Investigating the Effect of Rangeland and Hand-Planted Forest Land Uses on Runoff and Sediment Production at Plot Scale in Noorroud Watershed

One of the important and effective measures in controlling soil erosion and runoff production is the use of watershed management methods, which is currently receiving less attention. This natural phenomenon is a global environmental problem that reduces soil fertility and water quality, increases sedimentation and the possibility of floods. Therefore, using erosion plots in natural areas can play an effective role in controlling runoff and sediment production. The present study was prepared with the aim of investigating the effect of precipitation and vegetation on the production of runoff and sediment in the Noorroud watershed of Mazandaran province.

Noorroud watershed is located in Mazandaran province, the political area of Noor city, Beldeh and southwest of Amol, and the most important population center is Beldeh. This basin, with an area of 1299.78 square kilometers, is the largest sub-basin of Haraz River. To calculate the runoff from individual showers on a plot scale and two different land use types of hand-planted forest (Pine, Pinus halepensis) with seven and eight years old and rangeland lands, using test plots with a size of two by ten square meters with two treatments. And three repetitions were used in the months of April, April, June, October, November and December of 2016 and 2017 and Anova statistical analysis was used to check the relationship between the parameters.

The results of precipitation from 2017.04.17 to 2018.06.07 showed that the maximum amount of runoff occurred on May 31, 2018 and caused the production of 0.35 mg of sediment per plot unit. The results of the Kolmogorov-Smirnov test also showed that the eastern domain has a normal distribution at the level of 0.95 for the two dominant types. The results of the correlation between the canopy and litter percentage of each land use showed that the presence of natural factors such as litter and vegetation canopy has a strong relationship with the weight of sediment produced in two treatments. The highest value of the runoff coefficient is for rangeland use (33%) and the lowest for hand-planted forest (31%).

Conclusion and Suggestions :

According to the obtained results, it was found that in general, the amount of runoff and sediment produced in forest areas is more than rangeland. On the other hand, there was less relationship with production sediment in the rangeland areas with the eastern slope. One of the main cases in the destruction of national lands is grazing beyond the capacity of rangelands and forests. This factor causes the destruction of the rangeland, and with not very intense rains, the resulting runoff moves some of the soil. Various factors are involved in the occurrence and aggravation of runoff and sediment, and considering the conditions of each region, one or two factors may play a greater role. The role of its use and vegetation under different rainfall conditions has an important role in the amount of runoff. Therefore, it can be seen that the presence of vegetation has a direct effect on reducing the amount of runoff and sediment. According to the obtained results, in order to improve the results, it is better to use artificial rainmakers in the natural field so that the role of vegetation can be better understood.