| Title: | Simulation of hydrology and nutrient transport in the Hetao Irrigation District, Inner Mongolia, China |
| Authors: | Wu, Y., X. Shi, C. Li, S. Zhao, F. Pen and T.R. Green |
| Year: | 2017 |
| Journal: | Water |
| Volume (Issue): | 9(3) |
| Pages: | |
| Article ID: | 169 |
| DOI: | 10.3390/w9030169 |
| URL (non-DOI journals): | |
| Model: | SWAT |
| Broad Application Category: | hydrologic and pollutant |
| Primary Application Category: | nutrient cycling/loss and transport |
| Secondary Application Category: | irrigation impacts or irrigation BMP scenarios |
| Watershed Description: | 11,195 km^2 Hetao Irrigation District drainage area, located within the Bayenaoer region in southwest Inner Mongolia in north central China. |
| Calibration Summary: | |
| Validation Summary: | |
| General Comments: | |
| Abstract: | Intensive agricultural activities in the Hetao irrigation district have severely degraded
local aquatic ecosystems and water quality, and Ulansuhai Lake is now the most rapidly degrading
eutrophic lake in China. A better understanding of the hydro-agronomic and pollutant transport
processes in the area is thus urgently needed. This study simulated monthly streamflow, total
nitrogen (TN) and total phosphorus (TP) for the Hetao irrigation district using the Soil and Water
Assessment Tool (SWAT) to evaluate the nutrient load, source areas, and hydrological pathways.
The Nash-Sutcliffe efficiency (NSE) values obtained for the streamflow simulations were 0.75 and
0.78 for the calibration and evaluation periods, respectively. The SWAT model captured the temporal
variation in streamflow (R2 > 0.8) for two periods; the NSE values for the TN and TP loads were
0.63 and 0.64 for the calibration period and 0.48 and 0.42 for the evaluation period, respectively.
The predicted monthly TN load was correlated with irrigation (r = 0.61) and the monthly TP load with
precipitation (r = 0.89), indicating that nitrogen transport is primarily associated with soil leaching
and groundwater flow, and phosphorus is primarily transported by sediments caused by rainfall
erosion. A case study of split nitrogen fertilizer applications demonstrated reduced annual TN
load by as much as 13% in one year. Fertilization timing also affects the load in different pathways
especially in lateral subsurface flow and shallow groundwater. Better agricultural management could
thus reduce nitrogen losses, and buffer strips could minimize phosphorus transport. |
| Language: | English |
| Keywords: | hydrology in irrigation districts; Soil and Water Assessment Tool (SWAT) model;
agriculture non-point source pollution; groundwater |