New Procedure to Reservoir Depth and Islands Mapping for Badush Dam Reservoir Using DEM, Mosul, Northern Iraq

To determine the depths in water bodies as in the rivers, lakes, and dams reservoirs, it is necessary to use a bathometric survey, which sometimes requires cost and fieldwork, but in this study, the gradient in the depth of the Badush Dam Lake was estimated before the filling and real operation of the reservoir and found using a digital elevation model (DEM) with a resolution of 10*10 meters, where the obtained data was processed, the depth maps will be a data base for future depth monitoring, from the digital elevation (DEM) model using several programs (Global Mapper 18 & Global Mapper Pro.V.24) (Excel software), and after processing, depth maps are drawn using the (Surfer.16) software, it was noticed the increase in depth with increasing level, as the values represent the negative depths of the dam reservoir, where the minimum depth at the level of 228 m(a.s.l) ranges between (0 to -2.1 m), while at the maximum operational level at a level of 250 m(a.s.l), the depth ranges between (0 to -26 m), while at the maximum flood level of 312 m(a.s.l), the depth ranges between (0 to -90 m). As for the positive values, they represent the positive areas that fluctuate with the increase in the level due to the expansion of the reservoir area, the submergence of islands, and the emergence of new islands inside the body of the reservoir, where the lowest height was reach (0.7 m) at a level of 228 m(a.s.l), and the highest height was (35 m) at a level of 270 m(a.s.l).


Introduction:
Within the water resources management plan for Tigris River basin, it is proposed to construct Badush dam (currently under construction), as a dam to protect against the collapse of Mosul dam due to engineering or structural problems.Water resources are one of the most important requirements for the continuation and perpetuation of human life and life cannot continue without water, as it is a resource that has a major role in all aspects of life and is the basic factor for development.The need for water resources in Iraq is constantly increasing, as a result of population growth and economic and social development on the other hand.Decreased water resources as a result of the expansion and investment of water resources in the upstream countries that are located on the rivers that flow into Iraq, Water resources will remain the main axis for the growth and development of agriculture and industry, therefore decision-makers in water sector must follow policies and contexts that include full water rights by concluding agreements with the countries from which the rivers flow to Iraq, and adopting a water policy based on the optimal investment of these resources [1].The depth of water represents one of the dynamic body water factors, which affects the real distribution and characteristics of the water body, modeling of flow dynamics, water hydraulics, and forecasting flow hazard [2].This information is very important to understand the changes in water body parameters, which is necessary for developing better management [3].The identification and mapping of the depths of Badush Dam reservoir at each level are very important to determine the variation of depths within the reservoir at specific levels because of its impact on several operational properties and environmental characteristics, as the study of depth is important in determining the operational age of the reservoir by estimating the change in depth with the time and knowing the thickness of the sediments inside the reservoir by comparing the depth when the beginning of operation with the depth IOP Publishing doi:10.1088/1755-1315/1300/1/012022 2 in different time periods, in addition to the importance of depth in determining the navigation lines, fishing and the amount of submerge for boats, ships, and yachts, and in determining the areas of few depths within the reservoir.
The study aimed to determine the depths of the reservoir at the operating and flood level (negative areas) and island areas within the reservoir (positive areas), to give an idea of the extensions and distribution of the depths of the reservoir at each level, which is important in knowing the deep and shallow areas in the reservoir and knowing the locations of positive area (islands) that are important in determining the navigation line and the shoreline that are needed for the future operation program, transportation by yachts and boats, fishing and tourism.
The study area is located in northern Iraq, in Nineveh Governorate, where Badush Dam is located on Tigris River, about 40 kilometers south of Mosul Dam and about 16 kilometers northwest of the city of Mosul in northern Iraq, between the UTM coordinates 280000 -327000 East, and 4030000 -4060000 North, while the regulation dam located between the two mentioned dams, Figure 1.The Euphrates Formation (Lower Miocene) was first described by [4].The formation is composed of dolomitic, fossiliferous, and oolitic limestone with green marls at the top [5].It is exposed at the core of the Alan anticline; with highly karstified rocks [6].Depending to [4], as for the age of this formation, it is the middle Miocene.Fatha formation is cyclic, consisting of the repetition of carbonate (limestone/dolomite) anhydrite, gypsum, salt, and marl.These cycles are caused by either vertical block movements or changes in the lagoon's Eustatic water level, both of which can play an important role in the development of these cycles [7].Fatha formation outcrops on both sides of the surface along the Tigris Valley between the dam site and the reservoir.Upper Fatha it consists of successions of limestone, mudstone, siltstone, and thin layers of gypsum [8].That is less dangerous to the dam and the reservoir.Lower Fatha it consists of marly limestone and gypsum, and the thickness of these rocks is usually not fixed in sedimentary cycles [8].The formation is divided into lower and upper members and forms the majority of the Alan anticline and surrounding areas [6].In a study basin, the Injana formation is a series of interbreeding of sandstone, siltstone, sand (the sandstones and sands are medium to fine-grained), and claystone following one after the other.Recent alluvial deposits (river terrace deposits and alluvial deposits silt, silty clay, sand, gravel pebbles and cobbles) cover the major portion of the reservoir area, thickness of these sediments vary from several centimeters to more than ten meters [9].Badush Dam and reservoir areas represent a part of the unstable shelf, foothill zone, and Mosul Butmah subzone.The prevailing structural shapes are folded in an east-west direction, which formed in the Plio-Quaternary period.Allan Anticline is the most outstanding structure in the reservoir area.It is an asymmetric double plunging Anticline fold, the southern limb of which is inclined by 22° and the northern limb is inclined by 10°, and the length of the Anticline is 26 km and the width of it is 4 km approximately [10].[11; 12; 13; 14; 15&16] the researchers in this research studied the depth analysis of lakes and reservoirs by bathometric survey of the lake after filling and at the operational level, but in our current study, depth maps were made for the reservoir before filling and operating at the operational and flood levels of the reservoir.

