The ability to simulate algal systems is critical for watershed-scale models. The objective of this study was to develop and evaluate a modified algal module that simulates the dynamics of three major algal groups (cyanobacteria, green algae, and diatoms) in a stream using variables available in the Soil and Water Assessment Tool. The proposed module 1) models the dynamics of the three algal groups while accounting for nutrients from algal die-off and 2) has temperature multipliers that consider the effect of temperature changes on kinetic rates. Data to test the module were collected from a forest-dominated watershed over two years. The modified module was efficient in predicting seasonal variations in algal group biomass and simulated the regeneration of nutrients after algal die-off. This module will be useful in predicting the dynamics of the three studied algal groups and evaluating the best management practices for algal blooms in watersheds.

模拟藻类系统的能力对于分水岭规模模型至关重要。这项研究的目的是开发和评估改进的藻类模块，该模块使用“土壤和水评估工具”中可用的变量模拟河流中三个主要藻类组（蓝藻，绿藻和硅藻）的动力学。提出的模块1）在考虑藻类死亡造成的营养物的同时对三个藻类的动力学模型进行建模，以及2）具有考虑温度变化对动力学速率影响的温度倍增器。测试模块的数据是在两年内从一个森林为主的流域收集的。修改后的模块可有效预测藻类生物量的季节性变化，并模拟藻死亡后营养物质的再生。