Changes In Water Productivity Research Articles

Economics of Water Scarcity and Efficiency

Over the coming decades, global freshwater withdrawals are expected to grow, especially in low- and middle-income countries. Unless there are significant improvements in the efficiency of water use by economies, freshwater stress, crises, and scarcity will worsen. This paper explores further the economic relationship between water use efficiency and scarcity. Because growing scarcity of freshwater in many regions and countries is not adequately reflected in markets, there are often insufficient incentives for investment and innovation to improve the efficiency of water use. To explore further changes in water use efficiency across countries, we conduct a panel analysis of water productivity changes for 130 countries from 1995 to 2020. Countries with lower initial levels of water use efficiency tended to have higher water productivity growth, whereas more agriculturally dependent economies displayed lower improvements in water use efficiency. Better institutional quality and capacity for innovation may also increase water use efficiency. We discuss the implications of these results for improving water use productivity in economies, and in particular, the opportunities and challenges for improving water markets and trades to alleviate water scarcity. We conclude by identifying further areas of research.

Evaluation of Automatic Irrigation System for Rice Cultivation and Sustainable Agriculture Water Management

The water-resource policy of South Korea has been changing from that of securing water to that of saving water through sustainable water management. Moreover, population aging in rural areas is leading to agricultural water-management problems. In this study, an automatic irrigation system for rice crops was investigated and compared with conventional irrigation, and changes in water productivity and required labor power were quantified. The effect of the proposed system on economic feasibility was verified on farmland by monitoring irrigation water and rice yields for three years. Under the automatic irrigation system, on-site water productivity improved by an average of 12.7% and the labor power required for paddy water management decreased by an average of 21.8% compared to the conventional irrigation system. The internal rate of return was 8.6% higher than the discount rate of 4.5%. The net present value was 406,411 KRW, and the benefit-cost ratio was 1.23. The results can serve as a reference for the on-site introduction of irrigation water-supply automation for sustainable water management and are expected to benefit farmers in saving water and reducing labor demands through sustainable agricultural activities.

Interannual variability of water productivity on the Eastern Snake Plain in Idaho, United States

Water productivity of crops must be increased to meet global demand for farm products while conserving limited water resources. Throughout the western United States, highly productive agricultural regions face more frequent and severe droughts and must allocate limited water resources among competing uses. Irrigated agriculture accounts for the majority of consumptive water use and has a proportionately important role in managing water shortage. Water productivity accounting helps inform objective decision making regarding these allocations at the regional, local, and farm scales. Publicly available data from several government agencies were re-analyzed and combined to quantify interannual changes in consumptive water use. Water productivity was determined using county-level crop survey data, satellite-based maps of evapotranspiration, and weather records for 21 counties located in the Eastern Snake Plain in the US state of Idaho for nine years during the period 2009–2019. Changes in water productivity over this period suggest trends that correspond to crop-specific irrigation practices, interannual variability in water supply, and regional attempts to curtail water consumption and improve water use efficiency. Results indicate that, at regional scales, water productivity for alfalfa can increase despite or as a result of water limited conditions, increasing from 0.5 to 1.75 kg ha-1 m-3 in some individual counties over the 10 year period, which may indicate increasingly efficient water use. Water productivity of barley and wheat crops also varied year to year, but did not demonstrate clear independence from total water consumption. Instead, irrigated areas and crops with adequate water supply follow a general trend of increased yield with increased water consumption, and the resulting water productivity approximately follows a linear function of actual evapotranspiration.

Exploiting genotype × management interactions to increase rainfed crop production: a case study from south-eastern Australia.

Crop yield must increase to keep pace with growing global demand. Past increases in crop production have rarely been attributable to an individual innovation but have occurred when technologies and practices combine to form improved farming systems. Inevitably this has involved synergy between genotypic and management improvements. We argue that research focused on developing synergistic systems that overcome clear production constraints will accelerate increases in yield. This offers the opportunity to better focus and multiply the impact of discipline-focused research. Here we use the rainfed grain production systems of south-eastern Australia as a case study of how transformational change in water productivity can be achieved with research focused on genotype × management synergies. In this region, rainfall is low and variable and has declined since 1990. Despite this, growers have maintained yields by implementing synergistic systems combining innovations in (i) soil water conservation, (ii) crop diversity, (iii) earlier sowing, and (iv) matching nitrogen fertilizer to water-limited demand. Further increases are emerging from synergies between genetic improvements to deliver flowering time stability, adjusted sowing times, and potential dual-purpose use. Collaboration between agronomists, physiologists, and crop breeders has led to development of commercial genotypes with stable flowering time that are in early phases of testing and adoption.

