Water-saving Technologies,Solar Green House and Ecological Rehabilitation in Minqin Oasis of Gansu Province,China

Abstract

Land degradation and desertification have become severe environmental problems in arid areas due to excessive use of water resources. It is urgent to reduce agricultural water use for ecological rehabilitation, which may result in a decrease in agricultural production and farmer’s welfare. This paper focused on the impacts of some main measures including extensions of water-saving irrigation, expanding solar green house and increasing off-farm employment, which are generally recognized to be important to alleviate water shortage and poverty. A bio-economic model is applied taking Minqin Oasis in Gansu Province as a case study site. Simulation results showed that the effect of expanding solar greenhouse was more positive than other ones so it drew more attention. On the view of the different effects between each irrigation zone, mixed policy patterns suitable for them are suggested. In Baqu, expanding solar greenhouse should be the most important, auxiliary with encouraging pipe irrigation. Inversely, with regard to Quanshan, the major attention should be paid to subsidy for pipe irrigation and it would be better to supply the off-farm employment opportunities to the households in Huqu, where the expanding of solar greenhouse should also be summoned. Finally, it should be noted that farmer’s income would only resume to 90% of the current level in the short run by putting more effort into local policies. Thus, the ecological compensation is needed to ensure farmer’s welfare.     

Unraveling the water and land nexus through inter- and transdisciplinary research: sustainable land management in a semi-arid watershed in Brazil’s Northeast

For decades, large reservoirs have been built for hydropower plants in Brazil’s São Francisco River Basin. Rural development has been a simultaneous goal with a primary focus on irrigation. Irrigated agriculture, however, has suffered from poor soils, insufficient water management strategies, and a disregard for integrating grazing-based smallholdings outside of the irrigation schemes. Recurrent droughts are distressing all sectors. This synthesis assessed sustainable land management options by investigating the aquatic and terrestrial land use systems alongside their underlying ecosystem functions and services. Decisions about the allocation of scarce water proved to be both the major issue of land use discourses and driver of practices. The primarily hydroelectricity-focused water management practice cannot be maintained at the same level in the long run, as it has become ever more adverse towards competing water usages. The increasing use of the water and adjacent land also constitutes a major potential threat to water quality. Managed water level fluctuations should generally mimic natural patterns. Wind and solar power generation are suitable complements to agricultural land use. Cycling scarce nutrients between aquatic and terrestrial sectors is ambitious but promising, ultimately improving the generally poor soils in the area. Smart management of biodiversity can foster intensively-irrigated cropping, although the non-irrigated Caatinga ecosystem needs better management of its conflicting uses. Aims and responsibilities of multi-level planning and management require clarification and coordination between sectors, while practices of public participation should be revised in order to better support a comprehensive and transparent transition towards sustainability.     

农业生产对土壤盐渍化影响的经济分析

研究农业生产活动对土壤盐渍化的负面影响，有利于合理安排农业公共投资，促进生产与环境协调发展。在介绍我国土壤盐渍化概况的基础上，利用相关文献分析影响土壤盐渍化的不同因素，同时利用省级Panel数据和计量模型进一步探索农业生产活动对土壤盐渍化的影响。结果表明，灌溉程度、单位钾肥投入会对土壤盐渍化产生显著影响。单位耕地上灌溉面积越多，耕地发生盐渍化的概率也越高；同时单位面积上钾肥使用量越高，耕地发生盐渍化的概率也越高。此外，还在统计意义上发现排灌对抑制土壤盐渍化具有明显作用。因此，针对农业生产活动对农业生态环境可能造成的负面影响，进一步提出应该在增加农业公共投资的背景下，加强农业基础设施的建设，引导农户采用合理的农业生产方式，以协调我国农业生产与农业生态环境的和谐发展。     

长江流域农业用水效率研究:基于超效率DEA和Tobit模型

提高农业用水效率对于农业可持续发展和保障粮食安全具有重大意义。考虑降雨量中绿水资源对农作物生长的重要性,将绿水资源纳入农业用水总量,全面分析长江流域农业用水效率变动趋势。基于1998~2011年长江流域10个省份的面板数据,运用超效率DEA和Tobit模型对流域农业用水效率进行了测度和影响因素的检验。研究发现:(1)在研究期间内,长江流域农业用水效率呈现出波段式上升态势;流域各区段的用水效率呈下游、上游、中游依次递减的区域分布格局。(2)灌溉费、节水灌溉技术和农业对外开放度对流域农业用水效率有显著的正向效应;人均水资源量和年降水量均对流域农业用水效率有负向关系,但只有降水量在统计上显著。研究结果表明应当提高长江流域,尤其是中上游水资源禀赋较高地区的农业用水效率;在农业节水的具体政策方面,调整农业灌溉水价、加强农业技术创新能力和扩大农业经济对外开放程度能够取得较为显著的节水效应。     

