Top PDF Temperature effects in alluvial streams

Temperature effects in alluvial streams

Temperature effects in alluvial streams

The significant results of the discussion can be summarized as follows: a At any given velocity above the critical value for sediment movement with discharge held constant, a cool water [r]

218 Read more

Effects of Tetracycline Son Soil Enzyme Activities in an Alluvial Soil

Effects of Tetracycline Son Soil Enzyme Activities in an Alluvial Soil

The soil sample selected for this study was collected from a farm of Aligarh district at plough layer (0-30 cm). The soil sample was air dried at room temperature and passed through a 2mm sieve and analysed for physico-chemical properties. The pH and electrical conductivity (EC) (1:2.5 water) of the soil were 8.1 and 7.6dS m -1 respectively. Its cation exchange capacity (CEC) cmol(p + ) kg -1 and organic carbon were 83, 27.9gkg -1 respectively. The soil contained 61% sand, 26% silt and 13% clay; the surface area of soil was 224 m 2 g -1 .

10 Read more

Effects of Agricultural Conservation Practices on Oxbow Lake Watersheds in the Mississippi River Alluvial Plain

Effects of Agricultural Conservation Practices on Oxbow Lake Watersheds in the Mississippi River Alluvial Plain

Agricultural activities are a significant source of nonpoint source pollution in the United States that have been documented in various agricultural regions like the Midwest, (Pereira & Hostet- tler 1993). In cultivated watersheds, nutrients in runoff have been tied to eutrophication in ox- bow lakes (Rebich 2004; Heatherly et al. 2007; Dubrovsky et al. 2010). Cooper and McHenry (1989) demonstrated that agricultural activities within the watershed increased sedimentation in oxbow lakes. Miranda et al. (2001) found that deposition of suspended sediments to be the most significant contributor to secession in oxbow lakes and further demonstrated that deposited sedi- ments profoundly affect temperature and dissolved oxygen. Legislation such as the 1987 Clean Water Act recognized the effectiveness of agricultural conservation practices, also known as, Best Man-
Show more

11 Read more

EFFECTS OF STREAMS ON DRINKABLE WATER RESERVOIR: AN ASSESSMENT OF WATER QUALITY, PHYSICAL HABITAT AND SOME BIOLOGICAL FEATURES OF THE STREAMS

EFFECTS OF STREAMS ON DRINKABLE WATER RESERVOIR: AN ASSESSMENT OF WATER QUALITY, PHYSICAL HABITAT AND SOME BIOLOGICAL FEATURES OF THE STREAMS

The results also indicated that physical fea- tures such as temperature, conductivity, TDS, flow, stream width were complying with the typical seasonal changes of Mediterranean type of streams as expected (Butturini et al., 2002; Cobelas et al., 2005). These types of streams were characterized by slow flow, high tempera- ture, TDS, conductivity in summer while vice versa in winter months. Basically, changes in these variables are due to mostly temperature fluctuations. Higher conductivity and TDS values in the streams can be explained by either direct effect of temperature or some particles trans- ported by sediments in the streams. pH values ob- tained in the present study were in agreement with the previous studies conducted in the Ömerli Reservoir (Albay and Akçaalan, 2003; Gürevin et al., 2006). However, SSM, TP and o-PO 4 con-
Show more

12 Read more

Controls on and Morphodynamic Effects of Width Variations in Bed-load Dominated Alluvial Channels: Experimental and Numerical Study

Controls on and Morphodynamic Effects of Width Variations in Bed-load Dominated Alluvial Channels: Experimental and Numerical Study

The Shields stress during the initial conditions of uniform flow experiments, computed using median grain size, ranged between 0.05 and 0.1. These values of Shields stress corresponding to median grain size of sediment at bank full conditions are common in gravel bed rivers [Garcia, 1999]. The natural sand-bed rivers usually have Shields stresses an order of magnitude higher than those observed in gravel-bed rivers. The bed and banks of the experimental channels were composed of the same non- cohesive material. So the banks and the bed had same degree of erodibility. In most natural gravel- bed rivers, the bank materials differ from the to the material forming the bed. The bank material may contain fine cohesive sediment or composite layers of different materials which make them less erodible compared to the channel bed [Hey and Thorne, 1986; Leyland et al., 2015]. In addition, in real rivers the presence of vegetation greatly influences the erodibility of the banks [Rinaldi and Darby, 2007]. So, the channel in our experiments would correspond to natural gravel-bed rivers with bed and banks composed of similar materials and without riparian vegetation. Such conditions are commonly found in pro-glacial streams [Chew and Ashmore, 2001] The aim is however, not to reproduce any specific type of river but to study channel evolution processes considering it as 1:1 scale experiments. Numerical simulations were also carried out at the initial Shields stress equal to 0.09.
Show more

