Basin impacts of irrigation water conservation policy

Climate change, uncertain future water supplies, growing population, and increased water demands continue to raise the importance of finding cost-effective water conservation measures. Irrigated agriculture is the world's largest water user, so governments, donor organizations, water suppliers, and farmers continue to look for measures that would produce more crop per drop. Despite the importance of promoting water conservation in agriculture, little work has been done that integrates hydrologic, economic, institutional, and policy dimensions of water conservation. This paper presents an integrated basin scale analysis of water conservation subsidies for irrigated agriculture. A dynamic, nonlinear programming model is developed and applied for the Upper Rio Grande Basin of Colorado, New Mexico, and Texas, USA. Several potential public subsidies of drip irrigation are analyzed for their economic and hydrologic impacts at both the farm and basin levels. Results indicate that water conservation subsidies for drip irrigation produce several effects. These include greater on-farm implementation of water-conserving technology, less water applied to crops, more water consumed by crops, increased farm income, greater crop production, more land irrigated, and increased total water-related economic benefits for the basin. Findings provide a framework for designing and implementing water conservation policies for irrigated agriculture.     

Modeling economic and agro-environmental dynamics of potato production systems

Crop rotation and other input management practices are of particular interest for their potential impacts on economic and agro-environmental components of potato production. Although crop yield and experimental impacts of rotations of grains, oilseed and legume crops have been published for several experimental studies in Canada there are few models related to the economic and environmental dynamics of potato production. We describe a dynamic model which integrates environmental and economic processes in potato production. The potato rotation model consists of interconnected modules of irrigation and precipitation, soil characteristics, soil erosion, soil water, phosphorus, nitrogen, soil organic matter, farming operations, crop yield and the related calculation of economic return. While not all aspects of crop production have been interlinked, including nitrogen carry-over, this model is the first step in the analysis of experimental data for irrigated potato rotations conducted in southern Manitoba.      

A dynamic analysis of water footprint of Jinghe River basin

Water footprint in a region is defined as the volume of water needed for the production of goods and services consumed by the local people, Ecosystem services are a kind of important services, so ecological water use is one necessary component in water footprint. Water footprint is divided into green water footprint and blue water footprint but the former one is often ignored.In this paper waterJootprint includes blue water needed by agricultural irrigation, industrial and domestic water demand, and green water needed by crops, economic forests, livestock prochtcts, forestlalands and grasslands. The study calculates the footprint of the Jinghe River basin in 1990, 1995, 2000 and 2005 with quarto methods. Results of research show that water footprints reached 164.1 ×10^8m3, 175. 69 ×10^8m3 and 178. 45 ×10^8m3 respectively in 1990, 1995 and 2000 including that of ecological water use, but reached 77.68×10^8m3, 94.24×10^8m3, 92.92×10^8m3 and 111.36 ×10^8m3 respectively excluding that of ecological water use. Green water.footprint is much more than blue water footprint; thereby, green water plays an important role in economic development and ecological construction The dynamic change of water footprints shows that blue water use increases rapidly and that the ecological water use is occupied by economie and domestic water use. The change also shows that water use is transferred from primary industry to secondary industry In primary industry, it is transferred from crops farming to forestry, and animal agriculture. The factors impelling the change include development anticipation on econonomy; government policies, readjustment of the industrial structure, population growth, the raise of urbanization level, and structurul change of consumption, low level of waler-saving and poor ability of waste water treatment.With blue water use per unit, green water use per unit, blue water use structure and green water use structure, we analyzed the difference of the six ecologieal function districts of the Jinghe River     

Substitution between water and other agricultural inputs: Implications for water conservation in a River Basin context

