Evaluating China's Slope Land Conversion Program as sustainable management in Tianquan and Wuqi Counties

Increased soil erosion on sloped land has become a significant environmental concern in China that has been attributed to human activities such as deforestation, over-cultivation, and over-grazing of livestock. In order to reduce soil erosion on sloped lands, the Chinese government has responded by implementing large-scale, ecological rehabilitation programs, including the "Grain for Green" reforestation project. This program involves financial incentives to transition farmers into other economic activities with the goal of reducing ecological pressures and degradation. Because of the scope and potential impacts from these programs, detailed research is needed to understand their social and ecological effects. This paper reports on research conducted in Tianquan County, Sichuan Province, and Wuqi County, Shaanxi Province, that evaluates the effects of the program upon local economies and household livelihood systems. The paper argues that the successful conversion of farmland under "Grain for Green" depends upon local government involvement, local economic development, and funding for local projects. Without economic development within rural economies, we conclude that farmers will remain dependent upon continued subsidy assistance to meet the policy's ambitious environmental restrictions, thereby undermining the program's long-term sustainability.     

探析模糊控制无线节点网路技术在石油化工安全中的应用

在石油化工领域,为了有效预防和控制易燃易爆有毒气体的泄漏燃烧爆炸,利用计算机技术和电信通讯网络,处理信息和传输信息,以监测探头、无线接收发模块、监控主计算机三部分构建一套安全预警监控系统。在化工厂或危险源区域的危险点,设置多处监测节点,接受信息传输到无线接收发模块,进行模糊化计算、推理,判断后输出结果到监控主计算机,监控主计算机向安全管理人员、现场工作人员等发出报警信息。     

自然降雨下蔬菜地土壤侵蚀及氮素流失特征

为探究自然降雨下露天蔬菜地土壤侵蚀及氮素养分流失特征,基于径流小区原位观测试验,设置叶菜类和果菜类这2种处理,测定次降雨下不同类型蔬菜地坡面地表径流、侵蚀及其氮素(铵态氮和硝态氮)流失量,探讨露天蔬菜种植坡面土壤侵蚀及氮素流失特征及影响因素.结果表明：(1)果菜类(茄子-辣椒)蔬菜地的地表径流、侵蚀量及铵态氮、硝态氮流失量显著高于叶菜类(油麦菜-红薯叶),是后者的1.27～2.00倍.不同处理下第二季蔬菜坡面地表径流、侵蚀及其铵态氮和硝态氮流失占总流失量的50.86%～68.83%,是第一季蔬菜的1.03～2.04倍.蔬菜地坡面地表径流、侵蚀及其氮素流失集中在6月和7月,地表径流和侵蚀泥沙中氮素主要以地表径流中的硝态氮形式流失.(2)次降雨下,不同处理蔬菜地坡面地表径流、侵蚀及其养分流失在蔬菜生长期内呈波动变化,且流失量主要集中在几场典型降雨.整体上不同处理下第一季蔬菜地表径流和侵蚀泥沙中硝态氮和铵态氮流失量及含量低于第二季蔬菜,果菜类地表径流、侵蚀量及铵态氮、硝态氮流失量高于叶菜类.(3)蔬菜地坡面地表径流、侵蚀及其铵态氮和硝态氮流失量与降雨量和最大30 min降雨强度等降雨参数呈极...     

中晚全新世六盘山流域土壤侵蚀的湖泊沉积记录

流域土壤侵蚀是流域水文—气候—生态的集中表现之一,对生态、环境等有着重大影响,重建过去流域土壤侵蚀强度对理解区域人类活动具有重要意义.本文选取黄土高原西南部高山湖泊——六盘山天池沉积岩芯为研究对象,基于XRF岩芯元素数据分析,结合可靠的AMS 14C年代序列,重建了中晚全新世以来六盘山流域土壤侵蚀强度变化记录.结果显示:5570?—?1600 cal BP,流域土壤侵蚀整体较强,侵蚀强度逐渐减弱,其主要受控于降水变化,也受植被覆盖等因素的影响;随着晚全新世气候逐渐变干,1600 cal BP之后的侵蚀强度整体弱于前一时期,此时段由于人类活动的显著影响,加剧了流域的土壤侵蚀.太阳辐射可能是研究区土壤侵蚀强度变化的初始驱动力,ENSO通过驱动亚洲季风变化影响区域降水,进而直接影响流域土壤侵蚀的强度变化.     

布哈河流域不同时间尺度下土壤侵蚀对气候变化的响应特征

全球气候变暖极大地影响了地表侵蚀过程,但影响机制尚无统一定论.河流悬浮物是示踪地表侵蚀的常用手段.本文通过分析青海湖流域最大河流布哈河2008?—?2015年的日径流量、悬浮物浓度、气温及降雨数据,讨论了该流域在日、月以及季节尺度下土壤侵蚀对气候变化的响应特征.结果表明:降雨是半干旱布哈河流域土壤侵蚀的主要控制因素,气温通过影响冻融作用控制侵蚀行为.此外,该流域的土壤侵蚀具有明显的季节性差异,大部分的侵蚀发生在雨季.最重要的是,冻融作用导致春季解冻期/雨季前期产生额外的沉积物累积,表现为在相同流量下,沉积物输出明显高于雨季后期.上述结果对深刻认识全球变暖背景下侵蚀的响应机制具有重要的作用.     

