Studying the effects of flood water spreading on changes of topsoil and vegetation (case study: Hamun Region of Sistan,Iran)

ABSTRACT: Flood water spreading is one of the most important steps taken to protect and amend the soil which not only prevents surface flow, but causes an increase in water influx, improves the fertility of the soil, reduces the damages caused by flood, restores the pastures and helps fighting desertification. The purpose of this research is to study the changes in some features of the topsoil and vegetation in the land affected by flood and comparing its results with the control area. Since each time that a flood occurs 4 fields were drowned and 2 werenʹt, the 4 fields were considered as the under effect area and those 2 fields as control area. Samples were taken in all of the fields using the random-systematic method. To this aim, 3 transects of 100 meters was established in each field and each one had 10 plots of 1 square meters regarding the dispersion of vegetation. Vegetation crest percentage and accumulation were calculated through the use of plots and dispersion of plant growth in the current year was regarded as plant production. Also, to measure some features of the soil in Flood water spreading and control areas, 6 profiles were gathered from each transact (3 profiles were gathered from bush-covered soil and 3 from bare soil), and factors regarding EC, pH, nitrogen percentage of the soil, and organic matter percentage were calculated. In order to compare the results regarding soil features, we used 2*2 factorial tests and for the factors regarding vegetation we used non-placental T test in spss. The results of analyzing the data indicate that the flood water spreading has a considerable effect on vegetation crest percentage and the amount of plant production but based on the statistics, there is not much of a considerable difference between the field that’s flooded and the field thatʹs not. Also, statistics show that Flood water spreading has a considerable effect on the percentage of organic matter, overall nitrogen percentage, acidity decrease of the soil, and EC.