest aerial diatom reservoir, but also since soil water from the riparian zone was a major streamflow source during rainfall events under both wet and dry antecedent conditions. In comparison to other tracer methods, diatoms require taxonomy knowledge and a rather large processing time. However, they can provide unequivocal evidence of hydrological connectivity and potentially be used at larger catchment scales.
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Wainwright, Haruko M., Sebastian Uhlemann, Maya Franklin, Nicola Falco, Nicholas J. Bouskill, Michelle E. Newcomer, Baptiste Dafflon, et al. "Watershed zonation through hillslope clustering for tractably quantifying above- and below-ground watershed heterogeneity and functions." Hydrology and Earth System Sciences 26, no. 2 (January 31, 2022): 429–44. http://dx.doi.org/10.5194/hess-26-429-2022.
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Abstract. In this study, we develop a watershed zonation approach for characterizing watershed organization and functions in a tractable manner by integrating multiple spatial data layers. We hypothesize that (1) a hillslope is an appropriate unit for capturing the watershed-scale heterogeneity of key bedrock-through-canopy properties and for quantifying the co-variability of these properties representing coupled ecohydrological and biogeochemical interactions, (2) remote sensing data layers and clustering methods can be used to identify watershed hillslope zones having the unique distributions of these properties relative to neighboring parcels, and (3) property suites associated with the identified zones can be used to understand zone-based functions, such as response to early snowmelt or drought and solute exports to the river. We demonstrate this concept using unsupervised clustering methods that synthesize airborne remote sensing data (lidar, hyperspectral, and electromagnetic surveys) along with satellite and streamflow data collected in the East River Watershed, Crested Butte, Colorado, USA. Results show that (1) we can define the scale of hillslopes at which the hillslope-averaged metrics can capture the majority of the overall variability in key properties (such as elevation, net potential annual radiation, and peak snow-water equivalent – SWE), (2) elevation and aspect are independent controls on plant and snow signatures, (3) near-surface bedrock electrical resistivity (top 20 m) and geological structures are significantly correlated with surface topography and plan species distribution, and (4) K-means, hierarchical clustering, and Gaussian mixture clustering methods generate similar zonation patterns across the watershed. Using independently collected data, we show that the identified zones provide information about zone-based watershed functions, including foresummer drought sensitivity and river nitrogen exports. The approach is expected to be applicable to other sites and generally useful for guiding the selection of hillslope-experiment locations and informing model parameterization.
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Martínez-Carreras, N., C. E. Wetzel, J. Frentress, L. Ector, J. J. McDonnell, L. Hoffmann, and L. Pfister. "Hydrological connectivity as indicated by transport of diatoms through the riparian–stream system." Hydrology and Earth System Sciences Discussions 12, no. 2 (February 24, 2015): 2391–434. http://dx.doi.org/10.5194/hessd-12-2391-2015.
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Abstract. Diatoms (Bacillariophyta) are one of the most common and diverse algal groups (ca. 200 000 species, ≈10–200 μm, unicellular, eukaryotic). Here we investigate the potential of terrestrial and aerophytic diatoms (i.e. diatoms nearly exclusively occurring outside water bodies, on wet, moist or temporarily dry places) to infer surface hydrological connectivity between hillslope–riparian–stream (HRS) landscape units during storm runoff events. We present data from the Weierbach catchment (0.45 km2, NW Luxembourg) that quantifies the relative abundance of terrestrial and aerophytic diatom species on hillslopes and in riparian zones (i.e. surface soils, litter, bryophytes and vegetation) and within streams (i.e. stream water, epilithon and epipelon). We tested the hypothesis that different diatom species assemblages inhabit specific moisture domains of the catchment (i.e. HRS units) and, consequently, the presence of certain species assemblages in the stream during runoff events offers the potential for recording if there was or not hydrological connectivity between these domains. We found that a higher percentage of terrestrial and aerophytic diatom species was present in samples collected from the riparian and hillslope zones than inside the stream. However, diatoms were absent on hillslopes covered by dry litter, limiting their use to infer hillslope–riparian zone connectivity in some parts of the catchment. Our results also showed that terrestrial and aerophytic diatom abundance in the stream increased systematically during all sampled events (n = 11, 2010–2011) in response to incident precipitation and increasing discharge. This transport of terrestrial and aerophytic diatoms during events suggested a rapid connectivity between the soil surface and the stream. Diatom transport data was compared to two-component hydrograph separation, and end-member mixing analysis (EMMA) using stream water chemistry and stable isotope data. This research suggests that diatoms were likely sourced exclusively from the riparian zone, since it was not only the largest terrestrial and aerophytic diatom reservoir, but also riparian zone water was a major streamflow source during rainfall events under both wet and dry antecedent condition.
