Impacts of climate change scenarios on the Kor River stream flow using SWATT model

Extended Abstract

1. Introduction

Changes in weather patterns in comparison to expected long term observations, defines as climate change. This phenomenon affects water resources, precipitation and runoff amount and frequency. According to new approach CMIP6, world temperature increases about 1.1 °C till 2050s in comparison to 1850-1990. Economic dependence to agriculture and natural resources in developing countries causes increasing consequences of climate changes to residents. Hence, climate change and related droughts are the biggest challenges in Iran agricultural activities. Therefore, recent studies investigate the effects of climate change on water resources and runoff at the basin scale. In this study, climate change effects on discharge of Kor river basin investigated by SWAT and LARS-WG V7 models.

2. Research Methodology

SWAT model applies to simulate runoff, sediment, plant growth, nutrients in soil, contamination transfer, etc. To do this, model divides basin into several sub-basins and each of them to several HRUs which are different in terms of soil characteristics, slope and land use.

Since the SWAT model is semi-distributed, it is necessary to calibrate primary results to minimize differences of observed and simulated data.

On the other hand, climate change effect is not predictable. Application of climate scenarios is an alternative solution. The most common models are GCM models. LARS-WG method uses to micro-scale GCM data.

3. Results

In this study, climate change effects on Kor river basin investigated using SWAT and LARS_WG models. Land use map extracted from Landsat 7 satellite imagery. Chamriz and Dehkadeh-Sefid were chosen as hydrometric stations. Statistical data considered from 1988 to 2018, divided into three parts include warm-up, calibration and validation. In dehkadeh-Sefid, Nash-Sutcliffe and R2 coefficients for calibration was 0.65 and 0.69 respectively while for validation was 0.54 and 0.65 respectively. In Chamriz, Nash-Sutcliffe and R2 coefficients was 0.65 and 0.73 for calibration and 0.78 and 0.79 for validation respectively.

In this study, CMIP6 models used to predict temperature and precipitation. Precipitation, minimum and maximum temperature data match with HadGEM3-GC31-LL model very well. Average minimum and maximum temperature of all months increases under SSP2-4.5 and SSO5-8.5 scenarios in the future. Also, precipitation under this scenarios increases in September to December varied in different stations.

Monthly discharge in hydrometric stations shows that the most increase will occur in October which is explainable due to increase in nearby stations precipitation.

4. Conclusion

Evaluating the impact of climate change on regional and watershed scales regarding water resources management is important for implementing policies to achieve sustainable development.

According to this study, it is necessary to adopt strategies to infiltrate rainfall, increase water resources volume and minimize dangers of flood includes increase natural coverage by planting fast-growing trees.



Abstract

A wide area of Iran has arid and warm climate. Hence, it is important to prospect the condition affected by the climate change in future. In this study, climate change effects on Kor river basin evaluated by SWAT and LARS-WG V7 climate model. For this purpose, at first stream flow of Kor river estimated by SWAT model during baseline. Then, by using LARS-WG V7 model, precipitation and temperature in future estimated. At last, effect of climate change on Kor river stream flow evaluated. According to results, the mean minimum and maximum monthly temperature under SSP2-4.5 and SSP5-8.5 increased in all months in future which increased more in October, as well as changes in monthly flow in Dehkadeh-Sefid and Cham-Riz stations due to increase in precipitation in this month rather than baseline. Based on findings, increase in precipitation will happen. So, it is inevitable to choose approaches in order to make rain water percolate, groundwater resources increase and lower the risk of increasing in runoff and subsequently flood occurrence.

Key Words:

Cham-Riz station, Climate change, Kor river, SWAT.

Abstract

A wide area of Iran has arid and warm climate. Hence, it is important to prospect the condition affected by the climate change in future. In this study, climate change effects on Kor river basin evaluated by SWAT and LARS-WG V7 climate model. For this purpose, at first stream flow of Kor river estimated by SWAT model during baseline. Then, by using LARS-WG V7 model, precipitation and temperature in future estimated. At last, effect of climate change on Kor river stream flow evaluated. According to results, the mean minimum and maximum monthly temperature under SSP2-4.5 and SSP5-8.5 increased in all months in future which increased more in October, as well as changes in monthly flow in Dehkadeh-Sefid and Cham-Riz stations due to increase in precipitation in this month rather than baseline. Based on findings, increase in precipitation will happen. So, it is inevitable to choose approaches in order to make rain water percolate, groundwater resources increase and lower the risk of increasing in runoff and subsequently flood occurrence.

Key Words:

Cham-Riz station, Climate change, Kor river, SWAT.