Analysis of Isochronal Areas Over a Watershed Using Diffusive Wave Model Based on Rainfall Intensity Variation (Study Area : Kamanaj Olia Watershed-Tabriz)

Document Type : Research Paper

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Abstract

The aim of this research is the application of two dimensional Saint-Venant equations for determenation of isochronal areas over the Kamanaj Olia watershed, a sub-watershed of Ajichay, located in East Azarbaijan Province, Iran.  For this purpose watershed area was divided into 250×250 meters cells using GIS, then digital elevation model was prepared. Kostiokov infiltration model , as the best fitted model to measured infiltration data was selected for expressing infiltration component in Saint-Venant equations. Saint-Venant equations were solved using explicit method of  finite difference numerical technique. Flow trajectory was calculated cell to cell to reach the outlet. Considering the momentary infiltration, the cell to cell flow rate was simulated using diffusive model for the purpose of spatial and temporal analysis.The equilibrium time for each cell was calculated to achieve the drivation isochronal maps for any rainfall event. Based on these maps the relation of concentration time with rainfall intensity as well as that of drainage area with rainfall intensity were developed.The eqiuilibrium time increased as the cell size changed from 250×250 to 300×300 and350×350 meters, because of topographic and hydraulic parameters variation. 

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شکوهی  ع ،1380.  بررسی یک مدل ریاضی بارش- رواناب با مبنای هیدرولوژیکی در بستر GIS (برای استفاده در سیستم­های پیش­بینی زمان واقعی رخداد). پایان نامه دکتری تاسیسات آبیاری، دانشکده کشاورزی دانشگاه تهران.
محمد صالحی پ و همکاران، 1385. تدوین مدل هیدرولیکی- هیدرولوژیکی مبتنی بر GIS  برای شبیه سازی فرآیند بارش- رواناب در حوضه آبریز امامه. اولین همایش ملی مدیریت شبکه­های آبیاری و زهکشی. دانشگاه چمران، اهواز.
علیزاده ا، 1378. رابطه آب و خاک و گیاه. انتشارات دانشگاه امام رضا (ع).
غیور ح، 1371. پیش­بینی ‌سیلاب ‌در مناطق ‌مرطوب. فصل نامه‌ تحقیقات ‌جغرافیایی، شماره ‌25.
Akan AO, 1986. Time of concentration of overland flow. Journal of Irrigation Drainage Engineering. ASCE 112(4):284-292.
ChowVT, Maidment DR and Mays  LW,1988 . Applied Hydrology, Mc Graw – Hill International Book company.
Hjelmfelt  AT,1978. Influence of infiltration on overland flow. Journal of  Hydrology 36:179-185.
Julien PY, Saghafian B and OgdenFL, 1995. Raster- Based hydrological modeling of spatially-varied surface. Water Resources Bulletin 31(3):523-536.
Moussa  R  and Bocquillon C, 2000 . Approximation  zones  of  the  Saint-Venant equations for flood  routing with  overbank  flow . Hydrology  and  Earth  System   Sciences 4 (2): 251-261.
Rodriguez I, 1979. The geomorphological structure of hydrologic response.Water Resources Research 15 (6):1409-1420.
Saghafian B, Julien PY and Rajaie HM, 2000. A spatial travel-time method for watershed routing. 4th International Conference on Integrating GIS and Environmental Modeling (GIS/EM4): Problems, Prospects and Research Needs ,September 2-8, Banff, Alberta,Canada.
Saghafian B and Julien PY, 1995. Time to equilibrium for spatially variable watersheds. Journal  of  Hydrology  172: 231-293.