# Study of the Dynamic Adaptive Calculation Method for River Water Environmental Capacity
## 1 Introduction
[4] proposed a machine learning-assisted method to estimate the watershed-scale WEC through process-based model simulations of pollutant concentrations and an artificial neural network (ANN). Through the global optimization method, a watershed-scale WEC that meets water quality constraints can be obtained. Considering the relationship between the water environment and pollutant emissions, [PERSON] et al. [25] analyzed the uncertainty of WEC based on Copula and Bayesian models. Most of these WEC calculation methods have specific computational conditions and are suitable for different situations. In practical applications, it is necessary to choose reasonably according to a river's situation and the level of data collected. In addition to studying the calculation model for WEC, scholars have also studied the effects of changes in the calculation conditions on WEC, such as flow rate, background concentration, degradation coefficient, and design frequency. Some scholars [26; 27; 28] have set different design frequencies and used a one-dimensional water quality model to calculate the WEC of river sections in their study areas. Other scholars [29] have proposed that for the calculation of WEC, because the hydrological and hydraulic processes in different regions of the basin are different, the whole basin needs to be divided into different regions to ensure the accuracy of river WEC calculations. Some scholars [30] have established a water level-like area-reservoir relationship model and found that dynamic changes in WEC in the lake area depends on the dynamic changes in the hydrology and water quality. Some scholars [31] have proposed that different hydrological conditions will affect the value of parameters, and the determination of WEC parameters should be dynamically determined according to the actual situation of a river. Most of the aforementioned research on WEC calculation focuses on model construction, calculation condition setting, and parameter analysis, with limited research focusing on a systematic and universal framework for WEC determination. WEC is influenced by numerous factors, including the water cycle, hydrological elements, natural factors, inflow processes, and discharge processes, and is dynamic in nature. However, the current model is difficult to adapt to changing environmental conditions, and the research results obtained under fixed conditions are mostly used to make plans, which are difficult to apply in practice. Given the dynamic nature of WEC, in this paper, a dynamic adaptive calculation method is proposed for river WEC, aiming to achieve dynamic WEC calculations and adapt to the development of river. This method synthetically considers various variable factors, including temporal-spatial scale changes, river flow changes, parameter changes, hydrological conditions changes, calculation method changes, etc., and calculates the result interval of river WEC at various time scales. WEC is a variable interval. Supported by an integration platform, a dynamic adaptive calculation simulation system for WEC in the Wei River was constructed. By considering the dynamics of spatial-temporal scales, hydrological conditions, model methodologies and their parameters, and the dynamics of design guarantee rate, the calculation results of WEC are expressed in intervals, and the dynamic simulations and adaptive calculations of river WEC are realized. It can solve the problems caused by various uncertainties, such as difficulty in accurately quantifying WEC, poor adaptability, and poor operability, and provide decision support for managers.