Changes in Groundwater Levels and its Salinity (Badra Basin Iraq)

A fact that human-induced greenhouse gas emissions have led to an increased frequency and/or intensity of some weather and climate extremes since pre-industrial time, in particular for temperature extremes which affected lots of regions by reducing precipitations. Accordingly, this reduction causes a lowering of groundwater levels which was adopted as a goal of this study and its effects on quality of it. The study area is Badra - Jassan basin located to the north of Kut city, the center of Wasit governorate, and bordered by the international boundary with Iran from the east and northern east covering an area of about (1020) Km2. Badra - Jassan basin is an important hydrogeological basin in which groundwater can be used for agricultural purposes; especially with decreasing surface water supply. The research studied a predictive mathematical model of groundwater by ten wells distributed randomly within the boundaries of the study area; all of them fall within the unconfined aquifer the mathematical model for the study area has been developed using the Geographic Information System (GIS) software. The Groundwater level map for the ten existing wells was drawn from data in (2021) and a comparison with else published in (2002) for the study area. Likewise, the salinity concentration map variations for the same periods were estimated. The present study showed a decline in groundwater levels which conjunction with an Increasing in the range and value of groundwater salinity concentrations.


Introduction
Surface water is the main source utilized for various purposes, for example, modern, rural, and household purposes but, when it is depleted or scarce groundwater will assume the first job in local water assets.Nowadays, with expanding populace and life gauges, there is a developing requirement for the usage of groundwater assets.In any case, because of some human-centric causes, for example, impromptu urbanization and industrialization, the number of groundwater assets keep on diminishing [1].
It is a fact that human-induced greenhouse gas emissions have led to an increased frequency and/or intensity of some weather and climate extremes since pre-industrial time, in particular for temperature extremes which affected lots of regions by reducing precipitations .[2] As a result of the climatic changes reduction in precipitation influences mainly and directly on the levels of groundwater and its quality, and it has become a tangible matter in regions that depend generally on groundwater sources such as wells.
Groundwater quality management can be effectively carried out by mapping for groundwater vulnerability to contamination.[3].It is rarely treated and presumed to be naturally protected, and it is considered free from impurities, which are associated with surface water, because it comes from deeper parts of the earth.[4].However, the salinity of groundwater is affected by the variation of groundwater recharge sources, ion exchange activities, and the ability of substitution between the main ions.A group of factors, including recharge and drainage areas, groundwater movement trends, in addition to the depth and rockiness of the aquifer, play an effective role in this variation.Groundwater recharge reduces the concentration of water salinity through dilution and mixing processes between groundwater and the water feeding it [5].The open aquifer is fed by direct feeding operations from rain, in addition to potential groundwater recharge from the former Kalal Badra River, at specific locations along its course.The quality of groundwater changes according to its location in the hydrogeological basin and its depth in the aquifer.Geological and topographical conditions play an important role in determining the quality of groundwater and the possibility of using it for various purposes and the potential for its contamination.Adopting samples of water collected from several locations within the basin area in order to indicate the levels of variation and classification of water quality and the possibility of using it in the light of its validity.
In (2002), Batool.M. presented research for the Badra Basin including studying groundwater hydraulic characteristics of the aquifers in the basin, in addition, the levels of aquifer recharge and their locations were determined.In addition, areas encouraging the drilling of wells and the exploitation of groundwater were identified, with good hydrogeological specifications, and areas of groundwater pollution, if any, were identified, and it was recommended to exclude the drilling of wells in them.[6].
In (2012) Issar M. and Batool M. carried out a study of the hydrological relationship between surface and groundwater in Badra -Jassan basin and study the level of water feeding and drainage between them by relying on the manual and tube wells spread in the basin and the level of variation in the hydro chemical characteristics.[7].
In general, the groundwater level map of the Badra-Jassan basin is obtained from the hydrological data in (2021) in order to compare it with the appropriate groundwater map for data presented in (2002).Likewise, the chemical data for the same area for the two time periods are compared for the two time periods to clarify the effects of climate changes in the region during two decades.
The study area is necessary because it contains a large reserve of groundwater which is evident from many flowing wells, especially after the flow stopped in the Kalal River which originates from Iranian territory.Therefore, it is a strategic area for water harvesting purposes because of its topographical and geological characteristics and water needs, as groundwater is mainly used in agricultural activities and urban requirements, and many farms are supplied with water from groundwater through wells dug in the area.[8].

