Climate Parameter Uses as Indices For Assessment of Climate Change and Water Balance in Erbil Sub-Basin North –Iraq

The main goal of this study was to assess the climatic parameters in a valuable basin in northern part of Iraq, Erbil central sub-basin. Rainfall, relative humidity, temperature, evaporation, sunshine duration, and wind speed are the climate variables used in this study. The investigated periods (1980-2021) of Erbil meteorological data were used to assess the climatic and drought conditions in the studied basin. The results show a noticeable drop in relative humidity and rainfall over the past two decades, as well as a considerable rise in temperature and evaporation. The mean annual rainfall was 416mm, relative humidity is 48.74% used as term of water availability, and mean annual temperature is 22°C, total annual evaporation was 2257.59mm, sunshine duration was 8.2 hours/day, and wind speed is 1.7m/s were used as water loss elements. Kharufa technique was applied to determine the potential evapotranspiration, water deficit and water surplus periods. According to the findings, there is a total of 2257.59 mm of potential evapotranspiration, water excess, and water deficit, 89.22mm, and 1953.95mm, respectively. Annual surface runoff was 37.85mm, and annual recharge from rainfall was 13.07%. Alkubaisi classification for climate type were utilized to identify the Erbil central sub-climatic basin's type. The results showed that the climate is arid based on the initial categorisation, moist to sub-arid


Introduction
Due to growing usage of the world's resources in recent years, humans have been impacted by global climate change.As a result, between 1850 and 1990, the average yearly air temperature over the world increased by around 0.5°C.Due to the growing usage of fossil fuels, carbon dioxide levels have grown by around 25%.Both respiration and volcanic eruptions release carbon dioxide (CO2) [1].The waters disperse it, and plants eat it during photosynthesis.There are currently 359 parts per million by volume (ppm) of CO2 in the atmosphere, a concentration that is increasing as a result of anthropogenic emissions.The semi-arid climate of Iraq has scorching, dry summers and chilly, wet winters.Rainfall occurs between November and April, with May being the exception.While, May to October months, are the hottest and with no rain [2].In Iraq, the highest recorded temperatures vary from above 48°C in July and August to below zero °C in January [3].Hydrologic catchments are influenced hydrological mechanisms like evaporation and precipitation, and the interaction of rivers and aquifers because they are part of the universal water cycle.If the basin's meteorological circumstances and climatic factors are known, the valuable notion of the water balance may be utilized [4].Meteorological and water balance study aimed to clarify and obtain a good imagination of flood and drought forecasting, climate change impact assessments, reservoir management, water resources and water quantity.Hence, this integration will provide better understanding into the water resource management in Erbil basin.Using hydro metrological tools such as: First Investigate evapotranspiration, water loss, and availability of water.Second achieve hydrometeorological data to evaluate the rainfall variation analysis (monthly, seasonally, and annually).Third determining the basin's water surplus and deficit using multiple techniques.Forth determine runoff, recharge, and other water balance parameters, and fifth determine the climate category and the effect of climate change in the area based on climate factors.

Description of the study area
The study area is located in Erbil province in northern Iraq, with a total area of approximately 1400 km 2 (3.5% of Iraq).The territory of the city of Erbil is around 70 km 2 large inside the 1400 km 2 core basin of the Erbil plain.The region has an average elevation of 412 meters and is bounded on the north by latitude 36 o 08'30"-36 o 14'15"N and by longitude 43° 51'20"-44° 12'28"E on the east (Figure 1).Tectonically the basin is located in low folded zone, while the oldest exposure geologic formation is Bai-Hassan (Upper Bakhtiari) Formation (Pliocene)in western part of the basin, but most part of the basin are covered by quaternary these deposits are non-effected by Alpine orogeny, consist of clay, loam silt, sand, and gravel.The Quaternary deposit is unconformable with underlying unit (vertically and horizontally appeared gravel (repeat) coarse, medium, and fine grain size) [5].The age of quaternary deposits is Pleistocene to Holocene.These deposits were divided according to our field expert: River Terrace River terraces were produced by recent flood plain exposed along each side of valley, produced by variation in base level or by climate variation in area along valley.The age is Pleistocene; consist of rock fragment limestone, fragment, gravel (silica) and little amount of igneous and metamorphic rock fragments.

Flood Plain Deposit
The sediments originate as a result of river erosion during flood periods.They consist of clay, silt, sand, and gravel with some fine pebbles, and rock fragment.The age of this deposit is Holocene.

