Effect of drip irrigation method, nitrogen source, and flushing schedule on emitter clogging

Field experiments were carried out at the National Research Center farm, Nubaria area, Behura Governorate, Egypt, to study the effect of nitrogen source, flushing schedule and irrigation method on emitter clogging. Peanut Giza 5 variety (Arachishy pogaea L.) was planted in sandy soil during two successive growing seasons (2010-2011) in the 1st week of May and harvested after 130 days. Treatments used are: 1) two irrigation methods: surface drip irrigation and sub-surface drip irrigation (SDI;SSDI), 2) nitrogen source (NS):NH4NO3, (NH4)2SO4 and Ca(NO3)2 (NS1, NS2 and NS3) and 3) flushing number (FL) 0, 1 and 4 (FL1, FL2;FL3). The experiments design was split-split plot and three replicates were used. Data obtained were subjected to statistical analysis. The main effects of treatments used on clogging per cent could be written the following ascending orders: SDI 3 2 1, NS1 2 3. Concerning the 1st interaction the following ascending orders denote their effects on clogging percent: SDI × FL3 2 1, SDI × NS1 2 3, SSDI × FL3 2 1, SSDI × NS1 2 3, FL1 × NS1 1 × NS2 1 × NS3, FL2 × NS1 2 × NS2 2 × NS3 and FL3 × NS1 3 × NS2 3 × NS3. The differences between any two treatments and/or any two interactions in clogging percent were significant at the 5% level. The effect of the 2nd interaction on clogging percent was significant at the 5% level. The maximum value of clogging (20.18%) and the lowest one (3.9%) were archived in the interactions: SSDI × FL1 × NS3 and SDI × FL3 × NS1, respectively.

Application of SWAT99.2 to sensitivity analysis of water balance components in unique plots in a hilly region

Although many sensitivity analyses using the soil and water assessment tool(SWAT) in a complex watershed have been conducted, little attention has been paid to the application potential of the model in unique plots. In addition, sensitivity analysis of percolation and evapotranspiration with SWAT has seldom been undertaken. In this study, SWAT99.2 was calibrated to simulate water balance components for unique plots in Southern China from 2000 to 2001, which included surface runoff, percolation, and evapotranspiration. Twenty-one parameters classified into four categories, including meteorological conditions, topographical characteristics, soil properties, and vegetation attributes, were used for sensitivity analysis through one-at-a-time(OAT) sampling to identify the factor that contributed most to the variance in water balance components. The results were shown to be different for different plots, with parameter sensitivity indices and ranks varying for different water balance components. Water balance components in the broad-leaved forest and natural grass plots were most sensitive to meteorological conditions, less sensitive to vegetation attributes and soil properties, and least sensitive to topographical characteristics. Compared to those in the natural grass plot, water balance components in the broad-leaved forest plot demonstrated higher sensitivity to the maximum stomatal conductance(GSI) and maximum leaf area index(BLAI).

Quantitative analysis of morphometry on Ribb and Gumara watersheds: Implications for soil and water conservation

Morphometric analysis is a quantitative measurement and mathematical analysis of landforms.It plays a significant role in understanding the geohydrological characteristics of a drainage basin in relation to the terrain feature and its flow patterns.It also helps to estimate the incidence of infiltration and runoff,and other related hydrological character of a watershed like erosion and sediment transport which has a strong implication for natural resource conservation.This study has attempted to quantify the morphometric characteristics of Guna-Tana watershed for proper implementation of soil and water conservation practices.ASTER (DEM) was used for extracting morphometric parameters.The watershed covers a total area of 3601.5 km2 and it has a basin length of 78.89 km.It has been tried to generate morphometric parameters which account basin drainage network,geometry,drainage texture,and relief characteristics together with hypsometric characteristics.The morphometric analysis of drainage density of the study watershed is 0.49 km/km2 which indicates the basin is highly permeable and result with better underground water storage capacity.Ruggedness number is 0.02 that implies the area is less prone to soil erosion.In addition,it has stream frequency of 0.32 and form factor 0.57 which indicates slightly elongated basin shape.Comparative analysis of its sub watersheds Gumara and Ribb was also undertaken.Therefore,practicing soil and water conservation in the watershed could enhance/strengthen the water storage capacity,prevent sediment loss and related natural resource from the watershed that rehabilitate its productivity.

