多目标线性规划在水土保持规划中应用的探讨

多目标线性规划是单目标线性规划的发展。它同时考虑数个目标函数。文章以金溪县付家小流域水保规划为例,建立三个目标函数:一是经济效益,以纯利润最大为目标;二是生态效益,以控制后土壤侵蚀量最小为目标;三是社会经济承受力,以总投资量最小为目标。据此建立约束方程,求得各目标函数的合理解。本文只作为多目标线性规划的一个算例,至于该规划在水保生态效益、经济效益及社会效益方面的可行性及合理性,还需从各个方面作进一步的分析论证。     

Adoption of soil conservation practices: An empirical analysis in Ontario,Canada

Soil degradation threatens environmental quality and sustainable food production. As a result of efforts to promote soil conservation, farmers in Canada are thought to be reasonably aware of both the importance of conservation and the existence of remedial and preventive practices. Despite this, the adoption of conservation practices has been less than overwhelming. Forces other than awareness and positive attitude seem to be constraining many land managers from employing available conservation methods. This paper presents the findings from an empirical investigation of the use of soil conservation practices and barriers to their adoption in the southwestern region of Ontario, Canada. The analysis is set in the context of literature on technology adoption. A scheme for measuring farm-level conservation effort is developed, and barriers to adoption are derived from an analysis of a range of independent physical, personal, and economic factors, and from the obstacles or constraints identified by producers themselves. Key barriers relate to economic pressures, the complexity and compatibility of practices, and perceptions regarding the actual need for practices. The findings have relevance for the design of public policies and programs, notably the importance of supplying information on farm-level implications of conservation methods and the need for a stable economic environment for agriculture to allow longer-term planning.     

基于Bayes判别分析模型的水土保持区划

为了更加合理地对甘肃、宁夏、青海3省份的黄土丘陵沟壑区进行水土保持区划,基于Bayes判别分析理论建立水土保持区划的数学模型.结合甘肃、宁夏、青海3省份的自然条件,社会经济情况和水土资源流失特点,以垦殖率、林草覆盖率、人口密度、单位面积粮食产量、降雨量和蒸发量等6个指标作为区划判别因子.计算分析表明,该模型与按土壤侵蚀类型进行区划的效果一致,与甘肃、宁夏、青海地区实际区划情况吻合,准确率为100％,可在其他水土保持区划中进行推广.     

“猪-沼-果”水土保持综合治理模式简析

 “猪—沼—果”工程是20世纪90年代以来江西省赣南等水土流失严重地区综合治理水土流失的一种新模式,对巩固和促进治理成果取得了积极有效的作用。通过介绍“猪—沼—果”综合治理模式的内涵及“猪—沼—果”产业循环生态链,对“猪—沼—果”综合治理模式在小流域治理中的作用和效益进行全面阐述。其作用主要表现在3个方面:1)缓解能源紧缺的矛盾,保护自然植被,巩固治理成果;2)提供有机肥料,改善水土流失地土壤养分条件,促进开发性治理;3)促进小流域经济的发展,加快脱贫致富的步伐。同时,取得了显著的水土保持效益、生态效益和经济效益。     

为什么治理典型地区水土流失还增加

全国第四次水土保持工作会议表彰的治理典型——陕西省的淳化县和长武县以及河南省的(艹渀)河流域,近几年的侵蚀模数都增加了,这应引起高度重视,必须弄清情况,深入到问题的实质中去。有增无减的原因,除了坝库塘堰等工程措施淤死失效和溃决外,就是失策的经营管理和对治理措施的作用机制的认识问题。必须强调,治理措施要建立在防治水土流失的基础上,否则只能是掠夺式的经营,最终自我毁灭。     

山东省水土保持区划探讨

本文对山东省水土保持区划工作进行了探讨。作者根据全省自然条件、社会经济情况, 影响土壤侵蚀的诸因子, 及水土流失现状等综合因素, 提出了山东省水土保持区划原则, 并依据分区原则, 在水利部统一划分一级区、二级区的前提下, 将全省共划分3个三级区、12个三级亚区。     

生产建设项目水土保持设计理念与原则

生产建设项目水土保持设计理念是水土保持设计的主导思想,也是主体工程设计思想的重要组成部分。在对近10年来我国不同工程类型生产建设项目独具特色的水土保持设计方案及其实施后效果调研的基础上,总结提出水土保持设计理念的内涵与外延,指出水土保持设计理念核心是最大限度地保护生态、控制扰动范围、减少植被破坏和水土流失、快速有效修复生态系统,并在更高层次上达到工程、生态、景观的协调,达到人与工程、人与自然和谐。在这一设计理念的指导下,提出生产建设项目设计的5项基本原则:1)落实责任,明确目标;2)预防为主,保护优先;3)综合治理,因地制宜;4)综合利用,经济合理;5)生态优先,景观协调。     