城市化背景下中国水电移民安置的政策选择——以龙滩水库为例

中国水电发展深受城市化的影响，因此水电移民问题应该放在城市化的大背景下来审视和解决，将沿海发达地区和主要大城市作为水电移民永久安置的主体之一。无论从水电移民产生地的生态条件和经济社会发展水平（即“推”的方面），还是沿海城市对劳动力的需要（即“拉”的方面），都存在着将水电移民彻底城市化安置的必要条件。通过龙滩水库的实例，给出一个政策组合和一个极端状态下的财务估算，说明移民问题彻底城市化解决的充分条件也是成立的，并在此基础上进一步讨论了非农安置的方式、户口准入、移民就业培训和多次安置选择等问题。     

有机无机肥料对农业环境影响述评

论述了有机肥在中国的使用情况和对农业生产的作用、化肥对农产品质量的影响、化肥对土壤肥力的贡献、有机肥和化肥对大气环境和水体的影响。目前人们在对化肥使用的认识上普遍存在误区,认为施用化肥一定会对环境产生污染,只有使用有机肥才能解决问题。中国是一个人口大国,今后在一个相当长的时间内,农业产品的生产在养分的投入上仍然需要以化肥为主,充分、合理、平衡的化肥投入不仅能满足人们对农产品数量上的需要,而且一定能满足人们对农产品品质的要求。化肥的合理施用可以改善和提高农产品品质,提高土壤有机质含量,改善土壤理化性质,减少温室气体的排放和水体污染。化肥本身是无害的,有害的是对化肥的不合理施用。在肥料问题上,今后需要关注 的应该是生产和使用更优质、更高效的化肥,推广科学合理的施肥技术,提高化肥的利用效率。     

崇明北滩鱼类群落生物多样性初探

对1994~2003年崇明北滩鱼类群落进行了研究,用多种指数对该群落生物多样性进行了描述。该群落共有鱼类33种,分别隶属于10目19科29属。生态类型为江海洄游鱼类、河口鱼类和海水鱼类,小型鱼类占绝对优势。群落优势种为凤鲚、棘头梅童鱼和小黄鱼。多样性特征值年间平均指标为：Margalef指数0.84,Wilhm改进指数1.51,Pielou指数0.63,McNaughton指数0.67。崇明北滩鱼类群落经济鱼类趋于小型化,生物多样性呈下降趋势。水环境污染及工程建设的不利影响应得到重视,无选择性网具的使用应受到严格控制。     

Efficiency and Economy of a New Agricultural Rainwater Harvesting System

Shortage of water is the key limiting factor for agricul-tural development of Beijing. Rainwater harvesting (RWH) could provide an alternative water source for greenhouse agriculture, but local natural and socioeconomic conditions challenge the applica-tion of the technology. This article analyses the advantages and disadvantages of different types of greenhouse RWH in Beijing,and describes a new greenhouse RWH system demonstrated in 2008 in Huairou, a suburb district of Beijing. It analyses the ef-ficiency, cost-benefit ratios and limiting factors of the new system.The results show that with the new system, RWH efficiency can be as high as 66% (of total rainfall) and the rainwater usage rate can reach 69% of total water usage. The ratio of benefit to cost of government investment can be 1.84, and the ratio of benefit to cost of a farmer's investment could be 1.68 provided the project is designed to save water and also increase income. However, the price of groundwater for agriculture directly influences the potential for applying and scaling up the project. If the RWH system does not increase the farmers' incomes at the current water price, they will not use it until the water price rises to a critical point, which is de-termined by external factors. This article also suggests a number of measures to increase the efficiency of the system in order to apply it on a large scale.     

