Recent Advances in Energy, Environment, Biology and Ecology
The impact of climate changes on water balance from western Romania
using computer tools
HALBAC-COTOARA-ZAMFIR RARES
Hydrotechnical Engineering Department
“Politehnica” University of Timisoara
nd
2 Victoriei Square, 300006, Timisoara, Timis
ROMANIA
[email protected]
Abstract: - Global climate is changing and the impacts on water resources can be hardly predicted. Climate
change creates variations in water storage and fluxes at the land surface, in storage in soil moisture and
groundwater, seasonal snow packs; wetlands and reservoirs, precipitation, runoff and evapotranspiration.
This paper will use a program to analyze the impact of climate changes on water balance from western
Romania using as input data temperature and precipitation values for a period of 30 years.
Key-Words: climate changes, water, Romania, water balance
high plain regional climate, hills regional climate
and mountains regional climate [1].
The annual average temperatures presents
variability depended on the relief forms, with values
from 4º - 7ºC (in mountain areas) to 10º - 11ºC.
During spring and summer, the dominant air masses
are temperate type of oceanic provenience and they
bring the most important contribution regarding
precipitation volume. In this sense, an obvious
example is the flooding from 2005. The cyclones
and warm air masses influence from Adriatic Sea
and Mediterranean Sea are felt especially during
winter by the frozen and solid precipitation missing
while during summer are periods with extreme hot
temperatures [2].
The precipitation regime has an irregularly
character, with wetter years than the average
followed by years with very few precipitations.
1 Introduction
Climate changes are alterations on long-term of
weather components as temperature, precipitation
etc. Generally, when we discuss about the impact of
climate change, we firstly talk about water. Water is
a vital component of our environment, society and is
one of the main components of climate changes.
The impact of climate change on water is
undeniable and is experienced most directly on
water availability. Perhaps the most visible direct
impacts of climate change on water, relentless in
expression and covered area, are land degradation
and floods.
2 Climate change influences in water
balance
The water balance plays a key role in the
interactions between climate and biosphere. Water
balance, which includes elements as precipitation,
runoff, evapotranspiration will not remain
unaffected by these shifts induced by climate
change. Climate change alters precipitation patterns
leading to fundamentally differences in comparison
with a past situation. Evapotranspiration also
presents variations across a landscape due to
temperature, humidity, wind and vegetation cover.
3 Climate in Western Romania
For Timiş County, characterized by a moderated
continental temperate climate with Mediterranean
influences, and with periods in which the climate in
unpredictable, were identified 4 major regional
climates as it follows: low plain regional climate,
ISBN: 978-960-474-358-2
Fig. 1 Geographical map of studied area [3]
The analyzed area covers the Aranca River’s
hydrographic basin, a plain area having a slope
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- Calculation of linear regression, non-linear, simple
and multiple regression and polynomial;
- To assess whether a data series fits to a series of
distributions: normal, log-normal, gamma, logPearson Type III, Gumbel and log-Gumbel. If the
data set fits a distribution, to calculate such flows or
design rainfall with a return period or given a
certain probability of occurrence;
- Calculate from the curve of seasonal variation or
duration curve, design events with certain
probability;
- Conduct analysis and calculate storm intensities
from rain data; it also allows the calculation of the
average rainfall for the simple average method,
Thiessen polygon and isohyets;
- Calculation of maximum flow with empirical and
statistical methods;
- Calculation of evapotranspiration using
Thornthwaite, Blaney-Criddle, Penman and
Hargreaves as well as water balance calculations.
around 0.30 ‰, meaning that the plain is almost
horizontal. Aranca Plain is low subsidence plain of
meadow with microform beds and abandoned
meanders, surface drainage channels, fluvial and
anthropogenic mounds. Climate falls under
temperate continental climate with mild winters and
significant amounts of rainfall. The summer is
defined by unstable weather with showers and
thunderstorms. The hydrography of the analyzed
area is the result of the combined action of climatic
factors, morphology and geology. The region
Aranca groundwater contributes to excess soil
water, but only up to a depth of 2 m; starting from a
2.3 m depth, the groundwater has no influence on
soil, but contributes to his water supply during
drought. The channel water supply is from
precipitation, groundwater springs and fountains of
waters. In terms of soils, we can find in this area
large surface with Chernozem, Fluvisols, Vertisols
and Pelosols [2, 3].
