Alleviate Water Shortages Research Articles

Quantitative analysis on sensitive factors of runoff change in Fenhe watershed based on integration approach

Abstract. The runoff of the Fenhe River flowed into the Yellow River (RRY) is reducing significantly due to the influence of climate change and human activities. It is generating bad situation of shortage of water resources and led to the deterioration of ecological environment of Shanxi Province. At the same time, the reduction in RRY causes the runoff reduction in Yellow River and exacerbated the water resources shortage of the middle area of the Yellow River. Therefore, it is important to alleviate water shortage and develop the soil and water conservation measurements and regional water policy by analyzing the influence of human activities and climate change on the RRY. The existing study quantified the reduction in amount of RRY which caused by human activities and climate change using statistical methods and watershed hydrological model. The main results of the study were as follow: Using hydrological variation diagnosis system, the variation characteristics of long time series of measured annual runoff were analyzed in Hejin station that is the Fenhe River control station. The results showed that the runoff of Fenhe River run into Yellow River declined year by year, in 1971, fell the most obviously. The impact of LUCC on runoff was calculated using the method of area ratio in the Fenhe River basin. Human activities were major factor in the reduction of RRY than the climate change, contributed 83.09 % of the total reduction in RRY, Groundwater exploitation gave the greatest contribution to the decrease in RRY in the scope of several kinds of human activity (30.09 %), followed by coal mining (26.03 %), climate changed contributed 19.17 % of the total reduction of RRY, and the decrease of precipitation contributed 20.81 %. But the variation of air temperature and wind speed would result in the increase of the amount of RRY.

The Use of Desalination Technologies to Alleviate Water Shortages in Sub-Saharan Africa (SSA): Challenges and Recommendations

<p><em>Water scarcity is a major and growing problem in SSA. A SSA country (South Africa) has adopted desalination as a strategy for dealing with water shortages; while the construction of new desalination plants have been proposed in some others (Ghana, Namibia and Cape Verde). </em><em>This review paper </em><em>examines the use of desalination technologies for augmenting supplies in sixteen SSA countries, using data derived mainly from published literature. Results reveal that the usage of desalinated freshwater to augment supplies in the region is relatively recent; however the usage is on the increase, especially in countries with arid climate. Several factors including massive failures of </em><em>public water supply systems, increases in the demand for freshwater, rapid and high rates of urbanization, population growth and the reoccurring droughts</em><em> account for increases in the demand for desalination technologies in SSA.</em><em> </em><em>Many critical issues and constraints make the desalination option</em><em> neither the most feasible nor a priority for</em><em> water supplies within the humid parts of SSA. </em><em>The paper recommends that for quality and sustainable service delivery to be attained in the region</em><em>, governments should develop alternative freshwater sources,</em><em> address infrastructural decay, employ new management strategies in the water sector and distribute water infrastructure equitably. </em><em></em></p>

An Ameliorative Whale Optimization Algorithm for Multi-Objective Optimal Allocation of Water Resources in Handan, China

With the deepening discrepancy between water supply and demand caused by water shortages, alleviating water shortages by optimizing water resource allocation has received extensive attention. How to allocate water resources optimally, rapidly, and effectively has become a challenging problem. Thus, this study employs a meta-heuristic swarm-based algorithm, the whale optimization algorithm (WOA). To overcome drawbacks like relatively low convergence precision and convergence rates, when applying the WOA algorithm to complex optimization problems, logistic mapping is used to initialize swarm location, and inertia weighting is employed to improve the algorithm. The resulting ameliorative whale optimization algorithm (AWOA) shows substantially enhanced convergence rates and precision than the WOA and particle swarm optimization algorithms, demonstrating relatively high reliability and applicability. A water resource allocation optimization model with optimal economic efficiency and least total water shortage volume is established for Handan, China, and solved by the AWOA. The allocation results better reflect actual water usage in Handan. In 2030, the p = 50% total water shortage is forecast as 404.34 × 106 m3 or 14.8%. The shortage is mainly in the primary agricultural sector. The allocation results provide a reference for regional water resources management.