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Burt, T. P., and G. Pinay. "Linking hydrology and biogeochemistry in complex landscapes." Progress in Physical Geography: Earth and Environment 29, no. 3 (September 2005): 297–316. http://dx.doi.org/10.1191/0309133305pp450ra.
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This review seeks to examine connections between hydrology and biogeochemistry at the landscape scale. A review of research on landscape structure and organization provides a context for what follows, and seeks to integrate work at relevant scales in ecology and geomorphology; the degree of functional ‘connectedness’ between different landscape elements provides the key theme. Following a review of hillslope hydrology, links between hillslope runoff pathways and nutrient dynamics are then considered. We focus in particular on riparian zones, where nutrient dynamics has relevance for water-quality management in catchments. In conclusion, we argue that future studies need to focus on the critical near-stream zone, given its importance in coupling hillslope and channel systems.
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Bernal, S., and F. Sabater. "Changes in discharge and solute dynamics between hillslope and valley-bottom intermittent streams." Hydrology and Earth System Sciences 16, no. 6 (June 4, 2012): 1595–605. http://dx.doi.org/10.5194/hess-16-1595-2012.
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Abstract. To gain understanding on how alluvial zones modify water and nutrient export from semiarid catchments, we compared monthly discharge as well as stream chloride, carbon, and nitrogen dynamics between a hillslope catchment and a valley-bottom catchment with a well-developed alluvium. Stream water and solute fluxes from the hillslope and valley-bottom catchments showed contrasting patterns between hydrological transitions and wet periods, especially for bio-reactive solutes. During transition periods, stream water export decreased >40% between the hillslope and the valley bottom coinciding with the prevalence of stream-to-aquifer fluxes at the alluvial zone. In contrast, stream water export increased by 20–70% between the hillslope and valley-bottom catchments during wet periods. During transition periods, stream solute export decreased by 34–97% between the hillslope and valley-bottom catchments for chloride, nitrate, and dissolved organic carbon. In annual terms, stream nitrate export from the valley-bottom catchment (0.32 ± 0.12 kg N ha−1 yr−1 [average ± standard deviation]) was 30–50% lower than from the hillslope catchment (0.56 ± 0.32 kg N ha−1 yr−1). The annual export of dissolved organic carbon was similar between the two catchments (1.8 ± 1 kg C ha−1 yr−1). Our results suggest that hydrological retention in the alluvial zone contributed to reduce stream water and solute export from the valley-bottom catchment during hydrological transition periods when hydrological connectivity between the hillslope and the valley bottom was low.
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Voytek, Emily B., Caitlin R. Rushlow, Sarah E. Godsey, and Kamini Singha. "Identifying hydrologic flowpaths on arctic hillslopes using electrical resistivity and self potential." GEOPHYSICS 81, no. 1 (January 1, 2016): WA225—WA232. http://dx.doi.org/10.1190/geo2015-0172.1.
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Shallow subsurface flow is a dominant process controlling hillslope runoff generation, soil development, and solute reaction and transport. Despite their importance, the location and geometry of these flow paths are difficult to determine. In arctic environments, shallow subsurface flow paths are limited to a thin zone of seasonal thaw above permafrost, which is traditionally assumed to mimic the surface topography. We have used a combined approach of electrical resistivity tomography (ERT) and self-potential (SP) measurements to map shallow subsurface flow paths in and around water tracks, drainage features common to arctic hillslopes. ERT measurements delineate thawed zones in the subsurface that control flow paths, whereas SP is sensitive to groundwater flow. We have found that areas of low electrical resistivity in the water tracks were deeper than manual thaw depth estimates and varied from the surface topography. This finding suggests that traditional techniques might underestimate active-layer thaw and the extent of the flow path network on arctic hillslopes. SP measurements identify complex 3D flow paths in the thawed zone. Our results lay the groundwork for investigations into the seasonal dynamics, hydrologic connectivity, and climate sensitivity of spatially distributed flow path networks on arctic hillslopes.
