TITLE:
Hydrological Modeling of Upper OumErRabia Basin (Morocco), Comparative Study of the Event-Based and Continuous-Process HEC-HMS Model Methods
AUTHORS:
Mohamed Msaddek, George Kimbowa, Abdelkader El Garouani
KEYWORDS:
HEC-HMS Model, Land-Use and Land Cover Change, Soil Moisture Accounting (SMA), Upper OumErRabia Watershed
JOURNAL NAME:
Computational Water, Energy, and Environmental Engineering,
Vol.9 No.4,
October
21,
2020
ABSTRACT: Human population growth and land-use changes raise demand
and competition for water resources. The Upper OumErRabia River Basin is
experiencing high rangeland and matorral conversion to irrigated agricultural
land expansion. Given Morocco’s per capita water availability, River-basin
hydrologic modelling could potentially
bring together agricultural, water resources and conservation objectives. However, not everywhere have hydrological models
considered events and continuous assessment of climatic data. In this study,
HEC-HMS modelling approach is used to explore
the event-based and continuous-process simulation of land-use and land cover change (LULCC) impact on water
balance. The use of HEC-GeoHMS facilitated the digital data processing for
coupling with the model. The basin’s physical characteristics and the
hydro-climatic data helped to generate a geospatial database for HEC-HMS model. We analyzed baseline and future
scenario changes for the 1980-2016 period using the SCS Curve-Number and the
Soil Moisture Accounting (SMA) loss methods. SMA was coupled with the
Hargreaves evapotranspiration method. Model calibration focused on reproducing
observed basin runoff hydrograph. To evaluate the model performance for both
calibration and validation, the Coefficient of determination (R2), Nash-Sutcliffe
efficiency (NSE), Root Mean Square Error (RSR) and Percent Bias (PBIAS) criteria were exploited. The average calibration NSE
values were 0.740
and 0.585 for event-based (daily) and continuous-process (annual) respectively.
The R2, RSR and PBIAS values
were 0.624, 0.634 and +16.7 respectively.
This is rated as good performance besides the validation simulations were satisfactory for subsequent hydrologic
analyses. We conclude that the basin’s hydrologic response to positive and
negative LULCC scenarios is significant both positive and negative scenarios. The study findings provide useful information
for key stakeholders/decision-makers in water resources.