Geometric Analysis of the Proposed Al-Baghdadi Dam Reservoir, Anbar Governorate, Iraq

Abstract


Introduction
Iraq suffers from water scarcity in recent times in addition to the obstacles imposed by the policies of neighboring countries, which led to a sharp decrease in the amount of processed water that reaches Iraq, because water resources are of great importance and are considered the most important nerve of life, and because the process of water consumption has become much more intensive than previous years due to the development of economic and social conditions in addition to the large consumption of water in agricultural projects and irrigation.Among the proposals of the Ministry of Water Resources is the establishment of the Baghdadi Dam on the Euphrates River, which works as a dam storage and generation of electrical energy, from this point of view came the idea of conducting the process of geometric analysis of the reservoir of the Baghdadi Dam.Dams are one of the most important pillars of water resources management and were built for many purposes, including flood control and hydroelectric power generation, agriculture, irrigation, and tourism.The construction and design of dams for any region in the world depend on the geometric analysis of reservoirs or channels, as the geometric analysis operations aim to find the optimal operating level and characteristics of the reservoir and others and to create a database of geometric elements represented in negative volume, positive volume, positive surface area, negative surface area, positive planer area, and negative flat area.Planer Area, the average depth of the reservoir, and the average thickness of the islands are equations of their own.The importance of geometric analysis lies in its use to determine the optimal operating level of water reservoirs among several levels, and using the digital elevation model )DEM ( (Ministry of Water Resources, 2019) to find the geometric elements for each of these selected levels.
The methodology of geometric analysis based on DEM is one of the modern methodologies that are used in limited form inside Iraq and in the countries of the world, some of the research and studies that may be somewhat similar to this study, including a study (Al-Kraaey, 2016), which dealt with the site of the Jarnaf Dam, Al-Sharqat Through this study, an integrated database was established in order to support investment and development in water resource management, and the study of (Saleh, 2014) hydrogeometric to choose the optimal level of the reservoir of Makhoul Dam, the study included an analysis of spatial variables at selected levels of the reservoir, the geometric characteristics were calculated from the level ranges 140-155 m above sea level, and a study (Al-Shahri, 2016) Flood Tracking of the Tigris River in Baiji and the reservoir of Makhoul Dam proposed for hypothetical operation of the dam, and also (Al-Bayati, 2020) conducted a geological and geometric analysis process to fill the proposed opening as a dam for the Makhoul Dam, North Baiji, as well as a study (Al-Qaisi et al., 2018) geometric analysis of the reservoir of the Al-Wand Dam in northeastern Iraq using geographic information systems and spatial analysis systems, from 26 selected levels, starting from the level of 195 to 219.5 m above sea level, and the research dealt with a study of the spatial variables at these selected levels, and also, the study (Al-Kraaey et al., 2022) dealt with the extraction of the geometric elements of the reservoir of the Bakhma Dam by automated methods based on the DEM, as well as the study (Badowi et al., 2023) the spatial analysis of the geometric elements of the reservoir of Badush Dam / Mosul, northern Iraq.
The study aims to find the optimal and safest operational level capable of absorbing the amount of water released from the Haditha dam above the demand to reduce the process of water waste.
Deriving the geometric elements represented in the volume of storage, the positive and negative surface area of the reservoir, the positive and negative planer area, the depth of the water column, and the average height of the islands, and analyzing their relationships with the level and with each other and the variation of the shape of the reservoir in order to extract a reliable database in the case of the construction of the Baghdadi Dam.
The study area is located in western Iraq in the northwestern part of Anbar Governorate, and the reservoir extends towards the south of the Haditha Dam and 48 km from the back of the dam.The study area is determined by the geographical coordinates between the longitudes 42 ̊ 28 ̍ 13 ̎ and 42 ̊ 34 ̍ 49 ̎ E, and the latitudes 33 ̊ 53 ̍ 09 ̎ and 33̊ 59̍ 07̎ N. Fig. 1 shows the study area.
Geologically, the study area is almost devoid of surface structural elements except for the convex fold in the northwest of the study area (Sissakian et al., 2018), and quaternary sediments are abundant in the Euphrates River basin and are found in the form of hills with a little inclination, and the exposed rocks are mainly limestone, dolomite, and rare marl of the Euphrates Formation (Early Miocene) (Sissakian et al., 2023), consists of crystallized chalky limestone well bedded or contains shells, Many fossils were included in list by the National Metallurgical Foundation, including foraminifera, ostrakuda, algae (Al-Sayab et al., 1983).Anah Formation( Upper Oligocene) consists of dolomitic limestone rocks, It is found along the right bank of the Euphrates River (Al-Dulaimi, 2011), and contains a high abundance of karst and branched vertical dividers and Fatha Formation (Middle Miocene) Consists of gypsum and marl layers successive with limestone or dolomite layers and contains lenses of sand and clay, so this composition is characterized by heterogeneity of permeability in addition to  2 show the geological map.The geomorphology of the Haditha area includes many features such as sinkholes, isolated hills, flood plains, and islands along the Euphrates River (Ibraheem et al., 2020).