Climate
Hydro-meteorological measurements aid in the planning, managing, creating, and building of water resources.They generate the data required for hydrologic and developing models.
The hydro-meteorological strategy for water balancing is frequently utilized when the production of a small basin, within which urbanization occupies a portion, is recognized.
Empirical methods were taken into consideration because such output isn't always available.As a consequence, probable water surplus and deficit periods are identified using the input parameters for this type of water balance.The factors in first set of these characteristics have to do with water availability, while the ones in the second group have to do with water loss [6].The main air masses that influence the climate are the marine and continental three types of air masses: Polar air masses, tropical air currents on land, and tropical air masses at sea.The semi-arid climate of the study region is recognized for having annual precipitation totals of less than 500 mm [8] (Figure 1).Compared to the northern and northeastern zones of the research area, the air temperatures are greater, and a blizzard is uncommon.According to [9], the climate is continental and is characterized by scorching summers and chilly, wet winters.The steppe climatic region is known for having scorching summers and chilly, wet winters [10] [11] [12].The impacts of global warming in Erbil have been documented.His key conclusions and assumptions for this study included declining detrimental impacts on plants and soil, increased precipitation per year, boosting the monthly average temperature and altering the present precipitation trends (especially in low-rainfall areas), accelerating evaporation and evapotranspiration.
Meteorological data from the Erbil station were utilized to assess the hydroclimatic state of the Erbil basin since this station, located at latitude 36°.12'N and longitude 44° 02' E, provides a reliable source of information, and elevation 420m above nasty sea level, is used for analyzing and studying weather information between 1980 and 2021.Precipitation, surface temperature, sunshine duration, relative humidity, evaporation, and other climatic variables were used in the current study, which launched in Erbil and was eventually covered by the installation of a meteorological station.

Water Availability Elements
The primary factors of water availability are rainfall and relative humidity, together with resources to battle climate change and surplus water.

Precipitation
Data that have been reported indicate [8] the yearly precipitation varies from year to year, and this is also true for the monthly and daily precipitations.From 1980 to 2021, the year 2018 had the highest annual precipitation with 733.6 mm, the lowest with 229 mm, and the average was 416 mm (Table 1 and Figure 2) .The whole period has four cycles.First cycle started from 1980 to 1990 the highest in 1988 was 626.9 mm, and lowest in 1983 was 302 mm.Second cycle is from 1991 to 2000 the highest was 751mm in 1992, while the lowest in 1999 was 232mm.3, 4).Minimum average rainfall measured in July and August (no rainfall).Throughout the year, November, December, January, February, March, and April are the wettest months, which together account for 98% of the year's total precipitation.But the almost dry months are June, July, August, and September.According to rainfall data from 1980-2021, there is significant shortage in rainfall especially from 1999 to 2021 (Figure3, and Table 1).

Relative Humidity
The picture is not complete after a vapor pressure value has been established until that worth is contrasted with the fullness vapor pressure at the air's temperature.Result of relative humidity is defined as the difference between the vapor pressure (e) and the saturation vapor pressure (es(t)) at the corresponding temperature (h) [14].H=100 e/es(t) ……………………………………………………………………………… (1) Keeping in mind the concept of dew point temperature provided previously, we obtain H=100 es(td)/es(t) ………………………………………………………………….……… (2) And never es(td) can be greater than es(t).For an interpretation see (Table3,Figure5) When h = 100%, Condensation results upon reaching saturation.Some exposed surfaces frequently warm up to a temperature that differs from the air.An equal relative humidity for such surfaces is defined as: H=100 e/es(ts)=100 es(td)/es(ts) Where ts is the current surface temperature.For instance, a surface that is colder than the air (ts t) would facilitate soaking more readily than the surrounding air.This explains why dew can occasionally develop on plant leaves even the relative humidity in the air has not reached 100%.Similar expressions might be defined by taking into account the saturation pressure for ice.
Hygrometers are tools that measure relative humidity directly.Instead of using digital hygrometers, analogu hygrometers employ the variation in length that human hair especially that of a blond woman, experiences with a change in relative humidity which typically based on some change in the electric properties of some material as a function of the relative humidity of the air.

Water Losses Elements 3.2.1. Temperature
The most important climatic factor is temperature aspect because it both directly and indirectly impacts all other weather and climate aspects and circumstances.The terrain, length of the sun's rays, latitude position, as well as additional land and plant characteristics, all have a direct impact on air temperature.The average monthly temperature for a year follows a pattern that is essentially constant from year to year.Between 1980 and 2021, the Erbil meteorological station's lowest average temperature was 5.95 °C until January 2008.38.8 °C was the highest average temperature for the same period in August 2006.At the time, the average temperature was 22°C.The typical yearly temperature clearly shows that the climate is warming (i.e., the climate in the area is warming) (Figure 6). Figure 6 demonstrates a significant increase in the median annual temperature at the Erbil station from 1998 to 2021.According to averages (mean, maximum, and minimum), January was indeed the coldest month, and July was the warmest (Table 4; Figure 6).