172 Read more

Effects of climate change (precipitation variations), on rice crop yields in alluvial plains of the Tejo and Sado rivers

Effects of climate change (precipitation variations), on rice crop yields in alluvial plains of the Tejo and Sado rivers

Although our analysis has been focused on a single paddy, in both basins, it is well known that paddy rice production in the Sado basin was strongly conditioned in 2017 due to the scarce precipitation, while for 2018 rice and other spring crop productions are threatened and farmers struggle to find some alternative crops to monetize their land. Furthermore, the Instituto Nacional de Estatística (INE, 2018) states in the January report, that the minimum historical production land for winter cereals is 121,000 hectares. The average air temperature was 0.2ºC higher than normal for January and precipitation 35% less than normal amount. Thus, precipitation in the winter months was not enough to cover or approximate the normal values of soil moisture, and also not enough to maintain water demand to irrigation of spring crops, which leads farmers to equating production of alternative and more drought stress resistant crops. In February 2018, in 10 dams situated in the Sado basin, 6 of them present levels below 15% of its storage capacity, which have close relation to irrigation and present a dramatic situation to farmers, local economy and environmental planning (SNIRH, APA, 2018). Regarding Tejo basin, rice yields between 2008 and 2017 refers to Saragoça paddy, with 47.54 ha. Precipitation records of the closest meteorological station (Vila Franca de Xira) were crossed with yield data (Fig. 11). It seems that the yield is relatively constant despite the fluctuations in the precipitation amount. This independence may well be related to agronomical and technical factors which are not addressed in this study. However, it must be emphasized that from 2012 onwards, four different rice cultivars were used, probably in order to achieve the best options in terms of drought and pest resistance and yields. It is well known that climatic instability could increase the uncertainty of crop planning, leading to an income decrease to farmers and industrial players. Since paddy rice is an irrigated crop, shortage of water could seriously threaten production in both basins, although the lack of information regarding yields in a more extensive period and the absence of complementary data, such as cultivars used and temperature might give us a more comprehensive approach of interacting factors related to yield.
Show more

8 Read more

Impact of geomorphic structures on hyporheic exchange, temperature, and ecological processes in streams

Impact of geomorphic structures on hyporheic exchange, temperature, and ecological processes in streams

The primary objective of this study was to determine the independent effect of a wide range of potential controls on the vertical hyporheic exchange induced by a single IGS. This was accomplished by a sensitivity analysis where each of the parameters of interest was varied separately. Factors varied included structure type (weir, step, lateral structure) and size (s), represented by weir height (s w ), step height (s s ), and lateral structure width (s l ) ( Table 2.1, Figure 2.1). Stream discharge, background groundwater discharge, sediment hydraulic conductivity (K), channel slope, and depth to bedrock (Table 2.1) were also varied, but due to the extensive number of model runs and volume of output, this was undertaken only for weir type structures. When each factor was varied, all remaining factors were held constant at base case values. Note that when stream discharge rate was varied, the constant head boundary conditions for groundwater were adjusted to maintain a constant level of background groundwater discharge to the stream. This is appropriate for examining the effects of varying baseflow discharge but not for evaluating response to hydrographs.
Show more

175 Read more

Effects of temperature on wheat-pathogen interactions

Effects of temperature on wheat-pathogen interactions

24 provide enhanced resilience during the co-evolution between plants and their pathogens, due to evidence that some virulence factors are secreted most readily at temperatures below the optimum growth temperature for the plant (Smirnova et al., 2001). If expression of resistance is costly, then plants may have evolved temperature sensitive resistance genes to protect them against a particular pathogen within temperature ranges where they are at risk from invasion with the given pathogen (Figure 1.4, Alcázar 2011). However some temperature-sensitive resistances protect against multiple pathogens, so evolution cannot be due to this reason alone (Uauy et al., 2005; Krattinger et al., 2009). Importantly, Wang et al (2009) point out that there is no evidence that defence against necrotrophs is affected by temperature. Temperature modulation of resistance may therefore be a host strategy to deal with different types of pathogen with different virulence types attacking at different times. There is already evidence that plant resistance is tied into the circadian clock and that plants may be able to perceive an attack at dawn when pathogens are more likely to strike (Zhang et al., 2013; Wang et al., 2011). If this is the case then plants could also be using temperature to cue when to expect a challenge from a specific pathogen isolate or type. These hypotheses suggest that temperature-sensitive resistance genes could be useful in agriculture because they may be more durable. However before consideration for deployment of novel sources, more research is needed to evaluate how reliable they are in unpredictable weather conditions and their agricultural potential in the field.
Show more

177 Read more

Assessing residence times of hyporheic ground water in two alluvial flood plains of  the Southern Alps using water temperature and tracers