Materials and Methods
The DEM (Ministry of Water Resources, 2019) was used with an accuracy of 10 × 10 per pixel in order to extract the study area at the selected levels.
Arc GIS 10.8, Global Mapper 21.0, and Surfer 17.2 were used to extract the geometric elements.
The Global Mapper 21.0 program, is used to delineate the area of flood level of 106 m above sea level which represents the flood operating level of the reservoir, and then exported as a Global Mapper Package File.
Using the "Generate Contour" icon in the Global Mapper 21.0 program, the contour lines were determined for the ground heights of each of the different levels in order to find the values of the geometric elements and a contour interval of 0.5 m, starting from the lowest level of 77.5 m to the flood The values of the volumetric and cadastral geometric elements concerned with each level were extracted through the report issued by the Surfer17.2program, where the size of the islands was calculated as the positive volume, the volume of the negative surface area, the uneven area of the bottom of the reservoir negative surface area, the area of the projection of the islands within the boundaries of the reservoir positive planer area, and the water surface area in the reservoir negative planer area, and then the average depth of the reservoir and the rate of the thickness of the islands, and the results were included in Table 1..
The data for geometric elements obtained from the Surfer 17.2 report is tabulated in Excel, and then the relationships between geometric elements and the virtual water table are plotted.

Results and Discussion
The results of the geometric analysis showed the variation of the positive surface area, the negative flat area, and the size of the islands with increasing level due to the addition of new islands to the reservoir.Table 1 shows the results of the geometric analysis, and Figs. 2 and 5 show the reservoir extents at different levels.Figs. 6 and 9 represent the relationships between selected water level and geometric elements.The boundaries of the reservoir and its extensions are becoming clearer, as we notice large extensions towards the west and north, Fig. 3A.Whil the reservoir at level 92.0m.a.s.l is extension of towards the north with increase in submerged area, Fig. 3B.The reservoir shape at level 95.0m.a.s.l it gives clear view of the reservoir limits (Fig. 4A); and the reservoir at level 100.0 m .a.s.l is clearer view (Fig. 4B).
The remote technique was used by many researchers for studing water resourese; for example, Sadeq and Abdullah, 2022).Through remote sensing assessments, it is noted that there are 34 villages or buildings that can be flooded when the reservoir reaches the maximum level of 106 m (Fig. 5) (Ministry of Water Resources, 2008), which is one of the problems that may interfere with the construction of the dam.In terms of pollution, the lack of sewage treatment plants may cause and therefore be disposed of towards the river, which causes organic pollution in the event of the construction of the dam, it is concluded that the presence of the reservoir of the Al-Baghdadi Dam has negative and positive effects represented in the following: First: Negative effects, including (1) The study area covers soluble deposits belonging to the formation of the opening, thus affecting the quality of the water as well as the impact on the internal structures of the sides of the dam, (2) The areas in the dam basin are exposed to economic risks, including population displacement, so it requires resettlement of all residents of villages located within the boundaries of the reservoir before the dam is completed, (3) Areas adjacent to the reservoir are at risk of flooding during major rainstorms, loss of agricultural land, epidemics and others, (4) Some local sources reported the presence of archaeological remains within the area of the planned reservoir, which requires extensive surveys of the area.
Second: The positive effects, including (1) Benefiting from water storage operations inside the dam reservoir and benefiting from it during dry seasons, (2) Organizing the discharge operations coming out of the Haditha Dam and storing the surplus to reduce the waste that occurs in the Down Stream, (3) Take advantage of releases in electricity generation, (4) Exploiting the presence of the dam in creating recreational investment, enhancing the tourism aspect, and establishing recreational complexes at the back of the dam to benefit from their economic return, (5) Enhancing and benefiting from fisheries, (6) Reduced soil erosion (Ministry of Water Resources, 2008).