Indicating the wrong track? A critical appraisal of water productivity as an indicator to inform water efficiency policies

Water productivity is broadly used as an indicator to measure the success of policies aiming at efficient water management. Focusing on the agricultural sector, this paper provides the first critical analysis of the appropriateness of water productivity for this type of assessment. We apply Logarithmic Mean Divisia Index (LMDI) decomposition analysis together with descriptive statistical analysis to test our main hypothesis that is natural resources do not generate value added, and therefore changes in water productivity are related to well-known drivers of economic growth rather than to improvements in water efficiency. We use three different models with different levels of decomposition detail to identify the drivers of water productivity changes. Results show that indeed there is a weak relationship between changes in water productivity and water efficiency. In contrast, changes in water productivity are driven by changes in labor productivity and capital intensity. Thus, we discourage policy makers from using the indicator to monitor the progress on efficient water management or on decoupling between economic growth and water consumption. Rather, indicators independent from economic development such as biomass per volume of water should be used and the absolute volumes of water appropriated by society monitored.

Extraction of water from atmospheric air using double slope condensation surface

In this study, extraction of water from atmospheric air using double slope condensation surface is investigated. Solar energy as a heat source and Calcium Chloride (CaCl2) as the desiccant are used. The experimental apparatus involves two parts. The first part, which functions as absorber has nine channels containing mixture of Calcium Chloride (CaCl2) and sand while the second part, which functions as transparent and condensation surface has a prism shape. At night, the absorber is exposed to atmospheric air where Calcium Chloride (CaCl2) absorbs moisture from atmospheric air. At sunrise, the absorber is covered tightly with the transparent and condensation surface that allows the transmission of sun rays to the absorber. Condensate is collected in sloping channels that fixed at the bottom inner surface of transparent cover. The temperature of transparent surface, air-vapor mixture and absorber surface, solar radiations intensity and amount of collected water are recorded during the experiments at various operating days. Experimental measurements indicate that the condensed water productivity changes with ambient conditions. It is found that the maximum yield for Aug.19th,2015 was 735 gm /m2.day for accumulative solar radiation of about 7806 W.hr/m2.day. A mathematical model is developed to estimate the solar radiation intensity and amount of collected water. Its results are compared with the experimental data and a reasonable agreement between theoretical results and experimental measurements is attained

Assessing adaptation measures on agricultural water productivity under climate change: A case study of Huai River Basin, China

This study explored an integrated framework to assess the effectiveness of adaptation measures on the water productivity (WP) of the agricultural water management (AWM) system in the Huai river basin of China considering climate change impact. The adaptation measures include optimization of cropping pattern (OCP) and upgradation of irrigation techniques (UIT). The delta change method was used to downscale the climate variables from RCP4.5 and RCP8.5 of general circulation models (GCMs) during 2021–2050, the water footprint theory was used to estimate the spatial distribution of blue water to calculate the WP, and the nonlinear optimization model was used to seek optimal cropping pattern aiming at maximizing the system's WP. The changes in WP due to climate change and adaptation measures (e.g. combinations of OCP and UIT) were compared. Results indicated that WP under RCP4.5 and RCP8.5 would be 4.56% and 6.51% lower than those under the benchmark scenario, respectively. The mitigation rates to the negative impact of climate change on WP under RCP4.5 and RCP8.5 would be (1) 3.05% and 3.37% for the combination of spay irrigation technique and OCP, and (2) 4.34% and 4.59% for the combination of drip irrigation technique and OCP, respectively. It was revealed that the combination of drip irrigation and cropping pattern optimization could largely offset the adverse effect from climate change on WP under RCP4.5. Under such a scenario, the total plant areas of wheat and maize would reduce over the basin and so would the net export of crops in the basin; this would lead to a decrease in the crop trade benefit of 7.07 × 109 $ and a relief of 7.50 × 109 m3 of blue water loss. This study results could offer strategic decision support for long-term sustainable AWM of Huai river basin in a changing environment.