Climatic data (temperature and precipitation)
necessary to be used by Hidroesta program were
purchased from Sannicolau Mare.
5 Analysis of climate changes impact
on water balance using Hidroesta
The analysis was made on a 5 year step, from 1980
until 2012. The evapotranspiration values used in
calculations were obtained based on Thornthwaite
method. The results are presented in the following
figures:
Fig. 2 Hydrographic map of analyzed area [2]
4 Hidroesta
Hidroesta is a program for hydrological and
statistical calculations applied in hydrology.
Hydrological studies require substantial analysis of
hydrometeorological information; this information
may consist of rainfall data, flow, temperature,
evaporation. The data collected represent only raw
data, but if they are organized and analyzed
properly, provide the hydrologist a useful tool that
allows him to take the proper decisions. HidroEsta
is a tool that facilitates and simplifies the laborious
calculations, and the process of analyzing the wealth
of information that must be performed in
hydrological studies [4].
HidroEsta allows:
- The calculation of statistical parameters for
clustered and nonclustered data;
ISBN: 978-960-474-358-2
Fig. 3 Water balance for Sannicolaul Mare (1980)
area obtained with Hidroesta
Fig. 4 Water balance for Sannicolaul Mare (1985)
area obtained with Hidroesta
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Fig. 5 Water balance for Sannicolaul Mare (1990)
area obtained with Hidroesta
Fig. 9 Water balance for Sannicolaul Mare (2010)
area obtained with Hidroesta
6. U.S.G.S. model
This model analyses the allocation of water among
various components of the hydrologic system using
a monthly accounting procedure based on the
methodology originally presented by Thornthwaite.
As input data, this model requires mean monthly
temperature (T, in degrees Celsius), monthly total
precipitation (P, in millimetres), and the latitude (in
decimal degrees) of the location of interest (is
needed for the computation of potential
evapotranspiration (PET)) [5, 6, 7, 8].
Actual evapotranspiration (AET) results from
potential evapotranspiration (PET), Ptotal, soilmoisture storage (ST), and soil-moisture storage
withdrawal (STW). Monthly PET is estimated from
mean monthly temperature (T). PET represents the
climatic demand for water relative to the available
energy. PET is calculated with Hamon equation [9]:
Fig. 6 Water balance for Sannicolaul Mare (1995)
area obtained with Hidroesta
PET = 13.97 ⋅ d ⋅ D 2 ⋅ Wi
where d is the number of days in a month, D
represents the mean monthly hours od daylight in
units of 12 hours and Wi is a saturated water vapor
density term (g/m3). For Wi we have the following
relation [9, 10]:
Fig. 7 Water balance for Sannicolaul Mare (2000)
area obtained with Hidroesta
Wi =
where T is the mean monthly temperature in degrees
Celsius. In the situation when Ptotal for a month is
less then PET, then AET is equal to Ptotal plus the
amount of soil moisture that can be withdrawn from
storage in the soil. Soil-moisture storage withdrawal
(STW) linearly decreases with decreasing ST such
that as the soil becomes drier, water becomes more
difficult to remove from the soil and less is available
for AET. If Ptotal plus STW is less than PET, then a
water deficit is calculated as PET–AET. If Ptotal
exceeds PET, then AET is equal to PET and the
water in excess of PET replenishes ST. When ST is
greater than STC, the excess water becomes surplus
(S) and is eventually available for runoff [7, 8, 10].
Fig. 8 Water balance for Sannicolaul Mare (2005)
area obtained with Hidroesta
ISBN: 978-960-474-358-2
4.95 ⋅ e 0.062⋅T
100
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7. Results obtained with
Geological Survey model
U.S.
