| Title: | Effectiveness of contour farming and filter strips on ecosystem services |
| Authors: | Gathagu, J.N., K.A. Mourad and J. Sang |
| Year: | 2018 |
| Journal: | Water |
| Volume (Issue): | 10(10) |
| Pages: | |
| Article ID: | 1312 |
| DOI: | 10.3390/w10101312 |
| URL (non-DOI journals): | |
| Model: | SWAT |
| Broad Application Category: | hydrologic and pollutant |
| Primary Application Category: | BMP and/or cropping system assessment |
| Secondary Application Category: | sediment loss and transport |
| Watershed Description: | 840 km^2 combined Thika-Chania River system, located in southwest Kenya |
| Calibration Summary: | |
| Validation Summary: | |
| General Comments: | |
| Abstract: | The failing ecosystem services in Thika-Chania catchment is manifested in the deterioration
of water quality, sedimentation of reservoirs, and subsequent increase in water treatment costs due to
high turbidity. The services can be restored by implementing relevant soil and water conservation
practices to enhance flow regulation and control sediment yield. The impacts of contour farming
and filter strips on water and sediment yield were evaluated using Soil Water and Assessment
Tool (SWAT), Texas A&M University, USA. Sediment calibration and validation was achieved
using data obtained from a bathymetric survey. Model parameters were adjusted to simulate the
conservation impacts of contour farming and filter strips. Results indicated the average annual
sediment yield as 22 t/ha at the outlet of the catchment and average annual surface runoff of 202 mm.
The simulation results showed that filter strips of 5 m width would reduce the average annual
sediment yield from the catchment by 54%. The efficacy of filter strips in reducing sediment yield
was observed to increase with increasing filter width. Three-meter filter strips and contour farming
reduced the average annual sediment yield at catchment outlet by 46% and 36%, respectively. It was
concluded that the implementation of contour farming and filters strips reduced sediments by 63%
from the base value. Water yield at the sub-basin level was only influenced by contour farming.
The total water yield at the catchment outlet experienced no significant change |
| Language: | English |
| Keywords: | Thika-Chania catchment; sedimentation; SWAT; calibration; validation; Kenya |