Research on Relationship of Total Nitrogen Concentration and Runoff in the Xiangxi River Basin

The response relationship between pollutant and flow rate is very important and is one of the key factors for the reasonable simulation of the model for a basin. The basin land use type, soil types, weather, vegetation distribution, soil and water loss situation are taken as the influence factors to explore its concentration change in migration of pollutants in relation with the response of the flow in Xiangxi River watershed. Emphasis was put on the effects of nitrogen pollutants based on the mass conservation equation combined with the total nitrogen concentration of pollutants. Relationship between total nitrogen pollutants and flow of three types of response relation is preliminary established. Measured data of total nitrogen from 2014 to 2017 are used for verification and error analysis. Results show that the power function is the best relationship, while the logarithm function is the second one, and the exponential function is the third one through trend coincidence, fluctuation range and error analysis. This study is helpful to understand the response relationship between pollutant concentration and discharge in small watershed, so it can also be used for pollutant prediction in small watershed without measured data.