Resilience Changes in a River Basin: Identifying Hydrologic Regime Shifts Using Long-term Streamflow Data

River basins are unique dynamic systems shaped by hydrologic variation patterns that can adapt and thrive to changes in hydrologic patterns over time. River basins are resilient systems that can adapt and thrive to changes in hydrologic patterns over time and absorb disturbances. Persistent forcing, either natural or anthropogenic, can bring the system to a critical threshold or limit, causing undesirable regime shifts or ecosystem switching to an alternative state. How ecosystems react to perturbations is a central question in ecology today because these can cause catastrophic, undesirable, and even irreversible changes in natural systems. This study addresses how much forcing a river basin can take until the system undergoes a regime shift and into an alternative state? As a representative case, the Rio Conchos is selected. Resilient indicators for quantitatively assessing resilience require long-term records sampled as temporal and spatial scales. This study analyzes 110 years of daily natural flows from 1900 to 2010. First, the hydrologic variability of a river basin is analyzed to describe the hydrologic states or basins of attraction of the naturalized system compared to a regulated system using the Streamflow Drought Index (SDI). Second, the detection of regime shifts is captured by the quantitative indicator Fisher information, followed by quantifying anthropogenic pressures that have caused the shift. Preliminary results indicate that a resilience threshold was surpassed, and a regime shift occurred in the control point of the Rio Conchos subbasin after three substantial anthropogenic perturbations occurred by 1948.