水土保持功能评价及其在水土保持区划中的应用

随着国家对生态文明建设的日益重视,以及国家及地方主体功能区规划的实施,对于水土保持的功能研究也越来越多.结合全国水土保持规划工作的需要,提出水土保持功能的概念、类型确定原则和功能类型,阐述了水土保持基础功能和社会经济功能的评价方法,以及各基础功能的评价指标体系.以太行山东部山地丘陵区为例,举例说明水土保持功能评价的过程和结果.对全国水土保持区划三级区基础功能进行统计分析,明确各功能的区域比例,提出8个一级区水土保持工作主要方向,维护和提高区域水土保持功能将成为水土保持工作的重点和方向.     

水土保持工程的政府投资风险分析

以投资风险评估理论为基础,结合政府水土保持投资风险的特点,研究投资风险辨识体系,在全项目风险结构分解的基础上,提出基于蒙特卡洛风险模拟的政府水土保持投资风险分析方法,并以某水土保持工程为案例进行计算。结果与预期一致,表明用该投资风险分析方法可进行水土保持工程的政府投资风险分析。     

中国水稻生产成本地区性差异成因的实证分析

水稻是中国的重要粮食作物，水稻生产成本的高低既是决定产地竞争力的关键因素，又影响农民收入。该文对中国水稻生产成本地区性差异的原因进行了分析，并提出相关的政策建议，以期为降低中国水稻生产成本，促进水稻主产区农民增收，提高中国水稻生产的国际竞争力提供参考。     

中国水稻生产成本地区性差异成因的实证分析

水稻是中国的重要粮食作物,水稻生产成本的高低既是决定产地竞争力的关键因素,又影响农民收入.该文对中国水稻生产成本地区性差异的原因进行了分析,并提出相关的政策建议,以期为降低中国水稻生产成本,促进水稻主产区农民增收,提高中国水稻生产的国际竞争力提供参考.     

Nitrogen monoxide production and consumption in an organic soil

 Factors controlling NO production, consumption, and emission rates were examined in an organic soil. Emission rates were measured in the enclosed headspaces of intact soil cores under three fertilisation treatments (unfertilised or 100 kg N ha^–1 as NH₄Cl or as NaNO₃), with and without the nitrification inhibitor C₂H₂ (20–70 μl l^–1). Nitrification was always the main source of NO emitted across the soil surface, even when the soil was nearly saturated. Fertilisation of soil with NH₄Cl increased NO emission both by stimulating NO production from nitrification, and by decreasing the NO consumption rate constant. Addition of NaNO₃ also stimulated the production of NO and N₂O during nitrification in aerobic soil slurry experiments. This effect was eliminated by adding C₂H₂ and was therefore not related to denitrification. In loose soil samples, the increase in NO-N production after NH₄Cl addition represented as much as 26% of the added N. However, in intact cores, 95% of the NO produced through nitrification was oxidised within the soil column rather than emitted to the atmosphere. We concluded that nitrification is the primary NO source from this organic soil, that surface NO emissions are much lower than gross NO production rates, and that gaseous N oxide (NO and N₂O) losses during nitrification can be affected by both soil NH₄ ⁺ and NO₃ ^–. Received: 15 December 1998     

香沟流域综合治理的水土保持效益分析

香沟流域面积1.91 km2,是岚香河的一级支沟。经过几年的治理,共修梯田52 hm2,栽种柠条林54 hm2,乔灌混交林20 hm2,油松林6 hm2。据1998年~2003年间的观测资料,从拦蓄径流率来看:梯田可达100%,柠条林为40.29%~81.97%,油松林为42.33%~83.26%;从减蚀率来看:梯田为74.6%~98.8%,柠条为75.3%~99.2%,油松为100%。     

Integration of species persistence, costs and conflicts: An evaluation of tree conservation strategies in Cambodia

Cambodia forms part of the Indo-Burma hotspot. Its extent of biodiversity, however, is subject to considerable uncertainty, as there has been little systematic collection of flora and fauna. During the Khmer Rouge regime institutions were banned, academics were prosecuted and written documentation systematically destroyed. Compared with neighbouring countries Cambodia has a low population density and relatively large natural areas that are still intact. However, deforestation is expanding rapidly and a significant but un-estimated area of forest has been degraded by development of agro-industries, encroachment, illegal logging, over-harvesting and forest fire as well as the use of chemicals during war. The purpose of the paper is to: (i) apply reserve selection methods to design more robust conservation networks when knowledge of species occurrence is incomplete and habitat is threatened, and (ii) evaluate the usefulness of systematic conservation planning in a developing country where data are limited and institutions for implementation are weak. This study investigates the performance of four non-probabilistic strategies: (i) a so-called ‘rule of thumb’, (ii) hotspot, (iii) minimum cost representation, and (iv) maximum coverage; and one probabilistic design strategy, i.e. maximum expected coverage. The maximum expected coverage approach is between 15% and 24% more efficient than the non-probabilistic strategies. Finally, the relevance of such tools to real-world conservation planning in Cambodia is investigated. By incorporating experts in the generation of data, running the models and setting up premises, they acknowledge that it is possible to contribute to more systematic conservation planning in developing countries.     

