Geografski faktori kao determinante intenziteta erozije na primeru sliva Nišave
Geographical factors as erosion intensity determinants of the example of the Nišava river basin
Doktorand
Mustafić, Sanja Е.Mentor
Manojlović, PredragČlanovi komisije
Ducić, VladanDragićević, Slavoljub
Kostadinov, Stanimir
Metapodaci
Prikaz svih podataka o disertacijiSažetak
Erozija zemljišta zauzima sve značajnije mesto u sistemu savremenih
geografskih, geomorfoloških i interdisciplinarnih istraživanja vezanih za probleme
životne sredine. Kao globalni fenomen erozija zemljišta postaje važan faktor
kauzalnosti izmeñu prirodne sredine s jedne strane i demografskih, ekonomskih i
ekoloških aspekata razvoja odreñenog prostora s druge strane. Glavni karakter ovog
procesa je isti u celom svetu, ali je intenzitet procesa različit i zavisi od karakteristika
navedenih faktora koji na datom prostoru deluju. Shodno tome, nameće se potreba
proučavanja interaktivnog i multikolinearnog delovanja prirodne sredine i ljudske
aktivnosti na sam proces. Geografska proučavanja ove problematike predstavljaju
polaznu osnovu konkretizacije kauzalnih odnosa sredine u kojoj procesi erozije u većoj
ili manjoj meri deluju. Na taj način geografski pristup definiše determinaciju uzroka
stanja, ali i potencijalnih posledica koje proces erozije zemljišta, izazvan prirodnim i
antropogenim... faktorima, implicira na stanje i kvalitet životne sredine.
S obzirom na složenost problematike, u disertaciji je interakcija izmeñu
dominantnih fizičko-geografskih i antropogenih faktora, koji su uticali na promenu
intenziteta erozivnih procesa tokom vremena, utvrdjena na primeru sliva Nišave U tom
smislu osnovni ciljevi istraživanja su: kvantifikacija intenziteta mehaničke i hemijske
vodne erozije; prostorno-vremenska distribucija intenziteta erozije; utvrdjivanje trenda
promene intenziteta erozivnog procesa; utvrdjivanje odnosa izmedju hemijske i
mehaničke vodne erozije; determinisanje dominantnih geografskih faktora koji utiču na
intenzitet erozije zemljišta. Kako zadaci istraživanja proizilaze iz definisanog cilja
istraživanja, mogu se podeliti u više kategorija: ocena postojeće metodologije
istraživanja i koncepcijski pristup proučavanja erozije; optimizacija veličine jediničnih
polja u cilju ekonomičnog i egzaktnog utvrñivanja intenziteta erozije; numerička
diferencijacija fizičkogeografskih i antropogenih faktora; formiranje baze podataka i
njene inplementacije u GIS; statistička analiza raspoloživih podataka i formiranje
matematičkih modela koji definišu stanje intenziteta erozivnih procesa.
Imajući u vidu činjenicu da se erozijom zemljišta bave stručnjaci različitih
profila, svaka u domenu svog istraživanja koristi odgovarajuće modele i metode,
postavlja odgovarajuće ciljeve i ukazuje na složenost samog procesa. Iz tog razloga u
naučnoj i stručnoj literaturi figurira veliki broj različitih metoda i modela. Njihova
primena u prvom redu mora biti bazirana na usklañenosti samog metoda ili modela sa
stvarnim stanjem na terenu.
U metodološkom kontekstu okosnicu rada čini primena tri grupe metoda:
empirijski metod, hidrotehnički i hidrohemijski metad. Primenom empirijskog i
hidrotehnički metoda utvrdjen je intenzitet promene erozivnog procesa i promene u
pronosu nanosa za višegodišnji period osmatranja; a kombinaciija hidrotehničkog i
hidrohemijskog metada omogućila je utvrdjivanje pronosa suspendovanog i hemijski
rastvorenog nanosa u periodu neposrednih terenskih opservacija za period 2009-2010.
godina.
Kako intenzitet erozije zavisi od više faktora, u cilju diferencijacija faktora, kao i
utvrdjivanja koliki je njihov samostalni i interaktivan uticaj na promene intenziteta
erozije, u disertaciji su primenjene i druge naučne metode: metod geomorfološkog
kartiranja, metode daljinske detekcije i statističke metode. Uočavanje suštine
proučavane pojave, njenog trenda, kao i značaja diferenciranih faktora koji na nju utiču,
obradjeno je primenom korelacione analize, regresione analize, trend analize
vremenskih serija i faktorske analize. U tu svrhu korišćen je komercijalni program
Statistica 10.0, kao i Mann-Kendall test, koji pripada grupi neparametarskih statističkih
testova. Za prostorno sagledavanje stanja erozivnog procesa podaci su implementirani u
odgovarajući Geografski informacioni sistem. Izbor programskog paketa Geomedia
Intergraf omogućio je kompleksnu komparativnu analiza prostora, što je pružilo
mogućnost višestrukog modelovanja u smislu davanja različitih vrsta prospekcija, koje
mogu da odslikavaju mehaniku samog procesa erozije, ali i svih pratećih faktora koji
imaju veće ili manje dejstvo na isti.