Sun Shine Duration
The highest value was recorded in July while the monthly average lowest duration is 4.88 hours per day, there are 11.86 hours of sunlight every day.The average yearly sunshine duration was 8.2 hours/day from 1980 to 2021.(Table 5; Figure 7).

Wind Speed:
At the metrological station in Erbil, the daily average wind speed was 3.5 m/s.The average maximum and minimum worth for this limit in the research region is 0.1 m/s and 0.2 m/s, respectively, in the months of March and November.The average yearly wind speed at the Erbil station from 1980 to 2021 is shown in Table (6) and Figure 8.

EVAPORATION from class (A) pan
A technique for determining free water evaporation is to evaluate evaporation from a class (A) pan.Evaporation is determined by calculating using the change in water level in the pan.The pan coefficient, which typically has an annual average of approximately 0.7 but fluctuates from season to season owing to changes in heat storage, is the ratio of lake evaporation to pan evaporation.[15] Developed this formula to determine depending on pan evaporation and air temperature, daily free water evaporation: Efw = 0.  7 and Figure 9).

Climate Classification
One method was used to determine climate type for Erbil central sub-basin.The method is:
As demonstrated in Table 8, while value (AI-2) reflects a modification of the latter categorization, value (AI-1) represents the classification of the dominant climate.

Water Balance Method
There are other ways to compute water evenness, but the bulk of them rely on meteorological information that is already accessible.The actual and prospective evapotranspiration of the study region was computed using hydro-meteorological information from the metrological station in Erbil, and the computation was utilized to identify the times of water scarcity and abundance.The approach can forecast potential groundwater recharge when rainfall data is utilized to compute runoff, nonetheless, aquifer yield).Three distinct methods were chosen for determining evapotranspiration, there are water shortages and surpluses.The evaluation of evapotranspiration was done using Kharufa methods.

Evapotranspiration (ET)
Different techniques may be used to measure water balance, most of which are done based on weather information.The actual and prospective evapotranspiration of the study region was computed using hydro-meteorological information from the metrological station in Erbil, and the computation was utilized to identify the seasons of water excess and deficiency.The approach can forecast potential groundwater recharge when rainfall data is utilized to compute runoff, but not aquifer yield [18].As a result, the water balancing technique is an ideal approach [19].Three distinct methods were chosen for the current study find the basin's best suitable method for determining evapotranspiration, water deficit, and water surplus.The evaluation of evapotranspiration was done using Kharufa methods.For the examined region, potential evapotranspiration may be calculated using a variety of methods.

Kharrufa Method
To determine PET values Kharrufa (1985) created a straightforward formula.Many studies have used this approach in Iraq.This is done based on the correlation between temperature and sunlight length, and it is thought to be the most suitable approach for the climate in Iraq.(Hassan, 1998;[20]; Shwany, 2008; Dara, 2011; [21]; Qurtas 2013).The formula is as follows: at m =PET / ρ ……………………………………………………………………………………………… (8) Where: t: Mean monthly temperature (°C) ρ: The sum% of sun shine hours in each month to the sun Shine hours of one year.M: Constant (1.31) a: Constant (0.33) Table 9 Demonstrates that over the different months, the PET values estimated using this approach are comparable to those computed using the Blany-Criddle method.However, they are not the same as those determined using the Thornthwaite approach.In the earlier approach, the formulae used two parameters.The former, in comparison, only included one climatic element in the calculation, which was the mean monthly temperature plus a relative latitude adjustment factor.Figure 9 shows the water surplus and deficit in the Erbil basin as determined using this approach.

Water Deficit and Water Surplus
Over time, there is a surplus of water when precipitation exceeds potential evaporation, whereas the opposite is true when potential evaporation exceeds precipitation.When there is more water available, real evaporation approaches its potential value, nonetheless, actual evapotranspiration (AET) equals precipitation when there is less water available (4).P > EP then PE = AET P < EP then P = AET The water surplus includes total runoff (Rs), groundwater recharge (recharge), and soil moisture (irrigation).Because the groundwater table is so deep in the Erbil Sub Basin, there is no evaporation of groundwater.As a result, soil moisture is either consumed by plants or evaporates from the soil.The following is equation for the water balance: P = Rs + I + AET ………………………………………………………………. ( 9) WS = I + Rs WS = P AET Where: AET: Actual evapotranspiration Rs: Surface runoff I: Infiltration Using the Kharrufa method, the average monthly potential evapotranspiration statistics were determined (Table 10).The average monthly water surplus and deficit as well as the average monthly actual evapotranspiration in the study region were then calculated using these data.Because PET surpasses precipitation and, consequently, soil moisture use, there is a visible water scarcity from the start of March to the end of November.Precipitation surpasses PET between the end of February and the end of December, allowing soil moisture to return to its maximum level and turning any additional water into groundwater recharge and surface runoff.

