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Open Access Maced J Med Sci. 2020 May 15; 8(E):127-132. 127
Scientic Foundation SPIROSKI, Skopje, Republic of Macedonia
Open Access Macedonian Journal of Medical Sciences. 2020 May 15; 8(E):127-132.
https://doi.org/10.3889/oamjms.2020.4764
eISSN: 1857-9655
Category: E - Public Health
Section: Public Health Disease Control
Trend Analysis of Total Affected Water and Total Discharged
Wastewater of Nišava District (Serbia)
Nina Pavićević*
Megatrend University of Belgrade, Faculty of Management Zaječar, 19000 Zaječar, Serbia
Abstract
BACKGROUND: Water, as a natural resource, is the most basic substance of life that has immeasurable signicance
for the living world, ecosystems, and planet Earth. It is consumed by plants, animals, and humans.
AIM: We aimed to preform a trend analysis of total affected quantities of water and total discharged wastewater
(TDWW) of Nišava district (Serbia).
METHODS: In this paper, a trend analysis is given of total affected quantities of water, delivered quantities of drinking
water (DQDW), total discharged wastewater (TDWW), wastewater discharges to wastewater systems, and number
of households connected to the water supply network of Nišava district (Serbia).
RESULTS: The values for Nišava district (Serbia) for total affected quantities of water and DQDW for the period
2006–2018 and wastewater discharges to wastewater systems for the period 2009–2018 decreased, whereas
the values for Nišava district (Serbia) for TDWW for the period 2006–2018 and number of households connected
to the water supply network for the period 2007–2018 increased. The paper also provides regression models for
approximation DQDW (eq. 1) and TDWW (eq. 2) for Nišava district (Serbia) for the period 2006–2018.
CONCLUSION: Values for total affected quantities of water (×103 m³) for Nišava district (Serbia) for the period
2006–2018, they decreased from 41740 in 2006 to 9931 in 2018.
Edited by: Sasho Stoleski
Citation: Pavićević N. Trend Analysis of Total Affected
Water and Total Discharged Wastewater of Nišava District
(Serbia). Open Access Maced J Med Sci. 2020 May 15;
8(E):127-132. https://doi.org/10.3889/oamjms.2020.4764
Keywords: Natural resources; Trend analysis; Statistical
analysis; Polynomial regression model
*Correspondence: Nina Pavićević, Megatrend University
of Belgrade, Faculty of Management Zaječar, 19000
Zaječar, Serbia. E-mail: nina.pavicevic007@gmail.com
Received: 04-Apr-2020
Revised: 25-Apr-2020
Accepted: 03-May-2020
Copyright: © 2020 Nina Pavićević
Funding: This research did not receive any nancial
support
Competing Interests: The authors have declared that no
competing interests exist.
Open Access: This is an open-access article distributed
under the terms of the Creative Commons Attribution-
NonCommercial 4.0 International License (CC BY-NC 4.0)
Introduction
Natural resources (NR) are raw organic
materials or substances, which are found in nature, and
represent the general natural wealth which has usable
value and can be used for industrial production and/or
consumption [1], [2], [3], [4].
NR represents the natural wealth of a country
or region include of minerals, petroleum, natural gas,
coal, metals, stone, sand, air, sunlight, forests, land,
and water. In papers George and Schillebeeckx [5]
and George et al. [6] are given of the management of
NR and in papers Nelson et al. [7], Smith [8], Tarasyev
et al. [9], and Tarasyev et al. [10] are given of statistical
analysis of different NR.
There are NRs that are subject to depletion by
human use and that can be processed through various
production processes into a product, and thus have a
usable and economic value. Such NRs (PR) can be
subdivided into four categories: Mineral and energy
resources, soil and land resources, water resources,
and biological resources.
Based on the type of reproducibility, many NRs
are usually divided into two types [1] (Figure 1):
Renewable resources are resources that
can naturally replenish (sunlight, air, forests, wind,
water, etc.) and their consumption is slightly affected by
human consumption and
Non-renewable resources are resources
that do not naturally form in the environment or are
slowly being formed and/or renewed (land, fossil
fuels, crude oil, natural gas, coal, various types of
stone, metals, uranium, and other materials and
minerals, etc.).
On the basis of origin, NRs are divided into two
types [1]:
Biotic resources are resources obtained from
the biosphere (living and organic material such as
forests, animals, and plants), fossil fuels such as coal
Figure 1: Different types of natural resources: Renewable and non-
renewable resources
E - Public Health Public Health Disease Control
128 https://www.id-press.eu/mjms/index
and petroleum because they are formed from decayed
organic matter, etc., and
Abiotic resources are resources that come
from non-living (inanimate), non-organic material (land,
water, air, minerals, rare earth metals, and heavy
metals, including ores, such as gold, iron, copper, and
silver).
Water, as an NR, is the most basic material
of life that has immeasurable signicance for the
living world, ecosystems, and planet Earth. Water is
constantly circulating in nature between the Earth and
the atmosphere, and at the same time, enables life to be
maintained. Water moves, changing its appearance, but
it never really disappears. The water that is consumed
has been on Earth for hundreds of millions of years. It is
consumed by plants, animals, and humans.