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Williams, C. Jason, Frederick B. Pierson, Peter R. Robichaud, Osama Z. Al-Hamdan, Jan Boll, and Eva K. Strand. "Structural and functional connectivity as a driver of hillslope erosion following disturbance." International Journal of Wildland Fire 25, no. 3 (2016): 306. http://dx.doi.org/10.1071/wf14114.
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Hydrologic response to rainfall on fragmented or burnt hillslopes is strongly influenced by the ensuing connectivity of runoff and erosion processes. Yet cross-scale process connectivity is seldom evaluated in field studies owing to scale limitations in experimental design. This study quantified surface susceptibility and hydrologic response across point to hillslope scales at two degraded unburnt and burnt woodland sites using rainfall simulation and hydrologic modelling. High runoff (31–47 mm) and erosion (154–1893 g m–2) measured at the patch scale (13 m2) were associated with accumulation of fine-scale (0.5-m2) splash-sheet runoff and sediment and concentrated flow formation through contiguous bare zones (64–85% bare ground). Burning increased the continuity of runoff and sediment availability and yield. Cumulative runoff was consistent across plot scales whereas erosion increased with increasing plot area due to enhanced sediment detachment and transport. Modelled hillslope-scale runoff and erosion reflected measured patch-scale trends and the connectivity of processes and sediment availability. The cross-scale experiments and model predictions indicate the magnitude of hillslope response is governed by rainfall input and connectivity of surface susceptibility, sediment availability, and runoff and erosion processes. The results demonstrate the importance in considering cross-scale structural and functional connectivity when forecasting hydrologic and erosion responses to disturbances.
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Votrubova, Jana, Michal Dohnal, Tomas Vogel, Martin Sanda, and Miroslav Tesar. "Episodic runoff generation at Central European headwater catchments studied using water isotope concentration signals." Journal of Hydrology and Hydromechanics 65, no. 2 (June 1, 2017): 114–22. http://dx.doi.org/10.1515/johh-2017-0002.
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AbstractHydrological monitoring in small headwater catchments provides the basis for examining complex interrelating hydraulic processes that govern the runoff generation. Contributions of different subsurface runoff mechanisms to the catchment discharge formation at two small forested headwater catchments are studied with the help of their natural isotopic signatures. The Uhlirska catchment (Jizera Mts., Czech Republic) is situated in headwater area of the Lusatian Neisse River. The catchment includes wetlands at the valley bottom developed over deluviofluvial granitic sediments surrounded by gentle hillslopes with shallow soils underlain by weathered granite. The Liz catchment (Bohemian Forest, Czech Republic) is situated in headwater area of the Otava River. It belongs to hillslope-type catchments with narrow riparian zones. The soil at Liz is developed on biotite paragneiss bedrock. The basic comparison of hydrological time series reveals that the event-related stream discharge variations at the Uhlirska catchment are bigger and significantly more frequent than at Liz. The analysis of isotope concentration data revealed different behavior of the two catchments during the major rainfall-runoff events. At Uhlirska, the percentage of the direct runoff formed by the event water reaches its maximum on the falling limb of the hydrograph. At Liz, the event water related fraction of the direct outflow is maximal on the rising limb of the hydrograph and then lowers. The hydraulic functioning of the Uhlirska catchment is determined by communication between hillslope and riparian zone compartments.
Dissertations / Theses on the topic "Hillslope zones"
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Inamdar, Shreeram P. "Investigation of hydrologic and sediment transport processes on riparian hillslopes." Diss., This resource online, 1996. http://scholar.lib.vt.edu/theses/available/etd-10032007-172009/.
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Tootchifatidehi, Ardalan. "Development of a global wetland map and application to describe hillslope hydrology in the ORCHIDEE land surface model." Electronic Thesis or Diss., Sorbonne université, 2019. http://www.theses.fr/2019SORUS390.
