3.2. Soil erosion change (2005 - 2015)
The annual rate of soil erosion was estimated at 1 km spatial resolution
for 2005 and 2015 using the RUSLE (Figure 4). The soil erosion ranges
from <1 ton/ha/year to >20 ton/ha/year. In the
sloppy highlands areas of Gilgit-Baltistan, Azad Jammu & Kashmir,
Khyber Pakhtunkhwa and Balochistan high (5-20 ton/ha/year) and very high
(>20 ton/ha/year) annual rate of soil erosion were detected
while from medium (1-5 ton/ha/year) to low (<1 ton/ha/year)
values were noticed in the flattened areas of the Punjab and Sindh
provinces. The estimated average soil erosion at the national scale in
2005 was 1.79 ± 11.52 ton/ha/year (mean ± standard deviation at 95%
confidence interval) which increased to 2.47 ± 18.14 ton/ha/year in
2015. In the Azad Jammu & Kashmir administrative unit 14.44 ± 35.70
ton/ha/year soil erosion was detected in 2005 which increased to 28.03 ±
68.24 ton/ha/year in 2015. In the Balochistan, Islamabad Capital
Territory, Punjab, and Sindh, <1 ton/ha/year average soil
erosion was perceived in 2005 and 2015. In 2005, average 7.54 ± 20.25
ton/ha/year soil erosion was in Gilgit-Baltistan, which increased to
9.06 ± 29.69 ton/ha/year in 2015. Similarly, in Khyber Pakhtunkhwa
province average 8.73 ± 25.55 ton/ha/year soil erosion was 2005
increased to 12.84 ± 39.88 ton/ha/year in 2015 (Table 3). Among all the
administrative units, only in Azad Jammu & Kashmir average soil erosion
doubled from 14.44 ± 35.70 ton/ha/year in 2005 to 28.03 ± 68.24
ton/ha/year in 2015. In Khyber Pakhtunkhwa province average soil was
8.73 ± 25.55 ton/ha/year in 2005, which increased to 12.84 ± 39.88
ton/ha/year in 2015. Similarly, in the Gilgit-Baltistan administrative
unit of Pakistan in 2005 mean soil erosion was 7.54 ± 20.25 ton/ha/year
which increased to 9.06 ± 29.69 ton/ha/year in 2015. In Balochistan,
Punjab, and Sindh administrative units, the negligible average increase
was observed in ten years (2005 - 2015). In Islamabad Capital Territory,
mean soil erosion was 0.77 ± 2.22 ton/ha/year in 2005, which rose to
1.57 ± 4.56 ton/ha/year in 2015 (Table 3).
Figure 5 presents latitude wise
mean soil erosion in 2005 and 2015. Between 24º - 29.5º latitude as such
no soil erosion was observed, from 29.5º (dotted blue line) until 33º
(dotted yellow line) latitude very slight erosion detected in 2005 and
2015. Between 33º-37º latitude, a parabolic shape was observed which
reflects soil erosion in 2005 and 2015. At 35.5º N latitude (dotted red
line), in 2005 mean soil erosion was nearly 17 ton/ha/year, which
climbed up to 30 ton/ha/year in 2015.
Through cross tabular or change matrix method, in ten years (2005 -
2015) at the national scale, 35,252 km2 (4%) area
observed under negative change (commission) of soil erosion and 12,108
km2 (1.37%) area covered under positive change
(omission). Out of total area of Pakistan (881,913
km2), in 834,553 km2 (94.6%) area
no change of soil erosion observed between 2005 and 2015 (Table 4). From
2005 to 2015, 731,863 km2 (~83%) area
remained intact under the low (<1 ton/ha/year) soil erosion
while less than six ton/ha/year remained unchanged under the three soil
erosion classes (i.e. medium, high and very high). Between 2005 to 2015,
total 451 km2 (0.05%) area converted from very high
(> 20 ton/ha/year) to low (<1 ton/ha/year) soil
erosion class following only 43 km2 area transformed
from very high (> 20 ton/ha/year) to medium (1-5
ton/ha/year) and 1,012 km2 (0.11%) area shifter from
very high (> 20 ton/ha/year) to high (5-205 ton/ha/year)
soil erosion class. From 2005 to 2015, total 11,734
km2 (1.33%) area moved from medium (1-5 ton/ha/year)
to high (5-20 ton/ha/year) soil erosion. Similarly, 9,730
km2 (1.10%) soil erosion area moved from high (5-20
ton/ha/year) to very high (> 20 ton/ha/year) soil erosion
in ten years (2005–2015) (Table 4).