A new hydrologic model called HYSTAR was developed to simulate how water moves across landscapes over time. This model uses a time-area method to show where water flows and how much runoff is generated during storms. By considering factors like soil moisture and rainfall, HYSTAR can predict daily and monthly runoff accurately. The model doesn't rely on complex equations, making it simpler to use while still capturing the complexity of water flow. The results from testing the model on a watershed in Virginia showed that it effectively represents how water moves through different parts of the landscape, providing a useful tool for understanding and predicting hydrologic processes.