FACTORS AFFECTING MIGRATION FROM THE CROATIAN RURAL AREA

U radu se daju rezultati istraživanja migracija u seoskom području Republike Hrvatske. Cilj je istražiti čimbenike koji utječu na iseljavanje seoskog stanovništva Republike Hrvatske. Istraživanje je provedeno 2007. godine na uzorku od 914 ispitanika dobi od 24 do 45 godina u seoskom području Republike Hrvatske. Odabir naselja i ispitanika bio je slučajan. Provedeno istraživanje pokazuje da su najveće poteškoće života u hrvatskom seoskom području gospodarske naravi, manjak zaposlenja, slaba mogućnost izbora zanimanja i niža zarada u odnosu na zaposlenje u gradu. Petina ispitanika nije zadovoljna uvjetima seoskog života i namjerava se iseliti. To je zabrinjavajući pokazatelj budući da se radi o populaciji koja je u pravilu završila proces obrazovanja i većinom osnovala obitelj. Najviše mogućih iseljenika, što je bilo i za očekivati, je iz gospodarski nerazvijenih područja Republike Hrvatske. Daljnja depopulacija hrvatskog sela bila bi pogubna, a njene najveće posljedice bile bi: prevelika urbanizacija, posebice velikih gradova, daljnji neravnomjerni razvitak Republike Hrvatske te nedovoljno iskorištenje prostornog, proizvodnog i ljudskog potencijala. S obzirom na strateški cilj ulaska Republike Hrvatske u Europsku uniju, navedeno predstavlja bitno ograničenje njene uspješne prilagodbe europskoj ekonomskoj integraciji. Iseljavanje seoskog pučanstva može se spriječiti prvenstveno povećanjem zaposlenosti i dohotka te stvaranjem takve fizičke i društvene infrastrukture u seoskom području koja će bitno poboljšati životne uvjete seoskog pučanstva. Seoska područja, poglavito gospodarski nerazvijena, nemaju dovoljno vlastitih mogućnosti za ubrzanje razvoja odnosno za nužno smanjivanje razlika u kakvoći življenja prema gradskim područjima. Zbog toga je nužno da njihov razvojni proces više nego dosada potpomogne Država osmišljenim mjerama regionalnog razvoja, uz svekoliku potporu lokalne uprave i samouprave. U tome bi svoj znatan obol trebalo dati novo-osnovano Ministarstvo za regionalni razvoj.The paper presents results of the research study on migrations in rural areas of the Republic of Croatia. The aim was to determine factors influencing migrations of rural population in Croatia. The research was carried out in 2007 on 914 respondents from 25 to 45 years of age. The rural communities and respondents were selected on a random basis. The study results indicate that the major difficulties in rural life in Croatia are of economic nature: lack of employment opportunities, inadequate choice of profession and lower income in comparison with employment in urban areas. One fifth of the respondents is not satisfied with conditions of rural life and intends to leave villages. This is a very disturbing indicator, since it refers to population, which in general, has finished education and started a family. As we expect, the largest number of potential migrants comes from economically underdeveloped Croatian areas. Further depopulation of Croatian villages would have dramatic effects, and the worst consequences would be excessive urbanization, especially of large cities, further uneven development of the Republic of Croatia, and insufficient utilization of spatial, production and human resources. Since the strategic Croatian goal is to become a member of the European Union, this is a major obstacle to its successful adjustment to the European economic integration. The migration of rural population could be prevented primarily by increase in employment and income opportunities and creation of such physical and social infrastructure in rural areas that would considerably improve living conditions for rural population. The rural areas, particularly underdeveloped, have no adequate capacities for intensification of its development and diminishing differences in their quality of life compared to urban areas. Thus, the state support is increasingly required by introducing measures of regional development with complementary support of the local government. The newly founded Ministry of Regional Development is therefore inevitable in this process

Anisotropic and non linear effect on crystal morphology of precipitated chiral molecules as a function of the supersaturation and the optical purity

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The effect of wave-induced turbulence on intertidal mudflats: Impact of boat traffic and wind

Semi-diurnal and fortnightly surveys were carried out to quantify the effects of wind- and navigation-induced highenergy events on bed sediments above intertidal mudflats. The mudflats are located in the upper fluvial part (Oissel mudflat) and at the mouth (Vasiere Nord mudflat) of the macrotidal Seine estuary. Instantaneous flow velocities and mudflat bed elevation were measured at a high frequency and high resolution with an acoustic doppler velocimeter (ADV) and an ALTUS altimeter, respectively. Suspended particulate matter concentrations were estimated by calibrating the ADV acoustic backscattered intensity with bed sediments collected at the study sites. Turbulent bed shear stress values were estimated by the turbulent kinetic energy method, using velocity variances filtered from the wave contribution. Wave shear stress and maximum wave–current shear stress values were calculated with the wave–current interaction (WCI) model, which is based on the bed roughness length, wave orbital velocities and the wave period (TS). In the fluvial part of the estuary, boat passages occurred unevenly during the surveys and were characterized by long waves (TS450 s) induced by the drawdown effect and by short boat-waves (TSo10 s). Boat waves generated large bottom shear stress values of 0.5Nm-2 for 2–5 min periods and, in burst of several seconds, larger bottom shear stress values up to 1Nm-2. At the mouth of the estuary, west south-west wind events generated short waves (TSo10 s) of HS values ranging from 0.1 to 0.3 m. In shallow-water environment (water depth o1.5 m), these waves produced bottom shear stress values between 1 and 2Nm-2. Wave–current shear stress values are one order of magnitude larger than the current-induced shear stress and indicate that navigation and wind are the dominant hydrodynamic forcing parameters above the two mudflats. Bed elevation and SPM concentration time series showed that these high energy events induced erosion processes of up to several centimetres. Critical erosion shear stress (tce) values were determined from the SPM concentration and bed elevation measurements. Rough tce values were found above 0.2Nm-2 for the Oissel mudflat and about 1Nm-2 for the Vasiere Nord mudflat. These results demonstrate the advantages of combining the measurement of instantaneous velocity and bed elevation to determine in situ the erosion and deposition processes as a function of bottom shear stress variations

