The effect of changes in hydrological services caused by effective
watershed management measures on watershed health with the PSR approach
in the Efin watershed, South Khorasan, Iran
Abstract
Nowadays, the destruction of watersheds has increased under the
influence of various human and natural factors, and the performance of
watersheds and the provision of hydrological services have become a
problem. Therefore, carrying out management measures, including
watershed engineering and biological measures, is a human approach to
deal with these threats and increase the expected hydrological services.
Therefore, in this research, an attempt has been made to evaluate the
impact of watershed management engineering and biological measures on
the health of the Efin watershed in South Khorasan, Iran, with the
conceptual approach of pressure-state-response (PSR). To do this, after
determining the effective variables on the health and security of Efin
watershed and removing the variables with co-linearity using Principal
Component Analysis (PCA), the PSR indices were quantified and
standardized and was used based on the behavioral data for determining
the health and security of the watershed. In order to determine the role
of watershed management operations on health and safety indicators, the
variables related to watershed management measures including Normalized
Difference Vegetation Index (NDVI), concentration time and Curve Number
(CN) under three management scenarios of 50, 75 and 100% of the area of
the measures Efin watershed was re-determined and the health index was
calculated after implementing watershed measures and compared with the
conditions before the operation. The results showed that the PSR indices
were variable in the ranges of 0.35 to 0.73, 0.35 to 0.60 and 0.19 to
0.59, respectively. The health and security index of sub-watersheds also
changed between 0.37 to 0.50 and 0.22 to 0.69, respectively. The
research results showed that due to the non-change of the pressure
variables, this index has not changed under the management scenarios.
But on average, the status index in the first, second and third
scenarios has increased by 7.38, 4.92 and 6.41%, respectively. This
response index has increased in all three scenarios by 26.37, 18.95 and
14.65% respectively. In the first, second and third management
scenarios, the health index has experienced an increase of 10.31, 7.32
and 6.50%, respectively. Finally, under the influence of the first,
second and third management scenarios. The security index shows an
increase of 35.32, 24.92 and 21.88%, respectively. As the results of
the research show, the implementation of engineering and biological
measures alone cannot increase the health of Efin watershed and ensure
their security. Therefore, it is suggested to use comprehensive
management approaches of watersheds in the direction of better and
principled management of watersheds and help to improve their
performance.