Chemical Clogging Behavior in Drip Irrigation Systems Using Reclaimed Water

Abstract. Reusing reclaimed water in agricultural irrigation has become an effective way to alleviate water shortages in agriculture. However, the multiple substances in reclaimed water and their coupling effects easily lead to emitter clogging when using drip irrigation technology. The microorganisms present in reclaimed effluents secrete extracellular substances and absorb large amounts of solid particles, ions, nutrients, and organic matter and thus become the main part of the clogging substance. Meanwhile, traditional drip irrigation systems converted from irrigation to both irrigation and fertilization and the water-fertilizer coupling effects result in more chemical precipitation. Determining whether the chemical process has a significant impact on clogging and understanding the mechanism of this process was considered a difficult and important research question. For this reason, an indoor experiment, under a controllable environment, for drip irrigation emitter clogging using both reclaimed water with three Ca2++Mg2+ concentrations and groundwater was carried out. Several precise testing methods, such as x-ray diffraction, were applied to identify the mineral components in the clogging substances, and their characteristics and impacts on clogging were systematically explored. The results indicated that the emitter clogging characteristics were coincident under different treatments when using reclaimed water, and chemical precipitates were found in all treatments. Higher Ca2++Mg2+ concentrations led to more serious emitter clogging. The discharge ratio variation and Christiansen coefficient of uniformity for the reclaimed water treatments were lower than those for the groundwater treatment. Meanwhile, the total weights of the clogging substances were 5.6% to 58.8% higher. There were sufficient mineral components in the clogging substances, and they were identified as quartz, silicate, carbonate, and salt. Their contents all showed significant linear correlations with the degree of emitter clogging (R2 > 0.64, p < 0.05), which indicated that mineral components increased as the system continued operation. Among them, salt and silicate were linearly correlated to quartz contents, as they mainly originated from the water used for drip irrigation. However, carbonate contents increased in an exponential pattern with quartz contents (R2 > 0.67, p < 0.01), which demonstrated that carbonate was the main mineral component formed during the clogging process and the key component that increased clogging. The results obtained in this study provided insights into the chemical clogging process and the targeted chemical precipitates to be dealt with when using reclaimed water for drip irrigation. Keywords: Chemical precipitation, Emitter, Microirrigation clogging, Reclaimed water application.

Supply and Demand Analysis of Water Resources based on System Dynamics Model

Humans require clean water for industrial, agricultural, domestic and ecological purposes. Due to climate change and population increase, the lack of clean water resources is becoming more and more serious. A system dynamics model of water resources is proposed for alleviating water shortage, changing the imbalance between supply and demand, promoting sustainable patterns of consumption and production, protecting and managing water resources. First, a water supply and demand model combining principles and methods of system dynamics was constructed by analyzing the factors that influence water resources. The model is divided into five subsystems according to the water's purpose, i.e. a supply amount subsystem, an industrial water subsystem, an agricultural water subsystem, an ecological and domestic water subsystem, and a sewage water subsystem. In the model, the supply and demand index can indicate whether scarcity occurs as well as the degree of scarcity. The province of Shandong, China was picked as object of research. Relevant statistical data were analyzed to predict the supply and demand index in Shandong in 15 years using the model. Water scarcity in Shandong is explained through social and environmental drivers by addressing physical and economic decline. Finally, an intervention plan was formulated to avoid water shortage from occurring in the next 15 years.

Virtual water trade of agricultural products: A new perspective to explore the Belt and Road

The Belt and Road is an initiative of cooperation and development that was proposed by China. Moreover, most of the spanning countries faced water shortages and agriculture consumed a lot of water. Virtual water links water, food and trade and is an effective tool to ease water shortages. Therefore, this paper aims to understand the Belt and Road from the new perspective of virtual water trade of agricultural products. We considered agricultural products trade from 2001 to 2015. On the whole, the results indicated that China was in virtual water trade surplus with the countries along the Belt and Road. However, in terms of each country, >40 spanning countries were in virtual water trade surplus with China and eased water shortages. Russia had the largest net imported virtual water from China. Furthermore, the proportion of the grey water footprint that China exported to the spanning countries was much higher than that imported, no matter from the whole or different geographical regions. Moreover, more than half of the countries' virtual water trade with China conformed to the virtual water strategy, which helped to ease water crises. Furthermore, the products that they exported to China were mainly advantageous products that each spanning countries have. Virtual water trade is a new perspective to explore the Belt and Road. Agricultural products trade with China definitely benefits both the countries along the Belt and Road and China from the perspective of virtual water. The findings are beneficial for the water management of the countries along the Belt and Road and China, alleviating water shortages, encouraging the rational allocation of water resources in the various departments. They can provide references for optimizing trade structures as well.

