Water consumption is greatly rising as a result of global population growth, climate change, and other socioeconomic factors. The race to extract more water to meet the demands of various sectors is rising, making it difficult to ensure equitable water allocation. An effort was made in this study to assess the water supply and demand gap among several sectors, namely energy, agriculture, and navigation in the lower Danube river, where water is shared by Serbia, Romania, and Bulgaria. A literature review was undertaken to understand the possible approaches that may be used in this specific case. Data were collected from various sources and evaluated, to create input data for the water allocation and hydraulic models. To understand the water supply and demand imbalance under different conditions, three alternative scenarios were generated: dry, normal, and wet year periods. The Water Evaluation and Planning Model (WEAP) software tool was used to estimate the demand and supply gap in the research area for both energy production and irrigation. A hydraulic model was created utilizing the Hydrologic Engineering Center's River Analysis System (HEC-RAS) application to determine the water depth corresponding to the flow remaining in the river after energy and irrigation water consumption. In terms of water demand for energy production, the findings indicate that April has the highest demand fulfilment, while September has the lowest demand coverage. No water deficit has been found for agriculture water use, given the fact that available water in the system is much higher than the required crop water requirement (cwr) throughout the year. The hydraulic model results show that water depth is rather low in dry years, which will have a negative impact on navigation.