Substitution of irrigation water with other agricultural inputs could be an important means to conserve water in the face of growing pressures on water resources from both nonagricultural water demands and environmental water requirements. This paper discusses the potential of such substitution through an empirical analysis based on a multiple-input crop production function at the field and farm scales complemented with a numerical modeling exercise at the basin scale. Results from the crop production function analysis show that under both crop yield and net profit maximization, water is a substitute to other crop inputs for high-value crops, and is a complement to water for low-valued crops. At the basin scale, an integrated economic-hydrologic river basin model is used to analyze the role of other factors in crop input substitution, including the spatial connections among water sources and demands, hydro-agronomic conditions, and institutional settings for water allocation. Results show that in the case study area, the Maipo River basin in Chile, where water is very scarce, moving from the current, input-constrained, situation to full optimization of water resources leads to an increase in all crop inputs, including water. In that case, 301 million m³ of additional water use results in additional net profits of USD 11 million. However, if the water fee is raised by a factor of eight while overall basin irrigation profits are maintained at the original, baseline level, a reduction of water withdrawals by 326 million m³ is traded off with costs of USD 43.2 million for other inputs. Irrigation districts with a high share of low-value crops have a low potential for substituting water with other crop inputs. Therefore, investments for water substitution should also be kept low in these areas.     

Economic Benefits Resulting From Irrigation Water Use: Theory and an Application to Groundwater Use

Traditional economic analysis using a crop production function approachhas assumed that all variable factors, including irrigation water, arefully employed in the crop production process. However, this paper firstdemonstrates that economic benefits of irrigation water areoverestimated when the crop production function, and therefore theirrigation water demand function, is expressed in terms of irrigationwater supplied, rather than consumptive irrigation water use. Second,the paper demonstrates that the magnitude of the estimation bias isproportional to the rate of irrigation water losses through leaching,runoff and evaporation. Consequently, the model misspecification problemwould lead to increased irrigation water use and reduce incentives forfarmers to adopt improved irrigation technologies.     

The blue, green and grey water footprint of rice from production and consumption perspectives

The paper makes a global assessment of the green, blue and grey water footprint of rice, using a higher spatial resolution and local data on actual irrigation. The national water footprint of rice production and consumption is estimated using international trade and domestic production data. The global water footprint of rice production is 784 km³/year with an average of 1325 m³/t which is 48% green, 44% blue, and 8% grey. There is also 1025 m³/t of percolation in rice production. The ratio of green to blue water varies greatly over time and space. In India, Indonesia, Vietnam, Thailand, Myanmar and the Philippines, the green water fraction is substantially larger than the blue one, whereas in the USA and Pakistan the blue water footprint is 4 times more than the green component. The virtual water flows related to international rice trade was 31 km³/year. The consumption of rice products in the EU27 is responsible for the annual evaporation of 2279 Mm³ of water and polluted return flows of 178 Mm³ around the globe, mainly in India, Thailand, the USA and Pakistan. The water footprint of rice consumption creates relatively low stress on the water resources in India compared to that in the USA and Pakistan.     

Local irrigation response to ethanol expansion in the High Plains Aquifer

Global ethanol production has grown rapidly due to national renewable fuel programs. Concern has grown over impacts that land conversion and crop displacement driven by ethanol feedstock production might have on water resources. In this paper, we examine irrigation decisions of agricultural producers in the Kansas portion of the High Plains Aquifer in response to local ethanol market expansion. To identify the effects of ethanol expansion on irrigation decisions, we examine field-level data on irrigation water use, irrigated acreage, and crop decisions for the years 2003–2017 for nearly 23,000 fields in Kansas. We measure the response of three irrigation decisions, (i) irrigated acreage, (ii) irrigation per acre, and (iii) total water use to the introduction and capacity expansion of an ethanol plant. We find that ethanol market expansion did lead to increases in irrigation water use. Specifically, a 10 % increase in ethanol capacity within 50KM increases annual water use by 0.22 % per field (4.8 acre-inches/field). We predict that ethanol markets accounted for about 4% of total irrigated water use in 2017.     