Implications of Water Scarcity for Water Productivity and Farm Labor

Increasing water scarcity causes a variety of pressures on agricultural production given current and growing food demands. This paper seeks to add to our understanding of water scarcity adaptations by explicitly addressing linkages between water scarcity, water productivity, cropping choices, and farm labor. We challenge the widespread claim that tightening foreign (especially Mexican) labor supply will necessarily result in less labor-intensive crop choices. Instead, by linking water scarcity and farm labor through the lens of water productivity we illustrate scenarios under which climate and technological change result in greater future labor demand in agriculture, including temporary and seasonal workers, largely due to water productivity increases resulting from switching to more labor-intensive crops. We conclude that a focus on crop choices is central to understanding changes in water productivity, labor demand, and technological innovations in response to water scarcity.

Water productivity in meat and milk production in the US from 1960 to 2016

Global demand for livestock products is rising, resulting in a growing demand for feed and potentially burdening freshwater resources to produce this feed. To offset this increased pressure on water resources, the environmental performance of livestock sector should continue to improve. Over the last few decades, product output per animal and feedstuff yields in the US have improved, but before now it was unclear to what extent these improvements influenced the water productivity (WP) of the livestock products. In this research, we estimate changes in WP of animal products from 1960 to 2016. We consider feed conversion ratios (dry matter intake per head divided by product output per head), feed composition per animal category, and estimated the water footprint of livestock production following the Water Footprint Network's Water Footprint Assessment methodology. The current WP of all livestock products appears to be much better than in 1960. The observed improvements in WPs are due to a number of factors, including increases in livestock productivity, feed conversion ratios and feed crop yields, the latter one reducing the water footprint of feed inputs. Monogastric animals (poultry and swine) have a high feed-use efficiency compared to ruminants (cattle), but ruminants consume relatively large portion of feed that is non-edible for humans. Per unit of energy content, milk has the largest WP followed by chicken and pork. Per gram of protein, poultry products (chicken meat, egg and turkey meat) have the largest WP, followed by cattle milk and pork. Beef has the smallest WP. These data provide important information that may aid the development of strategies to improve WP of the livestock sector.

Evaluation of Drip Irrigation System for Water Productivity and Yield of Rice

Core Ideas Drip irrigation improved the aerobic rice yield and water savings by 29 and 50%, respectively. The subsurface drip laid out at 0.8 m lateral distance with 1.0 L per hour dripper discharge irrigation system performed better in rice growth, physiology, and yield. Drip irrigation favored the root oxidizing power, canopy photosynthesis, and dry matter partitioning. There is a twofold increase in water productivity of aerobic rice under drip irrigation system. The use of drip irrigation in upland rice (Oryza sativa L.) cultivation is a contemporary water‐saving strategy. However, inadequate evidence is available related to consequential changes in water productivity on rice yield. The effects of distinctive drip irrigation treatments, namely differences in lateral distances (0.6, 0.8, and 1.0 m), dripper discharge rates (0.6 and 1.0 L per hour, Lph), irrigation methods (surface and subsurface), and the conventional aerobic rice production system (control) on, physiology and water productivity of rice were studied during the summer of 2012 and 2013. Grain yield significantly increased in the subsurface drip irrigation method laid out at 0.8 m lateral distance and in 1.0 Lph discharge rate (5389 kg ha−1) compared with control irrigation method (4181 kg ha−1). This treatment mounts up dry matter partitioning, leaf photosynthesis as well as root oxidizing power. In addition, drip irrigation in aerobic rice production system had twice the water productivity and stimulates longer roots with higher density compared with control irrigation method. The subsurface drip irrigation system with drippers/laterals of 0.8‐m distance with flow rate 1.0 Lph, in aerobic rice production system is a cost‐effective method and had the potential to save water (27.0%) without compromising grain yield in comparison to control irrigation method. This could be the promising technology to be recommended for aerobic rice production system.

