慈溪市海岸变迁与滩涂围垦

根据历史和实测资料研究慈溪市海岸变化过程及其成因,结果表明:1)距今约2 500 a慈溪全境已形成南丘北海、中部为滨海平原的地貌格局;2)慈溪滩涂属于淤涨型滩涂,自宋代以来已修建11道海塘,新中国成立前海岸线平均每年向外推移25 m,之后则达到50~100 m;3)慈溪滩涂形成演变的影响因子包括地形约束、河川径流和人类活动等,近代人类活动的作用强度越来越大;4)西三闸附近涨潮潮位增高和庵东滩面淤高、扩大是西三潮沟形成的主要动力因素,其诱因是大规模的人类活动。西三潮沟的整治原则应是“因势利导,围涂治沟”。鉴于目前西三潮沟东西两侧都已完成直堤工程,建议在钱塘江连续丰水年时抛石筑坝,彻底截断西三潮沟。     

黄土高原旱作区马铃薯叶片和土壤水势对垄沟微集雨的响应特征

于2011年在黄土高原半干旱地区以平地不覆膜为对照,研究了不同沟垄和覆膜方式对马铃薯叶片和土壤水势水势的影响。结果表明：不同沟垄和覆膜方式在不同土层和不同生育期对土壤和叶片水势的影响差异显著。（1）土壤水势日变化趋势：0～20 cm土层,土垄处理在开花期为先下降后上升型,土垄和覆膜垄处理在块茎膨大期为先下降后上升型,覆膜垄和全膜双垄沟播处理在成熟期为先下降后上升型,其余为逐渐下降型;20～40 cm土层,各处理土壤水势呈逐渐下降趋势。（2）叶片水势日变化趋势：开花期和块茎膨大期表现为双低谷型,双低谷分别在13：00和17：00,成熟期为“V”型,即单低谷型,低谷出现在17：00。各处理变化趋势相同,但水势存在差异。土垄处理在水分关键期（开花期和块茎膨大期）叶片水势显著高于其他处理,而全膜双垄沟播处理在成熟期最高。（3）生育期土壤水势和叶片水势均表现为先减小后增大的趋势。20～40 cm土层对叶片水势影响较大,土垄处理在该土层具有较好的水分状态,蒸腾作用较强加速了水分运移速率,是导致覆膜垄和全膜双垄沟播处理水势低于土垄的主要原因。在前期降雨较少的年份,由于较小的蒸腾作用,土垄处理可以保证马铃薯承受较小的水分胁迫;在前期降雨量较多的年份,覆膜垄和全膜双垄沟播处理则可以凭借其较大的蒸腾作用发挥较大的增产效果。     

地面不同垄沟形式对径流调控机制的研究

在干旱缺水、水土流失严重的黄土高原地区,地面垄沟是控制侵蚀、保持水分的有效措施。而不同垄沟形式将直接影响沟中径流量和土壤水分状况。本文设计了两种不同垄上覆盖材料和三种不同垄沟比的6组试验处理,通过2002与2003年降水季节的连续田间试验观测。结果表明:覆膜垄沟(MR)的临界产流降雨量低于不覆膜垄沟(ER),约为不覆膜垄沟(ER)的10%,两种垄沟的临界产流降雨量分别为0.4mm、4.6mm。覆膜垄沟(MR)的径流效率远高于不覆膜垄沟(ER),覆膜垄沟(MR)与土垄的平均径流效率分别在45%~70%与5%~6%之间变化。     

Historical Constraints on Slope Movement Age: a Case Study at Broadway, United Kingdom

The Broadway area of the Cotswolds has been extensively investigated in an attempt to delineate areas of slope instability, including'relict'landslides, which may have been initiated under periglacial climatic conditions. It is, therefore, useful both in terms of the geomorphology and of the understanding of the evolution of the area, to investigate the rates and timing of any reactivation and subsequent movements of landslides in this area. The remains of ridge and furrow cultivation can be seen extensively throughout the Cotswolds. This particular agricultural practice, which documentary evidence suggests dates back to Anglo-Saxon times (approximately 10th century AD), has been disturbed in many places by slope movements. A detailed study of Parish Records and other local his-torical sources has revealed that ridge and furrow cultivation ceased on Parliamentary Enclosure, which in this area, occurred in 1771. Therefore, it is possible to identify patterms of slope movement between these dates. Landslides have been identified by ground mapping and aerial photography, and can be divided into three categories. Firstly, active landslides which are those which have shown evidence of movement during the study period. Secondly, suspended landslides, which show evidence of movement, but have not been observed to move during the study period. In this context, this has been taken to mean landslides, which have shown evidence of movement since 1771. Thirdly, relict landslides which have shown no evidence of movement since 1771 and thus were probably active under a different climatic regime. By incorporating historical data with the geomorphological survey it has been possible to identify areas of potentially difficult ground for engineering geomorphological purposes.     