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Les zones humides jouent un rôle important dans le fonctionnement du système Terre aussi bien à l’échelle locale via un effet tampon sur les crues et épurateur de l’eau (dénitrification) que régionalement, du fait de leurs interactions avec l’atmosphère et de leur contribution majeure aux émissions de méthane. Leur représentation dans les modèles climatiques planétaires requiert une connaissance approfondie à la fois de leur distribution géographique et de leur hydrologie. Il y a un vaste désaccord sur l’estimation de l’étendue globale des zones humides, comprise entre 3% et 21% de la surface terrestre continentale, selon les méthodes employées. Ces contradictions s’expliquent par une représentation incomplète par les modèles hydrogéologiques des zones régulièrement inondées identifiées par l’imagerie satellitaire, qui peine en revanche à détecter les zones humides alimentées par les eaux souterraines. Peu visibles, elles sont également sous-estimées par la plupart des inventaires. La première étape de la thèse s’est donc focalisée sur la construction d’une carte mondiale des zones humides visant à concilier ces différences, par la distinction de ces deux types de zones humides, obtenus par combinaison des méthodes d’imagerie des eaux de surface et de modélisation des eaux souterraines. La proportion de zones humides à la surface du globe (21%) se situe dans la fourchette haute des estimations précédentes et concorde avec de nombreuses études régionales récentes, notamment en France et aux Etats-Unis. Dans une seconde étape, cette carte a servi d’entrée à une nouvelle version du modèle ORCHIDEE, qui décrit les surfaces continentales dans le modèle de climat de l’IPSL. La carte permet de distinguer dans chaque maille du modèle une fraction humide qui correspond aux fonds de vallée et reçoit les écoulements de la fraction haute, ce qui y rend possible le développement d’une nappe proche de la surface dont la profondeur répond au climat. Cette nouvelle version, dite ORCHIDEE-GW, a été testée dans le bassin de la Seine par comparaison à des observations de débit, d’évapotranspiration et de profondeur de nappe et afin de mieux comprendre l’effet des paramètres mal contraints tels que la profondeur du sol ou la formulation du flux nappe-rivière. Les effets principaux sont une augmentation de l’évaporation, une baisse des débits et un effet refroidissant, dont les conséquences sur le climat présent mais aussi futur sont une perspective importante à ce travailWetlands have significant functions in the Earth’s climate system both at local scales through their buffering effect on floods and water purification (denitrification) and also at a larger scale with their feedbacks to the atmosphere and its role in methane emission. To include wetlands in climate models globally, both their geographic distribution and hydrology should be known. There is a massive inconsistency among wetland mapping methods and wetland extent estimates (from 3 to 21% of the land surface area), rooted in imagery disturbances, underestimation of the groundwater driven wetlands in inventories or imprecise representation of flooded zones in GW modellings. In the framework of this PhD project, first by developing a global wetland map through a multi-source data fusion method we provide a simple applied classification for wetlands hydrological roles. Wetlands’ global extent is estimated to be almost 24.3 106 km2 (including lakes). The core distinction between classes is the flooding conditions and the water source, either coming from surface streams or groundwater convergence. In the next step, we modelled the wetlands’ role on surface processes in ORCHIDEE land surface model which was the testing platform for this new hydrologic scheme at large scale. The basic assumption in the new version (ORCHIDEE-GW) in this sub-grid procedures is that the deep drainage from the uplands converges over lowland wet fraction in parallel to infiltration from precipitation. Simulations over the contemporary era under climate forcing shows that the water table goes deeper with increased potential wetland fraction. The water table is shallow enough to be considered actual wetland when the potential wetland fraction is less than 0.2 over the Seine River Basin. The evapotranspiration rate increases by almost 3% with ORCHIDEE-GW because of the increased soil moisture in the wetland soil column. Increased soil moisture in the wet fraction affects the soil surface temperature as well. The future applications of this PhD work can be to explicitly introduce the biogeochemical procedures in wetlands in a dynamic manner to study the feedback effects of wetlands on climate and the Carbon cycle
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Zegre, Nicolas P. "The Hillslope Hydrology of a Mountain Pasture: The Influence of Subsurface Flow on Nitrate and Ammonium Transport." Thesis, Virginia Tech, 2003. http://hdl.handle.net/10919/35473.