Dangerous levels of climate change for agricultural production in China

There are increasing attempts to define the measures of ‘dangerous anthropogenic inference with the climate system’ in context of Article 2 of the Framework Convention on Climate Change, due to its linkage to goals for stabilizing greenhouse gas concentrations. The criteria for identifying dangerous anthropogenic interference may be characterized in terms of the consequences of climate change. In this study, we use the water stress index (WSI) and agricultural net primary production (NPP) as indictors to assess where and when there might be dangerous effects arising from the projected climate changes for Chinese agricultural production. The results showed that based on HadCM3-based climate change scenarios, the region between the North China Plain and Northeast China Plain (34.25–47.75°N, 110.25–126.25°E) would be vulnerable to the projected climate change. The analyses on inter-annual variability showed that the agricultural water resources conditions would fluctuate through the period of 2001–2080 in the region under IPCC SRES A2 scenario, with the period of 2021–2040 as critical drought period. Agricultural NPP is projected to have a general increasing trend through the period of 2001–2080; however, it could decrease during the period of 2005–2035 in the region under the IPCC SRES A2 scenario, and during the period of 2025–2035 under IPCC SRES B2 scenario. Generally, while projected climate change could bring some potentially improved conditions for Chinese agriculture, it could also bring some critical adverse changes in water resources, which would affect the overall outcome. At this stage, while we have identified certain risks and established the general shape of the damage curve expressed as a function of global mean temperature increase, more works are needed to identify specific changes which could be dangerous for food security in China. Therefore, there is a need for the development of more integrated assessment models, which include social-economic, agricultural production and food trade modules, to help identify thresholds for impacts in further studies.     

四川马边彝族自治县土地利用/覆被变化分析

采用基于最大似然法的监督分类方法对四川省马边彝族自治县1988年和2001年两期Landsate5 TM影像进行解译,利用单项土地利用动态指数〖WTBX〗（LUDI）、双向土地利用动态指数（Ki）以及土地利用类型转移矩阵（Cx×y）〖WTBZ〗等定量分析方法分析解译结果,得到马边县13年间土地利用/覆被动态及转移特征,并对可能的生态影响进行了分析预测。结果显示：①次生林面积增加,针叶林面积有所下降,灌草地被农田大量取代;②城镇及居民点和次生林的动态最为活跃,转入面积明显高于转出面积;③中山区和亚高山区林地构成发生变化,高山草甸面积有所萎缩,河谷区的阔叶林带被次生林大量取代,低山河谷区的土地破碎化程度增加。研究表明,13年间马边土地利用/覆被变化具有动态高、转换活跃、空间性强以及人为活动干扰影响明显等特点。其中,低山丘陵区的灌草坡大量被农地替代、中山区和亚高山区次生林面积扩大应该作为生态退化的信号加以重视。另外,气候变化对马边森林植被演替可能产生的影响应在今后进行深入的分析研究     

Assessment of the impacts of climate change and variability on water resources and use,food security,and economic welfare in Iran

Climate change influences the agricultural sector by reducing available water resources, thereby influencing income, consumer and producer surplus, and crop prices. So, it is necessary to have a comprehensive integrated method to measure the effects of these changes on natural resources and social conditions. The present study aims to use the positive mathematical programming method to discover the trend and conditions of groundwater resources, agricultural water use, food security, and economic welfare of the agricultural sector in Iran. To this end, data for the period 2000–2015 was used under four different scenarios of normal climate change, climate change, climate variability, and concurrent climate change The results showed that the mean agricultural water use will amount to 35,103.6, 26,533.8, 35,216, and 26,510.7 million m³ and the mean decline in the reserves of aquifers will amount to 4422.22, 11,165.6, 4438.25, and 11,267.4 million m³ under the scenarios, respectively. With respect to food security, the net farm revenue will be 314,560, 248,753, 315,427, and 248,574 billion IRR, respectively. The mean crop price per ton will reach 905.3, 1141.8, 904, and 1142.8 million IRR, respectively. The mean consumer surplus will be 172,107.7, 166,450, 172,024, and 166,403 billion IRR and the mean producer surplus will be 419,959.2, 395,380, 419,751, and 395,204 billion IRR, respectively. Based on the results, to reduce the adverse impacts of climate change on different studied aspects, it is necessary to change policymaking in the water and agricultural sectors, especially regarding the shift from traditional agricultural water allocation to its market-based allocation and to change planting pattern.

     

Climate change and village adaptation impact on reliability of irrigation wells in China

This paper builds a water supply reliability econometric model to analyze climate changes and adaptation impact factors on water supply reliability of irrigation wells by using 100 villages’ three-year (2010–2012) field survey data of five middle and eastern provinces of China. The results show that long-run climate change factors, adaptation measures, village-level organizations of irrigation management, as well as extreme climate factors affect the water supply reliability of irrigation wells significantly. Meanwhile, there are significant differences impacting different crops and provinces. This paper suggests that agriculture meteorological disaster monitoring and warning systems should be strengthened by increasing irrigation facilities construction and maintenance, promoting reform of agricultural irrigation water management system, and developing various forms of peasant cooperation organization in order to improve agricultural production capacity to adapt to climate change.     

