Groupes fratries comme dispositifs d’accompagnement des frères et sœurs d’enfants porteurs de handicap et/ou maladie : une revue de la littérature

TL;DR: This paper propose a revue de litterature sur les groupes de parole a l'attention des freres et sœurs d'enfants porteurs de handicap et/ou maladie.

About: This article is published in Pratiques Psychologiques.The article was published on 2021-12-01 and is currently open access. It has received 4 citations till now.

Summary

1. Introduction

• Weather-driven simulation models, which link contaminant transport processes with soil hydrology, have been found to be particularly valuable for the study of diffuse pollution of water bodies arising from agricultural activities.
• This model has previously been calibrated and tested, using data from soil conductivity measurements, and from field sites instrumented to measure discharges via field drains of contaminants such as phosphorus, ammonium and E.coli micoorganisms (McGechan et al., 2002; McGechan, 2002; 2003a).
• The calibration measurements were very demanding in resources, but there are further opportunities for exploiting the model in scenario tests using long periods of weather data and for a field situation which differs slightly from that at the calibration sites.
• This study describes such scenario tests representing outwintering of beef and dairy cows in ‘sacrifice fields’, a practice which is becoming more common as a low cost alternative to providing and maintaining winter housing for livestock, but which is causing concerns about environmental pollution implications.
• This required some adaptations to the normal procedures where a uniform field is represented in MACRO simulations, to represent a field with a small area of severely damaged soil where animals congregate in wet winter conditions.

2.1. Description of problem

• Livestock systems pose a risk of water pollution by contaminants such as nitrates, ammonium, phosphorus and pathogens (Hooda et al., 2000).
• In general, grazing livestock tend to spend a proportion of their time congregating in certain areas of a field such as around gates, feeders, drinking troughs or where there is shelter from wind or rain.
• Also, a high proportion of the daily excretion of urine and faeces is deposited in the poached area.
• The only route by which water can move is by surface runoff to a less compacted strip at the periphery of the poached area, where the heavily contaminated water can infiltrate the soil surface.
• In comparison with the outwintering situation where excretion takes place directly onto the soil surface at a time and under conditions conducive to high losses by leaching to the drainage system, if livestock are housed during winter manure or slurry are collected for subsequent field spreading.

2.2. Through-soil transport in saturated soil

• Some simple soil hydrological models describe water movements only in the vertical direction, from rainfall infiltrating the soil surface, to the level where it is taken up by plant roots, or by deep percolation down to groundwater.
• Of particular interest is the process of ‘macropore flow’ or ‘by-pass flow’ in saturated soil where contaminants pass rapidly by the easy path around soil aggregates to field drains at a very short interval following deposition.
• The hydrological routines in MACRO are similar to many other soil water models, with the tension (water release) and hydraulic conductivity relationships for specified layers in the soil profile represented by mathematical functions, enabling Richards’ (1931) equation to be solved at successive timesteps.
• All simulations with MACRO require records of historic precipitation and other weather variables required to estimate evapotranspiration.
• Calibrated simulations with the special colloid version of MACRO and inorganic phosphorus as the contaminant (McGechan et al., 2002; McGechan, 2002) were similarly tested against drained plot field measurements following slurry spreading at a site near Dumfries (Hooda et al., 1999).

3.1. Field sites

• The outwintering project with which this modelling study is associated involved field observations at four sites in England, plus one in Wales and one in Scotland.
• Observations at the sites during two winters were records of cow numbers, dates of the beginning and end of the outwintering period in the sacrifice fields (Table 1), type and location of feeders, feedstuffs in the feeders, as well as assessments of the state of ground in different parts of the grazing fields.
• The procedure for putting silage bales into the feeders differed between the sites.
• Whenever a new bale was unwrapped, a feeding ring was placed over the top, having been moved from the previous unwrapped bale position.
• The most detailed and useful information was obtained from at the Scottish and Welsh sites, representing the two options regarding a static or moving feeder.