Effects of Erosion Control Measures on Mountain Floods： A Case Study of the Censhui River South Branch Watershed

To investigate the effects of various erosion control measures on mountain floods, a case study was conducted in Censhui River South Branch Watershed using scenario analysis and soil conservation service （SCS） methods. A distributed hydrological model was developed, and watershed parameters were determined based on satellite imagery, digital terrain models, digital maps and field investigations. Two types of erosion control measures were investigated： the variation of vegetation covers and the change of cultivation techniques. Seven scenarios were considered for the test watershed. The results show： （1） while the de-vegetation results in the increase of peak discharge, the improve of vegetation covers decreases peak discharge at watershed scale; （2） by both improving vegetation cover and enhancing terrace-cultivation technology, the peak discharge is reduced and the peak flow arrival time is delayed; （3） attention should be attached to both early warning system and measures changing the underlying surface and conveyance systems.

Effects of soil and water conservation practices on soil physicochemical properties in Gumara watershed, Upper Blue Nile Basin, Ethiopia

Background:Soil erosion is among the foremost causes of declining soil resources in Ethiopia,which in turn affect agricultural productivity.To limit this problem,for the last two decades in Gumara watershed,soil and water conservation measures have been practiced through free labor community mass-mobilization.However,their effect on soil fertility has not been evaluated.This study investigated the impact of implemented soil and water conservation measures on fertility improvement in the Gumara watershed.Both composite and core soil samples were taken from upstream,midstream,and downstream adjacent conserved and non-conserved cultivated and grazing plots.Selected soil fertility indicators were analyzed using standard laboratory procedures.Results:Soil and water conservation practices have resulted in a statistically significantly higher mean values of total nitrogen,exchangeable Na+and Mg2+at p<0.01,and of soil organic carbon and organic matter at p<0.05 in the watershed.The clay content,soil reaction,cation exchange capacity,and exchangeable K+showed nonsignificant,but higher mean values in conserved plots.Furthermore,the effects of conservation practices on soil properties were found more effective in cultivated land uses as compared to that of grazing land uses.This is because conservation treatments had significant effects on organic carbon,total nitrogen,exchangeable Na+and Mg2+in cultivated land uses but only on exchangeable Na+in grazing land uses.The interaction effect of treatments and land uses did not reach a statistically significant result for any of the soil properties considered in this study.Conclusion:Conservation measures have important implications for improving soil fertility in the Gumara watershed.Therefore,proper guidance and follow-up,use of agro-forestry and grass strips,and maintenance are required for the watershed’s sustainability and good soil conditions.

降雨和库水位升降条件下考虑非饱和渗透系数空间变异的边坡可靠度分析

降雨和水位升降对库岸边坡具有显著影响,传统确定性分析难以准确评估其稳定性。考虑降雨和水位升降联合作用下水力参数的空间变异性,进行非饱和土边坡可靠度分析具有重要意义。以赣江库区中的莒洲岛边坡为研究对象,以贝叶斯方法校准的多元水力参数的联合随机场为基础,建立非饱和土边坡的稳定性分析方法。根据有限的岩土力学室内试验数据,采用贝叶斯方法校准土水特征曲线的模型参数,并从VGM、VGB、VG和FX模型中选出最优模型;联合多元水力参数的随机统计特征,生成非饱和土边坡渗透系数的随机场空间分布;针对2021年5月赣江水位快速升降并伴随暴雨的工程背景,将上述方法应用于莒洲岛库岸边坡的稳定性分析。研究结果表明,暴雨与水位变化的联合作用对边坡安全系数的影响显著,确定性分析的边坡安全系数偏低,考虑非饱和渗透系数空间变异性后计算所得到的SWCC综合可靠指标不能满足规范要求,需采取额外的边坡工程加固措施以保证边坡的长期稳定性。

Understanding the attitudes and practices of paddy farmers for enhancing soil and water conservation in Northern Iran

The objective of this paper was to identify the factors affecting rice growers’attitudes and practices towards water and soil conservation in the Fumanat Plain of Guilan Province,Iran.Data were collected through a survey questionnaire addressing a cross section of 400 rice growers of the Fumanat Plain in four districts.Data were analyzed using both summary statistics and multivariate statistical procedures while content validity of the statements was first determined by a group of experts of water and soil conservation.It was found that more than 23% of the variance of attitudes towards water and soil conservation could be determined by a linear combination of variables included in a regression equation.Identifying the factors affecting rice growers’attitudes is suggested as a way of integrating rice cultivation into rural development.From a practical point of view,the above mentioned implications are of great importance generally for society,policy makers and related economic sectors.

