Generate Reservoir Depths Mapping by Using Digital Elevation Model: A Case Study of Mosul Dam Lake, Northern Iraq

Abstract

Not many bathymetric maps are available for many lakes and reservoirs in developing countries. Usually the bathymetric mapping requires investment in expensive equipment and fieldwork, both of which are not accessible in these countries. This work demonstrates the ability to develop bathymetric map of Mosul Lake by using a digital elevation model (DEM). The depths model of the lake was designed through the use of three main stages; a coastline extraction, dataset interpolation and a triangular irregular network model. The normalized difference water index (NDWI) was used for automatic delineation of the lake coastline from satellite images. The ordinary kriging interpolation with a stable model was used to interpolate the water depths dataset. Finally a triangulated irregular network (TIN) model was used to visualize the resulting interpolation model. Calculated values of area and volume of a TIN model during 2011 were compared with values of supposed initial operation of the reservoir. The differences of water volume storage between these stages at 321 m water level was about 0.81 × 10 9 m 3 , where the lake lost around 10% of storage value. Also the results of depths lake model show that the change in water storage between March and July 2011 was about 3.08 × 10 9 m 3 .

A New Digital Lake Bathymetry Model Using the Step-Wise Water Recession Method to Generate 3D Lake Bathymetric Maps Based on DEMs

“…We set a coordinate system on the assumed bottom point, where x denotes the distance from the assumed bottom point and z denotes the elevation. Based on this, there are two main formulas to calculate k1 i , as shown in Equations (4) and (5).…”

“…Conventionally, the accurate calculation of lake water storage or volume relies on the correct mapping of lake bathymetry, which is the key parameter for lake morphology study [1][2][3][4]. However, in situ mapping of lake bathymetry is costly and labor intensive [5]. Additionally, due to water's high attenuation of electromagnetic waves, big lake bathymetry cannot be retrieved directly using satellite remote sensing [6].…”

“…Additionally, due to water's high attenuation of electromagnetic waves, big lake bathymetry cannot be retrieved directly using satellite remote sensing [6]. Therefore, bathymetric maps for most of the lakes worldwide are still lacking, except for a small number of lakes (e.g., Lake Ontario in the United States) that were measured mainly by sonar [5].…”

“…The abovementioned methods can obtain acceptable and accurate lake bathymetric maps, which are inconvenient and expensive, especially for estimating the vast number of lakes regionally or globally. By utilizing a remote sensing approach, the capability of estimating lake volume in large areas can be improved [5,10]. Therefore, here we list some previously published methods for lake volume estimation:…”

“…We admit the measured data is indispensable for high accurate research, and more uniform distribution of the input data will lead to more accurate results. However, in considering the big cost of large-scale in-situ data [5], it is still important to develop remote sensing methods without these data. This is also the starting point of our method.…”