3.2. Observations at the Scottish field site

• Periodic visits were made to the Scottish field site (at Easter Howgate, near Edinburgh) over the outwintering periods in both winters, when qualitative observations were made about the state of the ground, and photographs were taken.
• Surrounding this seriously compacted area was a peripheral zone with patches of seriously compacted ground including water-filled hoofprints and some patches of deposited faeces, but with an area with standing grass and little damage between the patches.
• The radius of the outer boundary of the seriously compacted area was estimated at 5m, and of the outer boundary of the peripheral zone at 30m.
• Observations, supported by photographs, about the locations of the cows indicated that their time was divided roughly half-and-half between the damaged area near the feeder and the undamaged parts of the field away from the feeder.

3.3. Detailed assessment of poaching at Welsh field site

• A procedure for assessing the extent of poaching in different parts of a field after outwintering has been described by Barnes et al. (2015).
• The procedure was applied at all six sites in the project, but was most relevant where the feeder was moved to different locations over the winter such as at the Welsh site (at Trawsgoed, near Aberystwyth).
• At this site, the field had been divided into two, with a ‘sacrifice area’ with outwintered dry dairy cows, and a control area with no cows.
• After the winter grazing period, in the grazed and control parts of the field, visual assessments supported by photographs were made during site visits using a grid with 40 x 40 m divisions of the area, to give an average degree of poaching in each grid square.
• In practice, the most useful information for the simulation study was the size of a small circle with a radius of about 5m with over 80% poaching around each feeder position.

3.4. Weather data

• Recorded daily meteorological variables were obtained for precipitation, temperature, radiation and windspeed at Trawsgoed and Easter Howgate, near to the Welsh and Scottish experimental sites.
• In addition, hourly precipitation had been recorded for another location near Easter Howgate.
• A disaggregation procedure associated with the MACRO model was used to generate synthetic hourly precipitation data from the daily records at Trawsgoed.

4.1. Deposition of contaminants by excretion

• Assumptions about quantities and concentrations of liquid, nitrogen and phosphorus deposited by excretion for a single cow were based on various literature values.
• Derived daily quantities and concentrations are listed in Table 3, assuming that the total volume of slurry is made up of a 78% contribution from urine plus 22% from faeces, as assumed for dairy cows by Lantinga et al,.(1987).
• For the current modelling study, the quantities and composition of inorganic phosphorus deposited shown in Table 3 were assumed, with the adjustment of 62/142 as the model works with P rather than P2O5 vales..
• A higher value of 5.1 g/l than that listed in Table 3 was assumed for the N concentration in deposited urine.

4.2. Hydrology of field sites

• Hydrological parameters for two soils (Table 4) are based on measurements from which the MACRO model had previously been calibrated.
• For the sandy loam soil at the Scottish site were based on those for a nearby site with the same soil type.
• For the silty clay loam soil at the Welsh site, these were based on those for a site with a similar soil type at the Crichton Royal Farm near Dumfries (McGechan et al., 2002).

4.3. Subdivision of fields into zones for a static feeder

• For a situation with a static feeder, such as at the Scottish experimental site, the approach was to subdivide the field into three areas (designated as Zones 1, 2 and 3), with separate simulations for each (Fig. 1).
• It was necessary to simplify the subdivision of field areas from the situation observed in the field (as described in Section 3.2), by considering the small patches of damaged ground further away from the feeder to be added to the central completely damaged area, and described as ‘Zone 1’.
• The area of Zone 2 will vary in proportion to the rate of runoff from Zone 1, dropping to zero in hours with no such runoff.
• Zone 2 is considered to be completely saturated, leading to macropore contaminant transport as described in Section 2.2.
• Zone 3 is the remaining area which is like a grazed field with a stocking density lower than the average for the whole field.

4.4. Simulations for Zone 1

• For MACRO simulations, all measured conductivity values were reduced by a factor of 1000 to represent soil which is compacted by cows’ hooves so no infiltration occurs.
• The same form of dynamic equation for runoff from a surface pool (but with no ‘puddles’) has been assumed in hydrological models such as MACRO and SOIL (Jansson, 1991).
• A rate coefficient of 0.2 /h was assumed for this equation, again similar to that in the MACRO and SOIL models.
• Concentrations of ammonium, colloids and phosphorus in the surface pool and in the runoff water leaving the pool are adjusted each hour, taking account of additions by excretion and substance removal in runoff.
• Excretion took account of the stocking rate in Zone 1 being higher than the average for the whole field (Table 1).