In-situ rainwater harvesting and gravel mulch combination for corn production in the dry semi-arid region of China

A field study was conducted to determine the effect of a combination of ridge and furrow method of in-situ rainwater harvesting with gravel mulch on corn production, soil moisture storage, and water-use efficiency in the dry semi-arid region of China. Results showed that plastic-covered ridges had an average runoff efficiency (runoff/rainfall) of 87% as compared to 7% for bare ridges, and could generate runoff at a threshold value of 0·8±0·2 mm rainfall. Bare ridges produced runoff only under high intensity rainfall events, and was ineffective for harvesting rainfall in the study area. The plastic-covered ridge and gravel-mulched furrow method of rainwater harvesting was effective in conserving moisture and increasing yield and water-use efficiency. The grain yield in this treatment was 1·9 times that of the conventional flat soil cultivation (control), and the water-use efficiency was 1·8 times that of the control. The good performance of the film-covered surface ridges and gravel-mulched furrows is attributed to the better utilization of light rains, improvement of infiltration in the root zone, and suppression of evaporation losses.     

沟灌土壤湿润体空间矩特征参数估算模型

为进一步增加矩分析理论在研究沟灌土壤湿润体运移特性方面的实用性,采用数值模拟和理论分析相结合的方法,定量分析了土壤初始含水率、入渗水深、沟底宽和边坡系数等因素对沟灌自由入渗条件下土壤湿润体空间矩特征参数的影响,并建立了其与主要影响因素间的函数关系式。结果表明,土壤初始含水率、入渗水深和沟底宽对垂直向土壤水分分布的质量重心影响较大;水平向湿润锋的平均离散度主要受土壤初始含水率、入渗水深、沟底宽和边坡系数的影响,而垂直向对土壤初始含水率和入渗水深变化的敏感性较高;选取不同土壤质地对所建模型的可靠性进行了验证,结果表明所建模型估算不同入渗时刻的空间矩特征参数值与根据HYDRUS软件模拟结果所得计算值具有高度一致性,所有验证组合条件下两者相对误差绝对值均值均低于8.5%,且无显著性差异,说明所建模型估算沟灌土壤湿润体空间矩特征参数具有高度可靠性。研究结果可为沟灌灌水方案设计和管理提供理论基础和技术支撑。     

Measuring and modeling two-dimensional irrigation infiltration under film-mulched furrows

Furrow irrigation with film-mulched agricultural beds is being promoted in the arid region of northwest China because it im-proves water utilization. Two-dimensional infiltration patterns under film-mulched furrows can provide guidelines and criteria for irrigation design and operation. Our objective was to investigate soil water dynamics during ponding irrigation infiltration of mulched furrows in a cross-sectional ridge-furrow configuration, using laboratory experiments and mathematical simulations. Six experimental treatments, with two soil types (silt loam and sandy loam), were investigated to monitor the wetting patterns and soil water distribution in a cuboid soil chamber. Irrigation of mulched furrows clearly increased water lateral infiltration on ridge shoulders and ridges, due to enhancement of capillary driving force. Increases to both initial soil water content (SWC) and irrigation water level resulted in increased wetted soil volume. Empirical regression equations accurately estimated the wetted lateral distance (R_l) and downward distance (R_d) with elapsed time in a variably wetted soil medium. Optimization of model parameters followed by the Inverse approach resulted in satisfactory agreement between observed and predicted cumulative infiltration and SWC. On the basis of model calibration, HYDRUS-2D model can accurately simulate two-dimensional soil water dynamics under irrigation of mulched furrows. There were significant differences in wetting patterns between unmulched and mulched furrow irrigation using HYDRUS-2D simulation. The R_d under the mulched furrows was 32.14% less than the unmulched furrows. Therefore, film-mulched furrows are recommended in a furrow irrigation system.     

甘肃洮河裂陷槽金矿成矿地质条件探讨

洮河裂陷槽位于西秦岭合作—岷县断裂和腊子口—武都断裂之间的过渡地区,是以三叠系浊流沉积碎屑岩建造为主的重要金矿成矿带,后期构造活动相对较弱。通过对区内地质背景、地球化学特征和典型矿床特征的对比,分析了裂陷槽内金矿床成矿地质条件。认为三叠系碎屑岩地层是金的矿源层,地球化学异常是寻找该类矿床的直接标志,EW向和NW向断裂交汇部位的局部小规模褶皱、断裂和小岩脉的发育程度是矿体富集的决定因素。     

土壤侵蚀链内细沟浅沟切沟流动力机制研究

通过模拟降雨试验的方法,系统研究了细沟流流速与流量、水深与流量、流速与水深及阻力系数与雷诺数之间的关系,雨强与坡度对细沟流水力特性的影响,不同细沟流流型、流态及水动力要素作用下的侵蚀特点,并对浅沟与切沟流的水动力特性及侵蚀规律进行了初步探讨.研究结果对于揭示土壤侵蚀链内不同侵蚀方式下的水沙流动力学机制,以及土壤侵蚀演化规律具有重要意义.     

俄罗斯东北部提高寒冻土壤稳定性与肥力的工程措施

The rational usage of low productive cryogenic landscapes in the North-Eastern part of Russia is impossible without carrying out special engineering preparation [1]. The preventing from negative that often has destructive cryogenic processes in the area of ice-covered permafrost soils, provided by its thawing into the marginally necessary depth in the whole area. The simplest and the most effective engineering method of faulting as an age-old stock (reserve) of surplus moisture in the form of ice from the upper parts of permafrost soils is the creation of continuous furrows net on the whole surface. This method also raises the fertility of soils, reduces acidity, and raises microbiological activity and the degree of internal structure decaying. Thermophysical calculations and the results of the field study in the experimental firing grounds are the available evidences of this method which raises the thermal stability of cryogenic landscapes while mastering of global climate changes in different parts of cryolithozone.