【作者】 孟令钦；

【导师】 李勇；

【作者基本信息】 中国农业科学院 ， 土壤学， 2009， 博士

【摘要】 东北黑土区是我国的重要的粮食生产基地,也是我国水土流失严重的地区之一。本研究旨在通过对黑土区侵蚀沟的分布和形态特性分析,找出东北黑土区的侵蚀沟近年来迅速发育的原因,从而为东北黑土区的水土流失防治工作提供指导和参考。研究通过对黑土区5个位于不同气候带的研究流域的77条侵蚀沟进行测量统计,以及三岔河流域1986年的地形图和2007年卫片资料对比分析,对侵蚀沟的发育速度进行比较,发现侵蚀沟在基本相同的坡度下和坡面比较平整的情况下侵蚀沟发育速度却有着很大的不同,经过研究发现:1.侵蚀沟主要发生在坡耕地上:过对黑土区5个处于不同地貌、土壤类型和水土流失类型区的小流域的侵蚀沟进行研究后发现:5个流域共有切沟77条,发生在坡耕地上的为66条,占85.71%;发生在荒地上的是5条,发生在作业路边的切沟为3条,发生在疏林地中的侵蚀沟为2条,发生在耕地的切沟1条。2.坡耕地上侵蚀沟的形态特征揭示了坡耕地侵蚀沟动力很大程度上来自沟道两侧坡面:侵蚀沟的形态特征看,坡耕地切沟的宽长比和宽深比最大,说明沟道侧面的坡面来水较大,使沟道相对变宽。3.垄沟具有汇流作用:垄沟横截面为三角形,垄沟像一个沟渠,将降水汇集拢到垄沟中。在降水过程中,降水主要经过蒸发、农作物或植物截持、入渗等损失,多余的降水会在坡耕地的垄沟内出现径流。径流经垄沟聚拢后,其垄沟内的径流深为平地径流深的数倍。4.沟渠效应是造成切沟发育的主要原因:由于在实践中的大规模改垄,使得坡面汇流条件改变,一条条的垄沟就如同一条条细小的渠道,使得坡面径流横向汇集,并在垄沟的低洼处或薄弱处发生断垄溢流,汇成集中股流,造成冲沟,我们将这个现象定义为“沟渠效应”。由于“沟渠效应”的存在,造成坡耕地侵蚀沟发育迅速。5.汇流作用对沟蚀的形成起着巨大作用:根据研究三岔河流域的汇流情况,在降水产生的超渗径流情况下,水平改垄汇流造成的集中股流是顺坡垄的80～1700倍。集中股流造成坡面强烈冲刷,引发沟蚀。6.改垄越早,侵蚀沟发育速度越快:过对5条研究流域进行研究,最早改水平垄的坡耕地上的侵蚀沟发育速度最快,无论长度和侵蚀量的发展均处在发育速率的第一台阶。7.黑土区季节性高强度降水促进了沟渠效应:东北黑土区研究流域平均每年有垄沟不能容蓄的高强度降水概率是14%,大约7年左右有一次垄沟不能容蓄的高强度降水,在这种情况下,垄沟的容积将无法蓄积超渗径流,不可避免出现漫垄。8.黑土区的垄长大多超过临界垄长:在沟底存在均匀比降的情况下,一定长度垄沟内的超渗径流汇集量能够在低洼处或薄弱处溢垄,这时的垄沟长度为临界垄长。经计算,在三岔河流域出现一小时降水强度达到32mm/h的强度下,垄沟的临界长度为138.91m。东北黑土区的坡耕地垄长多超过500m,超过了垄沟的临界长度,易引发沟蚀。9.对侵蚀沟应采取组合技术进行分级治理:在广泛调查研究的基础上,给出了治理浅沟、小型沟、中型沟和大型切沟的治理模式,总结出了6个针对不同级别、不同类型侵蚀沟的防治与利用的组合技术,并论述了这些治理切沟模式的效果。更多还原

