The study was conducted in Lake Hayq watershed which covers 86 km2.The aim of this study was to assess the Lake morphometric change and to identify the causes and extent of Lake morphometric change using data from multi-sources. The cause of the Lake morphometric change detected through multi-temporal bathymetry surveys was the research problem for the present study. In order to address the main research problem, the study applied an integrated approach that includes remote sensing and Geographic Information System (GIS), soil erosion/deposition modeling and ground survey. The individuality and newly of this research is integrating multi-source data as well as multi-disciplinary approaches in improving knowledge and information on surface water resources related problems. The soil erosion/deposition from 1980 to 2019 is estimated by unit Stream Power Erosion Deposition(USPED) model through Arc GIS 10.1. The annual average soil erosion, deposition and net soil loss was 321,283, 209,642 and 111,641 tons/year respectively. The average sediment depth accumulated in Lake Hayq during the assessment periods was 3.8 cm. An average annual sediment deposition was 0.4 cm. The water abstraction was estimated to 1,268,809 m3 which reduces the Lake depth by 0.9 cm. The Lake evaporation was estimated for 8 years (1985 -2019) by Penman’s method and the average annual Lake evaporation was 1.69-meter. From those different data source assessments, the cause factor of Lake level reduction corresponding to Lake morphometric change was assessed and the conclusion was made. This research established the conclusion that the cause for the Lake level reduction, evaporation and abstraction has impacts, while the change in Lake depth shows a positive of 0.5 meter. This difference could be accounted for internal openings. For the estimated patchy bathymetry results it is concluded that there is instrumental, measurement or calculation error.