Collections > UNC Chapel Hill Undergraduate Honors Theses Collection > Assessing Water Storage and Discharge Dynamics at the Catchment Scale under Complex Wetting and Drying Conditions

Hysteresis in the soil water storage / discharge relationship is an important but poorly understood aspect of catchment response to rainfall, particularly in regards to spatial and temporal variations. In this study, a physics-based hydrologic response model was used to examine differences in hysteresis at the catchment and point scale for rainfall events with different durations and initial conditions. Additionally, the annual water balance of the catchment was analyzed to explore the factors that influence runoff and to identify possible predictors of runoff generation. Differences in topography that result from position within the catchment (hillslope vs. hollow) act as a major control on the timing and magnitude of discharge within the catchment and can influence the amount of hysteresis observed in the soil water content/discharge relationship. The results show that the direction of hysteresis across the catchment was unpredictable and did not correspond to either storm duration or initial conditions, which is an indicator of the complex spatial dynamics in response to rainfall. A soil moisture threshold for discharge was observed at 0.48 but was less likely to be observed for storms with short duration or dry initial conditions. Areas of average topography (CASMM sites) can be used to represent the average hydrologic state of the catchment, which has important implications for the role of topography and means identifying these locations could be useful for future research. The use of hydrologic response models and representative locations allows for high spatial and temporal resolution studies with lower costs and fewer measurement errors, making them valuable methods for studying catchment hydrologic properties.