Top PDF The influence of hydrologic and riparian factors on stream channel stability in a central Iowa stream

The influence of hydrologic and riparian factors on stream channel stability in a central Iowa stream

The influence of hydrologic and riparian factors on stream channel stability in a central Iowa stream

Bartley R, R.J. Keen, A.A. Hawdon, M.G. Disher, A.E. Kinsey-Henderson, and P.B. Hairsine. 2006. Measuring rates of bank erosion and channel change in northern Australia: a case study from the Daintree River catchment. CSIRO Land and Water 43. Belmont, P., K.B. Gran, S.P. Schottler, P.R. Wilcock, S.S. Day, C. Jennings, et al. 2011. Large shift in source of fine sediment in the upper Mississippi River. Environ. Sci.

121 Read more

Stream bank soil and phosphorus losses within grazed pasture stream reaches in the Rathbun Watershed in southern Iowa

Stream bank soil and phosphorus losses within grazed pasture stream reaches in the Rathbun Watershed in southern Iowa

Livestock grazing of riparian zones can have a major impact on stream banks if improperly managed. The goals of this study were to determine the sediment and phosphorus losses from stream bank soils under varying cattle stocking rates and identify other factors that impact stream bank erosion in the Southern Iowa Drift Plain. The study was conducted on thirteen cooperating beef cow-calf farms within the Rathbun Lake watershed in South Central Iowa. Stream bank erosion rates over three years were estimated by using the erosion pin method. Eroded stream bank lengths and area, soil bulk density and stream bank soil-P concentrations were measured to calculate soil and total soil-P lost via stream bank erosion. Results revealed that the length of severely eroded stream banks and compaction of the riparian area were positively related to an increase in number of livestock grazing on the pasture stream reaches. While there was no direct relationship between bank erosion and stocking rate, the erosion rates from two sites enrolled within the Conservation Reserve Program (CRP) were significantly lower than those from all grazed pasture sites especially when seasonal effect, specifically winter/spring, was considered. This result suggests that use of riparian areas as pasture has major negative impacts on water quality and channel integrity through increased sediment and phosphorus from bank erosion, and that impact could be reduced through management of livestock grazing within these riparian areas.
Show more

109 Read more

Stream channel erosion as a source of sediment and phosphorus in a central Iowa stream

Stream channel erosion as a source of sediment and phosphorus in a central Iowa stream

in P concentration was observed between Onion Creek bank strata, similar to observations by Schilling et al. (2009) in a south central Iowa watershed. The presence of P in similar concentrations in both the DeForest and the underlying Dows Formation confirmed that both strata were sources of P to the Onion Creek stream channel. The presence of P in the glacial till of the Dows Formation, in similar concentration to the higher strata, can likely be attributed to P adsorption from stream and groundwater flow. The similar P concentrations among bank strata may not necessarily imply similar P loads from erosion of each Formation, however. Differing soil characteristics among strata likely influence their erosion rates and, therefore, their rate of P delivery. Erosion rates specific to the DeForest and Dows Formations were not available in this study. The Dows Formation has a higher bulk density and clay content, and may therefore be more resistant to erosion (Knapen et al. 2007). Yet, it is subjected to hydrologic scour more frequently by small magnitude flow events that only partially fill the stream channel, and therefore only induce scour lower on the bank face.
Show more

120 Read more

Assessment of stability of a revitalized stream T12 in Orlické Záhoří

Assessment of stability of a revitalized stream T12 in Orlické Záhoří

HYDROCHECK application, version 5.0, was used to model the uneven fl ow within the stream bed. The stream path was inserted using function of path import from a text fi le of coordinates of 381 surveyed points. In total, 108 cross profi les were entered – the detailed surveying of the stream in 2007. Bed roughness was set to 0.05 in the places of boulder chutes (there are 20 of them in the selected section) and 0.033 in the remaining parts (material: unreinforced gravel). Stream banks are densely covered in vegetation – their roughness in the model was set to 0.055; roughness in the places of bridges: km 0.045–0.053 and km 0.508–0.516, which are made of concrete culverts, was set to 0.03.
Show more

8 Read more

Central Venous Catheter Related Blood Stream Infections: Incidence and an Analysis of Risk Factors