4.5. Simulations for Zone 2

• MACRO simulations were carried out for Zone 2 with a constant hourly infiltration rate, resulting from a constant hourly value of the ‘rainfall’ input driving variable.
• The size of Zone 2 was varied in relation to the runoff from Zone 1 to give an infiltration rate which maintains saturated conditions but without runoff in Zone 2.
• By trial and error, ‘rainfall’ rates (representing the saturation infiltration rate of the particular soil profile) of 2.0 mm/h with the sandy loam soil or 1.8 mm/h with the silty clay loam soil were found to maintain these conditions.
• In hours with no runoff from Zone 1, the area of Zone 2 was set to zero.
• Use was made of the facility in MACRO to specify the contaminant concentration in rainfall to indicate the quantity of ammonium, phosphorus or colloids being applied in this zone.

4.6. Simulations for Zone 3

• The procedure for MACRO simulations for Zone 3 was as it would have been if cows had been spatially distributed evenly throughout the field, but with a reduced stocking density.
• Again, use was made of the facility in MACRO to specify the contaminant concentration in rainfall to indicate the quantity of ammonium or phosphorus being applied in this zone.

4.7. Adaptation of simulation procedure for a moving feeder location

• The three-zone representation in the simulation procedure was adapted to represent the situation where the feeder location changed periodically during the outwintering period.
• In the first instance, a hypothetical scenario was set up for the Scottish site assuming that the feeder would be moved twice, to give three equal-length sub-periods.
• This required that Zones 1 and 2 would be each divided into three sub-zones in the spreadsheet calculations, each Zone 1 sub-zone having an area 7.5% of the total field area.
• The second and third sub-zones during the first sub-period and the third sub-zone during the second sub-period would receive low levels of excreted contaminants similar to Zone 3, and have soil conditions as in Zone 3.
• Analysis of the poaching records from the Welsh site with squares of approximately 40m side indicates high levels of poaching in each of three squares where the bales were located; poaching was at an intermediate level in squares adjacent to those with the bales and at a much lower level in squares well away from the bales.

4.8. Simulation sites, periods and scenarios representing outwintering experiments

• MACRO simulations were carried out for winters 2009-10 and 2010-2011, for both the Welsh and Scottish sites with the numbers of cows and the periods in the fields as recorded at each site (Table 1).
• A fixed location feeder was assumed for the Scottish site, and a moving location feeder, approximated by the procedure described in Section 4.7, was assumed for the Welsh site.
• By way of a scenario test, further simulations were carried out for the hypothetical situations of a fixed location feeder at the Welsh site, and a feeder moved to three locations in three equal length sub-periods at the Scottish site.
• In every case, daily and cumulative contaminant flows through the field drains for the whole field were calculated by combining simulated results from each of the zones or subzones, weighted according to the area of the zone or sub-zone.
• In general, the largest contribution was found to come from Zone 2 or its sub-zones.

4.9. Scenario simulations over 10 years’ weather

• A further set of scenario simulations was carried out to investigate the effects of weather variability between winters.
• In every case, it was assumed that a group of beef cattle with assumptions about excretion would be identical to that in the winter 2009-10 at the Scottish (Easter Howgate) experimental site.
• Simulations were carried out in each case for 10 winters (2001-02 to 2010-11), two weather sites (Trawsgoed and Easter Howgate), two soil types (sandy loam and silty clay loam), and both for a static feeder and a moving feeder.

5.1. Simulations for the field sites and experimental periods

• Daily losses of both contaminants for the second winter at the Welsh site are shown in Fig.
• This illustrates the event-driven nature of these losses, which rise to high levels during rainfall events but drop to zero during dry periods.
• Some surface runoff also occurred during this event Ammonium losses during the first winter at the Welsh site and during both winters at the Scottish site were somewhat lower, as were losses of phosphorus during the first winter at the Welsh site.
• Differences in loss levels between sites must be partially accounted for because of the different animal types at each site with different assumed values for their excreta quantities and composition.

