Evaluation and analysis of developed and vulnerable karstic areas (Case study: Khorin karst massif in Kermanshah province(

Evaluation and analysis of developed and vulnerable karstic areas (Case study: Khorin karst massif in Kermanshah province(

Introduction
The sensitivity of some sedimentary rocks to dissolution and its importance in the characterization of rough terrain is due to the appearance of certain forms called karst.Approximately 25% of the world's population, especially in Asia, the Mediterranean and the United States, supplies their karstic aquifers. Since many areas and cities are dependent on karst water resources, karstic resources will be very important. In Iran, about 5 percent of the country is made up of karstic areas, which play an important role in the country's water supply. In addition to the importance and role they play in the supply of water, karstic water resources have the potential to be highly vulnerable, which has made them always vulnerable to pollution. Because karstic resources are the major sources of water supply, vulnerability assessment and risk zoning mapping is very important. Due to the importance of the subject, in this study, the karstic mass of Khorin in the high Zagros has been evaluated. In this research, first, using WLC model and network analysis (ANP), the areas of karst development in the area will be evaluated and then its vulnerability status will be assessed using Paprika model.




Materials and Methods
In this research, information and tools have been used to achieve the desired goals, including the 5-meter SRTM digital model (to provide elevation, slope, slope and river layers), Topographic map 1: 50000 (to check the topography of the area) and geological map 1: 100000 (check the area's geology). The tools used in the study also include ARCGIS (for final mapping and output) and IDRISI (for WLC model implementation). The analysis of the information in this study was conducted in two stages. In the first step, using 8 factors (lithology, distance from fault, distance from river, land use, slope, slope direction, elevation and climate) and WLC and ANP integrated model, karst development areas are identified, In the second stage, the Paprika model identifies the areas most vulnerable to pollution. In the third stage, the vulnerable areas are identified based on the results of the first and second stages.

Discussion and Results
Karst areas are of particular importance because of the supply of water. One of the issues with karstic resources is their vulnerability to pollution.Various studies have been conducted on the development of karstic resources and their vulnerability, most of which have evaluated this research either on the development of karstic areas or their vulnerability, But in this study, first, using the WLC and ANP models, the identified areas of karst development are identified. For this purpose, 7 lithology parameters, fault distance, river distance, land use, slope, slope direction, elevation and climate were used and then vulnerable areas are identified using the Paprika model. In the Paprika method, factors including the upper subsurface water content (P), type saturation (R), penetration (I) and karst waves (Ka) are used. The results of these methods indicate that the central areas of the study area have both high development potential and high potential for vulnerability.

Conclusion
Evaluation of the results indicates that much of the study area has great potential for the development of karstic resources, thus, 68/3 km 2 the study area is located at a very high potential for the development of karstic resources. Surveying the zoned map indicates that the central areas of the study area, located at the altitudes of the Khorin massif, have great potential for the development of karstic resources. In fact, because of their good lithology, high altitude and low slope as well as the type of cover, these areas have great potential for developing karstic resources. From the center towards the Khorin massif, the potential for karstic resource development due to reduced altitude, change in lithology type and low density cover is also reduced. The results of the Paprika model indicate that the contamination potential is higher in the central part of the karstic mass and that the amount of contamination and vulnerability decreases as we go from center to margin. In this study, in order to identify areas susceptible to pollution, the most susceptible classes of development are identified as vulnerable areas. Evaluation of the floor area indicates that the vulnerable class based on the Paprika model has a size of 35.3 km2, the floor has a high potential for karst development of 68.6 km 2 and also areas with high potential for karst development and vulnerability based on the Paprika model, is 22.7 km 2.