Salt and nitrate exports from the sprinkler-irrigated Malfarás creek watershed (Ebro river valley,Spain) during 2010

Irrigated agriculture is a clear source of non-point pollution by salts and nitrogen species. The impact of such pollution should be quantified according to specific cases. The case of the Malfarás creek basin, a sprinkler irrigation district located in the semiarid Ebro valley in northeast Spain, has been evaluated. The main crops in the district were corn, barley and alfalfa, occupying 93 % of the irrigated area. The fate of water, salts and nutrients was evaluated by a daily water balance developed at a field scale for the natural year 2010. The yearly data of the whole set of 101 irrigated fields plus the non-irrigated area compared to the measured drainage produced a basin water balance with a low degree of error. The basin consumed 90 % of the total water input of which 68 % was used for crop evapotranspiration and the rest was lost due to non-productive uses. 16 % of the incoming water left the irrigation area as drainage water. The irrigated area was responsible for 87 % of the drainage. The average volume of drained water was 152 mm year^?1 for the whole basin area. The irrigated area drained 183 mm year^?1. The basin exported 473 kg of salt per hectare during 2010. This value was the lowest of the sprinkler irrigation areas in the Ebro valley, mainly due to the lower soil salinity. All the crops except barley received a nitrogen surplus of 10–50 % above their needs. The extra nitrogen entered the water cycle increasing the nitrate concentration in the aquifer water (150 mg L^?1) and drainage water (98 mg L^?1). In 2010 the mass of nitrogen exported by drainage was 49 kg per irrigated hectare. This value is too high for this type of irrigation system and implies that 17 % of nitrogen applied as a fertilizer was lost to drainage water. The key to decreasing the nitrogen leaching and pollution that it causes could be appropriate time-controlled fertigation along with better irrigation scheduling.     

A comparative study on energy balance and economical indices in irrigated and dry land barley production systems

This study was conducted to determine how energy balances and economical indices of barley production are affected by irrigated and dry land farming systems. Data were collected from 26 irrigated and 68 dry land barley farms. The complimentary data were collected through questionnaires filled by farmers in face-to-face interviews during 2010. The results indicated that total energy input for irrigated barley was 19,308.96 MJ ha^?1 and for dry land barley was 7,867.82. The non-renewable energy was about 66.83 and 71.02 % in irrigated and dry land systems while the renewable energy was 33.17 and 28.98 %, respectively. Energy use efficiency is energy output MJ ha^?1 divided by energy input MJ ha^?1. Energy use efficiency was 5.3 and 3.96 in dry land and irrigated systems, respectively. Although net return in the irrigated system (266.13$ ha^?1) was greater than that in the dry land system (208.64) but the benefit to cost ratio in irrigated system (1.38) was lower than that in the dry land system (1.58). Results showed that human labor as well as machinery energy inputs were the most important inputs influencing the dry land and irrigated barley production systems, respectively. The second important input in the irrigated barley was electricity (with 0.16) which was followed by water for irrigation and diesel fuel (0.14 and 0.13, respectively). In total energy consumption, the ratio of non-renewable energy was greater than that of renewable energy. Since the main non-renewable energy input was diesel, electricity, and chemical fertilizers; therefore, management and improvement in the application of these inputs would increase the proportion of renewable energy.     

Changes in irrigation management and quantity and quality of drainage water in a traditional irrigated land

Irrigated agriculture allows for the increase of agrarian yields and stability in food supply and raw materials, being, at the same time, responsible for the reduction of water resources availability and for the pollution by salts and nitrate. This work aims to analyze the impact of changes in irrigation management (establishment of an on-demand flood irrigated system, assignment of irrigation allowances and water payment for surface and irrigation water consumption) in a traditional irrigated land on drainage flow, electrical conductivity and nitrate concentration in irrigation return flows between the year 2001 and the period 2005–2008. Changes in water management significantly modified quantity (lower drainage) and quality (electrical conductivity and nitrate) of irrigation return flows, keeping similar evolution paths during the year with water ameliorants in summer due to the use of good irrigation water quality. Salinity in irrigation return flows is not a current problem in the area as electrical conductivity values in water did not exceed the limit established for water used in irrigation or intended for human consumption. Despite the fact that changes in irrigation management and crop distribution have reduced nitrate concentrations in irrigation return flows by 43 %, the water still presents nitrate values exceeding the 50 mg NO₃ ^?/l. Thus, nitrate remains as the main agro-environmental problem in this irrigation area. However, the nitrate concentration trends detected in this work mark the possibility of reaching nitrate values below 50 mg NO₃ ^?/l in the case of maintenance of the conditions in this agricultural system.     