Central Venous Catheter Related Blood Stream Infections: Incidence and an Analysis of Risk Factors

Six hundred and fifty-five central venous catheters (CVC) in 496 patients in the intensive care unit of Hospital Sultanah Aminah were studied to determine the incidence and risk factors for central venous catheter-related blood stream infection (CR-BSI). CR-BSI was diagnosed in 38 catheters, giving an incidence of 9.43 CR-BSI per 1000 catheter days. The mean duration in situ was 8.4 + 4.9 days for infected CVCs and 6.0 + 3.8 days for non infected CVCs (p=0.001). CVCs inserted in ICU had the highest infection rate (9.4%) compared to those inserted in the operating theatre (1.4%) and ward (2.8%) (p=0.001). The highest rate of CR-BSI occurred with 4-lumen catheters (usually inserted when patients needed total parenteral nutrition) with a percentage of 15.8%. The majority of the CVCs (97.9%) were inserted via the subclavian or the internal jugular routes and there was no statistical difference in CR-BSI between them (p=0.83). Number of attempts more than one had a higher rate of CR- BSI compared to single attempt with percentage of 7.0% vs 4.8% (p=0.22). The top two organisms were Klebseilla pneumoniae and Pseudomonas aeruginosa. In conclusion, the incidence of CR-BSI in our ICU was 9.43 CR-BSI per 1000 catheter days. The risk factors were duration of CVC in situ, venue of insertion and use of 4 lumen catheter for total parenteral nutrition. The site of insertion, number of lumen up to 3 lumens and the number of attempts were not risk factors.
Show more

5 Read more

Environmental stability: Its effect on stream benthic communities

Environmental stability: Its effect on stream benthic communities

UNSTABLE KowaiRiver Whitewater Stream Dry Stream Craigieburn Cutting Stream Bruce Stream STABLE Porter River Slip Spring Cora Lynn Stream Middle Bush Stream Grasmere Stream Lake Grasmere[r]

323 Read more

Linking soil  and stream water chemistry based on a Riparian Flow Concentration Integration Model

Linking soil and stream water chemistry based on a Riparian Flow Concentration Integration Model

In the effort to understand how stream water is influenced by catchment inputs, the riparian zone (RZ) has been identi- fied as a key part of the catchment, especially when consid- ering the short term dynamics of water chemistry which are of great ecological importance (Buffam et al., 2001; Fiebig et al., 1990; Gregory et al., 1991; Hill, 2000; Smart et al., 2001). As a simple starting point, the RZ can be thought of as a vertical array of soil solute sources that behave like chemostats, i.e. water emerges from each source with so- lute concentrations that are independent of the concentra- tion the water entered that source with. The temporal vari- ation of flow pathways through the riparian zone associated with changing groundwater levels connects different combi- nations of these solute sources in the RZ soil profile to the stream. The dynamics of stream water chemistry thus reflect the chemical “fingerprint” of the combination of chemostat- like soil solute sources in the RZ that connect to the stream at a given flow rate. The RZ is of special importance for to- tal organic carbon and related constituents, since TOC con- centrations increase markedly when passing through the RZ, relative to upslope concentrations (Bishop et al., 1990; Cory et al., 2007; Hinton et al., 1998; K¨ohler et al., 2009; Laudon et al., 2007; Sanderman et al., 2009). The RZ is a dominant control in first order catchments, which in turn are crucial for our understanding of water chemistry dynamics in larger aquatic systems (Bishop et al., 2008).
Show more

11 Read more

Field Assessment of Culvert Impacts on Stream Channel Morphology

Field Assessment of Culvert Impacts on Stream Channel Morphology

7 slope, and structure (Bates, 2003). Bates (2003) has committed to researching the fishway for pacific salmon and other organisms. Bates (2005) and others propose that stream simulation “will present no more of a challenge to movement of aquatic organisms than that of a natural channel”. Both traditional culverts partially filled with bed material and the “bottomless” arch culverts are being used in stream simulation. Research conducted by the US Fisheries and Wildlife Service supports the use of software to model fish passage through culverts (USFWS, 2007). FishXing™, HydroCulv™, and CulvertMaster™ are just a few examples of software developed to aid in the analysis of fish migration through culverts. The North Carolina Department of Transportation (NCDOT) also requires road crossing such as culverts to accommodate aquatic organism passage (Gardner et al, 2006). A study conducted by Angela Gardner (2006) at North Carolina State University developed a model and found that the velocity in culverts must remain below 0.55 m/s during the fish migration period.
Show more