Assessing residence times of hyporheic ground water in two alluvial flood plains of the Southern Alps using water temperature and tracers

tube. The coefficients of the contributions of the various dis- charge fractions cannot be inferred from the coefficients of the mixture, even if the contributing fractions are known. In the limiting case of a binary mixture, in which only a single groundwater stream tube carries the signal of a temperature change, the signal amplitude of the mixture is multiplied by the flow fraction of that stream tube, while the phase angle is not changed. As discussed above, seasonal temperature fluctuations are hardly dampened. Therefore, practically ev- ery shallow groundwater carries a seasonal temperature sig- nal. As a consequence, seasonal temperature fluctuations ob- served in monitoring wells in alluvial aquifers are difficult to interpret. Unless the well samples only hyporheic ground- water, the phase of the seasonal temperature fluctuation can- not be related to a particular residence time or flow velocity. Short-time events, by contrast, may be more specific: In most cases, a rapid temperature change in a flowing river (due to flash floods or diurnal changes) will not be accompanied by a similarly rapid temperature change in the “older” alluvial groundwater from regional recharge. Thus the transfer time of a temperature signal from the downwelling river to a mon- itoring well (delay) reflects the travel time of the “young” groundwater of river origin. The signal will be dampened by dispersion, thermal non-equilibrium and mixing with other groundwater stream tubes, but the observed time shift τ ¯ T is a
Show more

11 Read more

The Effect of Alluvial Foundation on the Earth Dams Settlement

The Effect of Alluvial Foundation on the Earth Dams Settlement

Perhaps it can be said that among aforementioned parameters, the importance of settlement and deformation is an important factor in the behavior of the dam during construction, impounding dam and in operational stage. In order to measure settlement and horizontal deformation of dams usually the precision instruments of settlement set and combined Inclinometer that is commonly re- ferred to IS instrument, will be used [2]. Installing IS instrument (Inclinometer- settlement set) in the rock foundation of earth dams with alluvial layers in fixed point or in other words, to determine the point at which the movement or de- formation of the pipes will be zero in it, is very difficult. In terms of another, be- cause of the correct placement of IS instrument in the bedrock, the results are always relative; however, it is necessary to compare this reading with the base magnet to analyze settlement set reading. This question has also been raised that what is the appropriate criteria for the results of IS pipe, according to the differ- ent physical characteristics in the alluvial layers of dam foundation.
Show more

15 Read more

Al Batin Alluvial Fan, Southern Iraq

Al Batin Alluvial Fan, Southern Iraq

-Al-Batin Alluvial Fan: It is one of the ideal cases of alluvial fans of a desert plateau. It comprises essentially of ill-sorted gravely sand, sandy gravel and gypcrete, with subordinate layers and lenses of silty and sandy clay. The sands and gravels are composed mainly of quartz and feldspars, with less limestone pebbles and occasional acidic igneous and volcanic rock fragments. Aqrawi et al. (2006) in [13] also mentioned the presence of heavy mineral assemblages, mostly of rutile and zircon; in these sediments. These heavy minerals prove the origin of the sediments to be derived from the Arabian Shield. The sands are commonly medium to coarse grained, occa- sionally pebbly, yellowish pink in color, which might be derived from erosion of the Fluvial Plain (Dibdibba Formation). The erosional materials are transported by Al-Batin stream during the Pleistocene. The apex of the fan is characterized by gravelly sand, whereas its toe, near Hor Al-Hammar, has fine and friable sands [7]. The gravels form thin lenses, lenticular beds, reach up to 2 m in thickness, or randomly scattered within the sand beds. The size of the gravels varies from coarse gravels (5 - 20 cm in size), around the apex of the fan in the main channel of Wadi Al-Batin, to fine gravels and pebbles (2 - 5 cm in size), in the peripheral parts of the fans. Planar bedding, cross-bedding and gravel lag are common fluvial sedimentary structures in this fan system. The gypcrete and gypsiferous cementing material are fairly common in surface beds. The thickness of the gypcrete beds varies in average between (0.5 - 1.5) m [16].
Show more

13 Read more

Downstream hydraulic geometry of alluvial rivers

Downstream hydraulic geometry of alluvial rivers

Abstract This article presents a three-level approach to the analysis of downstream hydraulic geometry. First, empirical concepts based on field observations of ‘poised’ conditions in irrigation canals are examined. Second, theoretical developments have been made possible by combining basic relationships for the description of flow and sediment transport in alluvial rivers. Third, a relatively new concept of equivalent channel widths is presented. The assumption of equilibrium may describe a perpetual state of change and adjustments. The new concepts define the trade-offs between some hydraulic geometry parameters such as width and slope. The adjustment of river widths and slope typically follows a decreasing exponential function and recent developments indicate how the adjustment time scale can be quantified. Some examples are also presented to illustrate the new concepts presented and the realm of complex river systems.
Show more