Relationship between water level and positive volume (volume of islands) shows an oscillation relationship where we observe the rise and fall through the scheme, The reasons that lead to the fluctuation of the positive volume is the result of the expansion in the boundaries of the reservoir, the wider of the reservoir, this leads to the inundation of new lands and thus new islands will appear within the boundaries of the reservoir, which results in an increase in the positive volume, but when the reservoir recedes as a result of the low water level, this leads to the disappearance of some islands as a result of their exit from the boundaries of the reservoir and results in a decrease in the positive volume, (Fig. 6A).Negative volume (storage volume) and water level relationship is direct and goes through three stages: the first stage is slow and starts from 77.5 m to 87.5 m, the second stage is a transition from 88.0 m to 97.5 m, and the increase is more than the first stage, and the third stage is from the level of 97.5 m to 106.0 m, where it comes out of the river from its natural course to the river plains and then to the banks (Fig. 6B).Fig. 7(A), shows the relationship of the water level with the positive surface area (uneven area of islands), where there is an oscillation relationship with the decrease and increase of the area surface as the level increases, The reason for the fluctuation in the relationship of the positive surface area with the water level is the result of the reservoir's departure from the natural course of the river to the surrounding lands, which results in surrounding new islands with water inside the reservoir, and the greater the breadth of the reservoir, in return, the more the number of lands exposed to inundation increases and the water level with the negative surface area (bottom of the tank) relationship increases in the area is gradual with the increase in the level as a result of the extension of The boundaries of the reservoir are out of the riverbed, resulting in the addition of new islands to the reservoir (Fig. 7B).relationship between the water level and the positive plane area (area of the projection of the islands), where an oscillating relationship increases and decreases the plane area as the level increases, the convergence of the curves of the positive planer area is observed to be with a positive surface area due to the low resolution of the DEM, The fluctuation factors that occur in the positive planer area relationship with the level are due to the same reasons as the positive surface area relationship with the level, all of which result from the expansion of the reservoir boundaries over time and the addition of new lands within its boundaries and its departure from the original riverbed (Fig. 8A), where the relationship between the water level and negative planer area shows in Fig. 8B.The relationship of the average depth of the reservoir with the water level is shown in Fig. 9A, where the increase is gradual as the level increases until it reaches a level of 106.0 m.a.s.l., where the average depth of the reservoir is 12.07m, which is the maximum average depth of the Al-Baghdadi dam reservoir.Water level with land height average oscillation relationship as the level increases, starts decreasing at the first levels and then starts to rise suddenly, followed by a series of highs and lows (Fig. 9B).

Fig. 1 .
Fig.1.Location map of the study area

Fig. 2 .
Fig.2.Geological map of the study area
curves of the positive surface area and the positive plane area in addition to the positive volume fluctuate with the water level due to the expansion of the reservoir boundaries and the addition of new islands.2. The relationship of the negative volume with the elected water levels indicates the existence of three stages at which the storage volume of the reservoir changes, the first stage in which the volume of the reservoir is small because the reservoir is within the boundaries of the natural course of the river, the second (transitional) stage shows a larger storage volume of the reservoir than the first stage as a result of the departure of the reservoir from the natural course of the river towards the flood plain, in the third stage the storage volume of the reservoir becomes much larger as a result of the expansion of the boundaries of the reservoir towards the river terraces and the addition of new islands.3. The congruence in negative surface area and negative plane area curves is due to the lack of accuracy in the numerical elevation model.4.Preventing the establishment of the facility in areas located within the boundaries of the proposed dam reservoir.

Table 1 .
Geometric elements for each of the selected levels of the reservoir in meters