Assessing the effects of adaptation measures on optimal water resources allocation under varied water availability conditions

Human activities and climate change have altered the spatial and temporal distribution of water availability which is a principal prerequisite for allocation of different water resources. In order to quantify the impacts of climate change and human activities on water availability and optimal allocation of water resources, hydrological models and optimal water resource allocation models should be integrated. Given that increasing human water demand and varying water availability conditions necessitate adaptation measures, we propose a framework to assess the effects of these measures on optimal allocation of water resources. The proposed model and framework were applied to a case study of the middle and lower reaches of the Hanjiang River Basin in China. Two representative concentration pathway (RCP) scenarios (RCP2.6 and RCP4.5) were employed to project future climate, and the Variable Infiltration Capacity (VIC) hydrological model was used to simulate the variability of flows under historical (1956–2011) and future (2012–2099) conditions. The water availability determined by simulating flow with the VIC hydrological model was used to establish the optimal water resources allocation model. The allocation results were derived under an extremely dry year (with an annual average water flow frequency of 95%), a very dry year (with an annual average water flow frequency of 90%), a dry year (with an annual average water flow frequency of 75%), and a normal year (with an annual average water flow frequency of 50%) during historical and future periods. The results show that the total available water resources in the study area and the inflow of the Danjiangkou Reservoir will increase in the future. However, the uneven distribution of water availability will cause water shortage problems, especially in the boundary areas. The effects of adaptation measures, including water saving, and dynamic control of flood limiting water levels (FLWLs) for reservoir operation, were assessed and implemented to alleviate water shortages. The negative impacts from the South-to-North Water Transfer Project (Middle Route) in the mid-lower reaches of the Hanjiang River Basin can be avoided through the dynamic control of FLWLs in Danjiangkou Reservoir, under the historical and future RCP2.6 and RCP4.5 scenarios. However, the effects of adaptation measures are limited due to their own constraints, such as the characteristics of the reservoirs influencing the FLWLs. The utilization of storm water appears necessary to meet future water demand. Overall, the results indicate that the framework for assessing the effects of adaptation measures on water resources allocation might aid water resources management, not only in the study area but also in other places where water availability conditions vary due to climate change and human activities.

Sustainability of mega water diversion projects: Experience and lessons from China

Water availability and water demand are not evenly distributed in time and space. Many mega water diversion projects have been launched to alleviate water shortages in China. This paper analyzes the temporal and spatial features of 59 mega water diversion projects in China using statistical analysis. The relationship between nine major basins is measured using a network analysis method, and the associated economic, environmental and social impacts are explored using an impact analysis method. The study finds the development of water diversion has experienced four stages in China, from a starting period through to a period of high-speed development. Both the length of water diversion channels and the amount of transferred water have increased significantly in the past 50years. As of 2015, over 100billionm3 of water was transferred in China through 16,000km in channels. These projects reached over half of China's provinces. The Yangtze River Basin is now the largest source of transferred water. Through inter-basin water diversion, China gains the opportunity to increase Gross Domestic Product by 4%. However, the construction costs exceed 150 billion US dollars, larger than in any other country. The average cost per unit of transferred water has increased with time and scale but decreased from western to eastern China. Furthermore, annual total energy consumption for pumping exceeded 50billionkilowatt-hours and the related greenhouse gas emissions are estimated to be 48milliontons. It is worth noting that ecological problems caused by water diversion affect the Han River and Yellow River Basins. Over 500 thousand people have been relocated away from their homes due to water diversion. To improve the sustainability of water diversion, four kinds of innovative measures have been provided for decision makers: national diversion guidelines, integrated water basin management, economic incentives and ex-post evaluation.