Methodology
The suggested procedure used in this methodology is to calculate the depth of water at each level and any point inside the reservoir within the relevant level, through which it is possible to know the variation of depth in the water reservoir at each level through a series of steps using the programs and calculations, to determine the depth with the following points:     6) Tight data process.5-Then, the file is converted as a grid format (GRID FIEL) by exporting it in (Export Elevation Grid Format) from (Global Mapper Pro.V.24) software by (Export) option.
6-A contour map is drawn with the software (Surfer.16)by calling the (GRID FIEL) through the COUNTOR MAP option.

Reservoir Water Depth Mapping Using DEM
The elevation data grid within Badush reservoir was derived from the DEM and exported as an Excel files, for 10 selected levels, and then the values of theses selected levels subtracted from the data of corresponding grids to obtain a grid of water depths within the reservoir at the maximum and lowest levels, and the elevations of Islands.Then Surfer.16software used to plot the depth maps at the specific levels (235, 241.5, 245, 250, 261.5, 270, 280, 290, 309, and 312 m (a.s.l)), as shown in Figures (7), ( 8), ( 9), ( 10), ( 11), ( 12), ( 13), ( 14), ( 15), ( 16), and (17).Where the depth scale ranges between (0 to -2.1) at the level ( 228) m (a.s.l), the depth is (0) at the shoreline of the reservoir, and the depth increases to (-2.1) near the dam, as observed and the presence of broad shallow areas in the northern part of the reservoir, and the presence of branches in the northern and northeast part of the reservoir.And at the level (235) m (a.s.l), the depth range is between (0 to -10)m, the depth is (0) at the shoreline of the reservoir and the increases to (-10) near the dam, there are large shallow areas in the northern part of the reservoir, as well as the presence of branches in the northern and northwestern part of the reservoir, the depth increases with the increase in the level to ranges between (0-16) when the level 241.5 m (a.s.l), the depth is (0) at the shoreline of the reservoir and the depth increases to (-16) near the upstream face of the dam, the depth decreases towards the west and northwest.where the level (245) m (a.s.l), the depth range is between (0 to -20) m, the depth is (0) at the shoreline of the reservoir and the depth increases to (-20) close to the dam, where the depth decreases in the north towards the direction of the reregulation dam and in level 250 m (a.s.l), the depth range is between (0 to -26)m, the shoreline of the reservoir with (0) depth and maximum depth is (-26) in close to the dam, and the shallow area decreases towards the west of reservoir.Wherever the depth in flood levels 261.5 m (a.s.l) the depth increases and ranges between (0 to -36)m, the depth is (0) at the shoreline of the reservoir and increases to (-36) on the area near to the dam, where the depth decreases in the north, in addition to the presence of shallow branches in the western, eastern and northern parts of the reservoir which represent the estuaries of intermittent valleys, while in level 270 m (a.s.l) the reservoir depth ranges between (0 to-45), the depth is (0) at the shoreline of the reservoir in addition to the small, shallow branches that surround the reservoir at this level, which have very few depths, and the depth increases to (-45) near the dam.With the increase in the level to 280 m (a.s.l), and new areas enclosed within the reservoir the depth ranges between (0 to -50), the depth is (0) at the shoreline of the reservoir and the depth increases to (-55) in the nearest areas to the dam, then the depth decreases in the western direction, northwest direction, and towards the north in addition to the presence of relatively large branches in the surrounding of the reservoir, and in level 290 m(a.s.l) the depth range is between (0 to -65)m where the depth increased more and more near Badosh dam, and (0) depth at shoreline of the reservoir with the expansion of branches in all directions of the reservoir, and in level 309 m (a.s.l) the depth increase and range is between (0 to -85), it is noticed that the gradient of depth from the shoreline with (0) and increased gradually to (-85) towards the dam body, while in the maximum flood level 312 m (a.s.l) the depth is range between (0 to -90), when the shoreline with (0)m depth, and increase gradually to(-90) towards the dam body, with the increase of branches in the surroundings of the reservoir.

