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This section shows a brief description of the methodology and information sources used to perform the hydrological simulation in Costa Rica.
The SRTM (Bamler, 1999) public domain digital elevation model was used with a pixel size of 30m corrected with the national water network as the basis for delimiting the country's catchments. The vegetation cover raster (300m) was obtained from the CCI Land Cover product (Bontemps et al., 2013) and the physical characteristics of the soils were obtained from SoilGrids at 250m (Hengl et al., 2017).
The precipitation product was corrected with observed data from 75 available stations in the country using a linear bias correction method (bias = Xobs / Xsatelite). The temperature data were corrected with the elevation of the terrain due to the lack of records for the correction of bias. Global potential evapotranspiration (PET) and current evapotranspiration (ETA) products from the MODIS 16A3 satellite (Mu et al., 2011) were used to adjust the hydrological balance.
The description of the sources used is shown in the following table:
Scheme of the discrimination in sub-catchments of the model and the processes simulated by HYPE. Source: Lindström et al. (2010)
HYPE calibration and validation were performed using observed daily flow data in 13 watersheds of Costa Rica, with a calibration period from 1991 to 1999 and a validation period from 2000 to 2003. Additionally, global potential evapotranspiration products were used (PET) and MODIS current evapotranspiration (AET) to adjust the hydrological balance for the period 2001 to 2010, with a validation period from 2011 to 2014.
A step-wise calibration procedure was incorporated for the model calibration, starting with the calibration of the monthly potential evapotranspiration (PET), the monthly evapotranspiration (ETA), the monthly streamflow (Qt) and finally using the daily streamflow (Qt) data. The following figure shows the performance of the model to simulate the monthly streamflow in the 13 monitored catchments.
The simulations correspond to the first version of the regional model of Costa Rica with the HYPE model (HYPE CR 1.0), which was selected from a set of models that generated similar performance with respect to the observed streamflow, however, HYPE CR 1.0 has generated a balanced performance with streamflow (Qt), actual evapotranspiration (AET) and potential evapotranspiration (PET). Likewise, it must be taken into account that there is uncertainty with the HYPE CR 1.0 model since different values of the parameters generated similar results, as can be seen in the following image.
The results of the hydrological model were generated for 605 basins in Costa Rica and cover the period from 1985 to 2019, at monthly and annual scales. The time series of the simulated hydrological variables, as well as the type of statistical aggregation, are shown in the following table:
Hydrological indices are particularly useful for the synthesis of the long-term hydrological behavior of catchments, allowing the evaluation of spatial patterns in large regions. From the results obtained with HYPE CR 1.0, different hydrological indices were estimated, and are available in the web application.
- Bamler, R. (1999). The SRTM mission: A world-wide 30m resolution DEM from SAR interferometry in 11 days. Photogrammetric Week.
- Bontemps, S., Defourny, P., Radoux, J., Van Bogaert, E., Lamarche, C., Achard, F., et al. (2013). Consistent Global Land Cover Maps for Climate Modeling Communities: Current Achievements of the ESA’s Land Cover CCI. In ESA Living Planet Symposium.
- Funk, C., Peterson, P., Landsfeld, M., Pedreros, D., Verdin, J., Shukla, S., et al. (2015). The climate hazards infrared precipitation with stations - A new environmental record for monitoring extremes. Scientific Data, 2, 1–21. https://doi.org/10.1038/sdata.2015.66
- Hengl, T., De Jesus, J. M., Heuvelink, G. B. M., Gonzalez, M. R., Kilibarda, M., Blagotić, A., et al. (2017). SoilGrids250m: Global gridded soil information based on machine learning. PLoS ONE. https://doi.org/10.1371/journal.pone.0169748
- Lindström, G., Pers, C., Rosberg, J., Strömqvist, J., & Berit, A. (2010). Development and testing of the HYPE (Hydrological Predictions for the Environment) water quality model for different spatial scales. Hydrology Research, 4(41.3), 295–319. https://doi.org/10.2166/nh.2010.007
- Mu, Q., Zhao, M. and Running, S. W. (2013). MODIS Global Terrestrial Evapotranspiration (ET) Product (MOD16A2/A3), Algorithm Theor. Basis Doc.