ارزيابي خطر سيل‌خيزي حوضه آبخيز خورخوره در استان كردستان

Risk assessment of flood in Khorkhore basin in Kordestan Province

استان كردستان با توجه به وضعيت اقليمي و فيزيوگرافي آن مستعد وقوع سيلاب است و اين عامل هر ساله موجب خسارتهاي فراوان مي‌شود. حوضه آبخيز خورخوه در استان كردستان با چهار زيرحوزه يكي از حوضههاي سيل‌خيز در سطح استان است. براي تهيه لايههاي اطلاعاتي مورد نياز از متغيرهاي شدت بارش، شماره منحني رواناب، مقدار پتانسيل نگهداشت و پتانسيل سيلخيزي استفاده شده است. با استفاده از روش راسميلر ضريب جريان سيلابي در حوضه و زير‌حوضههاي آبخيز تعيين و در نهايت پتانسيل توليد رواناب و سيلاب هر ناحيه محاسبه شد. بررسي نقشههاي بدست آمده حاكي از افزايش بارانهاي بيشينه روزانه از شرق به غرب حوضه آبخيز است. دامنه تغييرات شماره منحني رواناب از كمينه 70 تا بيشينه94 (عمدتا در مناطق شهري) متغير است. حدود نيمي از حوضه داراي شماره منحني 85 و 90 است. مقدار پتانسيل نگهداشت نيز به تبعيت از تغييرات شماره منحني در حوضه خورخوره متغير است. همچنين در حوضه مطالعاتي، زيرحوضه شماره چهار پتانسيل توليد رواناب بيشتري از ساير زيرحوضهها دارد. نتايج بيانگر كارايي مناسب روش راسميلر در اولويتبندي حوضهها از نظر سيلخيزي حوضههاي آبخيز است.

Flood is one of natural disaster that it has overabundant financial, fatality and environment losses. Basin Khur-khureh is one large watershed is situated in Kurdistan province. The area covers 1753 Km2, spanning latitude 35o48ʹ to 36o13ʹN and longitude 46o25ʹ to 35o46ʹE. Methodology of research is based on library methods and extensive search of various sources for theoretical principles. Borders and Digital Elevation Model (DEM) Basin Khur-khureh was extracted from topographic maps by WGS84 UTM coordinate system. Then using hydro model in ArcGIS software were extracted streams layer and land-use. In determining the Curve Number (CN) was used hydrologic soil groups, land productivity, hydrological conditions and aforetime soil moisture content and the increase spatial resolution was used Panchromatic band of IRS-LISSIII. Classification and land use were determined by image processing and fields investigate. To calculate the runoff coefficient was used Rasmiller Model. Also obtaining flood potential, with crossing information layers, 25 and 50 years Isohyets, S and Using relationship of rainfall altitude- SCS runoff, Sewage layer was prepared. Variation range of runoff curve number is variable from Minimum 70 to Maximum 94 (mainly in urban areas). About half of the field is curve number of 85 and 90. Potential amount of maintenance has changed agreement with changes in curve number. Considering the relationship and results in computing the potential amount of primary maintenance, Rasmillr have light sensitivity to intensity rainfall amounts and seems to be weight coefficients allocated to this factor is less than real. The results of evaluation and studies natural hazards caused by flood and watersheds runoff should be observe in local or regional planning and purposeful path defined for flood control in planning and aims. Because of lack sufficient to these is caused many financial and criminal damages in the short and long time.