Input–output analysis of virtual water transfers: Case study of California and Illinois

Increasing pressures on water resources in the two economically important states of California (CA) and Illinois (IL) have created a need for critical information related to sustainable water use and management. This paper applies input–output (IO) analysis to evaluate water use and quantify virtual water transfers involving the two states. Results show that aquaculture requires the largest input of direct water per unit of economic output, followed by crops, power generation, livestock, mining, services, domestic, and industry. Low water use intensity industry and services sectors contributed the largest proportions of value added and employee compensation. In 2008, the two states were net virtual exporters, with CA exporting 1.3 times the net export volume of IL. More than 72% of virtual water exports for each state originated from the high total water use intensity but low value added crops sector, with irrigation and rainfall contributing 99% and 97% of the crop-related exports for CA and IL, respectively. Virtual water export volumes were 59% for CA and 71% for IL when compared to actual water use. These results highlight the need to consider water use efficiency and opportunity cost when managing water under scarcity conditions.     

Biofuel policies and the environment: Do climate benefits warrant increased production from biofuel feedstocks?

We examine whether climate benefits warrant policies promoting biofuel production from agricultural crops when other environmental impacts are accounted for. We develop a general economic-ecological modelling framework for integrated analysis of biofuel policies. An economic model of farmers' decision making is combined with a biophysical model predicting the effects of farming practices on crop yields and relevant environmental impacts. They include GHG emissions over the life cycle, nitrogen and phosphorus runoff, and the quality of wildlife habitats. We apply our model to crop production in Finland. We find that under current biofuel production technology the case for promotion of biofuels is not as evident as has been generally thought. Only reed canary grass for biodiesel is unambiguously desirable, whereas biodiesel from rape seed and ethanol production from wheat and barley cause in most cases negative net impacts on the environment. Suggested policies in the US and the EU tend to improve slightly the environmental performance of biofuel production.     

Complementarity between water pricing, water rights and local water governance: A Bayesian analysis of choice behaviour of farmers in the Krishna river basin, India

To ensure efficient water allocation and use, policy designers have adopted various strategies, including price setting, decentralising irrigation water management or improving water rights. Most of these strategies have been applied individually, without considering the complementary relationships between them. This paper uses a discrete choice model to analyse the scope for combinations of tools for irrigation water demand management and farmers' acceptance of these. In terms of local irrigation water governance, the presence or absence of collective irrigation water management, in the form of a Water Users Association, is considered. Water rights are specified in terms of the duration and quality of the entitlement and its transferability. Finally, four types of water pricing methods (area, crop, block and volumetric pricing) are considered. Using a choice experiment, we elicit the most preferred water pricing method, under different water rights situations, at different price levels and under various contexts for local irrigation water governance. Our results indicated that under conditions of improved water rights, preference for volumetric pricing increases, whilst the presence of a Water Users Association reduces this preference. Furthermore, it was found that using an appropriate combination of water demand management tools considerably increases the willingness to pay for a change in scenario.     

Water trade in Andalusia. Virtual water: An alternative way to manage water use

The main idea of this paper is to analyse the relationships between the productive process and the commercial trade with water resources used by them. For that, the first goal is to find out, by means of the estimation of virtual water, the exported crops which have the highest water consumption. Similarly, we analyse the crops that are imported and therefore, might contribute to save water. The second objective is to put forward new ways to save water by means of the virtual water trade.This first conclusion contradicts not only the comparative advantages theory but also the environmental sustainability logic. The previous conclusion is derived from the great exports of water via potatoes and vegetables, and also via citrus fruit and orchards; and, on the other hand, from the imports, such as cereals and arable crops, with lower water requirements. The second conclusion affirms as Andalusia utilises large amounts of water in its exports, and in turn, it does not produce goods with low water requirements, the potential saving would be very significant if the terms of our trade were the other way round. We are convinced that the agricultural sector must modify the use of water to a great extent in order to reach significant water savings and an environmental sustainability path.     

Are virtual water “flows” in Spanish grain trade consistent with relative water scarcity?