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Nonpoint source (NPS) pollution is possibly the greatest form of contamination to our nation's waters. Nutrient pollutants, such as nitrate and ammonium, often enter aquatic ecosystems through surface and subsurface hydrological transport that drain agricultural watersheds. The over-abundance of nitrogen within these watersheds is easily transported to receiving stream and rivers, and result in aquatic ecosystem degradation. In response to the problem of nutrient loading to aquatic ecosystems, ecosystems scientists and federal and state governments have recommended the use of streamside management zones (SMZ) to reduce the amount of NPS pollutants. A small agricultural watershed in southwestern North Carolina was utilized to quantify subsurface transport of nitrate and ammonium to a naturally developing riparian area along Cartoogechaye Creek.
Vertical and lateral transport of nitrate and ammonium were measured along three transect perpendicular to the stream. Transects were instrumented with time domain reflectometry (TDR) and porous cup tension lysimeters to monitor soil water and nutrient flux through the pasture and riparian area located at the base of the watershed. The HYDRUS 2-D flow and transport model was used to predict and simulate subsurface flow. Predicted flow was coupled with observed field nutrient data to quantify nutrient flux as a function of slope location. HYDRUS 2-D was capable of simulating subsurface flow (saturated and unsaturated) as a function of observed soil physical properties (bulk density, saturated hydraulic conductivity, particle size distribution, water retention characteristics) and climatic data (precipitation, air temperature, wind speed, etc.).
The riparian area was effective in reducing the amount of nonpoint source pollution to a naturally developing riparian area from an agricultural watershed. Dramatic decreases in both NO3- -N and NH4+ -N in upland pasture water were observed within the riparian area. Seasonal percent reductions of NO3- from the pasture to riparian area in subsurface water within the study watershed are as follows: summer (2002) = 456%; fall (2002) = 116%; winter (2003) = 29%; spring = 9%, pasture and riparian, respectively.Master of Science
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Pangle, Luke A., Minseok Kim, Charlene Cardoso, Marco Lora, Neto Antonio A. Meira, Till H. M. Volkmann, Yadi Wang, Peter A. Troch, and Ciaran J. Harman. "The mechanistic basis for storage-dependent age distributions of water discharged from an experimental hillslope." AMER GEOPHYSICAL UNION, 2017. http://hdl.handle.net/10150/624350.
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Distributions of water transit times (TTDs), and related storage-selection (SAS) distributions, are spatially integrated metrics of hydrological transport within landscapes. Recent works confirm that the form of TTDs and SAS distributions should be considered time variant-possibly depending, in predictable ways, on the dynamic storage of water within the landscape. We report on a 28 day periodic-steady-state-tracer experiment performed on a model hillslope contained within a 1 m3 sloping lysimeter. Using experimental data, we calibrate physically based, spatially distributed flow and transport models, and use the calibrated models to generate time-variable SAS distributions, which are subsequently compared to those directly observed from the actual experiment. The objective is to use the spatially distributed estimates of storage and flux from the model to characterize how temporal variation in water storage influences temporal variation in flow path configurations, and resulting SAS distributions. The simulated SAS distributions mimicked well the shape of observed distributions, once the model domain reflected the spatial heterogeneity of the lysimeter soil. The spatially distributed flux vectors illustrate how the magnitude and directionality of water flux changes as the water table surface rises and falls, yielding greater contributions of younger water when the water table surface rises nearer to the soil surface. The illustrated mechanism is compliant with conclusions drawn from other recent studies and supports the notion of an inverse-storage effect, whereby the probability of younger water exiting the system increases with storage. This mechanism may be prevalent in hillslopes and headwater catchments where discharge dynamics are controlled by vertical fluctuations in the water table surface of an unconfined aquifer. Plain Language Summary Volumes of water reside within landscapes for varying amounts of time before they are discharged to a stream. That length of time determines how long the water has to interact chemically with soil and rock, and therefore influences the chemistry of water that ends up in stream channels. Quantifying the full range and variability of those travel times remains a challenge. We built an experimental hillslope, which allows us to keep track of all the water that enters and exits the soilsomething that is difficult to accomplish in open environmental systems. We introduced chemically distinct water into the hillslope at specific points in time and followed the movement of that water within, and upon exit from the soil. We discovered that the water being discharged from the hillslope tends to have resided in the landscape for shorter lengths of time when the hillslope is very wet (like a wetted sponge) than when it is very dry (like a dry sponge). This insight helps us understand how different rainfall regimes, and the associated wetness of the landscape, can potentially influence water transit times through the landscape, and their relationship with stream chemistry.