245 Read more

STREAM: The Stanford Data Stream Management System

STREAM: The Stanford Data Stream Management System

StreaMon also implements an algorithm called Adaptive Greedy (or A- Greedy ) [7], which maintains join orders adaptively for pipelined multiway stream joins, also known as MJoins [22]. Figure 4(c) shows the portions of StreaMon’s Profiler and Reoptimizer that comprise the A-Greedy algo- rithm. Using A-Greedy, StreaMon monitors conditional selectivities and or- ders stream joins to minimize overall work in current conditions. In addition, StreaMon detects when changes in conditions may have rendered current or- derings suboptimal, and reorders in those cases. In stable conditions, the or- derings converged on by the A-Greedy algorithm are equivalent to those se- lected by a static Greedy algorithm that is provably within a cost factor < 4 of optimal. In practice, the Greedy algorithm, and therefore A-Greedy, nearly always finds the optimal orderings.
Show more

21 Read more

The effect of mixtures on colonisation of leaf litter decomposing in a stream and at its riparian zone

The effect of mixtures on colonisation of leaf litter decomposing in a stream and at its riparian zone

Decomposition was studied on leaves of common alder (Al- nus glutinosa (L.) Gaertner) and hybrid black poplar (Pop- ulus x canadensis Moench). These two species were chosen because the genera are well known, with data available in literature, and common in riparian zones across broad geo- graphic areas. Senescent leaves were collected from the trees or from the ground when freshly fallen, during three con- secutive days on October 2011, air-dried in the laboratory and weighed to the nearest 0.001 g to form single species or mixture (1 : 1) portions of 2.8 g ± 0.08 g SE. The leaves were introduced in 5 mm mesh square bags (20 cm × 20 cm), tied in groups (1 alder, 1 mixture, 1 poplar) and placed at the riparian zone by the stream channel and in a riffle area of the stream on 2 November 2011. The riparian bags were deployed on the floor and loosely covered with dead fallen leaves. The stream bags were tied to nails fixed at the bottom of the stream.
Show more

10 Read more

Hydrological connectivity inferred from diatom transport through the riparian stream system

Hydrological connectivity inferred from diatom transport through the riparian stream system

Fortnightly, cumulative rainfall (R) and throughfall samples under deciduous trees (TH1) and coniferous trees (TH2) were collected using conical, volumetric rain gauges. A ten- bottle sequential rainfall sampler was installed at the rain gauge located within the Weierbach (modified from Kennedy et al., 1979). Three automatic water samplers (ISCO 3700 FS and 6712 FS) were installed immediately upstream of the weir to collect stream water samples (AS) frequently (0.5 to 4 h) during storm events. Sampling was triggered by flow conditions. Events were considered separately if they were separated by a period of at least 24 h without rainfall. Stream water at the catchment outlet (SW) and wells (GW1 to GW4) were sampled fortnightly, as well as prior to, dur- ing, and following precipitation events. Soil water was sam- pled fortnightly using Teflon suction lysimeters, installed at three locations: deciduous hillslope (SS1), coniferous hills- lope (SS2), and riparian zone (SSr). Three soil depths for each location: 10 cm for the organic layer (Ah horizon), 20 and 60 cm for the mineral layers (B and C horizons). Over- land flow (OF) that occurred on lower hillslope was sampled using 1 and 2 m long gutters sealed to the soil surface, which diverted surface runoff to 1 or 2 L plastic, blackened (to pre- vent light penetration which causes diatom growth) water bottles. Note that what we refer to as OF might in fact origi- nate within the forest litter layer (Buttle and Turcotte, 1999; Sidle et al., 2007). All gutters were covered to avoid the in- fluence of precipitation. Gutters were regularly cleaned with Milli-Q water to avoid diatom growth on their surfaces.
Show more

19 Read more

Alternative Management Techniques for Controlling Microstegium vimineum on Stream and Riparian Restoration Sites.