(Invited) Membrane Science and Technology for Water-Energy-Food Nexus Applications

Around the world, drought inflicts an increasingly unpredictable, frequent and devastating toll on human activities, ranging from, for example, struggling to secure access to sufficient clean water to simply survive, leading to political unrest and instability, increasing the cost of agriculture and manufacturing operations, and damaging the environment, both directly and indirectly. Climate change exacerbates stress on both water supply and demand. Water and energy are inexorably linked, with enormous volumes of water required to generate energy in many cases and large energy inputs required to purify water. In the U.S., thermoelectric power plants account for 41% of total water withdrawals, with nearly all the water requiring some form of purification before use. Horizontal drilling and hydraulic fracturing unleashed a sea of valuable hydrocarbons in the U.S., revitalizing the chemical industry, weakening dependence on foreign energy sources, and reducing oil and gas prices worldwide. However, oil and gas production comes at a substantial price in terms of the amount of water required and the amount of flowback or produced water generated. In many cases, for every barrel of oil produced, 5 or more barrels of water are also produced. This water is contaminated and requires substantial cleanup (i.e., energy input) for any form of beneficial use. An additional indicator of the importance of water is its significance for economic activity. It’s estimated that every million USD of economic activity requires 22,000 m3 of water per year; the faster our economies run, the more clean water we need. However, the world is not at a loss for water. We have more water than we could ever use. But, 96.5% of it is in the oceans, too contaminated with salt for many anthropogenic uses. Of the 2.5% that is freshwater, nearly 70% of it is locked in glaciers and icecaps, leaving precious little water that is both fresh and available, often not in locations where it is most needed. Membrane science is alleviating water shortages, weakening the linkage between energy and water, and arresting the environmental damage occurring due to agricultural runoff (e.g., uncontrolled algal blooms), conventional and unconventional oil and gas production, and energy generation based on fossil fuels. A “moonshot for water” has been proposed in the U.S. to reduce the cost of desalination to be comparable to that of conventional drinking water costs. Disruptive, membrane-based technologies will lead the way in bringing about this revolution. Membrane-based seawater desalination is already the least energy intensive way to desalinate seawater, and membranes are increasingly used for wastewater treatment and reuse. Basic and applied science discoveries are paving the way for next generation membranes that will be highly selective, fouling resistant, low energy and highly resilient. Rational control of pore size and pore size distribution in membrane filters is critical to such developments. Discovering and developing the underpinning science to predict ion and water transport across membranes designed to separate ions from water is already providing profound insight regarding molecular strategies to tailor next generation membranes. This presentation will frame the water/energy nexus challenges and opportunities and provide a glimpse of potential paths forward to supply the world with low energy, abundant access to clean water.

Advanced investigation on the change in the streamflow into the water source of the middle route of China's water diversion project

To alleviate water shortage in northern China, the middle route of the South to North Water Diversion Project (MRP) was constructed by the Chinese government. A dramatic reduction in the annual streamflow into Danjiangkou Reservoir (ASDR), the water source of MRP, during 1990 has raised some concerns on the MRP's operation. This paper employed an advanced segmented regression model with more recent data to have a clear picture and understand the changing pattern of the ASDR. Our study first revealed a zigzag changing pattern (decreasing‐increasing‐decreasing‐increasing) of ASDR during 1960–2013, which was supported by statistical criteria compared with a monotonic or single abrupt change. Particularly, the significantly decreasing trend from 1990s was reversed after 2000, and such change may relieve the concern about the water availability in the future. Sensitivity analysis showed that changes in streamflow were largely influenced by the combined effects of precipitation (P) and potential evapotranspiration (ET0) and were more sensitive to P than ET0. As ET0 is estimated from other primary variables, further analysis was conducted to understand the sensitivities of ET0 to its primary driving variables (wind speed, actual vapor pressure, temperature, and sunshine duration) and indicated that ET0 is mostly sensitive to actual vapor pressure during 1960–2013. The findings will assist the MRP's operation and management. Moreover, the results in this study also indicate that an adaptive water diversion plan, rather than the current plan with a constant annual amount of diversion water, might be a better option in the MRP's operation.

