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Integrated Hydrological Modelling of Surface-groundwater Interactions in Hard Rock System of the Sardon Catchment (Spain) and Comparison with Selected Satellite Product

Xu, Shixian (2021) Integrated Hydrological Modelling of Surface-groundwater Interactions in Hard Rock System of the Sardon Catchment (Spain) and Comparison with Selected Satellite Product.

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Abstract:Hard rock systems (HRSs) are widely spread over the world and known for relatively low groundwater productivity, but certain areas still heavily depend on groundwater in order to fulfil the need for irrigation and domestic water use, especially in a water-limited environment (WLE). HRSs are characterised by variable density of fault and fractures, shallow water table and low storativity. These characteristics lead to complex surface-groundwater interactions, therefore studying those such areas is critical for local groundwater management in sustainable manner. In this study, the selected study area, the Sardon catchment (Spain), represents typical HRS-WLE characteristics. An integrated hydrological model (IHM) was built for the Sardon catchment based on MODFLOW 6, the latest version of MODFLOW. Efforts were made in three directions: i) apply remote sensing techniques for improving driving forces estimation; ii) calibrate the Sardon model involving MODIS ET, next to hydraulic heads, as calibration state variables to improve water balance and overall model reliability; iii) compare the simulated soil moisture with SSM1km product. The Sardon model was calibrated in the transient state for 8 hydrological years (2009 ~ 2016) with daily groundwater heads and yearly MODIS ET. Even though the model was calibrated only by yearly MODIS ET (yearly difference within ±15%), the daily simulated ET showed surprisingly good match with daily MODIS ET (RMSE = 0.57mm). Overall, the simulated soil moisture showed a good agreement with the SSM1km product (RMSE = 0.081 m3 m-3 and Pearson correlation ( r ) = 0.65). Better agreement between simulated and satellite soil moisture was observed in dry days (RMSE = 0.057 m3 m-3, r = 0.69) than in rainy days (RMSE = 0.102 m3 m-3, r = 0.54). The transient model simulation showed that 8-year mean gross groundwater recharge ( Rg ) was 23.1% of precipitation ( P ). Over 90% of g R was lost out of the groundwater zone by groundwater exfiltration ( gwExf ) and groundwater evapotranspiration ( g ET ). The groundwater net recharge ( nR ) was highly spatial variable and temporally variable ranging from -28.17 mm yr-1 in dry year 2009 and 0.02 mm yr-1 in wet year 2010. The MODFLOW 6 showed great ability in simulating surface-groundwater interactions in complex hydrogeological hard rock systems, such as Sardon catchment and in derivation of realistic water balances for both unsaturated and saturated zones.
Item Type:Essay (Master)
Faculty:ITC: Faculty of Geo-information Science and Earth Observation
Programme:Geoinformation Science and Earth Observation MSc (75014)
Link to this item:https://purl.utwente.nl/essays/89002
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