Abstract:
Soil degradation is one of the most serious problems in Ethiopian highlands.
Poor conservation design, less perception and involvement of farmers, weak monitoring
and evaluation of soil and water conservation practice are the main constraints. Because
of this reason retaining soil moisture is very low in the area. Soil conservation is the way
to protect the productive land and improving soil moisture. Therefore, the study was
conducted to evaluate the effect of soil and water conservation practice (SWC) on soil
moisture dynamics for Dengora and Keritwuha watersheds in East and West Belessa
woredas respectively. The in- situ soil moisture data was collected by using Time
Doman Reflectometry (TDR) and qualitative data were collected by using Focus
Group Discussion (FGD) from watershed beneficiaries in Dengora and Keritwuha
watersheds. Soil moisture was estimated by using the new physical based Optical
Trapezoid Model (OPTRAM) driven from Copernicus Sentinel-2A level 1C Satellite
images. The model relies on a physical linear relationship between pixel distributions in
the shortwave infrared transformed reflectance (STR)-Normalized Difference Vegetation
Index (NDVI) trapezoidal space. The results were indicated that the soil moisture
estimates by OPTRAM model and in situ soil moisture at the two sites were showed that
a reasonable coefficient of determination R
2
ranges from 0.73 up to 0.95, RMSE and bias
was also ranges between within 0.01–0.08 cm3 /cm3. According to the evaluation,
therefor satellite soil moisture and in-situ soil moisture data‘s have good relationship. The
watersheds area coverage by soil and water conservation (SWC) practice were increased
from 2015 up to 2020 by 19.33 ha (40.03%) for Keritwuha watershed Menu catchment,
11.16ha (56.98%) Dengora watershed Megachoch catchment and 28.05ha (30.0%)
Dengora watershed Washkayna catchment and the corresponding soil moisture for these
watersheds was also increased from 0.12 cm
3
/cm
3
to 0.18 cm
3
/cm
3
, 0.15 to 0.38 cm
3
/cm
3
and 0.16 to 0.31 cm
3
/cm
3
respectively with in the insignificant change of rainfall pattern.
Therefor this change of soil moisture was related with SWC practice. From the focus
group participators in Dengora and Keritwuha watershed farmers perceived that soil and
water conservation practices were very effectives for improving soil moisture. These
respondents were willing to introduce new soil and water conservation technologies.
Key words: - Focus Group Discussion (FGD), OPTRAM, Sentinel -2, TDR