Islands Heights Mapping
The islands represent the positive area within the reservoir boundary, and through the depth mapping as shown in Figure ( 6), ( 7), ( 8), ( 9), ( 10), ( 11), ( 12), ( 13), ( 14), (15), and (16).The areas that are in the form of closed contour lines within the reservoir represent positive bodies (islands) at the level (228) m (a.s.l) the height of these areas are ranged between (0-0.7m) in the northern and northwest part of the reservoir, and at the level (235) m (a.s.l) the positive area is range between (0-8), it was noted that the positive areas are very clear in the southern and middle part of the reservoir and the height ranges between (0-18) in level 241.5 m (a.s.l), also it can observe an increase in the positive areas with the increase in the level and the enter of new area within the boundary of the reservoir.And in level 245 m (a.s.l), the positive areas areas height ranged between (0-16) with a decrease in the positive areas due to submerge of islands.And at level 250 m (a.s.l) the heights of positive areas are ranged between (0-22m), as the height of positive area increases to (22m) in the eastern and western parts of the reservoir, while in floods level 261.5 the height of positive areas is range between (0-14m), where it was noticed a decrease in the height of positive areas to (14 m) by submerge when Mosul dam breakdown flooding, and in the level 270 m (a.s.l) the positive areas height is range between (0-35m), where we notice an increase in the positive areas height due to the expansion of the reservoir due to the flood and the entry of new high lands inside the reservoir, where the height of island to about (35 m) in the northeastern part of the reservoir.In a level 280 m (a.s.l), the height of islands decreases to the range between (0-25m) because of the submerge that occurs due to the increase in the level.The height of islands decreases more in the levels of 290 m (a.s.l) and 309 m (a.s.l) respectively to the range between (0-20m) due to the increase in the level.The heights of positive areas are relatively increased in the maximum flood level of the reservoir 312 m (a.s.l) and the reservoir reaches its maximum capacity and the islands height ranges between (0-25m).

Conclusions
The depth of the Badush Dam reservoir reaches (-26) at the operational level from (226.5-245.5)m (a.s.l) and (-90) at the flood level from ( 250 -312) m (a.s.l) , as this depth qualifies to receive the flood wave resulting from the collapse of Mosul Dam, while the islands and positive areas reached the height of the highest point inside the reservoir at the operational level (22) while the highest point Inside the reservoir at flood level (25).

Fig. 1 .
Fig. 1.Location of the three dams in the study area (the boundaries of the area derived from the DEM by researcher, also, the locations of dams determined by differential GPS).The rock formations of the area which will be submersed in the reservoir are of sedimentary origin, ranging from Paleocene to recent ages.The lithostratigraphic sequence of the bedrock layers is composed of the Fatha formation (Fatha Series of Middle Miocene), Mukdadiya formation of Lower Pliocene, Injana Formation of Upper Miocene, Jeribe formation of Middle Miocene age, Euphrates formation of Lower Miocene age, Jaddala formation of Early Eocene-Late Eocene and Sinjar formation of Paleocene-Early Eocene as Figure (2) .The Euphrates Formation (Lower Miocene) was first described by[4].The formation is composed of dolomitic, fossiliferous, and oolitic limestone with green marls at the top[5].It is exposed at the core of the Alan anticline; with highly karstified rocks[6].Depending to[4], as for the age of this formation, it is the middle Miocene.Fatha formation is cyclic, consisting of the repetition of carbonate (limestone/dolomite) anhydrite, gypsum, salt, and marl.These cycles are caused by either vertical