Dalji rad podrazumeva uspostavljanje faznog postupka u cilju identifikacije
promena koje su nastale na prostoru predmetnog sliva. U prvoj fazi sagledan je opšti
trend promene intenziteta erozivnih procesa. U drugoj fazi su utvrdjeni dominantni
faktori koji su na date promene uticali. U sledećoj fazi pristupilo se analizi faktora koji
pod odredjenim uslovima mogu biti dominantni, odnosno u uslovima kada je njihov
uticaj vremenski i prostorno ograničen.
Izabrani metodološki i koncepcijski pristup i naglasak istraživanja na
posmatranje dinamike procesa erozije zemljišta u okviru prostorno-vremenske
dimenzije, rezultirao je sledećim zaključkom. Analiza fizičko-geografskih karakteristika
terena pokazala je da je prostor sliva Nišave predisponiran za pojavu intenzivne erozije.
Medjutim, uporedna analiza stanja erozivih procesa 1970. i 2010. godine pokazala je da
je došlo do smanjenja intenziteta i produkcije nanosa na prostoru čitavog sliva, dok je
trend analiza vremenskih serija, takodje, pokazala uzastopno smanjenje pronosa
suspendovanog u poredjenju sa prethodnim periodom.
Kontinuirano smanjenje produkcije i pronosa suspendovanog nanosa bilo je pod
snažnim uticajem antropogenog faktora, a delimično i klimatskih promena. Uticaj
klimatskih promena najviše se odrazio na pojavu faznog pomeranja koncentracija i
pronosa suspendovanog nanosa. Konstatovane sezonske promene u količini i intenzitetu
padavina, odrazile su se na promene u trendu proticaja, koje su ostavile posledice na
erozivni proces - došlo je do faznog pomeranja koncentracija suspendovanog nanosa od
početka leta ka početku proleća.
Rezultati analize odnosa izmedju padavinskih uslova, oticanja, koncentracija i
pronosa suspendovanog materijala ukazuju na složenu transportnu dinamiku
sedimentnog nanosa od njihovog izvora do rečnog toka. Unutargodišnja raspodela datih
varijabli pokazala je postojanje dugoročnog histerezis efekta, koji je prostorno
diferenciran kroz pojavu tri različite vrste petlji, što znači da u slivu ne postoji
jedinstven obrazac preko koga je moguće utvrditi njihovo medjusobno delovanje.
Pronos suspendovanog i hemijski rastvorenog nanosa u najvećoj meri definiše
promena u količini oticajne vode. Oba tipa rečnog nanosa posmatrana kroz hidrološku
komponentu imaju snažno izraženo sezonsko obeležje. Sliv u celini, zapravo,
karakteriše postojanje dve sezone u pronosu nanosa. Sezone su polarizovane na zimskoprolećnu
i letnje-jesenju sezonu, koje po svojim karakteristikama predstavljaju
ekstremne varijante. Definisanje odnosa izmedju suspendovanog i hemijski rastvorenog
nanosa prema količini oticajne vode pokazalo je da u periodu malih i srednjih voda hemijska erozija dominantna, dok je u uslovima povećane vodnosti mehanička vodna
erozija ta koja dominira u sumarnom pronosu. Vremenska raspodela količine oticajne
vode pokazala je da velike vode vremenski traju znatno kraće, ali se za vreme njihovog
trajanja trasportuje najveći deo suspendovanog nanosa, što ovaj tip rečnog nanosa
definiše kao ekscesivnu kategoriju.
Soil erosion occupies more and more prominent place in the system of modern
geographical, geomorphological and interdisciplinary researches related to
environmental problems. As a global phenomenon, the soil erosion is becoming an
important factor of causality between the environment on the one hand and the
demographic, economic and environmental aspects of development of a particular area
on the other side. The main character of this process is the same all over the world, but
the intensity of the process varies and depends on the characteristics of the specified
factors acting on the given area. Consequently, there is a need to study the interactive
and multicollinear influence of the environment and human activities on the process
itself. Geographical studies of this problem represent the basis of specifying causal
relations of the environment where erosion processes are more or less active. In this
way, the geographical approach defines determination of the condition causes, but al...so
the potential consequences which the soil erosion process, caused by natural and
anthropogenic factors, implies on the condition and quality of the environment.
Considering the complexity of the problem, in the thesis the interaction between
the dominant physical-geographic and anthropogenic factors, which have contributed to
the transformation of the erosion process intensity over time, is established on the
example of the Nišava Basin. In this respect, the main objectives of the research are the
following: quantification of the mechanical and chemical water erosion intensity;
spatio-temporal distribution of the erosion intensity; trend determination of changes in
the erosion process intensity; establishment of relations between the chemical and
mechanical water erosion; determination of dominant geographical factors that affect
the soil erosion intensity. As research assignments arise from the defined research
objective, they can be divided into several categories: evaluation of the existing research
methodology and conceptual approach to the erosion study; optimization of the unit
field size in order to determine a cost-effective and exact erosion intensity; numerical
differentiation of physical-geographic and anthropogenic factors; establishment of a
database and its implementation in the GIS; statistical analysis of the data available and
formation of mathematical models that define the condition of the erosion process
intensity.
