The Study On Design For Control Project Of Small Watershed Of Land Consolidation Engineering Of Gully Channel In The Loess Hilly And Gully Region

Based on real demand for farmland and food security in the Loess region. The major engineering of yan’an land consolidation engineering of gully channel begun to be implemented in 2012, through the major engineering the tense relationship between man and land relationship alleviated in a certain extent. Especially through torrential rain with one hundred years’frequency of the year of 2013, large-scale land consolidation engineering of gully channel appeared as part of different damage problem of the part of the new renovation land and the dam system, and the influence of change of underlying surface dramatically caused by land consolidation in the loess region on river basin water environment such as runoff yield and concentration and flood have been paid more and more attention at home and abroad. To this end, the effect of different land consolidation proportions (0%, 20%,30%, 40%,50%) and rainfall intensities (40mm/h,60mm/h,80mm/h, 100mm/h,120mm/h) on channel surface runoff hydrodynamic parameters, the impoundment volume in front of dams,runoff coefficient and the flood standard of gully channel were studied by field investigations and lab simulations, and get the following conclusion:(1) The factors of land consolidation proportion have significant influence on surface runoff hydrodynamic parameters such as velocity, flow depth, flow width. With the increasing of land consolidation proportion, the average velocity of surface runoff decreased by 6.21%, 10.95%,19.85% and 21.78%, respectively. The average flow depth of surface runoff increased by 4.73%,8.92%,15.13% and 16.49%, respectively. The average flow width of surface runoff increased by3.39%,3.77%,6.97% and 8.18%, respectively. Land consolidation engineering of gully channel can obviously affect surface runoff hydrodynamic parameters.(2) The factors of land consolidation proportion have significant influence on the impoundment volume in front of dams. With the increasing of land consolidation proportion, the discharge of the rising stage decreased by 8.04%,16.22%,14.54% and 24.78%, respectively. The total duration of impoundment in front of dams decreased by 2.93%、 17.37%、22.12%、25.96%. The average impoundment volume in front of dams 3.94%,15.55%, 17.23% and 23.90%, respectively. Land consolidation engineering of gully channel can obviously affect the impoundment volume in front of dams.(3) The factors of land consolidation proportion have significant influence on the three elements of the designed standard of control engineering:peak discharge, flood volume, flood hydrograph. The land consolidation of gully channel overall can reduce the flood in some degree, and it decreases with the increase of flood return period. The change of peak discharge and flood volume characterized by the variation of runoff coefficient. With the increasing of land consolidation proportion, the average runoff coefficient decreased by 3.94%,15.55%,17.23% and 23.90%, respectively. With the increasing of rainfall intensity, the average runoff coefficient decreased by 21.02%,18.36%,11.17%,12.87%,13.70% respectively. The flood ratio of the falling stage and the rising stage decides the distribution relation. With the increasing of land consolidation proportion, the ratio of the falling stage and the rising stage decreased by 5.29%,22.63%,25.27%,28.03% respectively. With the increasing of flood return period, the total flood duration is increasing, and the flood ratio of the falling stage and the rising stage is also significantly increased.