无人机遥感技术在水土保持监测中的应用

在技术更新迭代越来越频繁,互联网技术应用范围逐渐拓展的当下,无人机遥感这一技术逐渐拓展自身发展领域,应用范围扩大。随着无人机遥感技术的快速发展,其在水土监测工作中的应用可以在一定程度上弥补以往传统检测方式的不足,进一步提升水土监测效率,降低成本投入。以实际工程为案例,针对其现场水土保持施工过程中的无人机遥感技术应用进行分析,并根据工程项目实际水土流失情况进行无人机遥感技术分析,有效体现了无人机遥感技术机动性高、成本低等一系列优势,希望能够为无人机遥感技术的应用发展提供参考。

1986-2018年黄土丘陵区典型小流域不同水文年水沙变化

[目的]探讨黄土丘陵区罗玉沟典型小流域水沙变化趋势以及不同水文年径流输沙对水土流失治理的响应差异,量化降水和人类活动对流域水沙影响的相对贡献,以期为黄土丘陵第三副区流域水土流失治理和水资源管理提供参考。[方法]基于罗玉沟流域1986—2018年的降雨、径流、输沙等数据,采用Mann-Kendall检验法、累积距平法及双累积曲线法分析流域水沙变化趋势及驱动因素。[结果]1986—2018年罗玉沟流域河流由常流河转变为季节性河流,干河日数显著上升(p<0.01),2000年以来干河日数多在300 d以上;同期,罗玉沟流域径流输沙显著下降(p<0.05),与基准期1986—1993年相比,1994—2007年减水减沙率分别为61.9%,44.3%,2008—2018年径流输沙分别减少67.5%,76.4%;在2008—2018年平水年和枯水年间罗玉沟流域输沙模数分别为(1 080.0±107.5) t/km^(2),(167.8±111.4) t/km^(2),而在暴雨频发丰水年,输沙模数仍接近4 000 t/km^(2);流域产流产沙能力降低,水沙关系发生改变,相同径流条件下输沙量减少,即流域径流含沙量水平降低,开始变清;相比降雨变化而言,人类活动是流域水沙变化的主导因素,1994—2007年人类活动对减水减沙的贡献率分别为83.3%和79.5%,而2008—2018年人类活动的贡献率分别为91.8%,94.4%,表明流域水沙变化受人类活动影响越来越大,其中,坡改梯及退耕还林还草工程是主要影响因素。[结论]因沟道治理工程建设不足,罗玉沟流域在丰水年因沟道重力侵蚀导致流域输沙仍然剧烈,因此,需要加强沟道治理进一步减少流域水土流失。

水土保持生态产品价值实现理论探索

水土保持生态产品价值实现具有重要意义。尝试界定水土保持生态产品概念,对产品进行分类,探索构建水土保持生态产品价值核算方法,分析水土保持生态产品价值转化路径,梳理浙江省安吉县石门坑清洁小流域水土保持生态产品价值转化经验,提出加快推动水土保持生态产品价值实现的对策建议,以期为推动水土保持高质量发展和建设美丽中国提供有益参考。

考虑砂土孔压影响的场地土层地震反应时域分析方法

基于动态骨架曲线土体动力本构模型,应用适用于非规则荷载作用下的砂土孔压增长公式,推导出一个适用于砂土场地的动力应力-应变关系式,并提出了一种考虑砂土孔压影响的场地土层地震反应时域分析方法。基于Matlab平台编写了场地土层地震反应计算程序。利用美国加纳山谷岩土台阵的观测数据,对所提出的地震反应时域分析方法进行验证。结果表明:该方法可以较好地模拟含饱和砂土的场地地震反应分析中孔压变化对场地地震动的影响,并得到了与实际观测记录拟合较为良好的孔压曲线,证明了方法的实用性及计算结果的合理性。

基于无人机倾斜摄影遥感技术的水土保持动态监测方法研究

为了能够充分了解土壤侵蚀分布,及时掌握水土流失变化趋势,提出基于无人机倾斜摄影遥感技术的水土保持动态监测方法。利用无人机从多个角度采集监测区域影像数据,并实施辐射定标和大气校正预处理,基于遥感影像数据提取土壤可蚀性因子、土地利用因子、植被覆盖监测因子、坡度因子,通过计算获取水土保持系数并划分等级。监测结果表明:区域1水土保持系数呈现“V字形”,区域2水土保持系数整体呈现“一字型”,区域3水土保持系数整体呈现逐渐上升状态。

小型河道流域整治工程水土流失危害分析及防治措施评价

针对小型河道流域整治工程的水土流失问题展开研究,首先分析了水土流失的现状和危害,然后对流域进行了水土流失防治分区划分,并提出了相应的水土保持措施和防治措施。通过对民田涌流域的实例分析和评价,提出了一些有效的防治措施,以提高防治效果和生态环境的稳定性。研究表明,采取合适的水土流失防治措施可以有效减少水土流失,改善生态环境,提高流域的可持续发展能力。

