| Title: | Impacts and implications of land use land cover dynamics on groundwater recharge and surface runoff in East African watershed |
| Authors: | Mengistu, T.D., I.-M. Chung, M.-G. Kim, S.W. Chang and J.E. Lee |
| Year: | 2022 |
| Journal: | Water |
| Volume (Issue): | 14(13) |
| Pages: | 2073-4441 |
| Article ID: | 2068 |
| DOI: | 10.3390/w14132068 |
| URL (non-DOI journals): | |
| Model: | SWAT |
| Broad Application Category: | hydrologic only |
| Primary Application Category: | land use change |
| Secondary Application Category: | hydrologic assessment |
| Watershed Description: | Gilgel Gibe River, a tributary of the Omo-Gibe River located in the semi-arid southwestern region of Ethiopia. |
| Calibration Summary: | The SWAT model was calibrated and validated on each LULC reference simulation scenarios. The statistical performance was tested and evaluated for prediction uncertainty of the hydrologic modeling processes using auto calibration techniques. |
| Validation Summary: | |
| General Comments: | |
| Abstract: | Assessing the spatiotemporal dynamics of land use land cover (LULC) change on water
resources is vital for watershed sustainability and developing proper management strategies. Evaluating LULC scenarios synergistically with hydrologic modeling affords substantial evidence of
factors that govern hydrologic processes. Hence, this study assessed the spatiotemporal effects and
implications of LULC dynamics on groundwater recharge and surface runoff in Gilgel Gibe, an East
African watershed, using the Soil and Water Assessment Tool (SWAT) model. Three different LULC
maps (2000, 2010, and 2020) were derived from Landsat images, and the comparisons pointed out that
the land-use pattern had changed significantly. The agricultural land and grassland cover increased
by 3.76% and 1.36%, respectively, from 2000 to 2020. The implications acquired for 2000 show that
forested land covers decreased by 5.49% in 2020. The SWAT simulation process was executed using
a digital elevation model, soil, LULC, and weather data. The model was calibrated and validated
using streamflow data to understand the surface runoff and groundwater recharge responses of
each Hydrologic Response Units on reference simulation periods using the Calibration and Uncertainty Program (SWAT-CUP), Sequential Uncertainty Fitting (SUFI-2) algorithm. The observed and
simulated streamflows were checked for performance indices of coefficient of determination (R2
),
Nash–Sutcliffe model efficiency (NSE), and percent bias (PBIAS) on monthly time steps. The results
show that there is good agreement for all LULC simulations, both calibration and validation periods
(R2 & NSE ≥ 0.84, −15 < PBIAS < +15). This reveals that for the LULC assessment of any hydrological modeling, the simulation of each reference period should be calibrated to have reasonable outputs.
The study indicated that surface runoff has increased while groundwater decreased over the last two
decades. The temporal variation revealed that the highest recharge and runoff occurred during the
wet seasons. Thus, the study can support maximizing water management strategies and reducing
adverse driving environmental forces. |
| Language: | English |
| Keywords: | groundwater recharge; Gilgel Gibe watershed; LULC; Soil and Water Assessment Tool
(SWAT); SWAT-CUP; surface runoff |