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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: Hydrological model parameterization using NDVI values to account for the effects of land-cover change on the rainfall-runoff response

Author
item Nourani, V. - University Of Tabriz
item Fard, A.f. - University Of Tabriz
item Hoshin, G.v. - University Of Arizona
item Goodrich, David - Dave
item Naizi, F. - University Of Tabriz

Submitted to: Hydrology Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/27/2017
Publication Date: 12/1/2017
Citation: Nourani, V., Fard, A., Hoshin, G., Goodrich, D.C., Naizi, F. 2017. Hydrological model parameterization using NDVI values to account for the effects of land-cover change on the rainfall-runoff response. Hydrology Research. 48(4):1455-1473.

Interpretive Summary: Computer models of watershed processes can, and are, used to predict runoff from rainfall events. To obtain good predictions, historical rainfall and runoff from a watershed are needed to calibrate the model. However, due to climate changes and human effects, the parameters of model change temporally. To overcome this problem we use a measure of the amount of vegetation derived from remotely sensed data as a measure of land use change. The study area consists of two sub-watersheds (Hervi and Lighvan) with varied land cover conditions. Results show that a simple model with one-parameter generates runoff forecasts with an acceptable level of confidence. The remote sensing data were employed to relate land cover properties of the watershed to the model parameter. Applying this methodology, the change in the watershed model parameter with time can be determined using remote sensing images that can be regularly obtained over time. This will allow the model to be responsive to watershed vegetation changes.

Technical Abstract: Classic rainfall-runoff models usually use historical data to estimate model parameters and mean values of parameters are considered for predictions. However, due to climate changes and human effects, the parameters of model change temporally. To overcome this problem, Normalized Difference Vegetation Index (NDVI) derived from remotely sensed data was used in this study to investigate the effect of land cover variations on hydrological response of watershed using a conceptual rainfall-runoff model. The study area consists of two sub-watersheds (Hervi and Lighvan) with varied land cover conditions. Obtained results show that the one-parameter model generates runoff forecasts with acceptable level of the considered criteria. The remote sensing data were employed to relate land cover properties of the watershed to the model parameter. While a power form of the regression equation could be best fitted to the parameter values using available images of Hervi sub-watershed, for the Lighvan sub-watershed the fitted equation shows somewhat lower correlation due to higher fluctuations of the model parameter. The average values of the Nash-Sutcliffe efficiency (NSE) criterion of the model were obtained as 0.87 and 0.55 respectively for Hervi and Lighvan sub-watersheds. Applying this methodology, the model’s parameter might be determined using temporal NDVI values.