Rainwater harvesting in North-East India: A strategy for alleviate water shortage

Rainwater harvesting in North-East India: A strategy for alleviate water shortage

Predicting remobilization characteristics of cobalt in riparian soils in the Miyun Reservoir prior to water retention

The Middle Route of the South-to-North Water Diversion Project is a significant water diversion project intended to alleviate water shortages in the north China plains, especially for the capital (Beijing). After water retention, the potential ecological risk of metal contamination in the riparian soils of the Miyun Reservoir (MYR) to water quality has raised public concern. The remobilization characteristics of cobalt (Co) in MYR riparian soils are still unknown. Riparian soil samples (considering five different land use types and three vertical elevations) were collected from the MYR prior to water impoundment. Total Co concentrations, soil properties, total Co in soil solution, Co chemical fractions and labile Co measured by diffusive gradients in thin films (DGT) are applied to investigate the Co remobilization characteristics. The results showed that the total concentrations of Co (Ctotal-Co) were approximately equal to background values of Co in Beijing and China at most of the sites. The highest values of Ctotal-Co were observed at 140m and 145m in recreational land (S3), which may be influenced by the anthropogenic activities. No obvious differences in Ctotal-Co and DGT-labile Co (CDGT-Co) were found with the variation of land use types and vertical elevations in the soils of the MYR. CDGT-Co made up 9%-52% of the total dissolved Co, with an average value of 25%, indicating that Co in the soil solution was partially sustained by the solid phase. The highest CDGT-Co were observed in grassland and mountain land, indicating that the previous intensive mining in the upstream areas of the MYR is responsible for the release of Co. The results of the sequential extraction showed that Co is mainly bound to the residual fraction. DGT-labile Co had no correlation with non-residual fractions measured by sequential extraction, but had a significantly positive relationship with CDGT-Mn, indicating that Co trapped by DGT mainly came from the dissolution of MnOx. When the MYR riparian soils are submerged, a reducing environment will be formed. In this case, Co associated with MnOx may be also released into the water.

Virtual water export and import in china’s foreign trade: A quantification using input-output tables of China from 2000 to 2012

Import virtual water is an effective way to alleviate water shortage. Since China is a country that suffers severely from the lack of water resources, it is badly needed to research in virtual water export and import in China's foreign trade. This paper conducted thorough research on these issues and lucubrated on the detailed destinations and origins of China’s virtual water export and import using the input-output model. Moreover, the factors that affect China’s virtual water trade have also been studied in this paper. The results indicated that: (1) from 2000 to 2012, the volume of virtual water export increased from 65.2 billion tons to 114.1 billion tons, and its import volume increased from 62.4 billion tons to 108.7 billion tons. China was a net exporter of virtual water; (2) the export of virtual water was mainly exported by sectors such as Textile &Garment and Leather Products, General Machinery and Equipment Manufacturing Industry, the import of virtual water was mainly imported by Agriculture, Petrochemical industry; (3) China has net exported large amounts of virtual water to developed areas such as the US, the European Union, and Japan, and has net imported from emerging economies and resource-oriented regions such as Taiwan (China), ASEAN, Brazil, Korea, Australia and Russia. Based on these conclusions, this paper proposed that China’s foreign trade structure needed to be adjusted to relieve the water shortage by the following methods the first is appropriately lower the export proportion of products from sectors such as Food, Beverage & Tobacco Products, Petrochemical Industry, which exported a large proportion of virtual water; the second is to enlarge the export proportion of products with low water consumption, such as service industry; the third is to make full use of the water saving effect of import.

Comparative assessment of joint water development initiatives in the Jordan River Basin

ABSTRACTThis paper presents a comparative assessment of developmental initiatives to increase regional water supply in the Jordan River Basin using a Multi Criteria Decision Analysis technique with sensitivity analysis on criteria weights. The results indicate that the Red Sea–Dead Sea Conveyance (RSDSC) constitutes an optimal option within the context of alleviating water shortage and promoting regional cooperation. While a surface water pipeline from Turkey emerges as an attractive option when the quantity of delivered water is emphasized, the potential for out of basin water transfers are becoming increasingly less desirable with population growth, political turmoil in the region, development, and climate change challenges.

