Hydrologic Footprint Residence: A New Metric to Assess Hydrological Alterations Due to Urbanization

Urbanization modifies hydrological processes in a watershed as surface alterations, such as the use of impervious cover, increase runoff volumes and modify the temporal patterns of the hydrograph. Higher peak flows and increased flood duration often lead to erosion and degradation of ecosystems. Typically, the peak flow for a design storm is used to assess the impact of land use change on the hydrological cycle. This approach, however, does not capture the extent of hydrologic change and impact on downstream communities. Floodplains have an important function in controlling downstream floods and sustaining sensitive ecosystems. This research proposes a new metric to quantify the effects of development based on the change in floodplain areas. The Hydrologic Footprint Residence (HFR) is proposed to evaluate the modification of floodplain areas and duration of a flood's residence. HFR can be used to analyze hydrological changes, gauge riparian ecosystem health, and develop watershed management plans. The use of HFR is demonstrated for a case study located on the Texas A&M University campus to evaluate the hydrologic impact of watershed development.