Alternative Management Techniques for Controlling Microstegium vimineum on Stream and Riparian Restoration Sites.

This plant has colonized a variety of sites, including disturbed sites in moist soils, especially stream and river floodplains throughout the 24 eastern U.S. states, Washington D.C. and Puerto Rico (Barden, 1987; Fairbrothers and Gray, 1972; Matthews et al., 2011; USDA NRCS, 2011; Warren et al., 2011). Barden (1987) showed that this exotic plant readily invaded disturbed areas in a North Carolina floodplain much more quickly than established areas. Because M. vimineum seeds float, floods can easily distribute them throughout riparian areas (Mehrhoff, 2000; Warren et al., 2011). Litter and soil disturbances help to facilitate greater invasions of the nuisance species (Marshall and Buckley, 2008), particularly those disturbances created by human activities (Rauschert et al., 2010). Recent efforts to restore streams and riparian areas throughout the eastern United States have resulted in large areas of disturbed floodplains allowing M. vimineum to invade and dominate these sites (Barbara Doll-pers. comm.). This can be a major setback in the establishment of naturally regenerating as well as planted vegetation on the restoration site. For example, Oswalt et al. (2004) found that first-year growth of Quercus rubra L. (northern red oak) seedlings planted along an intermittent stream in southwest Tennessee was impeded by a large population of M. vimineum as compared to seedling growth in areas without the invasive plant. In another study, Leersia virginica Willd. (whitegrass), Carex radiata
Show more

336 Read more

Data  Is  a  Stream:  Security  of  Stream-Based  Channels

Data Is a Stream: Security of Stream-Based Channels

seem to hold for confidentiality against active adversaries (IND-CCFA). While our proof lifts aIND-CPA to aIND-CCFA security by leveraging ciphertext-stream integrity and error predictability (via the compo- sitional result from Theorem 6.6), one may wonder whether requiring INT-CST and ERR-PRE is indeed necessary. A different route to achieve aIND-CCFA security of the encode-then-stream paradigm could be used to lift confidentiality against an active adversary directly from the IND-CCFA security of Ch (recall that CON-CST of Ch would be necessary also in this case, as explained at the beginning of Section 7.3). At first glance, one might expect lifting IND-CCFA to its analog in the atomic-message setting, aIND-CCFA, should not rely on integrity of the stream-based channel. We however conjecture that such integrity is in fact necessary. Without going into details, the reason for this is that a non-integrous stream-based channel may possibly allow an attacker to modify the sent message stream in an arbitrary manner from some point on. In particular, the adversary might be able to modify the atomic-message encoding, e.g., by moving an employed end-of-message symbol to some earlier position in the message stream. Such a modification does not imply a stream-based confidentiality break, as the preceding challenge-message stream would still be suppressed. In the atomic-message sense, however, the resulting received (challenge) message is shortened, hence considered to be different and output to the adversary in the aIND-CCFA experiment. We therefore expect that stream-based integrity is indeed necessary to bridge the gap from stream-based IND-CCFA to atomic-message aIND-CCFA security. This, in particular, provides a glimpse into the formal causes enabling the cookie cutter attack [BDF + 14]: ultimately, atomic-message encodings need integrity protection as otherwise an adversary can restructure application messages (in this case application-layer HTTP messages) in a way that may not only violate their integrity, but also confidentiality.
Show more

62 Read more

LANDSCAPES AND RIVERSCAPES: The Influence of Land Use on Stream Ecosystems

LANDSCAPES AND RIVERSCAPES: The Influence of Land Use on Stream Ecosystems

The demonstrated effectiveness of land use data in predicting many compo- nents of stream condition points to an expanding role for landscape analysis in catchment management (Gergel et al. 2002). At present, most current studies rely on static Geographic Information Systems (GIS) maps that may represent land cover some years displaced in time from stream condition measures. However, remotely sensed data are likely to become more widely used in the future, offer- ing greater opportunity to synchronize the time frame of land cover and stream condition measurement and to develop new landscape indicators. One promis- ing demonstration showed that stream chemistry, habitat, and stream fish indexes across multiple ecoregions of Nebraska, Kansas, and Missouri were correlated to various “greenness” metrics on the basis of the normalized difference vegetation index, an indicator of vegetation condition and physiological activity obtained from satellite or airborne sensors (Griffith et al. 2002). Although management to mitigate land use impacts on streams will require site-based analysis of interact- ing factors, detection of areas at risk and estimation of probable risk factors are important and complementary activities to site-based studies.
Show more