Virtual water flows in the international trade of agricultural products of China

With the rapid development of the economy and population, water scarcity and poor water quality caused by water pollution have become increasingly severe in China. Virtual water trade is a useful tool to alleviate water shortage. This paper focuses on a comprehensive study of China's international virtual water flows from agricultural products trade and completes a diachronic analysis from 2001 to 2013. The results show that China was in trade surplus in relation to the virtual water trade of agricultural products. The exported virtual water amounted to 29.94billionm3/yr. while 155.55billionm3/yr. was embedded in imported products. The trend that China exported virtual water per year was on the decline while the imported was on a rising trend. Virtual water trade of China was highly concentrated. Not all of the exported products had comparative advantages in virtual water content. Imported products were excessively concentrated on water intensive agricultural products such as soya beans, cotton, and palm oil. The exported virtual water mainly flowed to the Republic of Korea, Hong Kong of China and Japan, while the imported mainly flowed from the United States of America, Brazil and Argentina. From the ethical point of view, the trade partners were classified into four types in terms of “net import” and “water abundance”: mutual benefit countries, such as Australia and Canada; unilateral benefit countries, such as Mongolia and Norway; supported countries, such as Egypt and Singapore; and double pressure countries, such as India and Pakistan. Virtual water strategy refers to water resources, agricultural products and human beings. The findings are beneficial for innovating water resources management system, adjusting trade structure, ensuring food security in China, and promoting the construction of national ecological security system.

Study on the Effects of Irrigation with Reclaimed Water on the Content and Distribution of Heavy Metals in Soil.

Reclaimed water is an important resource for irrigation, and exploration in making full use of it is an important way to alleviate water shortage. This paper analyzes the effects of irrigation with reclaimed water through field trials on the content and distribution of heavy metals in both tomatoes and the soil. By exploring the effects of reclaimed water after secondary treatment on the content and distribution characteristics of heavy metals in tomatoes and the heavy metal balance in the soil-crop system under different conditions, the study shows that there are no significant differences in the heavy metal content when the quantity of reclaimed water for irrigation varies. Reclaimed water for short-term irrigation does not cause pollution to either the soil environment or the crops. Nor will it cause the accumulation of heavy metals, and the index for the heavy metal content is far below the critical value of the national standard, which indicates that the vegetables irrigated with reclaimed water during their growth turn out to be free of pollutants. The heavy metals brought into the soil by reclaimed water are less than that taken away by the crops. The input and output quantities have only small effects on the heavy metal balance in the soil. This paper provides a reference for the evaluation and safety control of irrigation with reclaimed water.

Integrated double mulching practices optimizes soil temperature and improves soil water utilization in arid environments.

Water shortage threatens agricultural sustainability in many arid and semiarid areas of the world. It is unknown whether improved water conservation practices can be developed to alleviate this issue while increasing crop productivity. In this study, we developed a "double mulching" system, i.e., plastic film coupled with straw mulch, integrated together with intensified strip intercropping. We determined (i) the responses of soil evaporation and moisture conservation to the integrated double mulching system and (ii) the change of soil temperature during key plant growth stages under the integrated systems. Experiments were carried out in northwest China in 2009 to 2011. Results show that wheat-maize strip intercropping in combination with plastic film and straw covering on the soil surface increased soil moisture (mm) by an average of 3.8% before sowing, 5.3% during the wheat and maize co-growth period, 4.4% after wheat harvest, and 4.9% after maize harvest, compared to conventional practice (control). The double mulching decreased total evapotranspiration of the two intercrops by an average of 4.6% (P<0.05), compared to control. An added feature was that the double mulching system decreased soil temperature in the top 10-cm depth by 1.26 to 1.31°C in the strips of the cool-season wheat, and by 1.31 to 1.51°C in the strips of the warm-season maize through the 2years. Soil temperature of maize strips higher as 1.25 to 1.94°C than that of wheat strips in the top 10-cm soil depth under intercropping with the double mulching system; especially higher as 1.58 to 2.11°C under intercropping with the conventional tillage; this allows the two intercrops to grow in a well "collaborative" status under the double mulching system during their co-growth period. The improvement of soil moisture and the optimization of soil temperature for the two intercrops allow us to conclude that wheat-maize intensification with the double mulching system can be used as an effective farming model in alleviating water shortage issues experiencing in water shortage areas.

