Climatic Water Balance and Groundwater Recharge in Abu-Jir Village, Al-Anbar Governorate, Western Iraq

The study area is located in Al-Anbar Governorate, western Iraq. The climatic data were collected from Al-Ramadi Meteorological Station for the period 1990 to 2020 and used to assess the climatic condition of the study area. The total annual rainfall, relative humidity, monthly average temperature, evaporation, wind speed and sunshine duration are 108 mm, 52.7 %, 22.6˚C, 2814.3 mm, 2.2 m/s and 8.8 h/day, respectively. The climate of the study area is described as an arid to sub arid and relatively hot in summer and cold with low rain in winter. During the data used, the highest potential evapotranspiration was 217.1 mm in July, while the lowest value was 10.7 mm in January, with a total amount of 1170.07 mm. The highest and lowest corrected evapotranspiration becomes 264.2 mm in July and 9.4 mm in January, with 1310.3 mm. water Surplus (WS) is 2.1mm, 10.71mm, and 5.65mm in December, January and February, respectively. The WS was 18.46mm, forming 17.09 % of the total annual rainfall. The groundwater recharge (18.46 mm) with a rate of 17.09% represents the recharge from the total rainfall zero surface runoff. It has been found that the low amount of rain and sandy soil are among the most important factors causing the absence of surface runoff.


Materials and Methods
The meteorological data were collected from the Iraqi Meteorological Organization based on Ramadi meteorological station from 1990 to 2020. The evapotranspiration was monthly calculated by using the [10] Two methods were used to determine the prevailing climate type, [11] [12],and [13] was used to compute the water balance. The six climate elements are temperature, rainfall, evaporation, sunshine duration, wind speed and relative humidity. The average monthly values for each parameter were measured for the studied period. The soil conservation service method (SCS) used the runoff curve number (CN) method to estimate runoff from storm rainfall. Later the value of groundwater recharge was also calculated. A significant water supply for many parts of the world is distinguished by its intensity, quantity, and distribution over time [14]. The precipitation includes snow, rain, hail, drizzle, fog, mist, and sleet; and varies naturally in time and space [15]. The total annual average of rainfall recorded by the Ramadi station is 108.2mm; the average monthly precipitation ranges from 0.3 mm in September to 20.2 mm in January, concentrated in October to May, while it is dry from June to June September (2). The ratio of the actual water vapour pressure in the air to saturated vapour pressure at the same temperature is relative humidity [16]. It is related to precipitation and temperature, as it rises in winter due to higher rainfall and lower temperatures but decreases in summer due to lower precipitation and higher temperature [17]. In the study area, the maximum monthly mean was 78% in January, and the minimum was 33.2% in July, while the average relative humidity was 52.7% ( Figure 3). Temperature is an essential component of climate, playing a significant role in rainfall, pressure, and evaporation [18]. It influences rainfall, which affects evaporation and evapotranspiration, resulting in an increase that has a detrimental impact on groundwater recharge sources. The maximum mean monthly temperature is 35 ᵒ C in July, and the minimum is 9.7 C in January. The mean annual mean temperature is 22.6 C ᵒ as shown in Figure 4. In dry and semi-arid locations, the wind is one of the most important elements of erosion that has a permanent effect on geomorphology. Evaporation is influenced by the wind, which is a climatic factor. Climatologists are primarily concerned with wind speed and direction.

Temperature (C ᵒ )
In the study area, the mean monthly wind speed values vary from 1.8 to 2.7 m/sec. Minimum values were recorded in October, November and December, while the maximum values were in June and July. The mean annual wind speed is 2.2 m/sec ( Figure 5).

Figure 5:
The mean monthly wind speed from Ramadi meteorological station for the period 1990-2020 Sunshine duration 5.
Sunshine duration means the number of hours of sunshine in a day. It is thought to be the most critical component influencing the evaporation process. The snlssils time in a certain location impacts its temperature.
In the study area, maximum sunshine duration occurs in July with a mean monthly of (12) h/day while the minimum monthly average is 5.4 h/day occurs during December, and the mean annual is 8.8 h/day ( Figure 6). SunShine (h/ day) 6

. Evaporation
Evaporation (E) is a crucial component of water balance and hydrogeology. Water is transferred from a liquid to a gaseous state [19]. A free water surface evaporates, such as lakes, rivers, soils, and moist vegetation. Evaporation is influenced by several factors, including relative humidity, air temperature, wind speed, and solar radiation. The minimum mean monthly evaporation is 61.2 mm in January, while the maximum monthly is 451.8 mm in July. The mean annual evaporation is 2814.3 mm (Figure 7).

Classification of climate
According to Al-Kubaisi [11], the climatic data of the study area for the period 1980-2020 was classified as arid, sub-arid, humid, and moist using Al-1 and Al-2 (snnnIiuls 1&2). Al -2= 2 *√ 108 / 22.6 =0.91 According to the total rainfall and average temperature of the study area, AI-1 is 0.41 and AI-2 is 0.91. The climate of the study area was classified as sub arid to arid for both modes 1 and 2  [12]. This is determined by the Aridity Index (AI), the ratio of rainfall to evapotranspiration (equation 3). The results are shown in Table 3. The Aridity index is given as follows: AI=  Depending on the classification suggested by Mather, 1974. The aridity index is -91.75, so the study area is an arid region.

