Upstream demand for water use by new tree plantations imposes externalities on downstream irrigated agriculture and wetlands*

Large‐scale tree plantations in high rainfall upstream areas can reduce fresh water inflows to river systems, thereby imposing external costs on downstream irrigation, stock and domestic water users and wetland interests. We take the novel approach of expressing all benefits and costs of establishing plantations in terms of $ per gigalitre (GL) of water removed annually from river flows, setting upstream demands on the same basis as downstream demands. For the Macquarie Valley, a New South Wales sub‐catchment of Australia’s Murray‐Darling Basin, we project changes in land and water use and changes in economic surpluses under two policy settings: without and with a policy requiring permanent water entitlements to be purchased from downstream parties, before plantation establishment. Without the policy, and given a high stumpage value for trees ($70/m³), upstream gains in economic surplus projected from expanding plantations are $639 million; balanced against $233 million in economic losses by downstream irrigators and stock and domestic water users for a net gain of $406 million, but 345 GL lower mean annual environmental flows. With the policy, smaller gains in upstream economic surplus from trees ($192 million), added to net downstream gains ($138 million) from sale of water, result in gains of $330 million with no reduction in environmental flows. Sustaining the 345 GL flow for a $76 million (406–330) reduction in gains to economic surplus may be seen to cost only $0.22 million/GL; but this is much lower than the market value of the first units of that water to agriculture and forestry.     

Economic effects of water recovery on irrigated agriculture in the Murray‐Darling Basin*

In October 2010, the Murray‐Darling Basin Authority (MDBA) proposed that a range of 3000–4000 GL per year, on average, of additional water be made available for the environment in the Murray‐Darling Basin (MDB) to mitigate the effects of what it considers to be inadequate environmental flows. To help quantify the costs of this water reallocation, a hydro‐economic model was constructed based on the 19 regions of the MDB. The model results indicate the following: (i) substantial reductions in surface water extractions of up to 4400 GL per year impose only a moderate reduction on net profits in irrigated agriculture, Basin wide, given competitive water markets, but the effects are much more pronounced in particular regions/catchments and (ii) the costs of the water reallocation are comparable with the amount budgeted by the Australian government to acquire water from willing sellers and increase environmental flows if inter‐regional water trade is unrestricted.     

Policy review of water reform in the Murray–Darling Basin,Australia: the “do's” and “do'nots”

The water reforms undertaken in the Murray–Darling Basin, Australia since 2007 have been viewed as a model for other countries seeking to respond to water insecurity. Here, a policy review is provided of this water reform and whether it delivers on key environmental objectives in the 2007 Water Act (the Act). The evaluation includes a review of the 2012 Basin Plan, a key instrument of the Act, and complementary policies associated with the acquisition of water entitlements for the environment via direct (reverse tenders) and indirect (infrastructure subsidies) means. Using the objects of the Act as a benchmark, an evaluation is provided of the following: (i) planned reductions in irrigation water extractions in the 2012 Basin Plan; (ii) risks associated with the 2018 amendments to the Basin Plan that, collectively, allow for an increase in irrigation water extractions of some 22 per cent, relative to the sustainable diversion limits specified in the 2012 Basin Plan; (iii) Basin‐scale environmental outcomes achieved, as of the end of 2018; and (iv) economic effects of direct and indirect methods of acquiring water for the environment. Findings from the review generate the “Do's” and “Do Nots” of water reform for Australia, and possibly other countries, when managing the trade‐offs between water for irrigation and the environment.     

Achieving environmental flows where buyback is constrained

Theory suggests that the development of common property increases national welfare, and consistent with this thinking Australia's Murray–Darling Basin (MDB) Plan uses a common property approach to recover environmental water rights in the national interest. Two water recovery instruments are used: purchasing water rights (buyback) from farmers, and saving water by subsidising irrigator adoption of technically efficient technology. A moratorium on buyback has focused environmental recovery on subsidised technically efficient technology adoption. Economists argue that national welfare is maximised via buyback and highlight the limitations of efficiency savings to recover sufficient environmental water. A risk is that water recovery targets may be reduced in future, limiting welfare gains from water reform. This article evaluates possible welfare trade‐offs surrounding environmental water recovery outcomes where arbitrary limits on buyback are imposed. Results suggest that, on average, strategies which attempt to obtain >1500 gigalitres (GL) of water from on‐farm efficiency investments will only provide sufficient resources to meet environmental objectives in very wet states of nature. We conclude that reliance on technically efficient irrigation infrastructure is less economically efficient relative to water buyback. Importantly, the transformation of MDB irrigation will significantly constrain irrigators' future capacity to adapt to climate change.     

