بررسي تاثيرمشخصات بارش برهيدروگراف سيل و واحد مطالعه موردي: حوضه آبريزرودخانه جاماش استان هرمزگان

The study of effects of precipitation on flood hydrograph and unit hydrograph (the case study: jamash river catchment’s basin in hormozgan province

از آنجا كه رودخانه جاماش با توان‌مندي سيل‌خيزي بالايخود،زيآن‌هايي رابه محيط هاي اطراف وارد نموده، بدين لحاظ با مطالعه بارش و رواناب شكل گرفته، تا حد امكان مي‌تواناز خسارات آن جلوگيري و از منابع آب سيلابي آن استفاده نمود. جهت نيل به اين هدف، با استفاده از دوره آماري15ساله(89-74)وقايع متناظر باران–رواناب وشاخص‌هايمعمول هيدرولوژي، به محاسبه پارامترهاي هيدرولوژيكي پرداخته شدهاست. به طوركلي دو دسته هيدروگراف در اين حوضه استخراج شده‌اند: هيدروگراف‌هايي كه داراي يك نقطه اوج و هيدروگراف‌هايي كه داراي چند نقطه اوج وهيدروگراف‌هاي با فرم نوك تيز و با شيب تند در هر دو شاخه صعودي و نزولي. فرم و شكل هيدروگراف مي‌تواند به الگوي بارش و شيب زياد حوضه و نفوذپذيري كم آن و وقوع رگبارهايي با شدت و زمان زياد در نواحي جنوبي نزديك به خروجي حوضه، وابسته باشد. زيرا سيستم‌هاي بارش‌زا بيشتر از جنوب وارد حوضه مي‌شوند و نتايج حاصلهاين موضوع را نشان داد ، كه همگي اين عوامل باعث مي‌شوند رواناب به سرعت از حوضه خارج شود

Since the Jamash River in Hormozgan province has a high potential of flood seismicity, and has caused a lot of detriments for its adherents, it seems so necessary to study its precipitation and the runoff formed within its basin in order to prevent further damage and to use its flood water as well. To achieve this goal, statistics for a period of 15 years (1996-2011), and were corresponding to its runoff has been selected and by the use of principals of hydrology and with some hydrologic parameters. In general two type of hydrograph was working out in two diffirent hydrometry station, in which all hydrograph has got with one or more diffirent ascendent point. The form and type of hydrograph its depend on runoff, precipitation intensity, slope of basin and low infitration, especially rain storm with high density time insouth area and near hydrograph station in which all this factors caused the raining water with high density becomes or convert to runoff flowing discharges from the basin where can be expecting and occuring the flood with high density in Jamash river with maximum rainfall intensity in the area.The results revealed that intensity of precipitation has been much stronger in the south area on the basin due to entrance of more powerful climate systems with higher rainfall potential and since the concentration time of the basin has been short, hydrographs are taper and steep both in ascending and descending branches.