Water use at Luxor,Egypt: consumption analysis and future demand forecasting

Water resources in Egypt are becoming scarce and the demand for clean drinking water supply is one of the most important priorities of the Egyptian government in recent years. Analyzing water use and future demand forecasting is a primitive clue for water demand management. Water in Luxor is used for agricultural, residential, institutional, commercial, and touristic purposes. The results of water use analysis indicated that for the time period from 1983 to 2012, agriculture is the highest consumer of water which reached about 94.76–97.38 % followed by residential water consumption (1.90–3.05 %), institutional water consumption (0.71–1.75 %), and touristic water consumption (0.02–0.43 %), respectively. The future demand forecasting results revealed that the present situation may continue to rise in the next 50 years which will increase the water demand with a water deficit ranging between 15 and 114 MCM/year. To fill the gap between the present water consumption and future residential, institutional, commercial, and touristic water demand, additional municipal facilities, and improvement and management of water supply/demand are needed. To cope with the predicted future water demand, it is recommended to improve the on-farm irrigation, reduce the demand for irrigation water, rationalize the irrigation water use, and enhance the integrated role of water users in integrated water resources management.     

河西走廊疏勒河流域水资源管理问题分析

从水资源管理体制、配置程序、市场化管理等方面探讨了河西走廊疏勒河流域水资源管理及存在的问题。目前流域已建成较健全的用水者协会体系,水价和水权在不断调整以适应水资源管理的需求。其管理存在以下问题：受地方行政、企业等多方权力博弈的影响,地表水和地下水处于双线管理状态,未能实现流域水资源的全面统一管理;用水者协会的职能未得到充分发挥,公众参与水资源管理不积极;流域内水价、水权制度不完善。建议如下：应在甘肃省水利厅和酒泉市政府之间形成协调机制,以协调各相关方的权益,完善流域管理局和地方政府统一协调的水资源管理体系,实现流域水资源的集成管理;加强流域机构立法,实现流域水资源的统一管理与调配;将协会的职责和义务融入到村委会的职务中,并完善水价制度,建立水权交易市场,以调动公众的自我管理和实现水资源的高效利用。     

中国的用水何时达到顶峰

从中国实际用水增长业已放慢的趋势、已经开始启动的供水价格的大幅上升趋势和水价与用水的关系、经济增长方式由粗放型向集约型转变(高耗水行业已经接近顶峰)和用水与产业结构的关系、日益严格的环境立法和执法对用水的影响、中国水资源本身的限制等5个方面,分析中国的用水变化趋势,提出中国的农业用水量、工业用水量和总用水量目前均已接近顶峰,可望在10年内达到顶峰,最大用水量不大可能超过6500×108m3。     

Climate and water budget change of a Mediterranean coastal watershed, Ravenna, Italy

It is generally difficult to quantify exactly the freshwater going in or out of the coastal watersheds along the northern Adriatic Sea because, on one hand, excess water is drained and pumped into the sea to prevent flooding but, on the other hand, water is brought onto the land from far away for irrigation. Fragmentation of water authorities makes it difficult to collect all the necessary information. Climate change and increasing salinization of the coastal aquifers make it imperative, however, to better know the quantities of freshwater involved in these small basins. The water budget of a small coastal agricultural watershed along the Adriatic Sea in Italy (The Quinto Basin near Ravenna) is presented here considering different land uses. The evaporation of open water and the evapotranspiration of wetlands, pine forests, bare soil and irrigated agriculture are calculated based on the Penman–Monteith equation and the Cropwat program. The current water budget is based on average climate data from 1989 to 2008 and drainage and irrigation data. Predictions for future evapotranspiration, net irrigation and hydrologic deficit are calculated with climate data from IPCC (The Fourth Assessment Report (AR4) 200, Climate change 2007). From the study results, the soil type may determine whether or not a crop will need more or less irrigation in the future. Regulations on land use should therefore consider which crop type can be grown on a specific soil type. Water budget analysis in scenarios A1b and A2 both show an increase of water deficits in the summer and an increase of water surplus in the winter. This is explained by the fact that a larger percentage of the rain will fall in winter and not during the growth season. The open water evaporation will decrease under future climate scenarios as a result of increased relative humidity in winter and decreased wind velocity. This may have a positive effect on the water cycle. The current irrigation is very abundant, but has beneficial effects in contrasting soil salinization and saltwater intrusion into the coastal aquifer.     

The key role of supply chain actors in groundwater irrigation development in North Africa

The role played by supply chain actors in the rapid development of groundwater-based irrigated agriculture is analyzed. Agricultural groundwater use has increased tremendously in the past 50 years, leading to the decline of water tables. Groundwater use has enabled intensification of existing farming systems and ensured economic growth. This “groundwater economy” has been growing rapidly due to the initiative of farmers and the involvement of a wide range of supply chain actors, including suppliers of equipment, inputs retailers, and distributors of irrigated agricultural products. In North Africa, the actors in irrigated production chains often operate at the margin of public policies and are usually described as “informal”, “unstructured”, and as participating in “groundwater anarchy”. This paper underlines the crucial role of supply chain actors in the development of groundwater irrigation, a role largely ignored by public policies and rarely studied. The analysis is based on three case studies in Morocco, Tunisia and Algeria, and focuses on the horticultural sub-sector, in particular on onions and tomatoes, which are irrigated high value crops. The study demonstrates that although supply chain actors are catalyzers of the expansion of groundwater irrigation, they could also become actors in adaptation to the declining water tables. Through their informal activities, they help reduce market risks, facilitate credit and access to subsidies, and disseminate innovation. The interest associated with making these actors visible to agricultural institutions is discussed, along with methods of getting them involved in the management of the resource on which they depend.     

