توصيفگر ها :
شبيهساز باران , رينگمضاعف , منبع رواناب , محل نفوذ رواناب , ذخيره چالابي , ميكروبانكت طبيعي , ميكروتراس طبيعي , نوارگياهي طبيعي , خصوصيات خاك
چكيده انگليسي :
The complexities of nature in terms of its constituent elements, although it challenges large-scale scientific and executive management, it strengthens small-scale perspectives. In watershed management, a sample of small-scale perspective is the encounter of a sheet flow with microtopography. The purpose of this study is to investigate the efficiency of microtopography in runoff control. This study was carried out in Sang Sefid sub basin, located in Najafabad region, Isfahan province, with an area of 10196 hectares, dry climate and 140 mm annual rainfall. In the study area, different types of microtopography were identified, in the mountainous and rocky areas, natural micro-terraces, between the mountains and plains or the knick line, natural plant strips and finally in the plains, natural microbanquet were identified. Each microtopography includes two general parts: the source and sinck area of the runoff, and of course, in the microbanquet, these two areas are practically developed in three sub-sections: erosion (source area), sedimentation and sand (sinck area), and depression storage volume is which corresponds to the sedimentation area, was also taken into consideration. By rainfall simulator, rainfall was simulated in 20.4 mm per hour in each microtopography components. By flow routing and determining the runoff coefficient, output runoff and sediment were obtained in each microtopography components. This process was done independently for each case. The infiltration curve was calculated in each microtopography component by double ring. Soil properties as; Texture, Sand Particles, Bulk density, Acidity, Salinity, Saturation percentage, CaCO3 and Organic Maters were obtained. Statistical comparison between different components of the microbanquet was done by analysis of variance. Comparing of mean- one sample t- test between the output of the microbanquet, micro-terraces and plant strip with themselves evidence sample performed at 5% significance level. The performance of microtopography was investigated in terms of runoff and sediment control and permeability. In micro-terraces, runoff control, in the plant strip, runoff and permeability control, and sediment control were significant. in the microbanquet, the difference in runoff control and permeability were significant. Sediment concentration was significant only in considering upstream runoff. Performance of the microbanquet were significant in all cases, even not considered depression storage, and compared to the evidence themselves. Examining soil characteristics showed that, bulk density in micro-terraces and percentage of organic matters, bulk density, percentage of silt, clay and coarse sand components in microbanquet were significant .In general, the results indicate the effectiveness of microtopography in runoff and sediment control, The soil characteristics had less significant, only in surface layer, which shows the mutual effect of microtopography and surface layer of the soil. Among the three microtopography, the microbanquet was more effective in runoff control.
