A gis-based method for estimating the load of nitrogen runoff loss in distributed paddy fields

Abstract

The invention relates to a GIS (geographic information system)-based distributed-type rice field nitrogen runoff loss load estimating method. The method includes: 1), collecting basic information of a studied area, namely collecting daily rainfall, evaporation capacity, administrative area, land use map and soil map of the studied area; 2), investigating basic data of fertilizing and field moisture management; 3), generating a related space distribution grid map layer; 4), measuring and calculating dynamic changing rules of rice field surface water nitrogen concentration under different soil types, namely dynamically monitoring rice field surface water under different soil types and different fertilizing levels, and calculating fitting equation parameters of the rice field surface water; 5), calculating rice field nitrogen runoff loss load including a water quantity balance module, an initial concentration calculating module and a load output module. By the GIS-based distributed-type rice field nitrogen runoff loss load estimating method, temporal and spatial change of non-point-source-generated pollution discharging coefficient can be reflected, few basic data and parameters are needed, model building is easy, and running efficiency is high.

Description

technical field [0001] The invention relates to a non-point source pollution load estimation method, in particular to a GIS-based method suitable for estimating the nitrogen runoff loss load of large-scale paddy fields in plain areas. Background technique [0002] In recent years, with the gradual control of point source pollution, the problem of non-point source pollution has become prominent. The loss of nitrogen and phosphorus in farmland is the most important part of non-point source pollution, and it is an international trend to pay attention to agricultural non-point source pollution. On June 5, 2013, the "2012 China Environmental Status Bulletin" published by the Ministry of Environmental Protection stated that more than 30% of the country's rivers and more than 50% of the groundwater did not meet the standards, and agricultural non-point source pollution was one of the culprits that could not be ignored. . The contradiction of more people and less land in the devel...

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Problems solved by technology

[0004] (1) The output coefficient method usually uses the area occupied by a certain land use type in the region and its corresponding unit loss coefficient to estimate the pollution load. This method is simple and easy, but because the loss coefficient is usually a single empirical value, it cannot used for rough estimation only;

[0005] (2) The on-site monitoring method usually selects a representative typical community in the research area, monitors the water quantity and water quality of rainfall runoff simultaneously, and estimates the non-point source load of the entire watershed based on the pollution load per unit of the community. This method is more intuitive. However, due to the temporal and spatial differences of non-point source pollution, its applicability is affected;

The typical representative of the mechanism model is a series of mature software such as SWAT and AnnAGNPS, whose essence is to use the "3S" technology as a platform to divide the watershed into several catchment areas based on data such as digital elevation model (DEM) and land use maps. unit, and simulate the migration and transformation of pollutants according to various kinetic equations and empirical formulas, which can simulate complex non-point source sewage production and discharge mechanisms, but the establishment of models has high requirements for the integrity of various data, and the domestic data sharing system is not enough Perfect, but data sharing is difficult

Moreover, due to the complex mechanism of non-point source pollution, it is almost impossible to accurately describe the process of non-point source pollution.

At the same time, people found that the infinitely fine formula description of the mechanism of non-point source can not increase the accuracy of the model, but may cause greater errors, and increase the input of the model, the operation is more complicated, and the operation cost increases. Therefore, such as the SCS hydrological model Statistical models such as the Universal Soil Loss Equation (USLE) are still widely used

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