Future crop yields and water productivity changes for Nebraska rainfed and irrigated crops

ABSTRACT We assessed future rainfed and irrigated crop yield and water productivity changes in Nebraska across multiple climate and emission scenarios using an empirical modeling approach. We found rainfed crops showed slightly increased crop water productivity while irrigated crops showed no change or decreased water productivity. Contrary to U.S.-wide studies reporting declines in crop yields, we projected Nebraska crop yields to increase overall with greatest increases in current rainfed fields due to combined effects from maximum and minimum temperatures. However, the increased rainfed yields are not sufficient to fully close the gap between rainfed and irrigated yields. Abbreviations: USDA: U.S. Department of Agriculture; RegCM4.3: ICTP Regional Climate Model version 4.3; NCEP: National Centers for Environmental prediction; DOE: U.S. Department of Energy; CGCM: Canadian Climate Centre general circulation model; GFDL: Geophysical Fluid Dynamics Laboratory general circulation model; CRCM: Canadian Climate Centre regional climate model; CCSM: National Center for Atmospheric Research general circulation model; HRM3: Hadley Centre’s Regional Model 3; HADCM3: Hadley Centre’s general circulation model; WRFG: the NCAR Weather Research and Forecasting model; CCCma: Canadian Centre for Climate Modelling and Analysis; CanESM2: Canadian Centre Earth System Model 2; ICHEC-EC: A European community Earth-System Model; IPCC: Intergovernmental Panel on Climate Change; RMSE: Root Mean Square Error

Low Water Productivity for Rice in Bihar, India—A Critical Analysis

Rice is the most important crop for food security and livelihoods of the rural population in Bihar, India. In spite of good soil and water resources, rice water productivity (WP) is very low in Bihar. Trends in WP and key factors influencing WP over 20 years (1991–2010) in 11 Bihar districts were analysed using panel data to help elucidate reasons for low WP values. The annual average rice yield of 938 kg/ha, WP of 0.22 kg/m3, and marginal physical productivity (MPP) of 249 g/m3 are very low in Bihar compared to both the national average for India and other rice growing areas in the world. Rice WP and MPP were higher for the garma (dry) season than for the kharif (monsoon) season. Temporal analysis showed that WP was slowly declining in most districts, while spatial analysis showed a significant variation in WP across the districts. Regression analysis showed that the availability of irrigation facilities, occurrence of flood and drought, and cropping intensity had significant influence on rice WP. Causes for temporal and spatial changes in WP are highlighted and actions to improve rice WP in Bihar are suggested.

Analysis of asymmetries in air pollution with water resources, and energy consumption in Iran.

Iran should pay special attention to its excessive consumption of energy and air pollution due to the limited availability of water resources. This study explores the effects of the consumption of energy and water resources on air pollution in Iran from 1971 to 2014. It utilizes the non-linear autoregressive distributed lag approach to establish a robust relationship between the variables which show that both long- and short-run coefficients are asymmetrical. The positive and negative aspects of the long-run coefficients of energy consumption and water resources were found to be 0.19, - 1.63, 0.18, and 2.36, respectively, while only the negative ones were significant for energy consumption. Based on the cumulative effects, it can be established that there are important and significant differences in the responses of air pollution to positive and negative changes in water productivity and energy consumption. In particular, CO2 gas emissions are affected by negative changes in H2O productivity both in terms of the total and the GDP per unit of energy use in Iran. In regard to short-run results, considerable asymmetric effects occur on all the variables for CO2 emissions. Based on the results obtained, some recommendations are presented, which policymakers can adopt in efforts to address the issues of pollution and consumption.

Evaluation of water harvesting and managed aquifer recharge potential in Upper Fara' basin in Palestine: comparing MYWAS and water productivity approaches

The Upper Wadi Fara' basin, located at the West Bank, Palestine, has an average annual rainfall of 500 mm, which occurs only during winter. Agriculture uses stored soil water and complimentary irrigation from groundwater. Water harvesting (WH) and managed aquifer recharge (MAR) therefore is essential for sustainable water resources management in the basin. This study focuses on the comparison between two methods to determine best practices for WH/MAR. The first method uses the change in water productivity and can be considered a one parameter cost benefit analysis (CBA). The other method concerns the multi year water allocation system (MYWAS), which uses water demand curves to evaluate economic scenarios. It is concluded that the highest cost effectiveness of WH/MAR measures in upper Wadi Fara' basin is reached when water is stored as soil water. However, this is a politically disputed measure in the Israel-Palestine shared aquifer. Both models are useful tools in decisive stakeholder participation processes.