Energy consumption and economic cost of typical wastewater treatment systems in Shenzhen, China

Wastewater treatment, a great potential alternative to alleviate water shortage, has been attached more and more importance in China, and has been developing very fast. The quantity of wastewater treatment plants in China has increased up to 3272 in June 2013, and has a total handling capacity of 0.14 billion t/day. However, wastewater treatment requires to consuming a lot of energy, and even energy consumption is often the main operation cost of wastewater treatment systems. Thus, it is very necessary to explore energy consumption of wastewater treatment systems and its influential factors, and seek for some possible pathways to save energy and lower cost. In this paper, we investigated the average energy consumption per unit wastewater treatment in Shenzhen, and analyzed the effect of treatment capacity and treatment technology on the energy cost per unit of wastewater treatment. The results showed that the average energy consumption of wastewater treatment plants in Shenzhen was about 0.20 ± 0.06 kWh/t, much less than those in some developed countries. This result may be related to the advanced wastewater treatment plants newly constructed and the low water quality requirements of wastewater treatment in Shenzhen. As the key to wastewater treatment, biochemical treatment sub-process consumed 50–70% of total energy cost in wastewater treatment. Secondly, the larger the treat capacity, the lower the energy cost per unit of wastewater treatment was. And the difference of treatment technologies can also significantly affect the energy consumption per unit of wastewater treatment. Finally, labor cost and electricity consumption respectively covered about 30.1% and 26.3% of total economic cost in the three typical wastewater treatment plants in original Shenzhen. Thus, upgrading treatment machines & equipment and improving management level are two effective alternatives to decrease energy consumption and lower total economic cost of wastewater treatment plants in Shenzhen and even China.

THE ROLE OF GROUNDWATER TO MITIGATE THE DROUGHT AND AS AN ADAPTATION TO CLIMATE CHANGE IN THE PHITSANULOK IRRIGATION PROJECT, IN THE NAN BASIN, THAILAND

The Phitsanulok Irrigation Project is located in the Nan Basin of the Upper Central Plain of Thailand where farmers depended on both surface water and groundwater. Land use and climate changes are the important factors to determine the runoff from the watershed. The changes also affected to runoff volume/pattern to the dam operation and may cause flood and drought situations in the downstream area. Sirikit Dam is one of the biggest dams in Thailand which cover about 25 % of the runoff into the Central Plain where the Bangkok Capital is located. Though there is the Sirikit Dams storing water to be used during dry period but water allocation is limited and still caused water shortage during dry season. The study aims to determine the role of groundwater to mitigate the drought situation from the past and to study the groundwater use for adaptation to climate change in The Phitsanulok Irrigation Development Project. In this study, the relationship of recharge rate with climate data was developed in terms of precipitation, evapotranspiration, temperature and soil type under monthly time series data and the study found that there were in good relationship. Groundwater will take an important role to alleviate from the water shortage situations in climate change conditions when compared with the situations based on the existing water use pattern. The limit of ground water to alleviate water shortage will be 80 and 77 MCM/year in average, in near future and far future periods to keep water table drawn down in the safe manner even when the Sirikit’s reservoir operation rule is improved.

Effect of Variation of Water-Use Efficiency on Structure of Virtual Water Trade - Analysis Based on Input–Output Model

Using input–output table of China in 2007, this paper built an input–output model and tested the effect of variation of water-use efficiency on the structure of virtual water trade. As the final water consumption coefficient increases (i.e., water-use efficiency decreases) in some department, the proportion of this department’s virtual water outflow/inflow increases while those of all the other departments decrease. As the direct water consumption coefficient increases (i.e., water-use efficiency decreases), the proportion of this department's virtual water outflow/inflow increases while the sum but not each of the other departments’ proportions decreases. The final water consumption coefficient of any department is bigger than the direct one, implying indirect water consumption exists and final water consumption coefficient is a better indicator for water-use efficiency. The paper shows that China is a net exporter of virtual water, but the departments of agriculture, mining, petrochemical are the net importers of virtual water. According to the results, China should use the strategy of virtual water trade to alleviate water shortage. Also, China should adopt water-saving technology in production, and improve the level of self-sufficiency of products in order to reduce reliance on foreign trade correspondingly.