|Sun, Xiaoling - Laboratory Functional Ecology And Environment|
|Bernard-jannin, Leopard - Orléans Institute Of Earth Sciences (ISTO)|
|Grusson, Youen - Swedish University Of Agricultural Sciences|
|Sauvage, Sabine - Laboratory Functional Ecology And Environment|
|Srinivasan, Raghavan - Texas A&M Agricultural Experiment Station|
|Perez, Jose Miguel - Laboratory Functional Ecology And Environment|
Submitted to: Water
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/6/2018
Publication Date: 4/23/2018
Citation: Sun, X., Bernard-Jannin, L., Grusson, Y., Sauvage, S., Arnold, J.G., Srinivasan, R., Perez, J.S. 2018. Using SWAT-LUD model to estimate the influence of water exchange and shallow aquifer denitrification on water and nitrate flux. Water. 10:528. https://doi.org/10.3390/w10040528.
DOI: https://doi.org/10.3390/w10040528 Interpretive Summary: The importance of groundwater and surface water interaction has been documented in numerous studies. However, these interactions have rarely been considered in large scale hydrological models. In this study, the Soil and Water Assessment Tool (SWAT) was modified to account for: 1) upland and floodplain areas independently, 2) surface-groundwater exchange, and 3) shallow aquifer denitrification. The model was then applied to the middle flood plain area of the Garonne River in France. Model results showed that denitrification was a major process that decreased nitrate from groundwater, however, denitrification associated with river water had little impact. From these findings, we can develop more effective control strategies to mitigate the impact of nitrates on the water supply.
Technical Abstract: Numerous studies have pointed out the importance of groundwater and surface water interaction (SW–GW) in a river system. However; those functions have rarely been considered in large scale hydrological models. The SWAT-LUD model has been developed based on the Soil and Water Assessment Tool (SWAT) model; and it integrates a new type of subbasin; which is called subbasin-LU (SL); to represent the floodplain area. New modules representing SW–GW exchanges and shallow aquifer denitrification are developed in the SWAT-LUD model. In this study; the SWAT-LUD model was applied to the middle floodplain area of the Garonne catchment in France. The results showed that the SWAT-LUD model could represent the SW–GW exchange and shallow aquifer denitrification appropriately. An annual 44.1 X 107 m3 of water flowed into the river from the study area; but the annual exchanged water volume was 6.4 X 107 m3; which represented just 1% of the river discharge. A total of 384 tons of N-NO3 - (0.023 t.ha-1) was consumed by denitrification in the floodplain shallow aquifer annually. The nitrate concentration (N-NO3 -) decrease in the channel was 0.12 mg_L-1; but in the shallow aquifer it reached 11.40 mg.L-1; 8.05 mg.L-1; and 5.41 mg.L-1 in LU1; LU2; and LU3; respectively. Our study reveals that; in the Garonne floodplain; denitrification plays a significant role in the attenuation of nitrate associated with groundwater; but the impacts of denitrification on nitrate associated with river water is much less significant.