An empirical assessment of the value of irrigation water: the case study of Murrumbidgee catchment*

Evaluation of value of irrigation water is essential for supporting policy decision making relating to investments in the irrigation sector, efficient allocation of irrigation water and water pricing and for crafting policies to compare the variable impacts of water reform within and across sectors of the economy. This paper asks the question of how much an established irrigator would pay for water and at what price farmers planning to expand the area they have under irrigation would consider paying for the right to access water. An analytical framework is developed to estimate the net present value of both annual and perennial agricultural activities in the Murrumbidgee catchment. Using these estimates the total value of water used in Murrumbidgee catchment is estimated. An aggregate water supply curve is derived for the catchment from where water may be acquired from irrigators for environmental flows.     

Exit fees and termination fees revisited: funding irrigation infrastructure in a manner compatible with water trade*

It has long been recognised that the mechanism for funding irrigation infrastructure in Australia may be incompatible with efficient trade in the rural water market. If the revenue received by an irrigation operator is dependent on the volume of water entitlements held in the operator’s region, out‐of‐region permanent water sales threaten the operator’s revenue stream, potentially leading to higher charges on remaining irrigators, encouraging an inefficient ‘rush for the exit’. In response, irrigation operators have imposed restrictions on permanent water trade, such as exit fees and termination fees, to protect their revenue stream. Previous economic analysis has suggested that exit fees, in particular, are a barrier to efficient trade in the water market and should be abolished. In contrast, this paper argues that allowing irrigators to cancel their water delivery rights without fees or charges leads to inefficient trade in the water market, hinders efficient on‐farm investment in sunk complementary assets and leads to inefficient network rationalisation decisions. Instead, the revenue stream of irrigation operators should be insulated from water trade decisions, through high termination fees, tying irrigation charges to the land, or tagging the obligation to pay delivery charges to the new owner of the traded water.     

Assessing the trade‐offs of increased mining activity in the Surat Basin,Queensland: preferences of Brisbane residents using nonmarket valuation techniques

The mining boom in Australia since 2003 has produced significant economic benefits for regional, State and National economies, creating new job opportunities and revenue flows. Despite the contribution of the resources sector to economic growth, questions are frequently raised about the concomitant negative social, economic and environmental impacts. The Surat Basin in southern Queensland is a traditional agricultural region with a small but growing coal mining sector and a rapidly developing liquefied natural gas industry (mainly associated with extracting coal seam gas). In this paper, the preferences of residents in Brisbane, the State capital, are explored in relation to the relative importance of social, economic and environmental impacts of the resource boom in the Surat Basin. A choice modelling experiment was conducted to assess the trade‐offs Brisbane residents would make (in monetary terms) between the economic benefits and the associated costs of increased mining activity on local communities. The results identify the strength of concerns about community and environmental impacts and can potentially be used to help evaluate the net benefits of resource development.     

Allocation trade in Australia: a qualitative understanding of irrigator motives and behaviour*

Governments in Australia are purchasing water entitlements to secure water for environmental benefit, but entitlements generate an allocation profile that does not correspond fully to environmental flow requirements. Therefore, how environmental managers will operate to deliver small and medium‐sized inundation environmental flows remains uncertain. To assist environmental managers with the supply of inundation flows at variable times, it has been suggested that allocation trade be incorporated into efforts aimed at securing water. This paper provides some qualitative and quantitative perspective on what influences southern Murray–Darling Basin irrigators to trade allocation water at specific times across and within seasons using a market transaction framework. The results suggest that while irrigators now have access to greater risk‐management options, environmental managers should consider the possible impact of institutional change before intervening in traditional market activity. The findings may help improve the design of intervention strategies to minimise possible market intervention impacts and strategic behaviour.     

‘Deal’ or ‘No Deal’? Impacts of Alternative Post‐Brexit Trade Agreements on UK Agriculture

Brexit will have important implications for UK agricultural commodity markets due to potentially significant changes to trade flows. We quantify the sectoral impacts on UK agriculture of three illustrative scenarios, which capture a broad range of potential trade arrangements: Bespoke Free Trade Deal , WTO Default and Unilateral Trade Liberalisation . It is estimated that the projected market impacts are relatively small if the UK negotiates a Bespoke Free Trade Agreement with the EU. The projected impacts are much greater under the two other scenarios, which capture potential trade arrangements if ‘no deal’ is reached. The high tariffs imposed under the WTO default scenario lead to significant adjustments in trade between the UK and EU‐27, with the impact on the domestic UK market depending on whether the UK is a net importer or a net exporter of the relevant commodity. All sectors experience price and production declines under the trade liberalisation scenario in which the UK unilaterally sets tariffs on imports from both the EU‐27 and the rest of the world to zero; the impacts are particularly severe in the beef and sheep sectors where international competition is very strong.     