Evaluation of water harvesting and managed aquifer recharge potential in Upper Fara' basin in Palestine: comparing MYWAS and water productivity approaches

The Upper Wadi Fara' basin, located at the West Bank, Palestine, has an average annual rainfall of 500 mm, which occurs only during winter. Agriculture uses stored soil water and complimentary irrigation from groundwater. Water harvesting (WH) and managed aquifer recharge (MAR) therefore is essential for sustainable water resources management in the basin. This study focuses on the comparison between two methods to determine best practices for WH/MAR. The first method uses the change in water productivity and can be considered a one parameter cost benefit analysis (CBA). The other method concerns the multi year water allocation system (MYWAS), which uses water demand curves to evaluate economic scenarios. It is concluded that the highest cost effectiveness of WH/MAR measures in upper Wadi Fara' basin is reached when water is stored as soil water. However, this is a politically disputed measure in the Israel-Palestine shared aquifer. Both models are useful tools in decisive stakeholder participation processes.

Sensitivity of crop water productivity to the variation of agricultural and climatic factors: A study of Hetao irrigation district, China

Crop water productivity is an important indicator of agricultural water use. Understanding the impacts of climatic and agricultural factors variation on crop water productivity will provide a theoretical basis for regional crop productivity improvement. In this study, crop productivities at two scales were estimated based on the analysis of the agricultural water use in Hetao irrigation district, China. The sensitivity analysis was used to explore the sensitivity of crop water productivity to the variation of climatic and agricultural factors. Contribution rate analysis method was adopted to quantitatively evaluate the driving force of water productivity changes due to the variation of climatic and agricultural factors during the study period. Results show that crop water productivity of wheat had an average of 0.85 kg/m3 over the study period at the field scale, and it had an average of 0.46 kg/m3 at the regional scale. Both displayed an obvious upward during the study period. Among the climatic factors, water productivity of wheat at both the field and regional scales had higher sensitivity to relative humidity and wind speed, and had a lower sensitivity to sunshine hours. Among the agricultural variables, the crop water productivity had a higher sensitivity to irrigation efficiency, and is less sensitive to the amount of fertilizer used. The increase of agricultural inputs and irrigation efficiency were the main factors contributing to water productivity increases in Hetao Irrigation district. Climatic variations within the study period had less impact on the water productivity of wheat.

Analysis of Spatial and Temporal Variations in Crop Water Productivity of the Rainfed Wheat for a Regional Scale Analysis

Analysis of Spatial and Temporal Variations in Crop Water Productivity of the Rainfed Wheat for a Regional Scale Analysis Water productivity is a suitable indicator in water potential analysis at a location. Hence in this study, changes in water use and productivity are studied in spatial and temporal scale simultaneously. Temporal changes in water productivity in Hamedan region (Iran), was determined with Standard Precipitation Index (SPI). To estimate regional water productivity, GIS and Kassam method were coupled to estimate the potential yield of rainfed wheat. Thus, layers of radiation and temperature were created using geo-statistical subprogram in GIS environment and subsequently, potential yield for the entire area were determined. To determine actual evapotranspiration, the region was discrete into homogeneous areas using Thieson method in Arcinfo software, and potential evapotranspiration of the crops were calculated by Cropwat software. Using the method recommended by FAO, these values were converted to actual evapotranspiration. The map of spatial coverage of the water productivity was prepared for the whole region by overlapping the two layers: the potential yield and the actual evapotranspiration. Results of this study indicate that the combined analysis of spatial and temporal characteristics is advantageous. This can help in carrying an effective analysis and results in a broader knowledge of the indicators under consideration. Amount of water productivity in drought condition in comparison with the other two conditions was higher and from geographical point of view, the southern parts of the region have higher potential production when compared to other locations of the province. The analysis shows that the variation in amount of active radiation received by the earth surface is causing these differences.