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Moore, Erin Amanda. "An analysis of solute transport on a harvested hillslope in the southern Appalachian Mountains." Thesis, Virginia Tech, 2008. http://hdl.handle.net/10919/32758.
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Interest in transport of dissolved nitrogen (N) and carbon (C) in forested ecosystems is growing because of potential effects of these solutes on streamwater quality and implications for C sequestration. Additional research will further the understanding about the dynamics of these soil solutes, particularly in response to harvesting of forests. Also, the purported role of riparian buffers, where logging is restricted along stream channels, in retaining soil solutes is not well studied in the steeply sloping terrain of the southern Appalachian Mountains. I examined solute transport in a first-order watershed in the Nantahala National Forest in North Carolina that was harvested in February 2006 with retention of a 10-m riparian buffer.
To quantify the movement of dissolved inorganic nitrogen (DIN), dissolved organic nitrogen (DON), and dissolved organic carbon (DOC), four transects of lysimeters, approximately 30 m apart, were installed perpendicular to the stream on one hillslope. Porous ceramic cup (2-bar) lysimeters were installed in each transect 1, 4, 10, 16, 30, and 50 m from the stream in the A horizon and B horizon, and 4, 16, and 50 m from the stream in the saprolite layer. Samples were removed from the lysimeters 24 hr after 50 centibars of tension were placed on them, and riparian groundwater well and stream samples were collected at the same time as lysimeter samples. Collection of samples from the lysimeters, wells, and stream occurred every four to six weeks for one calendar year beginning March 2007. A 16-wk laboratory N mineralization study was conducted on A horizon soils.
Mean nitrate values in the soil solution of the A horizon in the spring were 1.53mg-N/L and decreased through the growing season to 0.030mg-N/L. Mean soil solution nitrate values in the B horizon and saprolite layer were 0.40mg-N/L in the spring and summer and decreased to 0.031mg-N/L in the winter. Mean soil solution ammonium concentrations were higher in the A horizon (0.090mg-N/L) than the B horizon and saprolite layer (0.034mg-N/L) and were lowest during the summer and fall. Dissolved organic C was significantly higher in the A horizon, with values ranging from 2.3mg/L to 599mg/L, than in the relatively stable B horizon and saprolite (1.9mg/L to 36.6mg/L). Dissolved organic C was logarithmically correlated to DON (r2 = 0.64), and DON values were highest in the A horizon (0.70mg/L). Cumulative N mineralization potential ranged from 48.1mg-N/kg to 75.6mg-N/kg and was not a useful predictor for nitrate soil solution values.
Nitrate leached vertically, and a large percentage of nitrate was stored in the B horizon and saprolite. Ammonium, DON, and DOC did not appear to leach vertically because they did not increase in the B horizon or saprolite layer. Ammonium, DON, and DOC are less mobile in soil solution than nitrate. The 10-m riparian zone had little impact on nitrate, ammonium, DON, and DOC removal. Nitrate remaining in the A horizon was likely removed through plant uptake in the harvested area before reaching the riparian zone. There was no detectable difference between ammonium concentrations in the harvested area and riparian zone likely because of limited mobility. The riparian zone did not remove excess DON or DOC, and in some transects was a source of DON and DOC. Nitrate and DOC concentrations were highly variable among transects and locations within transects. This may be caused by sensitivity of these solutes to site heterogeneity. This suggests that a large number of lysimeters should be used to account for this variability in future studies to ensure accuracy.
This study observed limited vertical leaching of ammonium, DON, and DOC through the profile. However, excess nitrate was observed moving from the A horizon into the B horizon and saprolite layer, suggesting the potential for delivery to the stream via subsurface transport and the need for attenuation of nitrate by the riparian zone. Because of low concentrations of nitrate entering the riparian zone during this study, the capacity for riparian attenuation of nitrate was not demonstrated.Master of Science
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Quinton, William Leo. "Runoff from hummock-covered Arctic tundra hillslopes in the continuous permafrost zone." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/nq24043.pdf.
