| Title: | An alternative approach to overcome the limitation of HRUs in analyzing hydrological processes based on land use/cover change |
| Authors: | Meng, F., T. Liu, H. Wang, M. Luo, Y. Duan and A. Bao |
| Year: | 2018 |
| Journal: | Water |
| Volume (Issue): | 10(4) |
| Pages: | |
| Article ID: | 434 |
| DOI: | 10.3390/w10040434 |
| URL (non-DOI journals): | |
| Model: | SWAT (modified) |
| Broad Application Category: | hydrologic only |
| Primary Application Category: | land use change |
| Secondary Application Category: | hydrologic assessment |
| Watershed Description: | 42,000 km^2 Aksu River, which drains portions of southeast Kazakhstan, southeast Kyrgyzstan, and northwest Xinjiang Province, China. |
| Calibration Summary: | |
| Validation Summary: | |
| General Comments: | |
| Abstract: | Since the concept of hydrological response units (HRUs) is used widely in hydrological
modeling, the land use change scenarios analysis based on HRU may have direct influence on
hydrological processes due to its simplified flow routing and HRU spatial distribution. This
paper intends to overcome this issue based on a new analysis approach to explain what impacts
for the impact of land use/cover change on hydrological processes (LUCCIHP), and compare
whether differences exist between the conventional approach and the improved approach. Therefore,
we proposed a sub-basin segmentation approach to obtain more reasonable impact assessment of
LUCC scenario by re-discretizing the HRUs and prolonging the flow path in which the LUCC occurs.
As a scenario study, the SWAT model is used in the Aksu River Basin, China, to simulate the response
of hydrological processes to LUCC over ten years. Moreover, the impacts of LUCC on hydrological
processes before and after model modification are compared and analyzed at three levels (catchment
scale, sub-basin scale and HRU scale). Comparative analysis of Nash–Sutcliffe coefficient (NSE), RSR
and Pbias, model simulations before and after model improvement shows that NSE increased by up
to 2%, RSR decreased from 0.73 to 0.72, and Pbias decreased from 0.13 to 0.05. The major LUCCs
affecting hydrological elements in this basin are related to the degradation of grassland and snow/ice
and expansion of farmland and bare land. Model simulations before and after model improvement
show that the average variation of flow components in typical sub-basins (surface runoff, lateral
flow and groundwater flow) are changed by +11.09%, -4.51%, and -6.58%, and +10.53%, -1.55%,
and -8.98% from the base period model scenario, respectively. Moreover, the spatial response of
surface runoff at the HRU level reveals clear spatial differences between before and after model
improvement. This alternative approach illustrates the potential bias caused by the conventional
configuration and offers the possible application. |
| Language: | English |
| Keywords: | land use/cover change; SWAT model; hydrological response unit (HRU); discretization;
Aksu River |