پديد آورندگان :
پيروزي نژاد، نوشين نويسنده دانشجوي دكتري جغرافياي طبيعي گروه ژيومورفولوژي دانشگاه تبريز Pirouzi Najad, nooshin , پيروزي نژاد ، سجاد نويسنده كارشناس ارشد آبخيزداري، دانشگاه ساري ,
كليدواژه :
آزمون تي تست , رابطه همبستگي , تصاوير ماهواره‌اي , عكس‌هاي هوايي , شعاع قوس
چكيده لاتين :
This research is used historical method for investigation change in radius of curvatures size and relation with plan form change. In This study used aerial photography 1955, 1969, 1981, 2003 and IRS satellite imagery 2010 and landsat ETM satellite imagery 1981. Aerial photographs were orthophoto in ARC MAP software based on 1/25000 topographic map. Shoreline was digit and river divided 12 reach. Meander radiuses of curvatures are measured for 5 consecutive periods in AutoCAD software. Values radius is fiting in HYFA software. Result show that best distribution is Gumbel distribution. Correlation Coefficient between radius data in consecutive years showed, Correlation Coefficient between radius data in 1955 and 1969 (r=0.738), Correlation Coefficient between radius data in 1955 and 1981 is(r=0.275), Correlation Coefficient between radius data in 1955 and 1981 is (r=0.054) and Correlation Coefficient between radius data in 1955 and 2003 is(r=0.070). Also Studentʹs t-distribution (paired-samples T .Test) analyze in 5 consecutive years showed there are not difference between radius data in 1955, 1969, 1981 but there are difference between this data with data 2003 and 2010. Result showed change meandering plan form to braided and anabranching plan form have been caused change data radius size, happen cutoff and cause decrease Correlation between radius data.
Key word, satellite imagery, radius of the curvatures, correlation, T .Test analyze, Gamasiab River
Introduction
Alluvial Cannel Rivers would have various plan forms they are consisting straight, meandering, braided , anastomosing and anabranching plan forms . braided , anastomosing and anabranching rivers are muti channel that dividing around alluvial bars or islands these bars are usually easily moved in flood. Bars in braided plan forms are unstable and moved but in anabranching plan forms for long time they are stable there is different research about meandering change in all over the word. Investigation meander migration has a very important because migration and bank erosion in river cause distraction agriculture land and structure human. So Investigation meander migration in percent time and change detection in past years and plan form prefect is very important.
Methodology
for this research used aerial photography 1955 with 1/55000 scales, aerial photography 1969 with 1/20000 scales, land sat ETM satellite imagery 1981 with resolution 30 m, aerial photography 2003 with 1/40000 scales and IRS satellite imagery 2010 with resolution 5.8 m. Aerial photographs were orthophoto in ARC MAP software based on1/25000 topographic map. Shoreline was digited and river divided 12 reach. The radius of curvature in Hyfa software on the seven statistical distribution of normal, log normal, two-parameter log normal distribution, Pearson, Pearson Type 3 and Gumbel distribution is fitted and Best distribution to be determined. In these research for showed level of significance change data radius for 5 consecutive periods doing hypothesis testing,
H0: there is not different significance between size radiuses of curvatures meander.
H1: there is different significance between size radiuses of curvatures meander.
To assess the changes in river in the past 56 years is done correlating and T .Test analyze Between radius data in 5 consecutive years in SPSS software.
Results and discussion
Result showed that Gamasiab river plan form in 1955 and 1969 except 3 reach had a developed Meandering. But in 1981 in 4 reach some curvatures meander remove and river plan form change to braided but other reach have a meandering plan form. In the 2003 and 2010 in the 4, 5 and 6 reach total meander of curvature removed and change to braided plan form. But other reach have been a meandering plan form. Finally amount of in 1955 meander of curvatures was 112 and in 1969 arrive to 121 and in 1981 decrease to 111 and in 2003 and 2010 decrees to meander of urvaturec 92.
For investigated change size of radius in 5 consequent period , radius data values fit in HYFA software and change trend on the seven statistical distribution of normal, log normal, two-parameter log normal distribution, Pearson, Pearson Type 3 and Gumbel distribution is fitted and select Goodness of fit. Result showed best distribution is identified Gumbel distribution. This distribution show size of radius in Gamasiab River is very different.
Correlation Coefficient between radius data in consecutive years showed, Correlation Coefficient between radius data in 1955 and 1969 (r=0.738), Correlation Coefficient between radius data in 1955 and 1981 is(r=0.275), Correlation Coefficient between radius data in 1955 and 1981 is (r=0.054) and Correlation Coefficient between radius data in 1955 and 2003 is(r=0.070).
Correlating between radius data in 5 consecutive years has been showed planform change in Gamasiab River. radius data in 1955 and 1969 significant at the 0/01 level and with radius data in 1981 significant at the 0/05 level this result showed planform change is started in 1981, but radius data in 1955, 1969 and 1981 years haven’t any significant with radius data in 2003 and 2010 and this showed river plan form change and radius data change in this years.
Paired-samples T .Test analays showed radius data in 1955, 1969, 1981 significant at the 0/05 level and don’t difference between data but there are difference between radius data 1955, 1969, 1981 with data 2003 and 2010. Result showed change meandering plan form have been to braided and anabranching plan form is caused data radiuses change and remove some meander curvature and happen cutoff.
The results of statistical test paired-samples T .Test analays and Correlation are stated null hypothesis (H0) for 1955 and 1969 is true, there is not different significance between meander radius data and river didnʹt change in plan form. But in 1981, 2003 and 2010 yearʹs null hypothesis is false because river had been change in planform and there is different significance between meander radius data. Alternative hypothesis (H1) confirms and states that there is a difference between radius data.
Conclusion
Investigated radius data in 56 years ago Gamasiab river showed river had a very change in plan form river in 1955 and 1969 in total reach and all over river have a development meandring plan form. Thise years there are not different significance between meander radius data and river didnʹt change in plan form.
in 1981 in 4 river reach remove loop and river change to birded plan form and this year start change in river plan form , in 2003 and 2010 some reach change to brided and anabranching plan form And there are different significance between meander radius data.
