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Research Project: Understanding Water-Driven Ecohydrologic and Erosion Processes in the Semiarid Southwest to Improve Watershed Management

Location: Southwest Watershed Research Center

Title: Global sensitivity analysis of KINEROS2 hydrologic model parameters representing green infrastructure using the STAR-VARS framework

Author
item KORGAONKAR, Y, - University Of Arizona
item MELES, M. - University Of Arizona
item GUERTIN, D.P. - University Of Arizona
item Goodrich, David - Dave
item Unkrich, Carl

Submitted to: Environmental Modelling & Software
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/27/2020
Publication Date: 8/6/2020
Citation: Korgaonkar, Y., Meles, M., Guertin, D., Goodrich, D.C., Unkrich, C.L. 2020. Global sensitivity analysis of KINEROS2 hydrologic model parameters representing green infrastructure using the STAR-VARS framework. Environmental Modelling & Software. 132, Article 104814. https://doi.org/10.1016/j.envsoft.2020.104814.
DOI: https://doi.org/10.1016/j.envsoft.2020.104814

Interpretive Summary: Urbanization has a profound influence on watershed hydrology by increasing runoff volumes and peak runoff rates. Incorporation of green infrastructure (GI) into developments such as infiltration gardens, rainwater harvesting cisterns, and permeable pavement is gaining acceptance as a measure to reduce post-urbanization runoff. The Automated Geospatial Watershed Assessment (AGWA) Urban tool was developed to simulate the hydrologic behavior of the built environments that incorporate GI using the Kinematic Runoff and Erosion (KINEROS2 or K2) model. The K2 model provides an urban modeling element that can be used to represent various land cover types and GI while treating runoff-runon (e.g. from a roof to a lawn to a street) and infiltration between and within the parcel or lot in a physically realistic manner. There are 15 parameters (numbers) that help describe the K2 Urban Model Element (e.g. percent of impervious area, the rate at which storm runoff water infiltrates into soil, etc.). The goal of this study is to understand the sensitivity of the K2 model outputs (peak rate, total runoff volume, and outflow hydrograph) to these 15 parameters, across seven different precipitation events at the watershed outlet as well as the home lot scale. A special method of sensitivity study was undertaken that can provide parameter sensitivity throughout the storm causing the runoff. A high sensitivity to the storm shape or variations in rainfall intensity was found.

Technical Abstract: The KINematic runoff and EROSion model (version 2; KINEROS2) provides an urban component that is capable of modeling urban hydrology including green infrastructure (GI) practices at various scales. The KINEROS2 model provides 15 parameters that can represent a variety of GI practices. The goal of this study is to understand the sensitivity of the KINEROS2 model outputs (infiltration, peak flow, runoff volume, and outflow hydrograph) to these 15 parameters, across seven different precipitation events, and at the watershed as well as the parcel scale. A global sensitivity analysis (GSA) was performed using the Variogram Analysis of Response Surfaces (VARS) framework to produce sensitivity metrics. Results from the time-aggregate GSA indicate that parameter sensitivities follow trends based on precipitation intensity and duration. Time-varying GSA indicate sensitivity of parameters to hyetograph shape, especially the duration to maximum precipitation intensity. The variation in sensitivity is influenced by the peaks and valleys in the precipitation hyetograph.