Description of the study area
The study area is located in Wasit governorate, which represents a section from the hydrological basin of Badra -Jassan basin, bounded of the Iranian territory east at longitude 46°15´ and at longitude 45°50´ west.In addition, it is bounded of latitudes 32°55´ and 33°20´ with an area of (1020) km

Topography of the study area
Topographically, the basin slops from the high mountain in the east and northern east to the flat gentle plain in the west and south where the plain ends in Shuwaicha marshes [6].The topographic elevation is derived from the digital elevation model (DEMs) produced by U.S. Geological Survey (USGS).The US DEM data files are digital representation of cartographic information in a raster format.DEM consists of a number of terrain elevation ground positions at regular horizontal intervals.The wells point elevations were adopted from data of the investigated area provided by the General Administration of groundwater in Iraq.[9]. The

Geology of the study area
Badra -Jassan basin represents part of the feet hills and the sedimentary plain within the tortuous and unstable region of Iraq, which is characterized by the extension of wide convex and concave folds, as the region was affected by the mountain-building movements that began in the Cretaceous period and reached its climax at the beginning of the Pliocene era [6].
The exposed and visible geological formations in some parts of the basin range in age from the lower Miocene to the Holocene.There are detectors of geological formations dating back to the Lower Miocene era along the northeastern borders of the basin, while sediments of the Quaternary era (Pleistocene and Holocene) cover the center and south of the basin.[6] Figure 3.

Figure 3. Geological map of the study area
According to the existing wells data, the study area is considered as unconfined aquifer.The unconfined aquifer of the quaternary deposit extends along the area of the basin increasing in thickness towards south and west.

Methodology of work
This study devised a practical and clear method to Presentation and clarification of the wells' distribution and its hydrological data for the study area.For this purpose, a straightforward methodology is proposed for the achievement of desired objectives.The methodology of work can be divided into two categories: Firstly: The data of the investigated area was provided by the General Administration of groundwater , which includes hydrological data for ten existing wells, and general information about the area which includes hydrological and quality data.[6].secondly: State the suitable software for building up the study model such as the Geographic Information System (GIS) Software.The GIS is a system that creates, manages, analyzes, and maps all types of data.[10].

Data of investigated area
The prepared data for the study area includes the quadratic coordinates of the ten well sites, the natural ground levels at the well sites, the well depth and depth of the water relative to the ground level in addition to the operational data of the wells.Table (1) Table 1.Hydrographic characteristics of wells 3.2.Geographic Information system (GIS) software A geographic information system (GIS) is a computer-based tool for mapping and analyzing things that exist and events of many types.GIS technology integrates common database operations such as query and statistical analysis with the unique visualization and geographic analysis benefits offered by maps.[10].
The topographic data was applied using the program to produce a clear and accurate topographical map of the study area based from the digital elevation model (DEMs) produced by U.S. Geological Survey (USGS).Figure 4.
In addition, the hydraulic data of the wells has been applied to create a realistic perception of the reality of the situation according to the existing data.

Groundwater table system
Present study suggested using several wells which already exist in the study area as shown in figure (5).According to the General Administration of groundwater in Iraq the groundwater levels for the wells are listed in the table (2).