The economic,environmental and agricultural land use effects in the European Union of agricultural labour subsidies under the Common Agricultural Policy

In this study, we assessed the economic, environmental and agricultural land use impacts in the EU of a 20% reduction in the Pillar I budget of the Common Agricultural Policy (CAP) of the European Union (EU) and spending the saved money via a subsidy on labour in primary agriculture. The impact of such a policy has been assessed with a computable general equilibrium (CGE) model and a partial equilibrium (PE) model. It is concluded that reallocation of Pillar I budgets to a coupled agricultural labour subsidy increased employment in agriculture, especially in agricultural sectors and regions that are relatively labour intensive. Average employment in agriculture in the EU increased with 1.6% in the CGE model and with 0.6% in the PE model. Agricultural production and environmental emissions from agriculture increased as well. At the same time, prices of agricultural outputs decreased. Value added including subsidies increased for agricultural labour, but total value added in agriculture decreased. The latter was especially explained by decreased land prices and land-related value added. Measured in terms of equivalent variation, total welfare in the EU decreased. Welfare costs equalled about 1400 € per full-time work equivalent in agriculture extra. These results show that policy makers should weigh carefully the pros and cons of the direct and indirect overall economic, environmental and land use impacts of a subsidy on agricultural labour at the expense of the Pillar I budget of the EU CAP.

     

繁昌县后备土地资源多宜性评价

合理评价后备土地资源适宜性是有效进行后备土地资源的开发利用和农业结构调整的前提。以繁昌县后备土地资源为例,以区域自然与人为因子对其进行初步筛选,在此基础上建立适宜性评价指标体系,结合生态位适宜度理论构建多宜性评价模型,运用加权平均模型和限制因子模型,对后备土地资源评价单元耕地、园地和林地3种土地利用类型的生态适宜度及限制性生态因子进行评价。结果表明:(1)繁昌县59.38%的后备土地资源不能进行开发,能够开发且对生态环境影响较小的后备土地资源为387.03hm2;(2)繁昌县生境环境较为良好,对各土地利用类型的适宜性较强;单一土地利用类型评价中后备土地资源生态位适宜度值最大值为0.966 5。其中,耕地适宜性最高,林地次之,园地最低;(3)多宜性评价表明繁昌县后备土地资源中耕地适宜性面积最大,林地次之,园地最小;(4)限制繁昌县后备土地资源开发利用的生态因子主要为:排水条件、pH值、障碍层深度。为改善后备土地资源开发利用的生境条件,今后应重视土地质量管理,加强农田水利设施建设,使其适合开发利用的需要。     

无锡市区耕地最低保有量测算及空间配置研究

耕地资源是社会经济稳定发展的物质基础。无锡市区近年来经济发展迅速，人均耕地面积仅7.3×10-3 hm2，粮食安全问题十分突出，人地矛盾十分尖锐。从粮食最低保有量的内涵出发，测算出无锡市区粮食最低保有量应为1.65×108 kg，进而通过选择粮食最低保有量、粮食复种指数等4个参数测算无锡市区2009～2020年耕地最低保有量为26 116 hm2。借助ArcGIS空间分析技术，选取耕地发展引导性和耕地发展约束性两类评价指标，对无锡市区现有耕地进行适宜性评价，将无锡市区耕地分为高度适宜区、中度适宜区、勉强适宜区、不适宜区4种类型。进而，结合耕地最低保有量，对耕地资源进行空间配置，发现锡山区的东北部、惠山区的西北部、新区的东南部等地区为无锡市区耕地最佳空间配置区，占最低耕地保有量的90％以上。〖     

Ecological Impacts of Chile's Neoliberal Policies, with Special Emphasis on Agroecosystems

Although Chile has been touted for developing a broad market liberalization and opening to the international economy, evidence is emerging that such neoliberal economic policies are dramatically impacting biodiversity and the natural resource base. This paper examines the evidence on the plundering of forestry and fishery resources and the damming and pollution of aquatic ecosystems. Although it may be argued that economic liberalization policies have been effective in reallocating agricultural resources toward more competitive activities, the ecological toll imposed by the expansion of export-led modern agriculture has been heavy. An effective agricultural development strategy in Chile should confront such ecological costs and should promote alternatives to high input agriculture.     

