Mrs Elham Fahiminezhad, Dr M Ohammag Baaghide, Dr Iman Babaeian, Dr Alireza Entezari,
Volume 6, Issue 3 (9-2019)
Abstract
Changes in the mean and the extreme values of hydroclimatic variables are two
prominent features of the future climate. Therefore, simulating the climatic
behavior of Shandiz catchment area, an important tourist area in the northeast of
the country, will play an important role in identifying the climate condition and
potential vulnerability of these areas in the coming decades of climate change.
In this study, we will
evaluate the effects of climate change on extreme values of the basin micro scaling
precipitation and temperature in CanESM2 model using SDSM model and
simulating runoff with SWAT model in future decades.
To achieve this goal, the daily temperature and precipitation statistics of the 30
statistical years (1961-1990) of Mashhad synoptic station have been
used. The data of the CanESM2 general circulation model under RCP2.6, RCP4.5
and RCP8.5 scenarios are also used to predict precipitation, the minimum and
maximum temperature for 2041 to 2100.
According to the results, the annual precipitation rises 37 to 54 percent from 2041
to2070 compared to the observation period, and the increase in rainfall of the
2071-2100 rises 52 to 66 percent. Precipitation extreme values, the mean of
maximum and minimum temperatures in future periods in all seasons of Mashhad
station will increase compared to the observation period (1961-1990).In future decades, the average maximum temperature in Mashhad will increase from 4.6 to 0.65 degrees Celsius
and the average minimum temperature will increase 53/1 to 22/4.
By introducing micro scaled time series of the maximum temperature, temperature,
and micro scaled precipitation by SDSM model to SWAT model, the monthly time
series of Shandiz watershed runoff at Sarasiab Station was simulated for the two
periods of 2041-2070 and 2071-2100 under three distribution scenarios of RCP2.6,
RCP4.5 and RCP8.5. For this purpose, first, the model was calibrated and validated
using Shandiz hydrometric station runoff for 2003-2012, and the values of R2 were
65 and 52, respectively. Subsequently, with the introduction of micro scaled time
series of maximum and minimum temperatures, and micro scaled precipitation by
SDSM model to SWAT model, the average annual trend shows that runoff
increases in the coming decades. The lowest average annual increase for runoff is
in 2041-2070 and RCP4.5 scenario, with an increase of 56.1% over the observation
period. The highest increase of average annual monthly runoff is from 2071 to2100
under RCP 2.6 scenario with 53% to 104% runoff compared to the observation period.