中国收获面积差及其产量潜力情景分析

[目的]文章以提升耕地复种为切入点,从区域自然资源禀赋与利用的角度研究我国粮食产量潜力,能为国家科学优化水土资源配置,推进农业供给侧结构性改革提供有益参考。[方法]引入收获面积差的概念,在作物单产与耕地面积保持不变的前提下,从提升复种的角度估算我国收获面积差及其产量潜力。[结果]2005年左右网格尺度研究结果表明:第一,不同水资源分配情景下,中国可收获面积差在0.135亿~0.363亿hm~2(约合2亿~5.4亿亩)之间波动;第二,与不同农业土地利用水平下可能获得的作物产量相结合,该收获面积差最高可转化成7.4亿t的产量潜力;第三,最实际情况下,通过水资源、作物类型、灌溉措施3方面配置,我国拥有0.135亿hm~2(2亿亩)收获面积差,其可转化为1.17亿t的产量潜力,相对于现实产量5.97亿t,约增产19.6%。第四,长江中下游地区同时拥有好的水热条件与相对优良的灌溉设施,而该地区较大的收获面积差与产量潜力说明其水土资源利用还有较高的调整优化空间。[结论]粮食总产受作物单产、耕地面积、复种指数等3个方面综合影响,但前两大因素对我国粮食产量潜力的贡献已经非常有限。     

Effective use of public funding in the Murray‐Darling Basin: a comparison of buybacks and infrastructure upgrades

Policy instruments designed to increase environmental flows in the Murray–Darling Basin are compared using TERM‐H₂O, a detailed, dynamic regional CGE model. Voluntary and fully compensated buybacks are much less costly than infrastructure upgrades as a means of obtaining a target volume of environmental water, even during drought, when highly secure water created by infrastructure upgrades is more valuable. As an instrument of regional economic management, infrastructure upgrades are inferior to public spending on health, education and other services in the Basin. For each job created from upgrades, the money spent on services could create between three and four jobs in the Basin.     

休闲旅游农庄水生态承载极限研究——以四川省为例

随着生活水平的提高,人们越来越向往绿色生态的生活方式,然而,生态环境已经伴随着经济的发展不断恶化,水资源利用也逐渐偏离可持续发展理念。文章以可利用水资源量、人口和城镇化、农业用水、生态环境用水作为关键因素构建了休闲旅游农庄的水生态承载极限定量计算模型。通过对主要部门用水量和相关指标数据调查和总结,根据定量模型计算结果显示,总体看,四川省水生态承载能力足以维持远景规划,其中,成都平原、四川盆地、川东平行领谷区、川中丘陵区、川西高原等5个地区的水生态承载力分别为15 628万人、10 215万人、8 301万人、5 504万人、4 809万人。     

Integrated regional impact assessment of agricultural trade and domestic environmental policies

It remains challenging to derive general findings and conclusions from either economic theory or empirical studies on the relationship between international trade and the regional environment. Consequently, we aim to analyse environmental effects of agricultural trade policies in the Austrian Marchfeld region. We apply an integrated modelling framework that accounts for heterogeneity in agricultural production and environmental outcomes. Scenario analysis is applied to assess regional impacts of different trade policy scenarios. Sensitivity analyses reveal the relative influence of model parameters on outputs. The results indicate that lower domestic tariffs have small beneficial effects on the regional environment. The regional environmental impacts highly depend on the changes in world crop prices through global trade agreements. A laissez-faire market scenario that includes the elimination of trade barriers and agri-environmental payments (AEPs) leads to substantial environmental deterioration. Hence, the alignment of AEPs with WTO trading rules remains an important issue in the trade and environment debate.     

Double trouble: the importance of accounting for and defining water entitlements consistent with hydrological realities*

When entitlements to access water in fully allocated river and aquifers are specified in a manner that is inconsistent with the ways that water arrives, flows across and flows through land, inefficient investment and water use is the result. Using Australia's Murray Darling Basin as an example, this paper attempts to reveal the adverse economic and water management consequences of entitlement and water sharing regime misspecification in regimes that allow water trading. Markets trade water products as specified. When entitlements and the water sharing system are not designed in a way that has hydrological integrity, the market trades the water management regime into trouble. Options for specification of entitlement and allocation regimes in ways that have hydrological integrity are presented. It is reasoned, that if entitlement and allocation regime are set up in ways that have hydrological integrity, the result should be a regime that can autonomously adjust to climatic shifts, changes in prices and changes in technology without compromising environmental objectives.     

