河套灌区地下水氮污染状况

河套灌区浅层地下水氮浓度和地下水埋深的季节变化规律调查结果表明:3月地下水NO3--N和TN浓度显著高于5、7和9月,地下水埋深也比5月和7月深。不同类型的井水N浓度差异较大:农田与庭院的井水NO3--N浓度显著高于村庄附近的井水,而NH4+-N和TN则表现为庭院井水浓度显著高于农田和村庄。地下水氮形态以NO3--N为主,全年17.1%的水井地下水NO3--N浓度高于10 mg.L-1,最高达184.4 mg.L-1。在灌溉量和其他生产条件相同的情况下,沙壕渠试验站农场内施肥区井水NO3--N浓度[(17.55±15.02)mg.L-1]明显高于未施肥区[(7.67±4.48)mg.L-1],且65.5%的水样NO3--N浓度超过WHO规定的生活饮用水NO3--N浓度上限值(10 mg.L-1),而未施肥区仅有27.6%的水样超标。井水NO3--N的来源主要为农田氮肥与动物粪肥,当地地下水NO3--N污染已不容忽视。     

关中清灌区农田生态系统污染现状研究

对陕西关中地区清灌区土壤、粮食、地下水及农田退水中的重金属、含氮化合物等污染物进行了分析研究,结果表明：灌区土壤重金属含量在陕西土壤背景值范围内,主要粮食作物尚未受到污染（除F外）,但地下水已受到重金属、含氮化合物的污染。同时,灌区农田退水中三氮含量较高,直接排放渭河水体后,影响了渭河水质。另外还发现灌溉能减低土壤F污染。     

利用世界银行贷款灌溉农业二期项目江苏省项目区水环境评价

对利用世界银行贷款灌溉农业二期项目(1998年2002年)江苏省项目区的水环境进行了监测与评价。项目实施期间,对地表灌溉用水河段监测结果表明,各监测河段参评指标的单项污染指数及综合污染指数均小于1,地表灌溉水不构成单项指标污染和综合污染,其水质符合农业灌溉用水水质要求;对地表灌溉退水河段监测结果表明,退水河段中仅有部分监测指标比灌溉用水中的相应指标有所升高,但不构成综合污染,退水水质仍能满足其他地区农业灌溉用水水质要求;对地下灌溉水测井的监测结果表明,有个别地下灌溉井单项指标超标,但所测井的综合污染指数均远远小于l,对地下水环境未造成不利影响。     

高质量发展模式下内蒙古河套灌区的可交易水量

黄河流域必须推进水资源节约集约利用,推动流域高质量发展。水权交易是运用市场机制实现水资源优化配置,促进水资源高效流转的有效手段。可交易水量是水权交易的基础要件之一,如何在高质量发展模式下科学测算可交易水量,是保障转让方水资源安全,促进水权交易顺利实现的关键。文章提出高质量发展模式下水权交易中可交易水量的测算方法,为灌区开展水权交易,测算可交易水量提供理论依据。首先,充分考虑水权交易对转让方用水安全的影响,界定可交易水量是转让方在保障自身生产、生活、生态等用水的前提下,在水权交易中可转让的水量。其次,依据中国水权交易政策分析得出可交易水量来源于节水潜力,国内水权交易实践显示农业节水潜力是当前及未来可交易水量的主要来源。再次,遵循高质量发展模式下保障粮食安全、实现水资源节约集约利用的原则,提出农业节水潜力的估测方法。最后,分析可交易水量的影响因素,确定调整系数,提出农业节水潜力中能够转化为可交易水量的测算方法。将该方法应用于国家高质量发展战略的施力地区以及中国水权交易的典范——内蒙古河套灌区,得出2021—2025年内蒙古河套灌区农业节水潜力分别为11.0713亿m³、11.5496亿m³、12.0486亿m³、12.5692亿m³、13.1123亿m³。依据内蒙古河套灌区可交易水量影响因素分析以及内蒙古水权交易政策规定,取可交易水量调整系数为2/3,计算得出内蒙古河套灌区2021—2025年可交易水量为7.381亿m³、7.700亿m³、8.032亿m³、8.379亿m³、8.742亿m³,为内蒙古河套灌区乃至黄河流域测算可交易水量提供借鉴。     

基于GIS的沈阳沈抚灌区上游土壤质量现状评价

以沈阳沈抚灌区上游指定区域为研究对象,对停灌10多年来土壤中重金属镉和铬以及有机物石油烃进行了单因子指数法评价,同时运用Arcgis软件分析制定出了采样区域单项污染指数分布图,按照单项污染指数评价,结果表明:重金属总镉和总铬以清洁级为主,有机物石油烃以重污染为主。Arcgis插值分析得出空间分布图表明:重金属总镉含量不受灌渠分布影响。重金属总铬北部区域大于南部区域。灌渠对有机物石油烃含量影响明显,对于停灌10多年有机物石油烃修复效果,旱田作业要好于水田作业。     

Estimating irrigation water demand in the Moroccan Drâa Valley using contingent valuation

Irrigation water management is crucial for agricultural production and livelihood security in Morocco as in many other parts of the world. For the implementation of an effective water management, knowledge about farmers' demand for irrigation water is crucial to assess reactions to water pricing policy, to establish a cost-benefit analysis of water supply investments or to determine the optimal water allocation between different users. Previously used econometric methods providing this information often have prohibitive data requirements. In this paper, the Contingent Valuation Method (CVM) is adjusted to derive a demand function for irrigation water along farmers' willingness to pay for one additional unit of surface water or groundwater. An application in the Middle Draa Valley in Morocco shows that the method provides reasonable results in an environment with limited data availability. For analysing the censored survey data, the Least Absolute Deviation estimator was found to be a more suitable alternative to the Tobit model as errors are heteroscedastic and non-normally distributed. The adjusted CVM to derive demand functions is especially attractive for water scarce countries under limited data availability.     