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Mkunyana, Yonela Princess. "An assessment of water use by Acacia longifolia trees occurring within the hillslopes and riparian zone of the Heuningnes Catchment, Western Cape." University of the Western Cape, 2018. http://hdl.handle.net/11394/5977.
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Magister Scientiae - MSc (Earth Science)The increasing expansion of Acacia longifolia trees along the riparian zones in South Africa demands an urgent intervention as the species is listed in the National Environmental Management: Biodiversity Act (2004). This list includes species that are prohibited from growing, or being imported into South Africa. The detrimental effects of alien vegetation have been observed on the hydrology of the ecosystems invaded. However, the actual water use by Acacia longifolia has never been quantified. Therefore, there is inadequate knowledge of the actual rates and the differences in water use rates by A. longifolia occurring in the riparian zones and hillslopes. This study addresses this gap in knowledge by quantifying the diurnal and seasonal transpiration dynamics of hillslope and riparian A. longifolia. The variations of climate and soil water content on the hillslope and riparian zones were also examined in this study. The study was conducted on the Spanjaardskloof hills and along the Nuwejaars River (Moddervlei) in the Heuningnes Catchment, Cape Agulhas.
Book chapters on the topic "Hillslope zones"
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Wainwright, John, and Louise J. Bracken. "Runoff Generation, Overland Flow and Erosion on Hillslopes." In Arid Zone Geomorphology, 235–67. Chichester, UK: John Wiley & Sons, Ltd, 2011. http://dx.doi.org/10.1002/9780470710777.ch11.
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Hu, Xiasong, Gary John Brierley, Carola Cullum, Jiangtao Fu, Dongmei Yu, and Yuezhou Li. "Hillslope Stability in the Yellow River Source Zone." In Springer Geography, 101–15. Cham: Springer International Publishing, 2016. http://dx.doi.org/10.1007/978-3-319-30475-5_5.
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Foroughi, Maryam, Lori A. Sutter, Daniel Richter, and Daniel Markewitz. "Hillslope Position and Land-Use History Influence P Distribution in the Critical Zone." In Advances in Critical Zone Science, 171–202. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-95921-0_7.
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Jamir, Imlirenla, Pranaya Diwate, Vipin Kumar, and Gambhir Singh Chauhan. "Inferring Relationship of Landslides, Tectonics, and Climate." In Advances in Environmental Engineering and Green Technologies, 169–79. IGI Global, 2020. http://dx.doi.org/10.4018/978-1-7998-5027-4.ch009.
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Landslides, despite being the surficial impression of climate-tectonic-erosion linkage, are rarely explored in this context in Himalaya. The need for such study becomes more crucial in the evaluation of the regional hillslope denudation budget. We are of the understanding that the distributional pattern of landslides can reveal the relative significance of tectonic and climate. To test this hypothesis, ~ 55 landslides of the Tons River valley, Himalaya along with the tectonic and climate proxies are used in the present study. Steepness index and valley floor width to valley height ratio are used to infer the tectonic regime whereas; Tropical Rainfall Measurement Mission based daily rainfall data and swath profile of Normalized Difference Vegetation Index are used to deduce spatial variability in climate. The study revealed the possible existence of a positive feedback system in the Higher Himalaya Crystalline and the simultaneous role of tectonic-climate in the Lesser Himalaya Crystalline. The LHS is found to possess a zone of landslide cluster, possibly due to local fault.
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Yamakawa, Y., K. Kosugi, T. Mizuyama, and W. Liang. "Generation of a saturated zone at the soil–bedrock interface around a tree on a hillslope." In From Headwaters to the Ocean, 69–74. CRC Press, 2008. http://dx.doi.org/10.1201/9780203882849.ch11.
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Hobbie, John E., and Neil Bettez. "Climate Forcing at the Arctic LTER Site." In Climate Variability and Ecosystem Response in Long-Term Ecological Research Sites. Oxford University Press, 2003. http://dx.doi.org/10.1093/oso/9780195150599.003.0011.