28 Read more

Development and Comparison of Approaches for Automated Mapping of Stream Channel Networks

Development and Comparison of Approaches for Automated Mapping of Stream Channel Networks

Montgomery and Foufoula-Georgiou (1993) also con- clude that the printed blue lines do not represent a viable data source for many applications. The inaccuracies in the present published maps occur because stream chan- nels are often difficult to detect and because cartographic generalizations and decision rules lead to inaccuracies in published drainage networks. For example, Drummond (1974) found that each agency surveyed in his study created its own set of decision rules and criteria for the inclusion and length of stream channels. Dunne and Leopold (1978) point out that limitations in the recog- nition of small channels make measures of drainage density dependent on map scale and the technique used for manually extending channels up topographic swales. A better method is to use the location of actual stream channel heads to define starting points for topologically connected stream drainage networks. Mark (1983) is, to our knowledge, the first author to define the stream network mapping problem as a matter of identi- fying channel heads. Whereas Band (1986) asserts that channel networks are arbitrary and scale-dependent, other researchers have found that drainage channels are distinct fluvial geomorphologic features where overland flow on hillslopes crosses a threshold to create abrupt drainage channels (O’Callaghan and Mark 1984; Diet- rich et al. 1993; Montgomery and Foufoula-Georgiou 1993; Tarboton and Ames, 2001). Dietrich et al. (1993) found that the channel head represents a shift in hy- drologic process from mass wasting and diffusive flow to runoff-driven incision. Often, first-order channels are discontinuous, consisting of a well-defined channel head that gives rise to a distinct channel. This channel may, however, become less distinct over a section downstream of the channel head before being reinitiated in a con- tinuous form from that point downstream. Montgomery and Dietrich (1989, 1907) define channel heads as ‘‘the farthest upslope location of a channel with well defined banks.’’ This convention is followed here with the im- plication that short nonchanneled segments lying downstream of channeled segments are included in the mapped stream network. Our fieldwork, described below, also found that channel heads are clearly definable fea- tures on the landscape (Figure 1), but are also sometimes discontinuous in first-order reaches. Meeting the chal- lenge of locating channel heads is thus the key to ac- curate mapping of stream networks. Even small errors in locating channel heads results in major errors in the total stream network length, stream order, and drainage density (Garbrecht and Martz 2000).
Show more

14 Read more

Channel Evolution of a Restored Low Gradient, Sand Bed Stream

Channel Evolution of a Restored Low Gradient, Sand Bed Stream

The Corps of Engineers defined the analytical methodology for calculating the design discharge using long term (>10 yrs) discharge frequency and sediment transport data for the formation of a sediment rating curve. The method makes use of the effective discharge for channel design, since this value has been shown to have more analytical qualities than analog reference reach dynamic equilibrium values (Doyle et al., 2007). The frequency of effective discharge in the Coastal Plain has not been adequately quantified, nor the accuracy of using bankfull flow as the dominant discharge. Streams frequently overtop their banks in the lowland areas and marshes, at a rate of a few times per year. Stream restoration requires a greater understanding of the relationship between the channel-forming discharge and recurrence interval flow patterns for future design work in the Coastal Plain (Doll et al., 2004). The link between recurrence interval, bankfull flow, and the effective discharge are highly debatable in lower coastal plain and tidewater regions.
Show more