Institutional design in transformation: A comparative study of local irrigation governance in Uzbekistan

The irrigation sector constitutes the backbone of Uzbekistan's economy, providing social and economic stability in the region. The sector collapsed with the fall of the Soviet Union, due to worsening of infrastructure conditions causing tensions among resource users. Subsequent irrigation management reforms were implemented in a top-down manner. More than a decade after the initial reforms – which established local Water Consumers Association (WCA) and transferred operation and maintenance responsibilities for on-farm irrigation canals – the poor performance of these associations is still apparent, illustrating the heritage of the strong role of state agencies in Uzbek water management that still affects collective irrigation management today. This paper identifies the necessary and sufficient conditions for successfully managing common pool resources (CPRs) and, more specifically, irrigation canal maintenance in the rural Bukhara region of Uzbekistan. Fifteen WCAs were examined regarding conditions that may facilitate successful irrigation canal maintenance. Methods involved focus group discussions and in-depth interviews with the associations concerned. Data gathered was analyzed using fuzzy-set qualitative comparative analysis. The results indicate that two paths of local factors can lead to well-maintained irrigation canals: (1) the combination of appropriate chairmanship skills with sustainable resource appropriation or (2) the combination of appropriate chairmanship skills with the presence of effective participatory governance. The results also illustrate the role of path-dependence and traditional co-production of irrigation management in Uzbekistan.     

灌区工程生态环境影响评价特点与展望

随着我国人口的增长及人民物质生活水平的不断提高,灌区工程作为粮食安全的重要保障,未来其建设步伐将不断向前迈进,而作为预防、治理生态破坏的基础,灌区工程开展生态环境影响评价的现实意义及作用将日益显著。本文介绍了大中型灌区工程主要生态环境影响,及灌区工程生态环境影响评价特点和重点,并对灌区工程生态环境影响评价进一步完善与发展进行了展望。     

乌鲁木齐市安宁渠蔬菜基地土壤重金属污染现状及潜在生态风险评价

为了认识蔬菜产地土壤重金属富集现状，探索其解决途径，为污染防治措施提供科学依据，促进无公害蔬菜生产，确保蔬菜质量安全。在乌鲁木齐北郊蔬菜地采集26个土壤样品和7个水体样品，分别测定样品中Hg、As、Cr、Cd、Pb和Zn 6种重金属的含量。采用地积累指数（I_geo）、污染负荷指数（PLI）、潜在生态风险评价（RI）对蔬菜地土壤重金属污染及潜在生态风险进行分析。通过土壤与水样的结合，采用主成分分析法进行污染来源分析，结果表明：（1）乌鲁木齐安宁渠蔬菜基地土壤中Hg、Cr和Zn重金属含量的均值分别为新疆土壤背景值的5.74、1.74、1.52倍，其中Cd含量的均值是国家二级标准的2.69倍。地下水中Cr含量均值超过国家灌溉水限制标准，是其8.89倍。（2）6种重金属I_geo的平均值依次为Cd > Hg > Cr > Zn > As > Pb，其中Cd属于中-强度污染，Hg为中度污染，Cr为轻度污染，Zn、As和Pb均为清洁水平。研究区土壤区域污染负荷指数PLI_zone为1.91，属于中度污染，其中Cd的贡献率最大，为56%，其次是Hg，贡献率为22%。土壤RI均值为673.1，属于严重潜在生态风险态势。（3）研究区土壤Pb、Cr和Zn，主要来自交通和农业活动等人为污染，As、Cd主要受自然母质和大气沉降的影响。该蔬菜基地潜在生态风险主要来自Cd和Hg，建议在农业生产中防范Cd、Hg的污染。     

Investments in agricultural water management for poverty reduction in Africa: Case studies of Limpopo,Nile, and Volta river basins

Much of Sub‐Saharan Africa is burdened with water scarcity and poverty. Continentally, less than four percent of Africa's renewable water resources are withdrawn for agriculture and other uses. Investments in agricultural water management can contribute in several ways to achieving the Millennium Development Goals of eradicating extreme poverty and hunger and ensuring environmental sustainability. Increased yield and cropping area and shifts to higher valued crops could help boost the income of rural households, generate more employment, and lower consumer food prices. These investments can also stabilize output, income and employment, and have favourable impacts on education, nutrition and health, and social equity. Investments in agricultural water management can cut poverty by uplifting the entitlements and transforming the opportunity structure for the poor. The overall role of investments in agricultural water management in eradicating hunger and poverty is analyzed. This paper contributes to the present debate and efforts to identify strategies and interventions that can effectively contribute to poverty reduction in Africa. It provides an overview of population growth, malnutrition, income distribution and poverty for countries in three case study river basins — Limpopo, Nile, and Volta. With discussions on the contribution of agriculture to national income and employment generation, the paper explores the linkages among water resources investments, agricultural growth, employment, and poverty alleviation. It examines the potential for expansion in irrigation for vertical and horizontal growth in agricultural productivity, via gains in yield and cropping area to boost the agricultural output. Factors constraining such potential, in terms of scarcity and degradation of land and water resources, and poor governance and weak institutions, are also outlined. The paper argues that increased investments in land and water resources and related rural infrastructure are a key pathway to enhance agricultural productivity and to catalyze agricultural and economic growth for effective poverty alleviation.