【Abstract】 The black soil region of northeast China is an important food production area, as well as a serious soil erosion area in China. This research aimed to discover the reason of gully developing fast in resent 20 years than ever before, through investigate gullies’distributing and analyze its modality. Provide with reference for soil and water conservation in the black soil region in northeast China. Through research on 77 gulies in 5 watersheds that located in different climate region, and contrast Sanchahe watershed’s map (1986) with the watershes’s satellitic photo (2007), we found that the gully developing rate was very difference even the slope land conformed both in gradient and surface roughness. The research result show as follows:1. Gullies mainly take place on sloping farmland: through investigate 5 watersheds which located in different landforms, agrotypes and soil erosion zones, we foud that there are total 77 gulies in the 5 watersheds, 66 of the gullies take place in sloping farmland, account for 85.71%; 5 of the gullies take place in wasteland;. 3 of the gullie take place by roads; 2 of the gullies take place in open forest land; 1 of the gullies takes place in farmland.2. Gullies’modality in sloping farmland shows that the motivity of drive gully developing is largely from gully’s two sides: the modality shows that the gullies in sloping farmland, its WLR and WDR are big than others. That indicate run off from sloping farmland and inflood gully through its two sides are quite abundance. Consequentially, the gullies in sloping farmland are broadening.3. Furrow s between ridges in a field perform an important function of accordant junction: Furrow s’cross section is triangle, precipitation were gathered in Furrow s. Precipitation can produce runoff in Furrow s after subtract loss from evaporation, interception by crop or plant, infiltration. After runoff gathered by Furrow s, the runoff depth can be many times higher than it in flat ground.4. Effect of aqueduct is the main reson for gully developing quickly: because farmer changed sloping ridge into contour ridging, it makes accordant junction condition changed in sloping farmland. Each of furrows like a small ditchs or small aqueduct canals that caused runoff flow along furrow orientation and break out in low-lying and weak site of ridge. Runoff overfall can gather into stream flow and scour out gullies. We define this process as Effect of aqueduct. Because the reson of Effect of aqueduct, the gullies in sloping farmland were developing quickly.5. Effect of accordant junction play a significant role for give birth to gully and its developing: the result of research in Sanchahe watershed show that runoff occur in contour ridged furrow in a field of sloping farmland, the quantity of runoff gathered into stream flow can be 80～1700 times than the quantity caused in a single sloping furrow. Gathered stream flow can washed out sloping farmland and cause gully erosion.6. Changing sloping ridge into contour ridge early, the gully developing be at a high pitch: the resoult of research on 5 watersheds show that the gully developing quickly in the sloping farmland where changed the sloping ridge into contour ridge early, no matter in length and erosion quantity both at first level.7. High strength precipitation in summer promoted the effect of aqueduct: the average annully high strength precipitation probability which produced runoff run over the capacity of furrow in research watersheds is 14%. That means thare are high strength precipitation should occur in 7 years that the furrow unable to contain. In this case, overflow furrow is inevitably for the precipitation quantity exceeds the capacity of furrow.8. Most the ridge lengths in the black soil region are exceed the critical length of ridge: in the condition that furrow’s gradient is uniformily, runoff produced in a definite lenth of furrow can cause ridges break up in lower and weak site; the definite lenth is the critical length of ridge. According to the resoult of research in Sanchahe watershed, if the precipitation intensity reaches 32mm/h, the critical length of ridge should be 138.91m. The ridges lenth in the black soil region usually more than 500m, which exceed the critical length of ridge under the characteristic precipitation in the region. So that easy to cause gully erosion.9. Control gully erosion should take multiform combined-measures and used them according to gully size magnitude: through comprehensive investigation, 6 modes which used for control different kind of gullies and control gullies at different size magnitude were given in this paper. Such as control ephemeral gully, small size gully, middle size gully and big size gully. Then we discussed those modes’effect both in conservation and economic benefit.更多还原