Virtual water adds a new dimension to international trade, and brings along a new perspective about water scarcity and water resource management. Most virtual water literature has focused on quantifying virtual water “flows” and on its application to ensure water and food security. Nevertheless, the analysis of the potential gains from international trade, at least from a water resources perspective, needs to take into account both spatial and temporal variations of blue (groundwater and stream flow) and green (soil moisture) water, as well as the socioeconomic and policy conditions. This paper evaluates whether Spanish international trade with grains is consistent with relative water scarcity. For this purpose, the study estimates the volume and economic value of virtual water “flow” through international grain trade for the period 1997-2005, which includes 3 years with different rainfall levels. The calculations show that Spain is a net virtual water “importer” through international grain trade. The volume of net virtual water “imports” amounts to 3420, 4383 and 8415 million m³ in wet (1997), medium (1999) and dry (2005) years, respectively. Valuing blue water at its shadow price or scarcity value, blue water “exports” oscillate between 0.7 and 34.2 million Euros for a wet and dry year, respectively. Overall, grain trade is apparently consistent with relative water scarcity as net imports increase in dry years. However, the evolution of grain exports, expressed as a variation in quantity and volume, does not match the variations in resource scarcity. A disaggregated crop analysis reveals that there are other factors, such as quality, product specialization or the demand for a standardized product, which also influence trade decisions and are not included in the notion of virtual water. These facts, among others, can therefore create potential distortions in the application of virtual water to the analysis of specific trade patterns. Nevertheless, from a water resources perspective, virtual water can bring important insights across countries for improving water and land management globally, fostering adaptation strategies to climate change and to transboundary resource management.     

宁夏平原天然状态下作物水分亏缺研究

本文以宁夏平原为案例,对天然状态下的农田水分平衡状况进行了深入的定量研究,采用长系列(1961～2001年)、短时段(月)和多种作物类型(8种)相匹配的操作方法,建立农田水量平衡模型,计算得到了宁夏平原各个县域单元、各种作物、逐年、逐月的有效降水、盈水量、亏水量值。结果表明:自然降水不能满足作物生长发育的需求,水分亏缺是宁夏平原天然状态下农田水分平衡的主要特征;不同作物水分亏缺程度差异较大;宁夏平原未来农业发展必须推行"以水定产"战略。     

Water Trade in the Southern Murray–Darling Basin

In this paper, we use TERM-Water, a bottoms-up regional computable general equilibrium model of the Australian economy, to examine the regional effects of expanding trade of irrigation water in the southern Murray–Darling basin. We find that water trading dampens the impact of water allocation cuts on gross regional product (GRP). The benefits of introducing trading within irrigation districts are greater than those of a further expansion of trade between regions. Permitting trade of seasonal allocations allows irrigators to reallocate water in reaction to climatic conditions and water availability; and it is this flexibility that enables GRP reductions to be minimised.     

Adoption of safer irrigation technologies and cropping patterns: Evidence from Southern Ghana

The new irrigation technologies introduced in sub-Saharan Africa aim at ensuring safer vegetable production when untreated waste water is used as irrigation water. This paper examines the adoption of safer irrigation technologies and crop choices among vegetable farmers, using cross-section data from urban Kumasi in Ghana. The study employed a two-stage conditional maximum likelihood approach to examine the impact of crop choices and farm-level characteristics on the adoption of safer irrigation technologies. The empirical results indicate that apart from household and farm characteristics such as access to extension agents, belonging to a farmer's organization and education, cropping patterns tend to influence adoption of irrigation technologies for safer vegetable production.     

Sustainability of national consumption from a water resources perspective: The case study for France

It has become increasingly evident that local water depletion and pollution are often closely tied to the structure of the global economy. It has been estimated that 20% of the water consumption and pollution in the world relates to the production of export goods. This study analyzes how French water resources are allocated over various purposes, and examines impacts of French production in local water resources. In addition, it analyzes the water dependency of French consumption and the sustainability of imports. The basins of the Loire, Seine, Garonne, and Escaut have been identified as priority basins where maize and industrial production are the dominant factors for the blue water scarcity. About 47% of the water footprint of French consumption is related to imported agricultural products. Cotton, sugar cane and rice are the three major crops that are identified as critical products in a number of severely water-scarce river basins: The basins of the Aral Sea and the Indus, Ganges, Guadalquivir, Guadiana, Tigris & Euphrates, Ebro, Mississippi and Murray rivers. The study shows that the analysis of the external water footprint of a nation is necessary to get a complete picture of the relation between national consumption and the use of water resources.     