The most important characteristic of water is its
quality, which is assessed by the so-called water quality
index (WQI). Analysis of WQI index in different regional
territories is presented in the following papers Aščić and
Imamović [11], Bordalo et al. [12], Egborge and Benka-
Coker [13], Elezović et al. [14], Selvam et al. [15], and
Von der Ohe et al. [16], WQI index as management tool
is given in paper Ferreira et al. [17], and as classication
tool is given in papers Boyacioglu [18] and Kannel
et al. [19], for water quality is given in papers Gupta
et al. [20] and Kaurish and Younos [21], for prediction of
WQI index is given in paper Rene and Saidutta [22], etc.
In paper is given a trend analysis of total
affected quantities of water and total discharged
wastewater (TDWW) of Nišava district (Serbia).
Data and Methods
Data on values of total affected quantities of
water, TDWW, etc., of Nišava district (Serbia), are taken
from “Municipalities and Regions in the Republic of
Serbia” of the Statistical Ofce of the Republic of Serbia
for the period 2006–2018 [23], [24], [25], [26], [27], with
signicant calculations by the authors.
In the Nišava district, the following municipalities
are (Figure 2): Niš, Aleksinac, Gadžin Han, Doljevac,
Merošina, Ražanj, and Svrljig.
The total area for Nišava district in 2018 is
2728 km2. Population in Nišava district in 2002 is 381757
(of these men are: 187780 and the woman is: 193977)
and in 2018 is 362331 [27], which is less for 19426 or
compound annual growth rate (CAGR)=−0.33% and
cumulative growth index (CGI)=94.91%.
In 2018, the total number of employees
registered was 106931 (of these men: 55063 and the
women: 51868), while the number of employees per
1000 population was 295.
For the trend analysis, we used the following
parameters: AGR, CAGR, and CGI described in the
papers Dašić [28], Dašić et al., [29], Tošović et al., [30],
Turmanidze et al., [31], etc.
Standard statistical analysis methods and
MS-Excel software system were used to calculate
the statistical descriptions parameter, graphical
representation of data, and approximation of the total
affected quantities of water and TDWW for Nišava
district (Serbia) [32], [33], [34].
Results and Discussion
In Table 1, data are given about total
affected quantities of water, delivered quantities
of drinking water (DQDW), TDWW, wastewater
discharges to wastewater systems, and number of
households connected to the water supply network
for Nišava district (Serbia) for the period 2006–
2018 [23], [24], [25], [26], [27].
Trend analysis for total affected quantities
of water (×103 m³) for Nišava district (Serbia) for the
period 2006–2018 is shown in Figure 3.
The data about total affected quantities of
water (×103 m³) for Nišava district (Serbia) for the
period 2006–2018 changed in intervals from 5783 to
41740, with arithmetic mean AM=25771.85 and median
is Med=37782. Standard deviation is SD=15831.5 and
coefcient of variation is CoV=61.43.
Figure 2: Map of Nišava district
Pavićević. Trend Analysis of Total Affected Water and Total Discharged Wastewater of Nišava District (Serbia)
Open Access Maced J Med Sci. 2020 May 15; 8(E):127-132. 129
Values of trend analysis are CGI=23.79% in
2018 compared to 2006 and CAGR=−8.58% per year
for the period 2006–2018.
Trend analysis for DQDW (×103 m³) for Nišava
district (Serbia) for the period 2006-2018 is shown in
Figure 4.
Figure 4: Trend analysis for delivered quantities of drinking water
(×10 3 m³) for Nišava district (Serbia) for the period 2006–2018
The data about DQDW (×103 m³) for Nišava
district (Serbia) for the period 2006–2018 changed in
intervals from 19805 to 25418, with AM=22686.46 and
Med=23018. Standard deviation is SD=1541.88 and
CoV=6.80.
Values of trend analysis are CGI=85.81% in
2018 compared to 2006 and CAGR=−0.95% per year
for the period 2006–2018.
The data about DQDW (×103 m³) for Nišava
district (Serbia) for the period 2006–2018 can be
approximated using a linear regression model (LRM)
which has the form (Figure 5):
Figure 5: Approximated delivered quantities of drinking water
(×10 3 m³) for Nišava district (Serbia) for the period 2006–2018 using
linear regression
DQDW=649634.51–311.60×y (1)
With coefcient of correlation is R=0.7870,
coefcient of determination is R2=0.6194.
Where: y–year and DQDW–DQDW (×103 m³).
Trend analysis for TDWW (×103 m³) for Nišava
district (Serbia) for the period 2006–2018 is shown in
Figure 6.
The data about TDWW (×103 m³) for Nišava
district (Serbia) for the period 2006–2018 changed in
intervals from 15964 to 22669, with AM=19516.69 and
Med=19411. Standard deviation is SD=2310.23 and
CoV=11.84.
Values of trend analysis are CGI=104.19% in
2018 compared to 2006, and CAGR=0.26% per year
for the period 2006–2018.