5.2. Testing alternative feeder position scenarios

• Alternative scenarios of moving the feeder periodically during the winter at the Scottish site, and of a static feeder at the Welsh site, (as described in Section 4.7 and 4.8), were tested in simulations.
• In each case slightly lower losses were found for the actual situation at each site, ie a fixed location feeder at the Scottish site and the moving feeder at the Welsh site.
• Variability between years was much higher for phosphorus with a standard deviation roughly half the mean value, than for ammonium with a standard deviation around one fifth of the mean.
• Furthermore, for phosphorus with the hypothetical situations where soil type and weather site were reversed compared to the actual situation at the experimental sites, losses appeared to be significantly higher for the fixed compared to the moving feeder.
• The large differences for phosphorus in particular between sites where actual conditions at the experimental sites were considered were not born out in these scenario comparisons where the same animal type and length of outwintering period was assumed in every case.

5.4. Comparison of results with those in previous diffuse pollution studies

• In order to assess whether the pollution levels indicated by the simulated results should be of concern, it is interesting to make comparisons with pollution levels indicated by the previous studies in which the MACRO model had been calibrated and tested.
• Simulated losses for an outwintering period are generally at a similar level to those for a slurry spreading operation, although the cumulative phosphorus loss for the second winter at the Welsh site (Fig.4) was around three times as high as that for the worst slurry spreading operation.
• Hooda et al., 1999 measured inorganic phosphorus losses of 1.27-1.34 kg/ha/year, from fields cut for silage followed by grazing by sheep and dairy cows, and also receiving intensive cattle slurry inputs; these figures rose to 1.69-2.03 kg/ha/year where mineral phosphorus had been applied at 25 kg/ha in addition to manure or slurry.
• Since there was no adequate description of the river system in the catchment at the Welsh site, a simpler approach was adopted by comparing ammonium loads in kg/day taking account of the flow rates in the stream and of the area of the field (Fig.5).
• The justification for the predictions of high losses during wet weather periods can only be from previous studies with the MACRO model where predicted losses were tested against continuous measurements at fully instrumented experimental sites.

5.6. Implication of results for particulate contaminants in general

• In a previous study (McGechan and Vinten, 2003), the special colloid transport version of MACRO, as used in the current study to describe transport of particulate inorganic phosphorus, was used to describe transport of E.coli microorganisms.
• Simulated losses of Ecoli via field drains following slurry spreading in winter were found to be good fits to losses measured at a fully instrumented field site.
• Since both microorganisms and inorganic phosphorus are particulate contaminants excreted in livestock faeces, this implies that outwintering is likely to lead to water discharged to water bodies via field drains being contaminated by microorganisms including E.coli.

6. Conclusions

• A model of contaminant transport previously applied to spatially uniform field with field drains (tile drains) has been adapted to a situation where there are large variations in both inputs and surface conductivities in different zones of the field.
• It is an example of an opportunity for exploiting a model in scenario tests using long periods of weather data and for a field situation which differs slightly from that at the calibration sites.
• This study suggests that outwintering of beef and dairy cows on fields with field drains will lead to significant levels of water body pollution by ammonium and phosphorus, and probably also by other particulate contaminants including microorganisms such as E.coli.
• Such pollution arises due to rapid transport of components of deposited excreta to field drains through macropores in saturated soil during or after rainfall.
• There is little or no benefit in moving a feeder to different locations periodically over the winter, as simulated pollution levels appeared to be very similar with a moving feeder compared to a static feeder.

Frequently asked questions

Q1. What have the authors contributed in "Groupes fratries comme dispositifs d’accompagnement des frères et sœurs d’enfants porteurs de handicap et/ou maladie : une revue de la littérature support groups for siblings of children with disabilities and/or illnesses: a review of the literature" ?

This paper is aiming to a literature review on support groups for siblings of children with disability or illness. After describing the diversity of the sibling groups ' methodological/theoretical frameworks and approaches, their functioning and objectives, a comparative analysis of the benefits they provide is carried out according to whether they concern any type of disability/disease or focus on ASDs. 

Q2. What is the purpose of the entretien?

Dans une visée de recherche, un formulaire de consentement est demandé précisant les conditions du dispositif (volontariat, liberté, respect, confidentialité, respect de soi et des autres). 

Q3. What is the process of putting a group in place?

La procédure de mise en place de groupes fratries est décrite à travers les différentsarticles selon les étapes suivantes : une phase de recrutement avec ou sans entretien préalable à l’entrée dans le groupe, la mise en œuvre des séances, une phase d’évaluation des effets de la participation aux groupes.