Remote sensing-based dynamic estimation method for outflow process of ungauged free overflow reservoir

A remote sensing-based dynamic estimation method for the outflow process of an ungauged free overflow reservoir, wherein the flood releasing buildings of the free overflow reservoir employ overflow weirs without gate control, and there is no characteristic water level, storage volume curve and drainage curve of the free overflow reservoir, the method comprises the following steps:

• Step 1:
• Obtaining a water level-area relation curve of the water reservoir based on the digital elevation model (DEM) data;
• estimating the storage volumes of the water reservoir at different water levels from the water level-area relation curve of the reservoir, and establishing an area-storage volume relation curve of the water reservoir;
• Step 2:
• Extracting the water surface area of the ungauged reservoir from remote sensing images, and obtaining the storage volumes of the water reservoir in the time periods corresponding to the remote sensing images by using the water surface area data and the water level-area-storage volume relation curve in combination;
• Step 3:
• Obtaining the change of the storage volume of the water reservoir through the cumulative calculations on the storage volume changes in the time periods corresponding to the two remote sensing images with a hydraulic outflow calculation formula under a principle of water balance;
• Step 4:
• Gradually approximating an outflow coefficient of the water reservoir by using a bisection method, so that the change of the storage volume of the reservoir obtained through the calculation under the principle of water balance is consistent with the change of the storage volume in the time periods corresponding to the two remote sensing images;
• Step 5:
• Taking the final approximation result as the outflow coefficient of the ungauged reservoir, and calculating the outflow process of the water reservoir during floods.