Economic cost of environmental flows in an unregulated river system*

This paper applies a stochastic dynamic programming framework, incorporating links to hydrological and biophysical models, to assess the economic costs of environmental flows in an unregulated river system in the Namoi Valley of northern New South Wales, Australia. Structural adjustment decisions are included in the model to account for farmer responses to changes in environmental flows through the introduction of a water sharing plan. The results of the analysis indicate that the proposed level of environmental flows reduces water extractions by around 6 per cent, and imposes an opportunity cost of less than 1 per cent in terms of reduced net income over a 20-year period.     

中国木质林产品贸易条件分析

贸易条件可以衡量某国或地区的贸易处境。该文系统分析了1981-2001年中国木质林产品贸易条件及其变化导致的贸易损益。分析表明,与原材、刨花板、废纸、家具不同,原木、锯材、单板、胶合板、纤维板、木制品、木浆及多数纸和纸制品等木质林产品净贸易条件和收入贸易条件在多数年份是改善的,其进出口价格变化使中国贸易收益增加。木片、家具是中国的大宗出口木质林产品,尽快改善其贸易条件对提高中国木质林产品贸易收益尤为重要。     

湄公河流域水资源开发利用现状

根据湄公河流域自然特征、水资源现状、水利工程现状及规划资料,分析湄公河各流域国水资源开发利用特点及未来趋势,为湄公河水资源可持续开发利用及我国同湄公河各流域国开展相关合作提供最基本的依据。研究结果表明,湄公河水资源开发利用率呈上升趋势;老挝未来将加快水电开发节奏,其规划水电总装机容量占湄公河总装机容量的70.0%;泰国对湄公河水资源的开发利用主要体现在农业灌溉方面,未来泰国灌溉引水有增加的趋势;柬埔寨和越南分别在湄公河干支流上有水电工程规划,但柬埔寨的用水需求主要体现在为保证其洪泛区土壤肥力,对湄公河上游雨季充足的洪峰流量的需求,越南是湄公河流域灌溉面积最大的国家,其主要的用水需求是旱季湄公河三角洲灌溉需水。     

Impacts of climate change on lower Murray irrigation*

This article evaluates irrigated agriculture sector response and resultant economic impacts of climate change for a part of the Murray Darling Basin in Australia. A water balance model is used to predict reduced basin inflows for mild, moderate and severe climate change scenarios involving 1, 2 and 4°C warming, and predict 13, 38 and 63% reduced inflows. Impact on irrigated agricultural production and profitability are estimated with a mathematical programming model using a two‐stage approach that simultaneously estimates short and long‐run adjustments. The model accounts for a range of adaptive responses including: deficit irrigation, temporarily following of some areas, permanently reducing the irrigated area and changing the mix of crops. The results suggest that relatively low cost adaptation strategies are available for a moderate reduction in water availability and thus costs of such a reduction are likely to be relatively small. In more severe climate change scenarios greater costs are estimated. Adaptations predicted include a reduction in total area irrigated and investments in efficient irrigation. A shift away from perennial to annual crops is also predicted as the latter can be managed more profitably when water allocations in some years are very low.     

汉代江淮地区陂塘水利发展及其环境效益

两汉时期,江、淮地区的陂塘水利对农业进步及生态环境改善产生了良好作用。筑堤蓄水,改变了降水及山川溪水的时空分布,可防洪防涝,保障农田灌溉用水,又能发展水产养殖;陂塘工程还改善了当地的人居环境,从而在一定程度上消除了这里暑湿卑下、疾疫多发而带来的不良社会影响。汉代陂塘水利及其产生的环境效益奠定了后世江淮流域农业发展的基础。     

黄河流域粮食虚拟水流动对水资源空间均衡性的影响

采用引力模型、彭曼公式测算黄河流域省区间粮食虚拟水流动量,基于环境、经济、社会维度,通过比较虚拟水流动存在与否情景下的基尼系数,分析黄河流域粮食虚拟水流动对水资源空间均衡性的影响。结果表明：在2018年黄河流域省区间粮食虚拟水流动中,山东、河南、陕西、内蒙古的粮食虚拟水、虚拟蓝水呈净流出;山西、甘肃、宁夏、青海的粮食虚拟水、虚拟蓝水则呈净流入;黄河流域省区间粮食虚拟水流动在环境、经济、社会维度下均一定程度上促进了水资源空间均衡,其中环境维度下的促进作用较为微弱。