南京地区农业耗水量估算与分析

结合南京地区的农业生产状况 ,采用Penman -Montieth法计算参考作物的潜在蒸散 ,建立了本地区农业耗水的物理模型 ,计算了南京地区历年的农业用水量 ,并根据实际资料对模型进行了检验 ,结果表明该模型具有较高的精度 ,能够反映农业用水的实际情况。在分析该地区历年农业用水量变化及其用水现状的基础上 ,对影响农业用水量的因素和该地区的农业用水效率进行了分析和计算。南京地区农业用水量的大小很大程度上取决于耕地面积和各类作物播种面积的变化 ,同时也受当年气候状况的影响。南京地区多年的农业用水效率计算结果表明 ,该地区的灌溉水利用率较低。最后对该地区的水资源可持续利用提出了相应的建议     

政府主导、人口流动与城乡收入差距

中国经济增长具有典型的政府主导特征,通过构造一个包含城镇和农村经济产出的社会福利函数来分析政府主导型经济增长对城乡收入差距的影响关系,并基于中国城镇化发展实际分析了人口流动对城乡收入差距的影响,在此基础上提出研究假说,统计中国1997—2014年省际面板数据,采用泰尔指数测度城乡收入差距并分别进行静态和动态回归分析与检验。静态研究发现政府主导和人口流动显著地拉大了城乡收入差距,但是二者的交互项对城乡收入差距的确具有收敛效应,即随着人口流动的增加,政府主导对城乡收入差距的边际贡献会降低,同样随着政府主导的提升也会降低人口流动对城乡收入差距的边际贡献,这种影响关系在分区域的回归中依然成立,并通过了稳健性检验;动态研究发现全国和分区域中城乡收入差距的变动存在显著的正向路径依赖特征,全国层面政府主导显著地拉大了城乡收入差距,而人口流动及其与政府主导的交互项则显著地缩小了城乡收入差距,但分区域来看政府主导和人口流动对城乡收入差距的影响存在显著的区域异质性,并通过了稳健性检验。因此缩小城乡收入差距不应设置单一的政策目标,需要建立多方面的政策配套体系,逐步矫正政府主导型经济中造成的政府职能异化,精准识别地方财政收支量的规模和结构条件,扩大涉农业务投资的规模,激活农村经济发展活力;在城乡户籍制度改革中进一步打破城乡分割藩篱,大力发展非农产业,增加农民的非农就业机会,促进农民的非农化就业和城镇化迁移,提升城镇化发展质量;最终通过一系列的配套性制度安排,旨在加强支持农业发展和农村建设,促进农民收入增长的制度供给,实现城乡共享发展。     

四湖地区猕猴桃高效栽培模式与关键技术

针对地处四湖腹地的湖北省监利县果树资源利用率低及涝洼湿地的地理环境和生态条件 ,提出加快果树资源品种结构的调整 ,监北地势稍高 ,排灌方便的地方大力发展以猕猴桃为主的产业 ,同时利用架面下的行间土地套种蔬菜、瓜类作物、草莓、食用菌以及耐荫湿的中草药植物等立体生态农业的栽培模式 ,达到经济效益和生态效益的同步增长 ,与其相配套的栽培关键技术是采用地下通气排灌暗沟设施 ,重施有机质肥加磷肥 ;高畦壮苗定植 ;巧施追肥 ;适时排灌 ;树盘覆草保墒 ;人工辅助授粉和疏花疏果     

绿色技术进步、农业经济增长与污染空间溢出——来自中国农业水资源利用的证据

基于2002～2016年的省级面板数据,以农业水资源利用过程中的化肥源面源污染、厩肥源面源污染、灌溉过程碳排放及农药流失作为非合意产出,构建了以"蓝水-绿水"为中心的水资源分析框架,借助SBM模型和Malmquist-Luenberger指数,探析我国农业水资源利用过程的绿色技术进步情况,利用空间面板模型重点考察绿色技术进步、农业经济发展水平与农业水资源利用过程的污染排放之间的关系。化肥源面源污染排放量和农药流失量均表现出空间聚集的特性;在其他投入和产出不变的的既定条件下,促进农业水资源利用过程中的绿色技术进步能够缓解农业污染的局面;将农药流失污染作为非合意产出的农业水资源利用绿色技术进步带来的环境污染减排积极影响更强;农业经济发展水平与4类污染排放分别体现为倒N型、倒U型、正N型和倒N型的关系,随着农业经济发展水平的提升,我国绝大多数地区仍处于农药、化肥粗放使用的倒N型的上升阶段,农药流失和化肥施用引起的面源污染情况仍在加剧,农业经济发展水平与厩肥还田造成的面源污染相分离的状态逐渐消失,而农业水资源利用过程中产生的碳排放污染情况则不容乐观,大部分地区农业灌溉所产生的碳排放面临快速上升的趋势。