Surface Runoff
The Soil Conservation System (SCS) [22] approach uses rainfall data to compute surface runoff.The empirical rainfall-runoff connection is as follows: Q = (P -0.2 S) 2 / P + 0.8 S ………………………………………………………….. (10)   According to Alkubaisi et al., 2019, [25] the area has a moist to sub-arid climate, whereas the current study categorizes the climate as moist to humid, and this shows the reality of climate change in the region.We can notify a significant change in climate type according to [25] and current study that is effect of climate change.

Conclusions:
1.The metrological data were useful to assess climate change especially precipitation, relative humidity, temperature, and evaporation.In this study, there are significant shortages in precipitation and relative humidity whereas there are significant decrease in temperature and evaporation.The results of this study revealed that the climate parameters have changed dramatically during the past forty (40) years.
2. The rainfall variation is observed during the past 40 years (Figure 3) in which from 1980-2010 annual rainfall precipitation was 653mm/year, but during period 2011 to 2021 was about 425 mm/year we have significant shortage in precipitation about 228mm/year.This indicates that the Erbil basin is remarkably affected by climate change.
3. Figure 6 shows the average annual temperature in Erbil station it can be categorized to four stages.First stage from 1980 to 1990, the average annual temperature is18.5C° which shows less variation in temperature value.Furthermore, this study will provide information about water incomes to the basin which the government could rely make strategic plans for the basin such as building ponds and small dams.

Figure 2 :
Figure 2: Shows rainfall in the city of Erbil according to spatial distribution[13]

Figure 4 :
Figure 4: The average monthly precipitation of Erbil for the period between 1980 and 2021

Figure 5 :
Figure 5: The Erbil average monthly relative humidity for the years 1980 to 2021.

Figure 6 :
Figure 6: Average annual temperature for the period 1980 to 2021 in Erbil.

Figure 7 :
Figure 7: In Erbil, the average monthly sunlight duration ranged from 1980 to 2021

Figure 9 :
Figure 9: Evaporation class (A) pan average monthly in Erbil between 1980 to 2021

Figure 9 :
Figure 9:Mean monthly water surplus and water deficit calculated by Kharrufa method.
WS = P PE; P > PE WD = PE P; P < PE Where: WS: Water Surplus WD: Water Deficit P: Rainfall PE: Potential evapotranspiration Hamed Iraqi Journal of Science, 2023, Vol.64, No. 9, pp: 4518-4537 4532 Third cycle was from 2001 to 2010, highest was 487mm in 2003, while lowest was 229 in 2008.Fourth cycle was from 2011 to 2021, the highest was 789 mm in 2019, while lowest was 198 mm in 2021.March 2019 saw 220 mm of precipitation, which is the highest monthly total between 1980 and 2021.Maximum average monthly rainfall for the period from 1980 to 2021 is 70.4 mm in March in the study area (table 1,2 and figure

Table 2 :
Mean monthly precipitation (mm) in Erbil from 1980 to 2021

Table 4 .
Erbil's average monthly temperature from 1980 through 2021 (in degrees Celsius) (data was collected from Erbil meteorological station).

Table 6 :
The average monthly wind speed at the Erbil weather station during 1980-2021

Table 7 :
Mean monthly evaporation (mm) measurements with a Class-A pan in Erbil during period from 1980 to 2021

Table 9 :
Using the Kharrufa approach, potential evapotranspiration values were computed in Erbil from 1980 to 2021.

Table 10 :
Using data derived using the Kharrufa approach, compare the water surplus and shortfall.

Table 12 :
The value of the surface flow was calculated by the soil preservation system

Table 13 :
[23]ategorization Kubaisi's of the climate from 2004[23] Second stage from 1991-2000 average annual temperature is 20.6 C°.Third stage from 2001 to 2010, the average annual temperature is 22.29 °C, while fourth stage from 2011 to 2021 average annual temperature is 23.07 °C.It has been observed that the temperature value increased during the classified categories.More importantly, 4.57°C has been raised since 1980 compared to temperature value in 2021.4. According to the current study, 89.2 percent of the total precipitation (416 mm) is made up of water excess that is used to refresh the water supply.5.The water surplus is split between groundwater recharge (51.37 mm), which accounts for 13.07% of the total rainfall, and surface runoff (89.22 mm), which accounts for 13.07% of the total rainfall.The adjusted potential evapotranspiration, or (1953.95mm), is represented as the water deficit.6.By contrasting the current study with earlier research, a significant change in climatic type was found.According to Alkubaisi et al., (2019), the area has a moist to sub-arid climate, whereas the current study and AlKubaisi categorize the climate as moist to humid which indicated the impact of climate change during the past few decades.7. Outcomes of this study have provided a significant source for water resource management in central Erbil basin especially for those projects that use high quantity of water.