Evaluating the effects of low impact development on Texas A&M University West Campus
The west campus of Texas A&M University is located in the White Creek watershed and has experienced increases in urbanization in recent years. This urbanization has dramatically impacted White Creek, including bank erosion from higher runoff volumes and peak flows. This study uses HEC-HMS and SWMM models to evaluate the effectiveness of low impact development (LID) and best management practices (BMP) in lowering runoff volumes and peak flows on the Texas A&M Campus. The LID techniques evaluated were green roofs, rainwater harvesting and pervious pavements and the BMP evaluated was a detention pond. A new metric, the Hydrologic Footprint Residence, developed by Giacomoni and Zechman (2009) is used for further comparison. HFR incorporates the quantity of flow from a storm with the cross sections of the stream to determine the flood area. This flood area is plotted with respect to time and the area under the curve represents the HFR, in area-time. The LID and BMP technologies were applied to the watershed and evaluated using 77 historical precipitation events. A set of 10 representative storms were used for analysis. In general, the scenario that was the most effective in lowering the peak flow, runoff volume, and HFR of the storm was the combination of rainwater harvesting and pervious pavements. The detention pond was shown to effectively lower the peak flow for larger storms, but does not change the runoff volume of any storm. The LID techniques were shown to be more effective in reducing the impacts of urbanization for small storms. The results also gave insight into the importance of the precipitation intensity and duration. The importance of the Antecedent Moisture Condition of the soil is evaluated in the second part of the study. The AMC was found to have an impact on the peak flows with AMCIII (saturated soil) resulting in the highest peak flow for each storm event and AMCI (dry soil) resulting in lowest peak flow.