Morphological responses of an estuarine intertidal mudflat to constructions since 1978 to 2005: The Seine estuary (France)

International audienceSince 1834 the Seine estuary (France) has been the site of numerous construction projects with the aim to accommodate and secure boat traffic. Since 1978, the increasing of the activities of Le Havre port, located at the mouth of the estuary, has accelerated the construction work rate. Several dykes, a bridge, and new port facilities have been constructed in rapid succession, modifying considerably the hydrodynamic conditions which sustain a partially vegetated sandy–muddy tidal flat located in the North bank of the estuary between the new port of Le Havre and the Normandy bridge achieved in 1995. The present study deals with the morphological evolution of this zone from 1978 to 2005. The use of a low altitude remote sensing technique combined with traditional methods of ground survey and probes allow to demonstrate the impact of human activities on sedimentary and vegetation dynamics. The Northern mudflat of the estuary is the most affected by these human activities, which surface have reduced of 62% during the last 27 years with an intensified local erosion during the last 27 months corresponding to a loss 1250 000 m3 of fine-grained sediment. At the same time, the general sanding up in the channel of the zone has caused a loss of more than 31% of the tidal prism, more than three quarters of which occurred during the last three years. Results also establish that the response times of the sedimentary or topographic readjustment to an installation depend on the extent and the nature of the construction. In fact, the sedimentary readjustments to an installation can be delayed by up to 10 years in the case of the Seine estuary. This delay is explained by a rapid succession of construction works which may occult the effect of a single installation. Except in the case of a dyke built perpendicular to ebb and flood currents, the impacts of these installations reach a hydrosedimentary equilibrium on the level between 1 and 7 years after their completion

Behaviour of a floc population during a tidal cycle: Laboratory experiments and numerical modelling

International audienceAn approach combining laboratory experiments and numerical modelling was used to investigate the behaviour of a floc population during an idealized tidal cycle. The experiment was conducted on suspended sediments at a concentration of 93 mg l 1 collected in the field. It was based on a jar test device to reproduce tidal-induced turbulence and coupled with a CCD camera system and image post- processing software to monitor floc size distribution. At the same time, a 0D size-class based aggregation/fragmentation model (FLOCMOD) was developed to simulate changes in the floc population over the tidal cycle. Experimental results revealed strong variability of the behaviour of microfloc and macrofloc populations with respect to the varying shear rates observed in situ. In particular, the major dependency of floc sizes on the Kolmogorov microscale was confirmed. Time-scale differences were also observed for aggregation and fragmentation processes which led to asymmetrical floc behaviour despite symmetrical tidal forcing. Model results, i.e. average diameter, maximum diameter and floc size distribution, were in good agreement with experimental data with an RMS error between observed and computed average diameters of below 25 mm over the tidal cycle. FLOCMOD was optimized in terms of the time step, number of size classes and size range: only seven classes ranging from 50 to 643 mm associated with a dynamically-adaptable time step were needed to correctly reproduce experimental results, characterized by an RMS error of less than 5 mm with respect to the reference case (100 classes from 4 to 1500 mm). Sensitivity analyses were performed on major parameters or processes: initial floc size distribution, primary particle size, fractal dimension and fragmentation function (binary, ternary, erosion or collision-induced fragmentation). Results showed that initial floc size distribution played a role only during the first aggregation stage. Low variability of the fractal dimension did not significantly modify model results, while larger differences were observed when the primary particle size was changed, especially towards the largest sizes (10 mm). Nevertheless, these two structural parameters had a strong impact on the calculated mean settling velocity with differences of 0.2 mm scompared with the reference case. Different fragmentation functions were shown to significantly modify model results, except for collision-induced shear stress. In particular, combining floc erosion with binary breakup in the shear fragmentation term enabled us to reproduce bimodal distributions, patterns that are typically observed in situ

A differentiation method for separating a mixture of suspended particle size distributions

International audienceA simple method is proposed to partition a mixture of two populations in suspended particle size data. The method, termed here "the differentiation method" is based on the function of the lognormal distribution. Suspended material in marine or estuarine situations often consists of difficult-to-interpret complex populations. The treatment of particle size data by the method described enables the confirmation of the lognormal law and also the demonstration of the occurrence of a combination of a number of populations which may not be distinguished by the classical Gaussian transformation or automatic methods. A simple combination of graphical and numerical techniques permits the decomposition and the easy determination of the various statistical parameters (median diameter, mean diameter, etc...). The method is applied to interpret observed size distributions of suspended particulate matter in the Seine estuary. The method enables the determination of the relative sizes of the constituent sub-populations that comprise the total suspended matter. In the example used to illustrate the method, particles are shown to be resuspended as a function of different hydrodynamic parameter

Glacial, fluvial, coastal and offshore cascading-system to assess deglaciation in a polar environment, a case study in the Kongsffjorden area, Svalbard

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Galactofuranosidase – thioglycoligase potency for thiogalactofuranoside synthesis

International audienc