甘肃舟曲三眼峪沟泥石流粗大颗粒冲击力特征分析

本文通过对甘肃省舟曲县城后山三眼峪沟特大泥石流灾害的现场调查获取了舟曲三眼峪泥石流沟相关资料,并根据这些收集整理的资料分别对三眼峪沟及其支沟(大峪沟、小峪沟)泥石流动力学重要参数-冲击力,进行计算与特征分析,该参数计算结果对该沟泥石流防治工程参数设计有一定的参考作用,对灾区灾后重建有重要意义。分析发现泥石流流通区最大颗粒冲击力比堆积区的大,而堆积区粗大颗粒的冲击力呈先增大后减小的趋势并与粗大颗粒的最大直径呈单调线性关系;堆积区的粗大颗粒形态主要为棱柱状(长方体、立方体)、角锥状、菱形状。最后以利子依达沟为例对计算结果进行简要评估,并在上述计算与特征分析的基础上提出三眼峪泥石流沟针对性防灾减灾建议。     

三江源区东西样带土壤侵蚀的

运用137Cs和210Pb_ex联合示踪技术,考察青藏高原三江源区东西样带137Cs和210Pb_ex面积浓度的背景值和变化特征,以及东西样带土壤侵蚀速率、分布特征和主要影响因素. 结果表明:①青藏高原三江源区东西样带137Cs和210Pb_ex面积浓度背景值分别为453～1 714和2 612～7 377 Bq/m2,137Cs和210Pb_ex背景值从西向东样带随海拔高度的变化差异明显.137Cs(x)和210Pb_ex(y)面积浓度的背景值区域分布呈显著线性相关,相关性关系式为y3.587　2x+1　463.4,R20.951　7.②长江源区沱沱河137Cs的示踪结果表明,以沱沱河为中心的长江源区是典型的风蚀区,年侵蚀速率2.5 t/(hm2·a),该区是青藏高原重要的沙尘暴源区之一.③黄河源区玛多典型坡面137Cs和210Pb_ex的示踪结果表明,近40年来,玛多畜牧业为主的人类活动造成的土壤扰动比自然因素的影响大.④玛沁东倾沟乡和军牧场的比较研究结果表明,玛沁东倾沟乡高山草甸的水土保持效果较好,而玛沁军牧场的畜牧业活动造成了地表土壤的强烈扰动.⑤玛沁军功镇典型水蚀地貌土壤剖面137Cs和210Pb_ex的结果表明,20世纪50—60年代,该区的极端暴雨事件导致了严重的水土流失,土壤剖面中出现137Cs和210Pb_ex的空白区. 植被破坏导致玛沁军功镇出现了严重水蚀,净侵蚀速率为8.0 t/(hm2·a).⑥近40年来,随着人类活动的加剧和全球气候变暖,导致青藏高原三江源区出现了沙尘暴的传输源地.      

西南喀斯特山地的土壤侵蚀研究探讨

西南喀斯特山区具有独特的喀斯特土壤特征与土壤侵蚀的环境效应,普遍面临着因土壤侵蚀导致的"石漠化"问题.已有研究认为,在气候、地质地貌、植被和人为活动等环境因素的影响下,喀斯特山区土壤侵蚀以混合侵蚀方式进行.但由于对喀斯特山区土壤侵蚀过程的认识不同,致使研究者得出土壤侵蚀强度差异较大的研究结果.有关喀斯特土壤侵蚀系统研究重点应该在土壤侵蚀机制、土壤侵蚀分级强度与土壤合理流失量等方面开展研究.     

VALIDATION OF THE SWAT MODEL ON A LARGE RWER BASIN WITH POINT AND NONPOINT SOURCES1

ABSTRACT: The State of Texas has initiated the development of a Total Maximum Daily Load program in the Bosque River Watershed, where point and nonpoint sources of pollution are a concern. Soil Water Assessment Tool (SWAT) was validated for flow, sediment, and nutrients in the watershed to evaluate alternative management scenarios and estimate their effects in controlling pollution. This paper discusses the calibration and validation at two locations, Hico and Valley Mills, along the North Bosque River. Calibration for flow was performed from 1960 through 1998. Sediment and nutrient calibration was done from 1993 through 1997 at Hico and from 1996 through 1997 at Valley Mills. Model validation was performed for 1998. Time series plots and statistical measures were used to verify model predictions. Predicted values generally matched well with the observed values during calibration and validation (R²≥ 0.6 and Nash‐Suttcliffe Efficiency ≥ 0.5, in most instances) except for some underprediction of nitrogen during calibration at both locations and sediment and organic nutrients during validation at Valley Mills. This study showed that SWAT was able to predict flow, sediment, and nutrients successfully and can be used to study the effects of alternative management scenarios.     

SAMPLING FRAME FOR IMPROVING PEBBLE COUNT ACCURACY IN COARSE GRAVEL‐BED STREAMS1

ABSTRACT: Improved sampling techniques are needed to increase the accuracy of pebble‐count particle‐size distributions used for stream studies in gravel‐bed streams. However, pebble counts are prone to operator errors introduced through subjective particle selection, serial correlation, and inaccurate particle‐size measurements. Errors in particle‐size measurements can be minimized by using a gravel template. Operator influence on particle selection can be minimized by using a sampling frame, 60 by 60 cm, in which sampling points are identified by the cross points of thin elastic bands. Serial correlation can be minimized by adjusting the spacing between the cross points and setting it equal to the dominant large particle size (=D₉₅). In a field test in a cobble‐bed stream, the sampling frame developed in this study produced slightly coarser size distributions, particularly in the cobble range, than the traditional heel‐to‐toe walk that selects particles with a blind touch at the tip of the boot. The sampling frame produced more similar sampling results between two operators than heel‐to‐toe walks. The difference between the two sampling methods is attributed to an unbiased selection of fine and coarse particles when using the sampling frame.