Chaos Theory in Fluvial Geomorphology (Case study: Kol River Bed, Hormozgan Province, IRAN)



Extended abstract
1- Introduction
Chaos theory studies chaotic dynamic systems and tries to explain a kind of regulations which are hidden inside ir- regulations. Chaotic systems are nonlinear dynamic systems that are sensitive against their primitive conditions. A little change inside these primitive systems causes changes in future, so that their future behaviors cannot be predictive. In chaos theory only complex systems have chaotic and irregular appearance, meanwhile they follow a rule and regularity which formed by a non linear progress theory with a feed back. A system which has a chaotic processes makes variances and cycles that their periods are unlimited and don’t repeat during study period. Unrepeated and cycles inside a chaotic systems exists because of nonlinear boundaries moves inwards and outwards and tries to find a new direction that don’t overlay on its previous direction. These movements makes the Chaotic system a sensitive state against its’ primitive conditions. If changes inside the system has a little changes against its first conditions new timing trajectory of system will be apart of its previous time trajectory. We try in this paper to achieve variable that cause instability in river bed of Kol River by using chaos theory. We consider that there are regularities and none linearity pattern in kal river bed fluctuations despite of it in regular appearance. Seasonal limits and warm temperature during summer, none availability of access roads, especially for coastal regions, rareness of environmental studies of study region and unavailability of remote sensing temporal data were main limiting of the study.

Kol river catchment by an area about 205.9 Square km situated in Hormozgan Province of Iran. We used 19547 arterial photos of the region alongside to Landsat TM of 1977, 1989. 2001 and 2005to find river bed fluctuations and then used GIS soft ware ARC GIS (9.3) to record changes in a data base. We complete our study by field works to find stable and unstable areas and profile of Kol River by Geomorphologic considerations and methods. Finally we mapped all irregularities of river bed fluctuations for explanation of these changes by using Chaos theory concepts and methods.

Factors such as high slop profile of catchment basin, poor vegetations cover, impermeability of lithologic formations of the study regions’ rain shower state of precipitations and short concentration time for basin are main factors that leads to flooding state of Kol River so that the erosional potential of the basin is above normal state. Sediment analysis of the kol basin shows that suspended load of the river is above normal and this is result of fine alluvial deposits of the region.KOL delta has fine grains , by a little slope during flash floods and these leads to instability in middle course of the river and braided and widen it. During floods, the river course changes and human hazards and destructing constructions and bridges occurs, vesting arable lands , and human settlements. This means chaotic series that during their time courses may leads to abrupt failures and these makes their predicting very hard. If anyone tries to predict these chaotic series by using a set of observations, he/ she will oppose too many errors, even if he/she used high- tech observations. This is because that a series of chaos
behaviors are more different than a series of accidental ones.

We cannot consider all of those changes occur in Kol river bed as accidental and without any regulations inside, because these changes are results and depends on interactions among many form and processes variables. We can only consider these chaos situations in a systematic approach and in- equilibrium subject and can be explained in systematic geomorphology. Kol old courses are a state of the system that are not in balance by today processes and shoe an irregularities between form and process, but it is not show in- balance in whole system, it is showing a delay in system because of changes. Irregularities in whole trend after time delays and returning to old conditions. In balancing occurs when among dependent response variables ( forming variables) have delays against changes in dependent ( amount and processing factors) occurs and a delay occurs in relation of inputs and outputs of the system. We can conclude that we should change our approach to events, so that we can discover hidden constructed regulations.