Abstract:
This study was conducted to assess land use land cover changes and connected impacts on soil
erosion, sediment yield and ecosystem services in Tul watershed. Landsat images from 1990, 2000,
2010 and 2021 were used to produce four maps of the respective years using GIS and Erdas Imagine
2014 with field verification. Data collected from householdsheads (n=73), focus group discussion,
key informant interview and field observation were used to identify the major drivers of land use land
cover change. Data from satellite images, coupled with field observation and socio-economic survey
revealed an effective approach for analyzing the extent, rate and spatial pattern of LULC change.
Driving force pressure state imact response model was used for describing drivers of land use land
cover changes. A revised universal soil loss equation was used for estimating soil loss. InVEST and
the modified ecosystem services valuation model were used to estimate erosion regulation ecosystem
services and sediment yield and integrated valuation of the modified ecosystem service value
coefficient also used to explore the changes in ecosystem service values respectively. The different
layers of the spatio-temporal changes on the land use land cover changes were the basis for
examining the changes soil loss, sediment yield, erosion regulation ecosystem services and ecosystem
services value dynamics. The results of this study revealed that six LULCs, such as natural forest
land, grassland, shrubland, cultivated land, plantation, and built up area have been identified.
Forest, shrubland and grassland were decreased by 48.790ha yr
-1
, 210.33 ha yr
-1
,
in that order in the first period of the study (1990-2000). However, cultivated land, builtup area and
plantation were increased by 661.34ha yr
-1
, 6.39 ha yr
-1
and 71.73ha yr-1
-
. From 2010 to 2021,
cultivated land, built up area and plantation, respectively, continued to increase by 83.9ha yr
, 47.6
ha yr
-1
, and 9.88ha yr
-1
. Conversely, natural forest, shrubland and grassland were decreased with a
rate of 35.1ha yr
-1
,
25.5ha yr
-1
and 679.7 ha yr
-1
respectively. The major drivers of land use land cover
changes were expansion of farmland, expansion of settlement and urbanization, scarcity of grazing
land and high wood demand. The expansion of cultivated land and builtup area at the expense of
forest, shrubland and grassland had contributed to increase the annual soil erosion rate from 52.4
ton ha-
1
yr-
1
in 1990 to 61.4 ton ha-
1
yr-
1
2000. Similarly, expansion of cultivated land builtup area
was caused to increase the mean annual sediment yield from 9.07 ton-ha- yr-
1
yr-
1
in 2000.On the contrary, the mean annual in sediment yield was decreased from 15.74 tha
1
and 480.23ha yr
-1
in 1990 to 15.74ha-
in 2000 to 14.06 t ha
-1
yr
-1
in 2010 and to 7.93ha
-1
yr
-1
in 2021 due to watershed management
interventions. In the study period (1990 to 2021), the ecosystem service values of natural forest, shrub
and grassland were reduced, whereas the ecosystem service values of plantation, built up area and
cultivated land were increased. In the first period, the provisional, regulating, supporting and
cultural ecosystem services were declined due to land use land cover changes. However, these
ecosystem services were increased between 2010 and 2021 due to watershed management
intervention. Therefore, enhancing the existing land resource management practices, using
alternative energy sources, diversifying livelihood options and using appropriate family planning are
some of the appropriate interventions need to address to reduce the existing land use land cover
change and associated socioecolgical effects.
Kewords: Land use/cover changes; soil erosion; sediment yield; regulatory ecosystem service;
ecosystem service values; northwest highlands of Ethiopia
-1
yr
-1
-1