Catchment area critical rainfall calculating method based on DEM

Abstract

The invention discloses a catchment area critical rainfall calculating method based on a DEM. The method comprises the steps that a waterlogging minimum point hmin of a catchment area is firstly acquired, an elevation value of the waterlogging minimum point is added to a maximum value delta h of the waterlogging depth to obtain a waterlogging elevation value of the catchment area, a height difference delta h obtained by subtracting the waterlogging elevation value from an original DEM diagram layer serves as a waterlogging depth value of each grid, the grid waterlogging depth delta h is added to the average drainage capability d of the catchment area to obtain the runoff volume q of the grid, and the runoff volume q of all the grids is accumulated to obtain the total sum of the runoff volume of the catchment area; the ratio of the total runoff volume to a runoff coefficient alpha serves as the total rainfall of the catchment area; the total rainfall is divided by the area of the whole catchment area to obtain the unit area rainfall, that is, the catchment area critical rainfall generated when the waterlogging depth is delta h. According to the method, personal errors generated when the waterlogging depth is manually collected for regression analysis in the past are omitted, so that a calculating result is more scientific and reasonable.

Description

technical field [0001] The invention discloses a DEM-based method for calculating the critical surface rainfall of accumulated water in a catchment area, which belongs to the technology of surveying and mapping and geographic information. Background technique [0002] In urban waterlogging risk assessment, it is necessary to evaluate the critical surface rainfall of the water accumulation depth in a catchment area, that is, how many millimeters of rain falls in this area when the water accumulation reaches a certain depth in a certain watershed area. [0003] The critical surface rainfall in the catchment area is of great significance for the prediction of waterlogging in the catchment area. The traditional calculation of the critical surface rainfall in the catchment area often uses statistical analysis methods, that is, the regression analysis equation between the water accumulation depth and rainfall is established through several sample points. The critical surface rainf...

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Problems solved by technology

[0003] The critical surface rainfall in the catchment area is of great significance for the prediction of waterlogging in the catchment area. The traditional calculation of the critical surface rainfall in the catchment area often uses statistical analysis methods, that is, the regression analysis equation between the water accumulation depth and rainfall is established through several sample points. The critical surface rainfall at different water depths is calculated through the regression equation, but this method requires a large number of disaster investigation samples, and it is difficult to collect all the disaster samples that meet the requirements in a short period of time. At the same time, there are large errors in the calculation results, so it is not necessary. Cannot meet the needs of urban waterlogging monitoring and early warning