Fig. 14 Water balance components for Sannicolaul
Mare (1990) area obtained with USGS model
Fig. 10 Water balance components for Sannicolaul
Mare (1980) area obtained with USGS model
Fig. 15 Water balance components for Sannicolaul
Mare (1990) area obtained with USGS model
Fig. 11 Water balance components for Sannicolaul
Mare (1980) area obtained with USGS model
Fig. 16 Water balance components for Sannicolaul
Mare (1995) area obtained with USGS model
Fig. 12 Water balance components for Sannicolaul
Mare (1985) area obtained with USGS model
Fig. 17 Water balance components for Sannicolaul
Mare (1995) area obtained with USGS model
Fig. 13 Water balance components for Sannicolaul
Mare (1985) area obtained with USGS model
ISBN: 978-960-474-358-2
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Recent Advances in Energy, Environment, Biology and Ecology
Fig. 18 Water balance components for Sannicolaul
Mare (2000) area obtained with USGS model
Fig. 22 Water balance components for Sannicolaul
Mare (1985) area obtained with USGS model
Fig. 19 Water balance components for Sannicolaul
Mare (2000) area obtained with USGS model
Fig. 23 Water balance components for Sannicolaul
Mare (1985) area obtained with USGS model
7. Discussions and conclusions
First of all we should take a look at the main 2
factors used in these analyzes: precipitation and
temperatures.
Fig. 20 Water balance components for Sannicolaul
Mare (2005) area obtained with USGS model
Fig. 24 Precipitation variations for 1980-2012
Fig. 21 Water balance components for Sannicolaul
Mare (2005) area obtained with USGS model
Fig. 25 Temperature variations for 1980-2012
ISBN: 978-960-474-358-2
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bringing additional support in covering the
necessary water volumes.
Concluding on the used models, I can say that
Hidroesta is a good program for analyzing the water
balance but still needs some improvements. First of
all, this model doesn’t work with negative
temperatures which may represent a disadvantage.
On the other side, the lack of an English version (the
program has an interface in Spanish) reduce its
spread and use. U.S.G.S model is a better model
because it offers the possibility to analyze more
components of water balance, especially the runoff
values which, in agricultural sector, has a major
impact if is not managed properly. U.S.G.S. works
with both positive and negative values which offer a
better accuracy.
Fig. 26 Variation of PET and P-PET (1980-2010)
It can be observed that if the temperatures are
presenting a continuous increasing trendline,
precipitations reached a maximum volume around
2005. The period between 2000 and 2008 was a
relative rainy one which succeeds to support the
water requests from agriculture (especially) but also
from other domains. Unfortunately, in some years,
these rains were concentrated resulting in significant
flows which overrun the floodplains capacity.
After several discussions with farmers and
specialists involved in land reclamation and
improvement works, this positive precipitation
trendline is somehow a returning to a previous
situation from 1960 – 1980, when these volumes
were very important especially during summer
season for establishing a balance between plant
demands and available water resources.
The driest period is the one between 1985 and 2005.
We can consider that during these 20 years, climate
changes had the most significant impact. It can be
explained once through the existence of an
important industry activity in western part of
Romania especially from chemical sector. After
2000, many companies, big polluters, were closed.
Even the temperatures are continuing to present an
increasing trendline, the difference between P and
PET remains above the levels which we have 30
years ago.
The water balance presents, during the last 10 years,
a good improvement especially in the second half of
a year where, in the past, we had the worst situation.
For many years, precipitations were concentrated
between January and May while the autumn crops
faced water scarcity at different levels or, in some
isolated cases, heavy rains which affected their
development.
We can say that climate changes impact on water
balance from western Romania can be divided in
two periods: one between 1985 and 2005 when we
had climate conditions with aridization specific and
the second period, started after 2005 with high
temperatures but also with significant precipitations
ISBN: 978-960-474-358-2
References:
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