横垄坡面地表糙度的变化特征及其对片蚀的响应

为揭示地表糙度的片蚀效应,采用野外人工模拟降雨,研究了横垄坡面地表糙度在玉米不同生育期的变化特征,并分析了地表糙度的变化对片蚀过程的响应特征。结果表明:1.0mm/min降雨强度条件,随着玉米生育期的推进,地表糙度呈先增加后降低的变化趋势,且在玉米苗期增幅最大,在成熟期降幅最大。1.5,2.0mm/min降雨强度条件,随着玉米生育期的推进,地表糙度呈先降低后增加的变化趋势,且玉米苗期—拔节期地表糙度变幅却最大。降雨强度1.0mm/min条件下,随着玉米生育期的推进,地表糙度的变化与径流量变化同步,均呈先减小、后增加、再减小的变化趋势。降雨强度1.5,2.0mm/min条件下,在玉米苗期—拔节期—抽雄期,地表糙度与径流量呈同步的变化,而在抽雄期—成熟期,地表糙度呈减少的变化趋势,而地表径流量却呈增加的变化。不同降雨强度条件下,在玉米苗期和拔节期,地表糙度的变化与产沙强度呈同步变化;在抽雄期和成熟期,两者间表现出相反的变化趋势。玉米拔节期,地表糙度变幅与径流量呈极显著负相关关系,抽雄期地表糙度变幅却与径流量呈极显著正相关关系;玉米苗期、拔节期和成熟期,地表糙度变幅与侵蚀产沙量呈显著或极显著正相关关系,玉米抽雄期,地表糙度变幅却与侵蚀产沙量呈极显著负相关关系。研究结果为揭示地表糙度在片蚀作用下的本质特征和坡耕地水土流失有效防控提供理论和技术支撑。

Changes of Soil Surface Roughness and Its Response to Sheet Erosion in Sloping Cropland of Cross Ridge

To reveal the effects of soil surface roughness on sheet erosion, the changes of soil surface roughness on purple soils were studied during the whole growing stages of maize based on field artificial rainfall experiments, and the effects of soil surface roughness on runoff and sediment yield of sheet erosion process were analyzed. The results showed the soil surface roughness presented an increasing-first-and-then-decreasing trend with the advance of maize growing period under the rainfall intensity of 1.0 mm/min, and the maximum of increasing range appeared in maize seedling stage and the maximum of decreasing range appeared in mature stage. Under the rainfall intensity of 1.5 and 2.0 mm/min, the soil surface roughness presented a decreasing-first-and-then-increasing trend with the advance of maize growing period, and the changing range of soil surface roughness was the?greatest at the stage of maize seedling - jointing. Under the rainfall intensity of 1.0 mm/min, the changes of soil surface roughness presented a decreasing-first-and-then-increasing -and -decreasing trend, and these changeswere consistent with the changes of surface runoff under the rainfall intensity of 1.0 mm/min. At the stages of maize seedling-jointing and jointing-tasseling, the changes of soil surface roughness were consistent with the changes of surface runoff under the rainfall intensity of 1.5 and 2.0 mm/min, but inconsistent with the changes of surface runoff at the stage of maize tasseling- mature. At the stages of maize seedling and jointing, the changes of soil surface roughness showed the consistency with the changes of sediment yield intensity, however, they presented the opposite?changes in soil surface roughness and sediment yield intensity at the stages of maize tasseling and mature. In maize jointing stage, there was a very?significant negative relationship between the changing range of soil surface roughness and runoff amount, but a positive relationship between both in maize tasseling stage. In maize seedling, jointing and mature stage, there were the significant or very?significant positive relationships between the changed range of soil surface roughness and sediment yield amount, however, a very significant negative relationship in maize tasseling stage. These results would provide theory basis for posing the sheet erosion nature of soil surface roughness, and also serve for harnessing soil and water loss of the slope farmland.