排序方式: 共有19条查询结果,搜索用时 15 毫秒
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设置标准径流小区进行长期定位监测,探讨天然降雨条件下,流域内不同土地利用方式对坡面产流产沙的影响,以期为该流域土地利用规划、水土流失综合治理、生态环境改善提供理论依据。基于汾河上游阳坡小流域内2种坡度、6种不同土地利用方式的8个径流小区,开展自然降雨观测、径流泥沙观测。结果表明:(1)试验期降雨超过多年同期平均雨量,属于丰水年;且年内雨量分布较多年平均差异较大;(2)不同土地利用方式条件下,坡面产流量差异明显,坡面为15°时,各径流小区的产流量大小顺序为裸坡地>坡耕地>草地;而18°各径流小区的产流量大小为裸坡地>草地>油松林地>灌木林地(黄刺玫);(3)土地利用方式不同,坡面产沙量差异明显。15°径流小区坡面产沙量裸坡地>胡麻>土豆>草地;相比之下,18°径流小区产沙量以灌木林地和油松林地最少,均为0.30 t/hm2;裸坡地产沙量最多,是林地的92.08倍;林草地减流减沙效果明显。研究结果可为该流域的生态重建,土地利用以及汾河上游其他小流域的土地利用规划,从而减少水土流失提供借鉴。 相似文献
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西安地区丰水年农田深层土壤含水量研究 总被引:1,自引:0,他引:1
通过对西安南郊吴家坟、长安区郭杜镇大学城和双竹村附近丰水年(年降雨量883 mm)麦地、玉米地土壤含水量的测定,以及与正常年份该地土壤含水量的对比,研究丰水年该地区农田0~6 m土壤含水量的变化。结果显示,正常年份西安地区麦地0~2 m土层含水量高于12%,2~6 m土层含水量高于13%;丰水年西安地区麦地0~2 m的土壤含水量在18%以上,2~6 m土层含水量达24%以上,远远高于正常年份这一层位的土壤含水量。分析得出,西安地区农田深层土壤含水量高的主要原因是重力水带分布范围大于或等于农作物的强烈耗水层范围。 相似文献
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Wendy Peterman Richard H Waring 《中国林学(英文版)》2014,(4):214-226
Background: Frequent outbreaks of insects and diseases have been recorded in the native forests of western North America during the last few decades, but the distribution of these outbreaks has been far from uniform. In some cases, recent climatic variations may explain some of this spatial variation along with the presence of expansive forests composed of dense, older trees. Forest managers and policy makers would benefit if areas especially prone to disturbance could be recognized so that mitigating actions could be taken. Methods: We use two ponderosa pine-dominated sites in western Montana, U.S.A. to apply a modeling approach that couples information acquired via remote sensing, soil surveys, and local weather stations to assess where bark beetle outbreaks might first occur and why. Although there was a general downward trend in precipitation for both sites over the period between 1998 and 2010 (slope =-1.3, R2 = 0.08), interannual variability was high. Some years showed large increases followed by sharp decreases. Both sites had similar topography and fire histories, but bark beetle activity occurred earlier (circa 2000 to 2001) and more severely on one site than on the other. The initial canopy density of the two sites was also similar, with leaf area indices ranging between 1.7-2.0 m2. m-2. We wondered if the difference in bark beetle activity was related to soils that were higher in clay content at site I than at site II. To assess this possibility, we applied a process-based stand growth model (3-PG) to analyze the data and evaluate the hypotheses. Results: We found that when wet years were followed by drier years, the simulated annual wood production per unit of leaf area, a measure of tree vigor, dropped below a critical threshold on site I but not on site II. Conclusion: We concluded that the difference in vulnerability of the two stands to beetle outbreaks can be explained largely by differences in gross photosynthesis attributed to the fact that an equivalent amount of stored wat 相似文献
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研究了在不同初始盐度造墒条件下,滨海盐碱地覆膜棉田水盐分布及棉花生长动态特征。结果表明,棉花生育期结束后,经雨季淋洗T、D1、D2、D3处理0~40cm土层土壤电导率分别降低了40.60%、37.04%、45.12%、57.56%,0~100cm土层土壤脱盐率分别为33.02%、32.78%、28.19%和34.37%。D3处理干物质总量分别比T、D1和D2处理降低了98.09%、120.21%、76.34%。产量以D1处理最高(3 156.78kg/hm2),D3处理最低,较D1处理减少了30.25%;T处理纤维品质为B级,优于其他处理(均为C级),不同处理间断裂比强度、伸长率等差异不明显。降水对0~40cm土层内盐分淋洗效果明显,咸水滴灌未对棉花产量产生不利影响。 相似文献
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西安地区丰水年有林地土壤水分恢复效应研究 总被引:3,自引:0,他引:3
通过对西安南郊平水年与丰水年秋季有林地土壤含水量的测定,研究了地下0~6 m之间土壤含水量的变化与土壤水分恢复问题.研究结果表明,正常年西安地区人工林2~4 m土壤含水量为9%~10%,发育了明显的土壤干层,表明土壤干层在黄土高原分布具有普遍性;丰水年西安南郊人工林下2~4 m的土壤含水量在18%~24%之间,高出正常年份这一层位含水量的8%~14%,土壤干层已经消失;丰水年4~6 m的土壤含水量也明显升高.分析得出,在降水丰富的年份,土壤水分得到恢复,而且恢复的深度可达5 m,恢复的速度也较快. 相似文献
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单一采用工程节水措施,在海河平原的不少地方,加大了地下水位降幅.ET理论的再次提出,及其在世行贷款节水灌溉项目中的应用表明,综合节水措施的采用,配合地下水资源的水权分配计划和管理,能够有效地降低作物的蒸腾蒸发量,缓解地下水超采,丰水年可回补地下水. 相似文献
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青海湖南侧江西沟土壤水分研究 总被引:2,自引:0,他引:2
根据含水量和粒度测定,对青藏高原东部的青海湖南侧土壤水分含量特征、土壤干层与草原发育的适宜性和土壤水库等问题进行了研究。结果表明,青海湖南侧土壤含水量随深度增加呈现减小的趋势,在土壤1.0 m左右深度以下有长期性土壤干层发育;从上向下土壤干层发育强度呈现加重趋势,由轻度干层变为中度干层,这主要与气候暖干化和降水量少有关。虽然该区丰水年土壤剖面上部的水分明显升高,但还没有使土壤干层中的水分得到全部恢复。青海湖南侧土壤是与黄土相似的粉沙土,但该区土层较薄,土壤水库的调蓄能力较小。土壤干层的发育和较弱的土壤蓄水能力指示该区不适于植树造林,适宜发展消耗水分较少的草原植被。 相似文献
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