بررسي تاثير شاخص هاي مورفومتريك بر روي اندازه ي رسوبات در حوضه ي آبريز تبارك آباد قوچان (شمال شرق ايران)

The Effect of Morphometric Indexes on the Size of the Sediments in the Tabarak Abad (Quchan) Catchment (North East of Iran)

حوضه ي آبريز تبارك آباد يكي از زيرحوضه هاي آبريز قره قوم در شمال شرقي شهرستان قوچان و در استان خراسان رضوي مي باشد كه در زون زمين شناسي كپه داغ قرار دارد. به طور كلي هدف از اين پژوهش، ارزيابي تاثير شاخص هاي مورفومتري بر روي پارامترهاي بافتي مربوط به اندازه ي رسوبات در حوضه هاي آبريز است. در اين تحقيق دو زيرحوضه ي يدك و زيرآبه كه حوضه ي تبارك آباد را ايجاد مي نمايند انتخاب و برخي از شاخص هاي كمي مورفومتريكي كلاسه بندي گرديد. بر اين اساس زيرحوضه ي يدك در كلاس 1 و زيرحوضه ي زيرابه در كلاس 2 قرار گرفت كه نشان دهنده ي فعال بودن زيرحوضه ي يدك از لحاظ تكتونيكي است. به منظور بررسي پارامترهاي رسوب شناسي 6 نمونه رسوب از هر كدام از زيرحوضه ها برداشت گرديد. اندازه ي رسوبات نشان مي دهد كه زيرحوضه ي يدك رسوباتي درشتر از زيرحوضه ي زيرآبه دارد. نتايج نشان مي دهد كه زيرحوضه ي يدك كه بر اساس شاخص هاي مورفومتري در كلاس فعال تري قرار گرفته، پارامترهاي بافتي مربوط به اندازه ي بالاتري دارد.

Introduction Tabarakabad catchment is a sub-catchment of the Gharaghom in the northeastern the Quchan city and in the Razavi Khorasan Province between the 37 ? 02´41" until 37 ?21´ 8" latitudes and 58 ? 24´ 05" until 59 ? 03´ 55" longitudes, 145 km away from west of Mashhad, which is located in Kopet Dagh geological zone. The formations have forms in the Tabarak Abad sub-catchment from late Jurassic period up to early Cretaceous period. Further, young sediment deposits in this basin are associated with Quaternary period. The purpose of this study was to evaluate the effects of morphometric indexes on textural parameters related to the size of the sediments in the catchment. Methodology Two sub-basin catchment the Yadak and Zirabe the Tabarakabad catchment create a choice and some morphometric quantitative indexes like hypsometric integral (H), ratio of valley floor width to valley height (VF), drainage basin asymmetry (AF), index Gradient along the river (SL), transverse topographic symmetry index (T) and the index of mountain front sinuosity (Smf), the shape of the basin (BS) calculated using topographic maps and digital elevation model (DEM) and business information in the field study with the help of ArcGIS and the index (Iat) was classified. In order to study textural parameters related to the size of the main channel sediments 12 sediment samples (6 samples from the main channel the Yadak basin and of the main channel the Zirabe 6 samples) were taken. The sampling anywhere to help Hoes geological volume of a cylinder with a diameter of 20 and a depth of 25 cm deep were taken in this connection to the example of the local texture deposition was intact removal, as well as in The exact location of the samples were recorded by GPS. Dried samples were then transferred to the laboratory and seed dry sieve methods were classified. Discussion According to this Based on the study, the morphotectonic indexes include curves and hypsometry integral (H) of the Yadak 0.39 and class 1 in the Zirabe 0.7 class 3. The index Gradient along the river (SL) is an average value of 305.99 gradient meter in the Yadak and class 1 and 283.35 gradient meter in the Zirabe and class 1, the index of mountain front sinuosity (Smf) has been calculated as the Yadak 0.59 and class 1, and 0.86 in the Zirabe and class 2, the ratio of valley floor width to valley height (VF) index is the Yadak 0.23 and class 1 and the Zirabe 0.47 and class2, the drainage basin asymmetry (AF) is the Yadak 0.54 and class 2 and The Zirabe 0.59 and class 2, the shape of the basin (Bs) is in the Yadak 9.2 and class 1 and the Zirabe 0.47 and class 2, classification of the indexes based on Iat index suggested Class I for the Yadak and class 3 for the Zirabe sub-catchment, which represents the active sub-catchment Yadak of tectonic. The sediments size it shows that in the Yadak sub-catchment sediment median size is -3.3, mean -2.5, sorting 2.5, skewed -0.05 and kurtosis 1.1. The Zirabe sub-catchment has sediment median size is -1.6, mean -1.2, sorting 2.1, skewed 0.47 and kurtosis 0.87. According to the obtained values for each sub-catchment can be stated that average size of sediments in the Yadak sub-catchment is coarser of the Zirabe sub catchment. Which reflects the high energy sub-catchment of the Yadak relative to the sub-catchment is Zirabe. The skewed shows according to of gravelly the average size of deposits in the sub-catchment Yadak of asymmetric curves have been fine gravel. While in the sub-catchment Zirabe sand deposits have created asymmetry, which reflects the average size of sediment in the subcatchment Yadak is coarser of the sub-catchment sub-catchment in times of low energy flow. The kourtosis sediments in the Yadak sub- catchment far more than the Zirabeh sub-catchment that represents Zirabe Changes less to flow is in the Yadak sub-catchment. Conclusion The results show that the Yadak sub-Catchment that was more active in class based on the morphometric indexes related to textural parameters is much higher. Finally it can be concluded in the catchment that have same effective elements in sediment texture, textured sedimentary catchment that are more active morphometry create their coarser.