1-Introduction

Various forms of geomorphology in the region are a reflection of the rate of tectonic activities in that region. Folded Zagros structural unit is one of the active tectonic areas of Iran, where evidence of tectonic uplift can be seen in its growing anticline (Ansari Lari et al., 2019).Geomorphic indicators are a useful and reliable tool in evaluating these activities. The change in the axis of the folds causes a change in the shape of the drainage basins. Quantitative measurements of the watersheds and drainage network of the region make it possible to study the role of active tectonics in changing the shape of the landscape and geomorphological effects of the region by measuring geomorphological indicators. Many geomorphological indices.In the current research, the watersheds and drainage networks of anticlines in the southwest of Ilam have been studied. The purpose of this research is to evaluate the morphometry of the drainage networks of this region based on geomorphic indicators and its relationship with the tectonics of the region.

2- Methodology

In this research, first, scientific sources have been collected through library research. Research data includes DEM 30 meters STRM, topography map 1:50000, geological maps 1:100000, 1:250000 and Google Earth images. In order to evaluate the indicators and also prepare the final output map of the software Zmap, Arc Hydroo, SPSS, Arc Gis and of the indices ∆a, Ha, Dd, R, Bs Hi, Hs, AD, AR, FSI are used in order to investigate the tectonic relationship. The results of the indicators were analyzed using Pearson correlation coefficient and the seismic data obtained from the ZMAP software were extracted and the seismic status of the basins was evaluated.And finally, the final result of the tectonic activity status of each of the sub-basins has been determined.

3-Results

In this research, basins with parallel pattern and scaffolding have the highest increase in indicators R,RB,Hi,a,LN1 and have tectonic activity. The drainage pattern in most of the tectonically active areas is scaffold and parallel pattern(often on the side of anticline) and in some cases a branch pattern is seen in comb or eroded anticlines. According to the type of formations in the region, the waterways in Siah Kouh East and Samour flow in the direction perpendicular to the anticline axis. The difference in the results of morphometric indices is related to the type of formations in the region. Among the anticlines , the highest value of Δa is related to the black anticline of the to anticline Siah Kouh east (6.5), in anticline of Samour-Siyah Kouh East, the highest index LN1. The highest value is related to (Sieh Kouh East and Samour) with numerical values of 3.28 and 3.26 and In the Bifurcation index (R), the highest value is in anticline, Samour 23(0.34), 37(0.69) and The Siyah Kouh East (0.39) and the Siyah Kouh western is obtained (0.43) and in the hypsometric integral index (Hi).The highest Hi related to basin 32, 39 with a value of 0.67, 0.68 and basin 33 with a value of 0.56 (Siyah Kouh East). In the examination of HS, AR, FSI, Ad indices and seismic data of the regionAccording to the changes in the geometry of the folds in the region, the highest amount of tectonic activity in anticline, in order of age. In the Siyah Kouh East, the Siyah Kouh western, Samour and Gnu can be seen. in relational investigation between geomorphic indicators using Pearson's correlation coefficient between Dd-Dd1 indicators There is a strong positive correlation and On the other hand, there is a strong negative correlation between the pair of Dd-Hi indices

4- Discussion & Conclusions

The present research shows that the use of indicators to determine tectonic activity together with other sources provide valuable information about regional developments and the drainage network are among the most important features that have been used in this study., Changes in the geometry of folds in the region in some parts of the region have caused significant differences in the pattern of the drainage network and the anomaly of waterways. The indices (AD, AR, Hs, Fsi), It indicates the most tectonic activity in the eastern Siah kouh, according to the age of folding and the amount of erosion, the ratio of the direction of folding, the distance between the axes of the anticlines and the inequality in the two edges of the anticlines. The differences in the type of indicators are somewhat dependent on the type of regional formations and the type of faults and changes in the geometry of fold.In examining the statistical compatibility between the studied indicators, this point is also determined that the differences in the formations of the region have the greatest impact on the variables. In the calculation and analysis of the seismic parameter are observed. The highest frequency of indices ∆a, Af, Df, Dd, FLi.Hi and branch drainage pattern according to the type of formation is obtained in the eastern and southeastern parts, away from the ZFF fault and close to the MFF fault. and in the western and northwestern parts of the region, the indices of ∆a, R, RB have the highest frequency ratio and the highest a-value parameter and other geomorphological evidences according to the type of formation of the region and lithology and the pattern of parallel drainage and scaffolding. In general, the most active basins in the region are basins 42 (east), 31 (south), 11, 18 (center) and 2 in the west of the region, and among the taqdis, Siah Kouh Sharq and Samourmi, and the highest ratio of abundance in Dd, R, RB, LNI, ∆a, Bs, indicators has been obtained in these basins from the point of view of geology. The ratio of the pattern of waterways network is also changed from branch to scaffolding and parallel according to these activities. there is a connection between flowing waters with different patterns and the way of formation of waterways with different ranks and branches and tectonic activity andForms of erosio and they can be reasons for hydrocarbon traps or water sources.