9 Read more

Direct Contact Heat Exchange for Energy Recovery  from Hot Temperature Petroleum Refinery Streams

Direct Contact Heat Exchange for Energy Recovery from Hot Temperature Petroleum Refinery Streams

temperatures. In the recent work the heat exchanger design parameters and the heat transfer characteristics were calculated. The effect of the heating fluid inlet temperature and its mass flow rate on direct contact heat exchanger design parameters (heat exchange surface area, number of plates, number of channels per pass and pressure drop), and on rate of heat transfer were investigated theoretically throughout nine cases. The spreadsheet results of the nine investigations are summarized in table 4. The cases (from 1 to 5) are investigated at constant average temperature of kerosene (70°C), and different mass flow for kerosene ranging from (25 to 45) kg/s, while, and the cases (1 and from 5 to 9) are estimated at constant mass flow rate of kerosene (25 kg/s) and different kerosene inlet temperature range (65-97.5°C). The investigated operating parameters were correlated with the heat exchanger design parameters and the heat recovered from the heat transfer process.
Show more

10 Read more

Forest harvest effects on mercury in streams and biota in Norwegian boreal catchments

Forest harvest effects on mercury in streams and biota in Norwegian boreal catchments

Table 3 Discharge (sum, in mm) and element fluxes (Hg, MeHg, TOC, inorganic N species, totN and totP) of catchment LAE03 (reference catchment) and LAE11 (harvested catchment) as sum for[r]

43 Read more

The Effects of Bundling on Infant Temperature

The Effects of Bundling on Infant Temperature

body core temperature of newborn infants (mean age 36.2 hours [SD ± 16.7]) subjected to bundling in a warm environment.. We are not aware of any studies evaluating the effects of bundlin[r]

7 Read more

Narrative Streams

Narrative Streams

Night: Savage River It’s after 8pm and we’re camped in rainforest country by the Savage River.. The walk in was strenuous.[r]

14 Read more

Multiple Threshold Effects for Temperature and Mortality

Multiple Threshold Effects for Temperature and Mortality

The climate factors, namely the amount of precipitation, have significantly positive effects on mortality rate, which is consistent with Ebi et al. (2004). The effects of average dew point temperature on mortality rate are significantly positive, which is similar to the finding in Guest et al. (1999). Temperature variation has a significant positive effect on mortality rate, which is a similar to Applegate et al. (1981), Bull and Morton (1975, 1978), Conti et al. (2005), Ellis et al. (1973), Ellis et al. (1980), Greenberg et al. (1983), Jones et al. (1982), and Schwaetz (2000). In terms of macroeconomic conditions, real GDP per capita has a significantly negative influence on mortality rate, which indicates that higher income leads to lower mortality. Such outcomes are consistent with the findings in Breault (1988), Buckley et al. (2004), Burr (1997), Chung and Huang (2003), Gerdtham (2004), Gunnell et al. (2000), Huang and Huang (1996), Mcleod et al. (2003), Neumayer (2003), and Smith (1999).
Show more

34 Read more

The effects of temperature and size on swimming in fish

The effects of temperature and size on swimming in fish

Evolutionary adaptation of muscle power output to environmental temperature: force-velocity characteristics of skinned fibres isolated from antarctic, temperate and tropical marine fish.[r]

205 Read more

EFFECTS OF TEMPERATURE ON CROSSING OVER IN NEUROSPORA

EFFECTS OF TEMPERATURE ON CROSSING OVER IN NEUROSPORA

It has been demonstrated ( STADLER and TOWE 1962) that inbreeding results in an increase in crossing over in the asco-centromere region; a backcross to asco a of one of the [r]

7 Read more

Temperature effects in articular cartilage biomechanics

Temperature effects in articular cartilage biomechanics

Cartilage stress relaxation was faster at 60°C than at 24°C, as shown by both the normalized stress-relaxation data (Fig.2) and the 60% decrease in . Neither of the putative mechanisms of cartilage viscoelasticity (flow-dependent or flow-independent) can solely explain this observation. However, the combination of flow- dependent and flow-independent mechanisms does explain the data. Between 24 and 60°C, the viscosity of water decreases by 49% (http://webbook.nist.gov/chemistry/). Thus, faster fluid flow would predict a 49% decrease in , assuming a linear relationship between the stress-relaxation time constant and water viscosity. The remaining decrease in  may result from changes in the dynamics of the extracellular matrix biopolymers, which are predicted to be inversely proportional to the change in absolute temperature (Doi, 1995; Doi and Edwards, 1988). Absolute temperature increased by 12% in our experiments. The combination of a decrease in viscosity
Show more

7 Read more

Show all 10000 documents...

Related subjects