Climate change impacts on irrigation water requirements: Effects of mitigation, 1990–2080

Potential changes in global and regional agricultural water demand for irrigation were investigated within a new socio-economic scenario, A2r, developed at the International Institute for Applied Systems Analysis (IIASA) with and without climate change, with and without mitigation of greenhouse gas emissions. Water deficits of crops were developed with the Food and Agriculture Organization (FAO)–IIASA Agro-ecological Zone model, based on daily water balances at 0.5° latitude × 0.5° longitude and then aggregated to regions and the globe. Future regional and global irrigation water requirements were computed as a function of both projected irrigated land and climate change and simulations were performed from 1990 to 2080. Future trends for extents of irrigated land, irrigation water use, and withdrawals were computed, with specific attention given to the implications of climate change mitigation. Renewable water-resource availability was estimated under current and future climate conditions. Results suggest that mitigation of climate change may have significant positive effects compared with unmitigated climate change. Specifically, mitigation reduced the impacts of climate change on agricultural water requirements by about 40%, or 125–160 billion m³ (Gm³) compared with unmitigated climate. Simple estimates of future changes in irrigation efficiency and water costs suggest that by 2080 mitigation may translate into annual cost reductions of about 10 billion US$.     

An integrated analysis of the effects of local water institutions on irrigated agriculture outcomes in the arid western United States

Irrigation water rights and their governance structures constitute the foundation of local water institutions and profoundly influence water resource allocations, irrigated agricultural productivity and other consumptive water uses in the arid climate zones. This article explores the regional structures of irrigation water rights and water governance and empirically analyses the priority effects of water rights on irrigated agriculture at the micro level in Idaho, an arid and semiarid state in the western United States. We integrate a unique data set of water rights and water supplies with agricultural features and environmental characteristics into our empirical analysis. Results indicate that seniority in water resources allocation has significant, positive effects on both the average crop revenue and crop water use efficiency. Local water rights structures differ significantly in seniority and water sources from region to region. In response to the heterogeneity in local water rights structures, the aforementioned effect of allocative priority of water rights on average crop revenue per hectare and crop water productivity varies significantly, reaching up to an 87% difference, when measured across regions. In addition, the priority effects of water rights are nonlinear, which reflects the influence of historical patterns of water rights establishment on water institutions to date.     

Analyses of water footprint of Beijing in an interregional input-output framework

Beijing is under severe water resource pressure due to the rapid economic development and growing population. This study quantitatively evaluates the water footprint of Beijing in an interregional input-output framework with a focus on blue water resources and uses. The inter-connections of water resources between Beijing and other provinces are analyzed with a sectoral specification. The results show that the total water footprint of Beijing is 4498.4 10⁶ m³/year, of which 51% is from the external water footprint acquired through virtual water import. Agriculture has the highest water footprint of 1524.5 10⁶ m³/year with 56% coming from external sources. The main virtual water provider for Beijing is Hebei, another water scarce region, from which Beijing receives virtual water of 373.3 10⁶ m³/year with 40% from agriculture. The results of this study suggest that the interregional trade coordination, especially for the main sectors with high water use intensity, is important for enhancing the efficiency of regional and national water resource utilization.     

黑龙江省农业水资源利用研究

水是地球上一切生命赖以生存、也是人类生活和生产中不可缺少的基本物质之一。20世纪以来,由于世界各国工农业的迅速发展,城市人口的剧增,缺水已是当今世界许多国家面临的重大问题,尤其是城市缺水状况,越来越加剧。黑龙江省水资源属于中国北方较多地区,但降水分布不均,春旱和夏涝对农业生产影响较大。农业水资源丰富的地区,应优先发展水稻。农业水资源较少的地区发展旱田节水灌溉,应优先选择菜瓜果类高效益作物和对生产影响较大的种子苗木等。其次是扩大玉米催芽坐水种面积。第三是附加值较高的经济作物。