Late Maastrichtian to early Danian calcareous nannofossils at Elles (Northwest Tunisia). A tale of one million years across the K–T boundary

A detailed study of calcareous nannofossils of the Elles section (Tunisia) was extended over an interval of about 1 Myr including the K–T boundary. The late Maastrichtian assemblages are rich and well preserved. Pulses of surface water cooling, probably related to episodic upwelling are revealed by the increase in abundance of cool water taxa (mainly Kamptnerius magnificus, Nephrolithus frequens, Gartnerago spp.) in certain late Maastrichtian samples, paralleled by a decrease of the warm water species Watznaueria barnesae. A sensible decrease in abundance of Arkhangelskiella cymbiformis and its return to smaller specimens was also recorded at Elles, probably as the result of surface water productivity changes in the latest Maastrichtian. Some Maastrichtian samples at Elles contain Neobiscutum romeinii and Chiasmolithus? sp. These taxa, formerly thought to be Tertiary coccoliths, are here considered as truly Maastrichtian occurrences. As at El Kef, the Danian of Elles is characterised by successive blooms of surviving and newly evolved species. Though the abundance of calcareous nannofossils rapidly reached the same level as in the Maastrichtian, the lower diversity still points to a mesotrophic, poorly stratified marine environment. The reworking versus survivorship of Cretaceous species found in Danian samples remains an unresolved question, but a hypothesis of survivorship is also strengthened by the presence of several coccospheres of W. barnesae and Bidiscus rotatorius well above the boundary. The effect of the marine environmental change across an expanded K–T boundary section as Elles appears complex if seen through calcareous nannofossils. From a geological point of view, the K–T boundary floral turnover at Elles seems dramatically synchronous with the signatures of an extraterrestrial impact, superimposed on long-term, background environmental and climatic changes. However, a precise succession of events based on appearance/disappearance of nannofossil species across the Cretaceous/Paleocene transition is far from being unanambiguous.

The carbon isotope distribution in the deep ΣCO 2 and benthic foraminifers of the Alboran Basin, western Mediterranean: Implications for variations in primary production levels since the last deglaciation

High productivity in areas within the Alboran Sea could be responsible for a 0.9‰ 13C depletion of Uvigerina peregrina shells when compared to other western Mediterranean basins. At present however, the δ 13C variations of the total dissolved inorganic carbon of bottom waters do not exceed 0.2‰ within the Alboran basin, reflecting minor re-mineralization of organic matter. Thus, it is suggested that δ 13C values of modern U. peregrina can be linked to those of the pore water ΣCO 2 and that rain of particulate organic matter to the seafloor results in an important 13C gradient at the bottom water-sediment interface of the Alboran basin. Last deglaciation changes in the relative abundances of three species of endobenthic foraminifers, estimated through the following index: Log[( Melonis barleeanum + Globobulimina affinis)/( Uvigerina peregrina + 1)], record depth migrations within the sediments of the O 2 minimum level. These migrations are thought to correlate with surface water productivity changes. Low values of this index before approximately 13 kyr and after 9 kyr would indicate an enhanced flux of organic matter to the seafloor resulting itself from an increased surficial productivity. This is apparently supported by a high production of diatoms valves before 13 kyr, higher percentages of U. peregrina and lower Uvigerina δ 13C values before 13 kyr and after 9 kyr. In the time interval 9-6 kyr however, the absence of diatoms, the stronger Δδ 13C gradient between surface and subsurface dwelling planktonic foraminifers, suggest that recycling of the organic matter was intensified in subsurface waters. This event coincides in time with the deepening of the pycnocline at 9 kyr in the Alboran Sea, which marks the onset of present-day hydrographic conditions. It also coincides with the deposition of sapropel S1 and with the stagnation of the Eastern Mediterranean basin which induced a lower ventilation of Mediterranean Waters at intermediate depths. The relatively low organic carbon contents measured in one of the cores, apparently contradict the proposed scenarios. In fact, higher production levels do not necessarily imply a higher organic carbon content in the underlying sediments. Within well oxygenated bottom waters, the organic carbon preservation is also very sensitive to sedimentation rate as well as to near surface compaction effects on early diagenesis.