| To analyze the typical watershed runoff cell rainfall, runoff and sediment yield characteristics of different land use types in Dabie Mountain in Anhui, exploring different watershed rainfall runoff response to the change of land use, and studying rainfall runoff and erosion sediment in a typical watershed. Yue Xi river basin and the Shangshe small watershed in dabble mountain area as the research object in Anhui, as slope runoff plots,catchment areas,a typical small watershed, and in typical watershed scales for long time series observation, conclusions are as follows:(1)The rules of the typical land use type slope district scale of rainfall runoff and erosion and sediment yieldDifferent land use types of slope runoff plots average years of flood season runoff coefficient from big to small: control runoff plots、the slope runoff plots 、 pinus massoniana runoff plots、Cunninghamia lanceolata runoff plots、the moso bamboo forest runoff plots; Years of flood season average runoff coefficient in the order 0.085, 0.006, 0.108, 0.007, 0.010. Slope runoff plots and contrasting runoff watershed’s flood season runoff depth、runoff coefficient are significantly higher than other runoff plots; Flood season average erosion modulus respectively by big to small:control runoff plots, the slope runoff plots, Cunninghamia lanceolata runoff plots, pinus massoniana runoff plots, the moso bamboo forest runoff plots, Years of flood season average erosion modulus in the order 5484.90 t/(km~2·a)、3161.49 t/(km~2·a)、3.69 t/(km~2·a)、1.53 t/(km~2·a)、1.29 t/(km~2·a). Along with the increasing length of observation 5 slope runoff plots of flood season runoff depth, runoff coefficient, erosion modulus and sediment content in general a downward trend, slope runoff plots and contrasting runoff plots most significant downward trend.(2)Vegetation change on the influence of the rainfall runoff under the watershed scalesUnder the condition of light rain, farmland-mulberry field watershed shows a slightly runoff generation before returning farmland to forest and the early stage of the returning farmland to forest; under the condition of moderate rain and heavy rain, farmland-mulberry field watershed and pinus massoniana watershed are runoff produced in the process of rainfall observation; In the observation period, pinus massoniana watershed per unit area runoff produced is smaller than farmland-mulberry field watershed, farmland-mulberry field watershed runoff modulus of the interannual is more significant than pinus massoniana watershed; with the increase of year of observation, two watershed time under the condition of rainfall runoff modulus decreases gradually, and the gap is more and more small; in mid and late returning farmland to forest, two watershed under the condition of moderate rain and heavy rain, runoff, compared to the value of the modulus and rainfall intensity only slightly lagging.Slope land-mulberry field watershed and pinus massoniana watershed’s runoff depth years distribution is uneven, flood season runoff depth accounted for about 60% of the annual, pinus massoniana watershed flood season runoff depth of annual runoff depth ratio is higher than farmland- mulberry field water catchments from 1.8% to 4.0%, and two watershed runoff coefficient of the gap is more and more small with the increase of year of observation; Slope land-mulberry field watershed production flow per unit area significantly greater than pinus massoniana watershed’s with the same rainfall condition; as the growth of the observation years period, slope land-mulberry field watershed and pinus massoniana watershed’s month runoff depth ratio decreases, and the final ratio is more and more close to 1.0. Observation period horsetail pinus massoniana watershed of leaf area index were higher than in farmland-mulberry field watershed, two watershed leaf area index from 2000 to 2010 showed a trend of significant growth, late returning farmland to forest in 2010 after growth is easing, two watershed runoff coefficient and leaf area index change trend.(3)Study on the rule of Shangshe watershed’s rainfall runoff and sediment transportThe annual variability of Shangshe watershed’s rainfall is larger, for many years the average annual rainfall of 1345.0 mm, uneven distribution of years, accounted for 60.6% of annual rainfall, the other accounted for 39.4% of annual rainfall; watershed runoff distribution change is bigger in a year, for many years the average annual runoff and runoff coefficient in 5.192 million m3, and 64.0%, respectively, the runoff coefficient of annual change trend and the trend of annual runoff changes are similar, both were significantly positive correlation(P<0.05); on uneven distribution in Shangshe watershed runoff years and accounts for 69.1% of annual runoff, the other accounted for 30.9% of annual runoff, annual runoff and annual rainfall、flood season runoff and flood season rainfall has significant positive correlation(P<0.05). On Shangshe watershed years average sediment discharge and sediment modulus ratio 207.6 t, 34.3 t/km~2, a. yearly sediment as the growth of the observation years significantly decline, and its uneven distribution in sediment discharge year account for 87.7% of the annual sediment discharge and non-flood season accounted for 12.3% of annual sediment discharge and runoff and sediment yield mainly concentrated in the flood season.(4)Study on the rule of YueXi river basin’s rainfall runoff and sediment transportYueXi river basin annual precipitation change is bigger with no obvious law, flood and the non-flood season respectively 63.5%, 36.5%. The average annual rainfall precipitation, the higher the year of the flood season rainfall accounts for the greater the proportion of rainfall throughout the whole year. The watershed’s years of average rainfall(snow) days to 117 days, rainfall type is given priority to with light rain, moderate rain followed, heavy rain or heavy rain in fewer days and more appear in flood season; the change of runoff depth is larger annually with no obvious law, watershed’s annual precipitation and annual runoff depth and flood season rainfall and runoff in flood season was significantly positively correlated(P<0.01), the flood season and the non-flood season annual runoff respectively accounted for 72.6% 、27.4%; the watershed’s average annual sediment runoff discharge is 4902.5 t, average annual sediment modulus is 35.0 t/km~2; annual sediment modulus and annual runoff depth change laws are not clear and no significant correlation. The satershed’s annual sediment concentrated in the flood season, sediment runoff in the flood season accounted for 92.7% of the average annual sediment, sediment discharge of non-flood season accounted for 7.3%.This research is helpful to further reveal the relationship between rainfall、runoff and soil erosion, further reasonably effective use of surface runoff, reduce flooding, adjust the structure of land use, and realize the sustainable using of water and soil resources and the sustainable development of regional social economy. |
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