Figure 5. Location of the in study area
Table 2. Groundwater elevation By using the (GIS) program, a visualization of groundwater levels was drawn.This method is easy in implementing and available in almost GIS software as shown in Figure (6).[11].These data are useful to groundwater movement efforts because they provide evidence of the general direction that water will likely travel, from a high water level to a low water level.Figure (6) shows the direction of groundwater movement represented by two main directions, from the east towards the west in the north of the basin and from the northeast towards the southwest in the middle and south of the basin.

Total dissolved solids (TDS)
It is important to monitor groundwater salinity over time and in all seasons because of its great impact in determining water quality for different uses.The change in the salinity of groundwater is a major factor in changing the fertility of agricultural lands that depend directly on that water, and thus, the quality and quantity of agricultural crops.In addition, the urban and industrial consumption of groundwater is also in direct contact with the chemical and physical changes of groundwater.Table (3) shows the total dissolved solids concentrations of groundwater for present study in the study area.Figure (9) shows the distributions of TDS concentrations and levels of heterogeneity in the study area of present study.In general, the salinity of groundwater increases with the direction of its movement from the feeding areas to the drainage areas.[12] Figure 9. Distribution of salinity for present study in (2021) The salinity concentrations of the upper region of the Badra basin increase from the northeast towards the west, while the salinity of groundwater increases from the northwest of the basin to the south down the basin.
Figure (10) shows the distribution and trends of groundwater salinity concentrations presented for the study presented in 2002.Although the direction of groundwater flow was not affected by the interruption of the Kalal River and the factors of climate change, but the variation in the trends of salinity concentrations was clear due to the interruption of the water of the Kalal River, which is characterized by high salinity.[6].So, Figure (9) indicate that there is an evident increase in the range of salinity concentrations for the present study, as the average salinity concentrations range between (2900 to 4700) ppm in 2001, while it ranged between (1500 to 9000) ppm for the present study.According to the water classification for the (TDS) content in ppm, Table (4), the concentrations of salinity for the study area in the last twenty years from (2001 to 2021), are ranged between (1000 to 10,000) ppm, which considered within brackish water type as listed in the table (5) which classified water according to its (TDS) content in ppm.[13].

Conclusions
According to the results, the following conclusions may be drawn from the present study:  The groundwater levels of the basin have clearly decreased in the past two decades as a result of the region's vulnerability to climatic changes and the interruption of the Kalal River. The groundwater flow trends of the study area are mainly affected by the topography and geology of the basin, which classified the effect of the Kalal River to be a secondary influence. Increasing the concentration of groundwater salinity for the current study in conjunction with the decrease in the groundwater level of the basin. Also, the present study showed a semi-radical change in the direction of the salinity concentration of groundwater because of depletion in the Kalal River which is characterized by high salinity.

2 ,Fig.( 1 )Figure 1 .
Figure 1.Geographical location map of the study area relative to Iraq study area is characterized by a varying topography, showing the region of the low folds represented by Mount Hamrin in the eastern and northeastern part, and a flat plain with moderate slope towards the southwest.Due to US DEM data, the elevation of the study area reaches (400 m) above sea level (a.s.l) towards the northeast while the elevation is less than (25m) (a.s.l) in the southwest as shown in Fig. (2).

Figure 2 .
Figure 2. Topography map of the study area

Figure 4 .
Figure 4. Elevation Model (DEM) of the study area

Figure 6 .Figure 7 .
Figure 6.Level map of groundwater in (2021 ( In order to study the change in water table levels, the data of the same ten wells were taken for the year 2002, [6].The groundwater levels map presented in 2002 shown in the fig.(7),

Figure 8 .
Figure 8. the schematic diagram the groundwater level during the past two decadesThe flow direction of the groundwater was not affected by the dryness of the Kelal River because it feeds on the groundwater at times and feeds it at other times due to the rise in the level of the natural land and its fall along the watercourse with the groundwater level of the basin.[12]

Table 5 .
Water classification according to (TDS) content in ppm value

Table 3 .
groundwater level during the past two decades

Table 4 .
TDS concentrations of groundwater for the study area(2021)