Semester of Graduation

Summer 2018

Degree

Master of Science (MS)

Department

Engineering Science

Document Type

Thesis

Abstract

This study investigates two water balance models from different levels of complexity to recognize the impacts of climate change on water resources. The main objective is to examine the capacity of future runoff calculations of a parsimonious simple water balance model compared to a more complex model under the climate change variables. The selected water balance models are the simple one-parameter Budyko-type model using the Zhang’s equation with single parameter (a) and the more complex model (HELP3) applying Soil Conservation Service (SCS) curve number method to calculate future runoff predictions. The study has a twofold focus, first on explaining the simple model and complex model with their fundamental computation processes and characterizing model parameters according to their similar purposes of determining the precipitation partition, and later analyzing the runoff result comparisons for the study area and correlation between the model parameters under the climate change variables. The reconstructed one-parameter Budyko-type model and HELP3 model are applied to two watersheds: Loggy Bayou and Bayou D’Arbonne in Northern Louisiana and Southern Arkansas using the BCCA statistically downscaled datasets from 1950 to 2098 to calculate mean annual runoff and average monthly runoff. The main finding of this study is that the one parameter Budyko model is a good representation of future runoff projection under the climate change impact for mean annual runoff. The comparison results show the mean annual runoff values are found for each of the 2,320 hydrological response units (HRU) for early, mid, and late century with auspicious 0.99 R2 value for each period of the century for both subbasins. The runoff results comparing the aggregate of projected runoff of the entire subbasins for each year throughout the century indicates more than 0.80 NSE value for both watersheds. However, as the issue appeared in many other Budyko studies, the model performed poorly on the interannual time scale in consequence of neglecting the catchment water storage changes in time. The single parameter (a) from the one parameter Budyko model has a strong curvilinear relationship with the SCS curve number for both statistical and locational aspects with 0.97 R2 value for each subbasins.

Date

6-28-2018

Committee Chair

Tsai, Frank

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