Having in mind the fact that experts of various profiles deal with soil erosion,
each in the domain of his research uses the corresponding models and methods, sets the
appropriate objectives and points to the complexity of the process itself. For this reason,
in the scientific and expert literature figures a large number of different methods and
models. Their use in the first place must be based on compliance of the method or
model itself with the actual condition in the field.
In the methodological context, the framework is made by application of three
method groups: the empirical method, hydro-technical and hydro-chemical method. By
applying empirical and hydro-tecnical methods, changes of the erosion process intensity
and changes in deposit transport for the multi-year period of observation were
determined; and the combination of the hydro-technical and hydro-chemical methods
enabled the determination of silt and chemically dissolved deposit transport in the
period of direct field observations for the period 2009-2010.
As the erosion intensity depends on many factors, and in order to differentiate
the factors, as well as to determine what is their independent and interactive effect on
changes in the erosion intensity, other scientific methods were also applied in the thesis:
geomorphological mapping method, remote sensing methods and statistical methods.
Realizing the essence of the studied phenomenon, its trend, and also the importance of
differentiated factors that influence on it, was done by application of the correlation
analysis, regression analysis, trend analysis of time series and factor analysis. For this
purpose, a commercial program Statistica 10.0, and also the Mann-Kendall test, which
belongs to the group of non-parametric statistical tests, were used. For the spatial
assessment of the erosion process condition, the data were implemented in an
appropriate Geographical Information System. The choice of a software package
Geomedia Intergraph enabled a complex comparative analysis of space, offering the
possibility of multiple modeling in terms of providing various types of screening, which
may reflect the mechanics of the erosion process itself, as well as all supporting factors
that are more or less of the same effect.
Further work involves the establishment of the phase procedure in order to
identify changes that occurred in the area of the subjected basin. In the first stage the
general trend of changes in the erosion processes intensity was considered. In the
second phase, the dominant factors that influenced the mentioned changes were defined.
In the next phase, we started with the analysis of the factors which under certain
conditions could be dominant, that is, at a time when their influence was limited by time
and space.
Selected methodological and conceptual approach and research emphasis on
observations of dynamics of the soil erosion processes in the scope of a space-time
dimension, resulted in the following conclusions. Analysis of the physical-geographical
characteristics of the terrain showed that the area of the Nišava Basin was predisposed
for the intense erosion occurrence. However, the comparative analysis of the erosion
processes condition in 1970 and 2010, showed that there was a decrease in the intensity
and deposit production in the area of the entire basin, while the trend analysis of time
series also showed a consecutive reduction in the silt deposit transport compared with
the previous period.
Continuous reduction of the silt deposit production and transport was strongly
influenced by the anthropogenic factor, and partly by the climate changes. Impact of the
climate changes affected mostly the occurrence of phase shifts of the silt deposit
concentrations and transport. The identified seasonal changes in the amount and
intensity of precipitation, reflected in changes of the discharge trend, which left the
effects on the erosion process - there was a phase shift of silt deposit concentration from
the beginning of summer to the beginning of spring.
The analysis results of the relations between precipitation conditions, runoffs,
concentrations and silt deposit transport show a complex transport dynamics of
sediment deposit from their spring to the river course. Distribution within the year of the
given variables showed a long-term hysteresis effect, which was spatially differentiated
by the appearance of three different kinds of loops, which meant that there was no
single form through which it was possible to determine their interaction in the basin.
Transport of the silt and chemically dissolved deposit is largely defined by a
change in the runoff water quantity. Both types of the river deposit observed through the
hydrological component have strongly expressed seasonal characteristic. Basin as a
whole, in fact, is characterized by the existence of two seasons in the deposit transport.
Seasons are polarized in the winter-spring and summer-autumn season, which by their
performance represent extreme scenarios. Definition of the relations between the silt
and chemically dissolved deposit by the amount of runoff water showed that the
chemical erosion was dominant in the period of low and medium-sized water, while in
terms of increased water level the mechanical water erosion was the one that dominated
the summary transport. Temporal distribution of the runoff water quantity showed that
increased water level periods last much shorter, but within the course of their duration,
they transported most of the silt deposit, which this type of the river deposit defined as
the excessive category.
Fakultet:
Универзитет у Београду, Географски факултетDatum odbrane:
2012Projekti:
- Istraživanje klimatskih promena i njihovog uticaja na životnu sredinu - praćenje uticaja, adaptacija i ublažavanje (RS-MESTD-Integrated and Interdisciplinary Research (IIR or III)-43007)