Hydrological Modelling using Satellite-Based Crop Coefficients: A Comparison of Methods at the Basin Scale

Abstract

Abstract:The parameterization of crop coefficients (kc) is critical for determining a water balance. We used satellite-based and literature-based methods to derive kc values for a distributed hydrologic model. We evaluated the impact of different kc parametrization methods on the water balance and simulated hydrologic response at the basin and sub-basin scale. The hydrological model SPHY was calibrated and validated for a period of 15 years for the upper Segura basin (~2500 km 2 ) in Spain, which is characterized by a wide range of terrain, soil, and ecosystem conditions. The model was then applied, using six kc parameterization methods, to determine their spatial and temporal impacts on actual evapotranspiration, streamflow, and soil moisture. The parameterization methods used include: (i) Normalized Difference Vegetation Index (NDVI) observations from MODIS; (ii) seasonally-averaged NDVI patterns, cell-based and landuse-based; and (iii) literature-based tabular values per land use type. The analysis shows that the influence of different kc parametrization methods on basin-level streamflow is relatively small and constant throughout the year, but it has a bigger effect on seasonal evapotranspiration and soil moisture. In the autumn especially, deviations can go up to about 15% of monthly streamflow. At smaller, sub-basin scale, deviations from the NDVI-based reference run can be more than 30%. Overall, the study shows that modeling of future hydrological changes can be improved by using remote sensing information for the parameterization of crop coefficients.

Combining satellite data and appropriate objective functions for improved spatial pattern performance of a distributed hydrologic model

“…Allen et al (1998). Similarly, Hunink et al (2017) compared different applications of crop coefficients based on remotely sensed vegetation indices in hydrologic modelling. They found that the effect of crop coefficient parameterisations on the water balance is trivial and constant throughout the year; however, it has a major effect on seasonal evapotranspiration and soil moisture fluxes, showing the role of crop coefficients in spatial calibration.…”

“…Since AET cannot be measured directly by satellite, surface energy balance models are developed to estimate AET based on data from a range of spectral and thermal bands (Guzinski et al, 2013;Norman et al, 1995;Su, 2002). While these satellite-based estimates are usually employed as a tool to understand and improve the model parameterisations (Conradt et al, 2013;Hunink et al, 2017;Schuurmans et al, 2011), they can also be used to calibrate models (Crow et al, 2003;Immerzeel and Droogers, 2008;Zhang et al, 2009). Therefore, adding satellite-based observations to model calibration is not novel; however, specifically evaluating spatial patterns in the calibration has rarely been done (Stisen et al, 2011b).…”

Comparison of SCS and Green-Ampt Distributed Models for Flood Modelling in a Small Cultivated Catchment in Senegal

“…For cultivated catchments, the growth of the vegetation often induces a non-stationarity of the hydrological behavior of the catchment, and consequently, of the model parameters [22,23]. Such variability requires to be related to a reliable descriptor of the growth of the vegetation.…”

Hydrological response to climate extremes in mesoscale (pre-)Alpine basins at 0.5° and hyperresolution

“…The Spatial Processes in Hydrology model (SPHY) was used to simulate each basin (Lutz et al, 2013(Lutz et al, , 2014Terink et al, 2015;Lutz et al, 2016;Hunink et al, 2017). SPHY is a spatially distributed conceptual hydrological model, including repre-…”