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The Arctic LTER site is located at 68º38'N and 149º43'W, at an elevation of 760 m in the northern foothills of the Brooks Range, Alaska. The location, 208 km south of Prudhoe Bay, was chosen for accessibility to the Dalton Highway, which extends along the Trans-Alaska Oil Pipeline from north of Fairbanks to Prudhoe Bay on the Arctic Ocean (figure 5.1). The rolling foothills at the site are covered with low tundra vegetation (Shaver et al. 1986a), which varies from heaths and lichens in dry sites to sedge tussocks on moist hillslopes to sedge wetlands in valley bottoms and along lakes. Riparian zones often have willow thickets up to 2 m in height. Small lakes are frequent; the best studied such lake is the 25-m-deep Toolik Lake (O’Brien 1992), the center of the LTER research site. Some 14 km from Toolik Lake, the Dalton Highway crosses the fourth-order Kuparuk River, the location of much of the LTER stream research (Peterson et al. 1993). Climate records at Toolik Lake have been kept since the early 1970s when a pipeline construction camp was established. On completion of the road in 1975, climate stations were set up by the U.S. Army Cold Regions Research Laboratory (CRREL, climate reported in Haugan 1982 and Haugen and Brown 1980). Since 1987, the LTER project has maintained climate stations at Toolik Lake (http:// ecosystems.mbl.edu/arc/) whereas the Water Resources Center of the University of Alaska has continuous records beginning in 1985 from nearby Imnavait Creek. An automatic station at Imnavait now reports every few hours to the Natural Resources Conservation Service–Alaska of the U.S. Dept. of Agriculture. The characteristics of the climate in northern Alaska are summarized by Zhang et al. (1996), who pointed out the strong influence of the ocean during both summer and winter months. They reported that the mean annual air temperature is coldest at the coast (–12.4ºC), where there are strong temperature inversions in the winter, and warmest in the foothills (–8.0ºC). At Toolik Lake, snow covers the ground for about eight months, and some 40% of the total precipitation of 250–350 mm falls as snow.
Conference papers on the topic "Hillslope zones"
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Fernandez, Nicole M., Jia J. Wang, Daniella M. Rempe, and Jennifer L. Druhan. "DETERMINING VADOSE ZONE GEOCHEMICAL AND GROUNDWATER PROCESSES WITHIN A SOIL-WEATHERED ARGILLITE MANTLED HILLSLOPE." In 50th Annual GSA North-Central Section Meeting. Geological Society of America, 2016. http://dx.doi.org/10.1130/abs/2016nc-275662.
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Brady, Jordan, and Frank Weirich. "A FIELD STUDY OF THE PRESENCE OF ZONES OF ELEVATED SUBSURFACE WATER LEVELS AND PORE WATER PRESSURES IN HILLSLOPES AS A PREFERENTIAL LOCATION FOR SLOPE FAILURE IN UNBURNED HILLSLOPES IN SOUTHERN CALIFORNIA." In GSA Connects 2021 in Portland, Oregon. Geological Society of America, 2021. http://dx.doi.org/10.1130/abs/2021am-367716.
Full textReports on the topic "Hillslope zones"
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Rossi, Rebecca, and Gabrielle David. Field guide to identifying the upper extent of stream channels. Engineer Research and Development Center (U.S.), March 2022. http://dx.doi.org/10.21079/11681/43560.
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The upper extent of a channel is a transition zone from the hillslope to the beginning of the stream channel. Accurately and consistently identifying the upper extent of a channel in the field and locating where hillslope processes transition to stream-channel processes can be a difficult task. Physical characteristics located at the beginning of a channel (i.e., channel head), including geomorphic, sediment, and vegetation indicators, can vary significantly across different landscapes in the United States. Remote tools are useful for examining the upper extent of channels, but these re-mote tools have limitations for identifying the beginning of channels. Even as the resolution of remote data continues to increase, field observations are necessary to validate the remote data on the ground and to accurately and consistently identify and locate the transition from the hillslope to the stream channel. Use of a combination of remote and field evidence is likely the most successful strategy for identifying channel heads. This report presents a case study that demonstrates how a weight-of-evidence approach can combine field and remote evidence to locate the different parts of the transition and ultimately to identify the channel-head location.