生产建设项目水土保持准入条件研究内容与方法

 落实科学发展观,建设资源节约型社会和环境友好型社会都要求严把建设项目水土保持准入关,从源头上控制和遏制可能产生的影响和危害。从保护水土资源和生态环境的角度出发,深入研究了不同国土功能区、不同土壤侵蚀类型区、公路铁路、采矿、电力、水利水电、城建、农林开发等16类生产建设项目的水土保持项目准入条件和水土保持方案准入条件,提出否决、限批和缓批的准入条件,建议将表土剥离利用率、弃渣分类堆放率、土地裸露程度、复耕率、蓄水措施率、水土流失影响指数等量化指标,纳入生产建设项目水土保持准入条件。     

水土保持对黄河流域生态承载力的影响

 用生态承载力和生态足迹理论,评价人类活动对生态环境的影响。分析和计算显示,黄土高原水土保持综合治理有效地增加了当地和下游引黄灌区的生态承载力。以2000年为例,黄土高原水土保持增加的生态承载力达1444.24万hm2,其中黄土高原当地约占77.74%,黄河下游灌区约占22.26%,说明水土保持对提高黄河流域生态(人口)承载力的重要作用,以及黄土高原在国家可持续发展战略中的重要地位。     

生产建设项目水土保持准入条件通用条款

 以国家法律法规、国民经济和社会发展规划纲要、行业发展规划、国家的产业政策,以及国家和行业标准的规定和要求为依据,经系统收集、比照分析和深入研究,提炼出生产建设项目水土保持准入条件105条,其中基本条件86条、限批条件7条、缓批条件12条;提炼出生产建设项目水土保持方案审查审批条件86条,其中基本条件16条、不同类型区的特别条件35条、不同类型生产建设项目的特别条件12条、须由建设和设计单位对主体工程进行修正的条件12条、须修改完善水土保持方案的条件11条。共提出适用于全国生产建设项目水土保持准入条件通用条款191条。     

基于RUSLE模型的黑龙江省2000-2010年土壤保持量评价

黑龙江省是我国重要的粮食产区,同时也是东北地区重点生态保护区,黑龙江省土壤保持量的研究对维持生态安全与可持续发展有重要作用。基于黑龙江省2000年、2005年和2010年的降雨、土壤、高程等数据,结合GIS空间分析方法,运用修订的通用土壤流失方程(RUSLE),估算了2000—2010年黑龙江省土壤保持量,并对其空间分布及变化趋势进行模拟分析。结果表明:2000—2010年,黑龙江省土壤保持能力整体增强,土壤保持量增加了5.34%,且除牡丹江和哈尔滨地区外,各行政区的土壤保持量均有所增加;各土地利用类型的年均单位面积土壤保持量以森林最多,为3 384.36 t·km-2·a-1,裸地最少,为177.17 t·km-2·a-1,10年来除农田和灌丛外,各土地利用类型的单位面积土壤保持能力均增强;2000—2010年黑龙江省高等级土壤保持量比例及低等级转化成高等级土壤保持量的面积都在提高,黑龙江省土壤保持能力10年来趋于好转。     

红壤缓坡花生地不同水土保持措施效果分析

采用径流小区试验,以花生常规种植为对照,研究红壤荒坡花生地花生+草篱、花生+覆盖+草篱、花生+覆盖3种种植措施的水土保持效果.试验从4月份花生种植后开始测定,8月底花生收获结束.结果表明:1)3种种值措施地表径流量均随日降雨量的增大而增大;2)3种种植措施地表径流量、土壤侵蚀量均与对照差异显著(P＜0.01).表明,花...     

民营水保大户的经营模式与示范效应

据调查,吕梁市现有治理面积超过66 hm2的水土保持大户77户,民营水保大户已成为一支重要的水土保持力量。水保大户的成功经营模式主要为种养为主的牧工商一体型、以经济林为主的园区建设型、以生态林为主的水保生态经济型、以工致富反哺农业型。水保大户带动了农业的产业化发展,增加了农民收入,推动了流域治理深入开展。为了引导水保大户健康发展,要制定优惠政策,认真落实产权,提供优质服务。