The data about TDWW (×103 m³) for Nišava
district (Serbia) for the period 2006–2018 can be
approximated using 6th-degree polynomial regression
model (PRM6) which has the form (Figure 7):
Table 1: Data on water supply and wastewater for Nišava district for the period 2006–2018
Year Total affected quantities of water
(×103 m³)
Delivered quantities of drinking water
(×103 m³)
Total discharged waste water
(×103 m³)
Wastewater discharges to wastewater
systems (×103 m³)
Number of households connected
to the water supply network
2006 41740 23777 19097 -1423 (km)
2007 40536 25418 18940 - 58752
2008 38965 24214 17967 -57876
2009 37782 22982 15964 15964 58730
2010 38045 23099 16820 16820 59593
2011 40051 22918 16287 16287 60907
2012 41314 23030 22393 16661 63530
2013 8871 23018 22374 16576 62923
2014 5783 19805 19411 16046 62930
2015 10378 23306 22669 17181 63391
2016 10726 21775 21247 16765 63475
2017 10912 21180 20651 15887 63482
2018 9931 20402 19897 15357 63494
Figure 3: Trend analysis for total affected quantities of water (×10
3 m³)
for Nišava district (Serbia) for the period 2006-2018
E - Public Health Public Health Disease Control
130 https://www.id-press.eu/mjms/index
Figure 6: Trend analysis for total discharged wastewater (×10
3 m³) for
Nišava district (Serbia) for the period 2006–2018
TDWW=−309387888448786×105+
92237739224067200×y
−114578282688620×y2+
75909172177.8344×y3−
−28288393.7586×y4+
5622.3854×y5−0.4656×y6 (2)
Figure 7: Approximated (total discharged wastewater) (×10
3 m³) for
Nišava district (Serbia) for the period 2006–2018 using 6th-degree
polynomial regression model
With coefcient of correlation is R=0.8515,
coefcient of determination is R2=0.7251.
Where: y–year and TDWW–TDWW (×103 m³).
Trend analysis for wastewater discharges
to wastewater systems (×103 m³) for Nišava district
(Serbia) for the period 2009–2018 is shown in Figure 8.
The data about wastewater discharges to
wastewater systems (×103 m³) for Nišava district (Serbia)
for the period 2009–2018 changed in intervals from
15357 to 17181, with AM=16354.40 and Med=16431.5.
Standard deviation is SD=545.39 and CoV=3.34.
Values of trend analysis are CGI=96.20% in
2018 compared to 2009 and CAGR=−0.24% per year
for the period 2009–2018.
Trend analysis for number of households
connected to the sewer network for Nišava district
(Serbia) for the period 2007–2018 is shown in Figure 9.
Figure 9: Trend analysis for number of households connected to the
sewer network for Nišava district (Serbia) for the period 2007–2018
The data about number of households
connected to the sewer network for Nišava district
(Serbia) for the period 2007–2018 changed in
intervals from 57876 to 63530, with AM=61590.25 and
Med=62926.5. Standard deviation is SD=2252.67 and
CoV=3.66.
Values of trend analysis are CGI=108.07% in
2018 compared to 2007 and CAGR=0.49% per year for
the period 2007–2018.
Conclusion
Values for total affected quantities of water
(×103 m³) for Nišava district (Serbia) for the period
2006–2018, they decreased from 41740 in 2006 to
9931 in 2018 (CGI=23.79% in 2018 compared to 2006
and CAGR=−8.58% per year).
Figure 8: Trend analysis for wastewater discharges to wastewater
systems (×10 3 m³) for Nišava district (Serbia) for the period 2009–2018
Pavićević. Trend Analysis of Total Affected Water and Total Discharged Wastewater of Nišava District (Serbia)
Open Access Maced J Med Sci. 2020 May 15; 8(E):127-132. 131
Values for DQDW (×103 m³) for Nišava district
(Serbia) for the period 2006–2018, they decreased
from 23777 in 2006 to 20402 in 2018 (CGI=85.81% in
2018 compared to 2006 and CAGR=−0.95% per year).
Values for TDWW (×103 m³) for Nišava district
(Serbia) for the period 2006–2018, they increased from
19097 in 2006 to 19897 in 2018 (CGI=104.19% in 2018
compared to 2006 and CAGR=0.26% per year).
Values for wastewater discharges to wastewater
systems (×103 m³) for Nišava district (Serbia) for the
period 2009–2018, they decreased from 15964 in 2009
to 15357 in 2018 (CGI=96.20% in 2018 compared to
2006 and CAGR=−0.24% per year).
Values for number of households connected to
the sewer network for Nišava district (Serbia) for the
period 2007–2018, they increased from 58752 in 2007
to 63494 in 2018 (CGI=108.07% in 2018 compared to
2006 and CAGR=0.49% per year).
Values for DQDW (×103 m³) for Nišava district
(Serbia) for the period 2006-2018 is approximated by
LRM (eq. 1), with R=0.7870 and R2=0.6194.
Values for TDWW (×103 m³) for Nišava district
(Serbia) for the period 2006–2018 is approximated by
6PRM6 (eq. 2), with R=0.8515 and R2=0.7251.
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