Evapotranspiration
The evapotranspiration was measured every month using Thornthwaite's (1948) equation [10].  The maximum potential evapotranspiration value was 217.1 mm in July, while the lowest potential evapotranspiration value was 10.7 mm in January, resulting in 1170.07 mm. The total amount was 1310.3 mm, with the highest corrected evapotranspiration value of 264.2 mm in July and the lowest corrected evapotranspiration value of 9.4 mm in January. The relationship between corrected evaporation, potential evaporation, and evapotranspiration over the period (1990-2020) is shown in Figure 9. The total annual value of WS was 18.46 mm from total rainfall, which was recorded in December, January and February due to the rainfall exceeding PEc. The WS ratio from the yearly rainfall can be represented as: WS % = WS/P ×100 …………………………… 11 WS % = 18,46 /108 ×100 = 17.09% While the water deficit (WD) ratio can be represented as: WD % = 100 -WS % ……………………………… 12 WD % = 100 -17,09 = 82.91% Table 5 shows the monthly averages of APE, WS and WD and Figure 4 shows the relationship between the mean monthly rainfall (P) and corrected evapotranspiration (PEc), which shows the water surplus (WS) and water deficit (WD) periods.   The result of Ramadi station was compared with Karbala due to the locations (Table 6).

Soil Conservation Service Method (SCS)
The SCS uses the runoff curve number (CN) approach to measure runoff from storm rainfall., (CN) can be calculated depending on cover conditions and watersheds soil. This model represents hydrologic soil group, cover type, vegetation type and hydrologic condition. By United States' Natural Resources Conservation Service (NRCS), the curve-number model was developed by the Department of Agriculture. The most common method for estimating runoff. Where: ……………………………… (13) Runoff (mm), P: Total rainfall (mm) United States' Natural Resources Conservation Service (NRCS). The Department of Agriculture developed the curve-number model. The most common method for estimating runoff is to utilize the calculation below. S: maximum potential retention after runoff (mm). Ia = initial abstraction (mm). Ia can be an approximated by the following empirical equation: Ia = 0.2 S ………………………………(14) By Compensation value Ia, the equation becomes as follows: Rs = ………………………….. (15) S : related to soil and cover condition, of the watershed during CN, where CN represents range between (0 to 100), and S is related to CN by: CN = (S) in (millimeter) ………………………16) Soil infiltration rates vary greatly and are influenced by both surface and subsurface permeability. The soils are classified by soil scientists into four Hydrologic Soil Group A, B, C, and D according to their minimum infiltration rate or in another meaning based on the soil runoff potential (Table 7). Table 7: Definition of four SCS hydrologic soil groups [21] Hydrologic Soil Group Definition A Soils have low runoff potential, high rate of water transmission and high infiltration rates even when thoroughly wetted., well to excessively drained sand or gravel.
B soils with moderately fine to moderately coarse textures , and moderate infiltration rates when thoroughly wetted and consist chiefly of moderately deep to deep, moderately well to well-drained soils with moderately fine to moderately coarse textures.
C soils have a low rate of water transmission and have low infiltration rates when thoroughly wetted and consist chiefly of soils with a layer that impedes downward movement of water and soils with moderately fine to fine texture.
D That soil has very low infiltration rates and has high runoff., soils with a permanent high water table, soils with a clay pan or clay layer at or near the surface, These soil with a very low rate of water transmission.
CN was determined (Tables 7 and 8). Table 9 defines the four groups and provides a list of most of the soils and their group classification [21].  [22 & 23]. The soil in the study area is of class (A) type. Most parts of the study area are covered by shrubs and grass. According to the classification proposed by the method, the curve number (CN) for this soil condition is equal to 68 (Table 9). The surface runoff values (Rs) in the study area are zero, and one of the most important factors causing the absence of surface runoff is the amount of low rain, as well as soil type (sandy soil). This reflects that soil has high infiltration rates even when thoroughly wetted and low runoff potential (Table 7).

Groundwater Recharge (Re)
Because the soil is sandy loam and very thin, the groundwater recharge in the study region can be calculated using the equation below.: WS = Rs + Re …………………………….(17) Where (WS) water Surplus (mm). (Rs) surface runoff (mm). (Re) groundwater recharges (mm) record of Al-Ramadi meteorological station for the period (1990 -2020). The amount of rainfall is shown below, and when the soil type is sandy loam, the surface runoff will be absent in the study area Re = WS -Rs Re = 18.46 -0 = 18. 46mm. Re %= (18.46 /108) *100 = 17.09%, The following equation were used to calculate the value of groundwater recharge in the studied area during average water years.
The following equation can be used to compute the value of groundwater recharge in the research region during typical water years

Conclusions
The following findings were concluded: ▪ Total annual rainfall is 108 mm, evaporation is 2814.3 mm, temperature 22.6•C, wind speed 2.2 m/sec, sunshine 8.8 h/day, and relative humidity is 52.7%. ▪ In December, January, and February, water surplus values of 2.1mm, 10.71mm, and 5.65mm, respectively, indicate that the study area's climate is arid, with WS representing 17.09% of total annual rainfall. ▪ There was a large water deficit due to high temperature and thus increased evaporation rate and the climate in the study area is dry. ▪ Global warming and climate change have a remarkable effect even on the close geographical location of the meteorological stations such as Ramadi Karbala. it is evident that all the studied climate parameters have their print on the water surplus or deficit and minor changes within each geographical location. ▪ The groundwater recharge (18.46) with a 17.09% indicates a recharge 108 from total rainfall.