坝上地区典型防护林水源涵养功能对林分结构的响应

【目的】坝上是京津冀地区重要的生态屏障和水源涵养地,探究典型防护林林分结构对枯落物层和土壤层水源涵养功能的影响,为该地区防护林的抚育管理与林分优化提供科学依据。【方法】选取坝上地区御道口林场3种典型防护林(樟子松林、华北落叶松林、樟子松华北落叶松混交林)为研究对象,调查胸径、树高、林龄、密度、郁闭度和叶面积指数等林分结构指标,通过室内浸水法和环刀法进行枯落物层和土壤层持水性能的测定,运用冗余分析探究防护林结构对枯落物层和土壤层持水性能的影响机制。【结果】(1)樟子松华北落叶松混交林的枯落物层厚度、蓄积量、枯落物最大持水量和有效拦蓄量均大于纯林,其中总枯落物厚度差异显著(P<0.05)。(2)土壤总孔隙度、含水量和最大持水量都随着土层的增加而减小。其中土壤总孔隙度和最大持水量在0~30 cm土层表现为华北落叶松林>樟子松华北落叶松混交林>樟子松林,在30~60 cm土层表现为华北落叶松林>樟子松林>樟子松华北落叶松混交林。(3)冗余分析表明,林分结构与水源涵养功能密切相关,林分密度和树高对不同防护林枯落物层水源涵养能力影响显著,而树高和林龄对不同防护林土壤层水源涵养能力影响显著(P<0.05)。【结论】3种防护林中枯落物层和土壤层水源涵养能力最好的分别是樟子松华北落叶松混交林和华北落叶松林,林分密度、树高和林龄可以较好地解释水源涵养功能的变化。本研究对坝上地区生态平衡维护与可持续发展具有积极意义。

“三环节分析”及其在水土保持方案编制中的应用

管道项目是水土保持方案编制中难度最大的项目之一,科学地分析管道项目中的重要环节是做好水土保持方案编制的基础和关键。通过总结前人的成果和自身的工作经验,结合管道项目具有水土保持功能的特点,提出了“三环节分析”理论,有针对性地补充和完善了水土保持防治措施。项目实施后,水土流失能得到全面的控制和治理,为此类工程水土保持方案的编制提供了新的思路和方法。

软土地基新开河道挡墙水平位移影响研究

挡土墙桩基水平位移计算是上海地区软土地基上水利水运工程挡墙设计的重要环节。常用的m法在实际使用过程中存在多项局限。在上海地区某实地开挖河道工程中,为验证位移原因并计算最终位移量,采用了m法和有限元两种方法。结果表明:根据现行不同规范m值取值推荐进行计算,结果差异较大。将有限元法计算结果与m法计算结果进行比较可以看出地质条件对于位移的影响效应方面有限元法与采用m法按照《地基基础设计标准》和《防汛墙工程设计标准》测算的结果较为接近,但采用有限元法计算的墙顶累计水平位移值较采用m法计算的结果更大。

基于小型水利水保工程的小流域水土保持优化设计

针对小流域水土流失的加重,研究提出基于小型水利水保工程对其进行优化设计。通过水利水保工程、经果林、改梯田措施等,改进优化小流域。结果表明,水土流失面积治理程度为88.46%,项目产生的直接经济效益559.85万元,农民人均纯收入增加565元。研究表明,优化后小流域的保水保土能力增强,水土流失得到明显控制,可为安龙县社会经济发展提供生态保障。

西吉县葫芦河上段水土流失综合治理生态效益评价研究

针对西吉县葫芦河上段水土流失综合整治效果,利用AHP法与Delphi法构建起包含12个指标的生态效益评价体系,对该体系的一致性进行检验,并计算其包含的各指标层的权重,然后对无量纲化处理过后的各指标进行分值量化,结合评价等级,最终得到:综合整治后总体评分为89.07分,评价等级为Ⅳ级,说明工程的实施有效解决了水土流失的问题,基本实现了工程目的。

新疆奇台县水土保持评价及治理对策研究

以新疆奇台县为背景,基于全区水土流失类型、面积、强度以及区域分布现状分析,对该地区水土保持现状进行了评价,包括土地利用、水土流失消涨、水资源丰缺程度、饮用水源地面污染等评价,并对水土保持需求进行分析,提出了综合性、系统性和可持续性的治理对策,包括建立健全管理体系、推广可持续农业技术、加强生态恢复工程等,并促使全社会参与,调动农民积极性,共同努力实现水土保持目标,以推动奇台县的可持续发展。