**4. Climate change impacts on land suitability in KRB**

Considering the CPWF objectives, few studies were done on river basin climate change (CC) issues. The study done by Ghaffari et al. [17] on land suitability under current and CC scenarios in the KRB was the main study, and the results are summarized as follows;

Assessing the suitability of an area for crop production requires considerable effort in terms of information collection that presents both opportunities and limitations to decision-makers. Land suitability is assessed as part of a 'rational' cropping system, and optimizing a piece of land for a specified use should be based on its attributes. Furthermore, land may be considered either in its present condition or after specified improvements. Although criteria may vary, they are essentially based on climate, soil, topography, and water availability which are the most important categories of natural environmental information required for assessing land suitability.

The CC study in KRB describes a climate-soil-site model to assess CC impacts on land suitability for dryland winter wheat, focusing on the potential effects of temperature increase and rainfall variables on the land suitability in KRB. Assessments were made for the current climate condition and future climate scenarios by 2025 with GIS maps generated through a Simple Limitation Approach (SLA). Ghaffari et al. [17] used topography maps (10 m resolution), 25 years of climate data (1973–1998), physiological and phonological crop parameters, CC scenarios, soil management domain (SMD), and a simple limitation approach (SLA).

In **Table 5**, results of the projection of impacts of CC on land suitability classes for dryland winter wheat in upstream areas of KRB are provided.

It was concluded that by increasing temperature alone, it would be expected that highly and moderately suitable areas increases in the KRB. Increasing temperature and increasing precipitation increase highly and moderately suitable areas. Decreasing precipitation alone or increasing temperature will lower highly and moderately suitable areas. The main reason for this is water stress risk, not the direct effect of temperature [17].