253 Read more

Ice stream grounding-line stability on a reverse bed slope

Ice stream grounding-line stability on a reverse bed slope

impacting directly upon sea level. Many ice streams possess beds that are below sea level and typically deepen inland on a reverse-slope 9 . Theory suggests that ice discharge increases rapidly with water depth 3 , and in the absence of lateral-drag induced buttressing from a floating ice shelf, grounding lines (marking the transition from grounded to floating ice) on reverse-bed slopes may be unstable 1-2 . Bed topography is therefore cited as a strong control on ice-stream retreat rate 3,10 and modern satellite observations of rapid ice-stream thinning and recession appear consistent with this theory 4-6 . However, with just two decades of data, these records are too short to identify the longer- term centennial to millennial-scale trends crucial for constraining future sea-level projections. Major uncertainties in predictions of ice-sheet vulnerability 11 relate to limitations in understanding processes controlling grounding-line motion and, importantly, to deficiencies in grounding-line treatment in ice-sheet models 12 . In recent years, significant advances in model development have been made 3,12-17 , but tests have only been applied to simplified bed geometries or to steady-state conditions and lack validation against data over timescales longer than a few decades. We aim to understand the long-term controls and stability of marine ice streams and, for the first time, integrate a fully dynamic ice-stream model with the detailed geomorphological record of palaeo- ice-stream retreat imprinted on the sea-floor of Marguerite Bay, western Antarctic Peninsula (Fig. 1).
Show more

25 Read more

Decoupling of dissolved organic matter patterns between stream and riparian groundwater in a headwater forested catchment

Decoupling of dissolved organic matter patterns between stream and riparian groundwater in a headwater forested catchment

The capacity of streams to mineralize allochthonous DOM, and thus their ability to contribute to the net balance be- tween C storage and emission at global scales, remains elu- sive, and available results are contradictory. Most of the un- certainties associated with the estimation of biogeochemical processing rates at large scales (reaches > 100 m) rely on the fact that GW inputs are rarely measured (Tiwari et al., 2014; Casas-Ruíz et al., 2017). Our synoptic approach is unique in the sense that it explicitly considers GW inputs, allow- ing for more reliable C and N budget calculations (Bernal et al., 2015). However, the characterization of the exact DOM chemistry entering from the riparian GW to the stream is a complex issue (e.g., Brookshire et al., 2009). First, the two water bodies (stream and riparian GW) are hydrologi- cally connected throughout the hyporheic zone (Bencala et al., 2011). Thus, hydrological mixing cannot be completely ruled out because stream water can eventually penetrate to- wards the riparian zone (Bernal et al., 2015). Second, DOM in riparian GW is likely processed while traversing the near- stream and hyporheic zones (Fasching et al., 2015). Hence, by sampling only riparian GW (2 m from the stream chan- nel) and free-flowing water at the thalweg, we could not dis- tinguish whether in-stream processes occurred in the stream water column, the streambed, or the hyporheic zone. Another keen aspect of our study is that we characterized the spec- troscopic properties of DOM in both stream water and ri- parian GW to investigate whether stream DOM reflected al- lochthonous sources or if in-stream processes modified DOM quality.
Show more

14 Read more

The response of a small stream in the Lesni potok forested catchment, central Czech Republic, to a short term in stream acidification

The response of a small stream in the Lesni potok forested catchment, central Czech Republic, to a short term in stream acidification

desorption of Ca in greater proportion to Mg from the stream substrate (Fig. 4). The lowest ratio occurred at five hours, representing the start of the Ca and Mg resorption during the recovery stage. At 5 hours (Fig. 4), Mg was resorbed in greater proportion to its stream concentration than was Ca. Two hours after the acid addition stopped, Ca and Mg concentrations started slowly to increase (Fig. 2). Although the Ca/Mg ratio recovered to its original value by the end of the experiment, the concentrations had not. The rate of recovery was slower than the mobilisation of base cations during the acidification phase. The shape of the curve for “sum of base cations (BC)” through time (acidification and recovery) is consistent with the conceptual model of Norton et al. (1999).
Show more

12 Read more

Appendix H Dredging and Stream Channel Restoration

Appendix H Dredging and Stream Channel Restoration

properties to determine which measures are most appropriate. Based on this information the Task Force recommends the following actions: 1. That requests for State or Federal regulatory permits for dredging operations as a means of reducing flood damages be approved only after documentation demonstrates that environmental impacts are not excessive and annual maintenance is assured through executed agreements. This should not hinder previously permitted channel modifications that are designed and maintained to reduce flood elevations of high frequency floods (low level), stream restoration, or restoration of aquatic environments. Nor should this hinder efforts by any Federal or State agency to address major flood events through an
Show more

11 Read more

Show all 10000 documents...