1 -
To calculate depth maps with the (Surfer.16)program, the data at a certain level that is deduced from (DEM with resolution of 10 * 10 meters ) through the (Global Mapper 18) program is exported in the (XYZ Grid File) format as shown in Figures(3) and (4).

Fig. ( 4 )
Fig. (4) Grid export options for exported file from (Global Mapper 18).2-The XYZ Grid File that is exported from the (Global Mapper 18) software is opened in the Excel software, where it contains the coordinates (X and Y) and (Z), which represent the ground level and the attribute are issued in the form of an excel file.3-The depth is extracted in Excel software by subtraction of each selected water level at which the depth is to be calculated from the ground level obtained from the DEM, then the positive value represents the islands and the positive area within the reservoir body, and the negative value represents the deep of points within the reservoir.4-The excel file is inserted into (Global Mapper Pro.V.24) software, and the data is processed by (create Elevation Grid from 3D Vector Data) as in Figure (5) by assigning (point only all feature are points) and use the (Tight) as grid option Figure (6).

Fig. ( 17
Fig. (17) depths map of Badush reservoir (-), and islands heights (+), and shoreline (0) at a level (312 m).Where the depth scale ranges between (0 to -2.1) at the level (228) m (a.s.l), the depth is (0) at the shoreline of the reservoir, and the depth increases to (-2.1) near the dam, as observed and the presence of broad shallow areas in the northern part of the reservoir, and the presence of branches in the northern and northeast part of the reservoir.And at the level (235) m (a.s.l), the depth range is between (0 to -10)m, the depth is (0) at the shoreline of the reservoir and the increases to (-10) near the dam, there are large shallow areas in the northern part of the reservoir, as well as the presence of branches in the northern and northwestern part of the reservoir, the depth increases with the increase in the level to ranges between (0-16) when the level 241.5 m (a.s.l), the depth is (0) at the shoreline of the reservoir and the depth increases to (-16) near the upstream face of the dam, the depth decreases towards the west and northwest.where the level (245) m (a.s.l), the depth range is between (0 to -20) m, the depth is (0) at the shoreline of the reservoir and the depth increases to (-20) close to the dam, where the depth decreases in the north towards the direction of the reregulation dam and in level 250 m (a.s.l), the depth range is between (0 to -26)m, the shoreline of the reservoir with (0) depth and maximum depth is (-26) in close to the dam, and the shallow area decreases towards the west of reservoir.Wherever the depth in flood levels 261.5 m (a.s.l) the depth increases and ranges between (0 to -36)m, the depth is (0) at the shoreline of the reservoir and increases to (-36) on the area near to the dam, where the depth decreases in the north, in addition to the presence of shallow branches in the western, eastern and northern parts of the reservoir which represent the estuaries of intermittent valleys, while in level 270 m (a.s.l) the reservoir depth ranges between (0 to-45), the depth is (0) at the shoreline of the reservoir in addition to the small, shallow branches that surround the reservoir at this level, which have very few depths, and the depth increases to (-45) near the dam.With the increase in the level to 280 m (a.s.l), and new areas enclosed within the reservoir the depth ranges between (0 to -50), the depth is (0) at the shoreline of the reservoir and the depth increases to (-55) in the nearest areas to the dam, then the depth decreases in the western direction, northwest direction, and towards the north in addition to the presence of relatively large branches in the surrounding of the reservoir, and in level 290 m(a.s.l) the depth range is between (0 to -65)m where the depth increased more and more near Badosh dam, and (0) depth at shoreline of the reservoir with the expansion of branches in all directions of the reservoir, and in level 309 m (a.s.l) the depth increase and range is between (0 to -85), it is noticed that the gradient of depth from the shoreline with (0) and increased gradually to (-85) towards the dam body, while in the maximum flood level 312 m (a.s.l) the depth is range between (0 to -90), when the shoreline with (0)m depth, and increase gradually to(-90) towards the dam body, with the increase of branches in the surroundings of the reservoir.