Hydrogeological and mixing process of waters in deep aquifers in arid regions: south east Tunisia

This study addresses the hydrogeochemistry of thermal and cold waters from south east Tunisia. Temperature intervals are 38.5–68 °C and 22–27.8 °C for thermal water and cold water, respectively. Three distinct hydrogeological systems supply water either for irrigation or for drinking; they are: (1) the Continental Intercalaire geothermal aquifer (CI), (2) the Turonian aquifer and (3) the Senonian aquifer. A synthetic study including hydrochemical, hydrogeological and geothermal approaches have been applied in order to evaluate the inter-aquifers water transfer in south east of Tunisia. By using silica geothermometers and saturation indices for different solid phases, estimated thermal reservoir temperature varies between 52 and 87 °C and between 75 and 110 °C, respectively. Based on chemical and thermal data, mixing, which occurs between the ascending deep geothermal water and shallow cold water, is about 57 % cold water.     

Soil salinization and critical shallow groundwater depth under saline irrigation condition in a Saharan irrigated land

In the arid irrigated lands, understanding the impact of shallow groundwater fluctuation on soil salinization has become crucial. Thus, investigation of the possible options for maintaining the groundwater depth for improving land productivity is of great importance. In this study, under saline irrigation condition, the effects of shallow groundwater depth on water and salt dynamics in the root-zone of date palms were analyzed through a particular field and modeling (SWAP) investigation in a Tunisian Saharan oasis (Dergine Oasis). The model was calibrated and validated against the measured soil water content through the date palm root-zone. The good agreement between measured and estimated soil water content demonstrated that the SWAP model is an effective tool to accurately simulate the water and salt dynamics in the root-zone of date palm. Multiple groundwater depth scenarios were performed, using the calibrated SWAP model, to achieve the optimal groundwater depth. The simulation results revealed that the shallow groundwater with a depth of ~80 cm coupled with frequent irrigation (20 days interval) during the summer season is the best practice to maintain the adequate soil water content (>0.035 (cm³ cm^?3) and safe salinity level (<4 dS m^?1) in the root-zone layer. The results of field investigation and numerical simulation in the present study can lead to a better management of lands with shallow water table in the Saharan irrigated areas.     

Effects of biochar, cow bone, and eggshell on Pb availability to maize in contaminated soil irrigated with saline water

Toxicity of heavy metals adversely affects environment and human health. Organic materials derived from natural matters or wastes have been applied to soils to reduce the mobility of contaminants such as heavy metals. However, the application of cow bone powder (CB), biochar (BC), and eggshell powder (ES) is rarely investigated for the reduction of Pb bioavailability in soils irrigated with saline water. The objective of this study was to assess the effectiveness of CB, BC, and ES additions as immobilizing substances on Pb bioavailability in shooting range soil irrigated with deionized and saline water. Each additive of CB, BC, and ES at 5 % (w/w) was mixed with soils and then the deionized and saline water were irrigated for 21 days. With deionized water irrigation, the soils treated with CB, BC, and ES exhibited higher pH when compared with saline water irrigation. With saline water irrigation, the electrical conductivity, water-soluble anions, and cations were significantly increased in soils treated with CB, BC, and ES. The water-soluble Pb in soils treated with CB, BC, and ES was significantly decreased with saline water irrigation. On the other hand, the water-soluble Pb in soil treated with CB was increased with deionized water irrigation. Only BC with saline water irrigation decreased the Pb concentration in maize shoots.     

An assessment of the potential and impacts of winter water banking in the Sokh aquifer, Central Asia

The dynamics of artificial recharge of winter surface flows coupled with increased summer groundwater use for irrigation in the Sokh aquifer (Central Asia) have been investigated. Water release patterns from the giant Toktogul reservoir have changed, as priority is now given to hydropower generation in winter in Kyrgyzstan. Winter flows have increased and summer releases have declined, but the Syr Darya River cannot pass these larger winter flows and the excess is diverted to a natural depression, creating a 40?×?10⁹m³ lake. A water balance study of all 18 aquifers feeding the Fergana Valley indicated the feasibility of winter groundwater recharge in storage created by summer abstraction. This modeling study examines the dynamics of the process in one aquifer over a 5-year period, with four scenarios: the current situation; increased groundwater abstraction of around 625 million (M) m³/year; groundwater abstraction with an artificial recharge of 144 Mm³/year, equivalent to the volume available in low flow years in the Sokh River; and with a larger artificial recharge of 268 Mm³/year, corresponding to high flow availability. Summer surface irrigation diversions can be reduced by up to 350 Mm³ and water table levels can be lowered.     

BP神经网络在灌区需水量预测中的应用

随着塔里木河下游水量逐年减少的趋势,铁千里克灌区水资源危机显的越来越严重。运用BP神经网络方法预测需水量,对灌区适时调整产业结构,保护生存和生态环境,促进区域社会经济和谐发展有重要意义。     

Techno-economic analysis of grid-tied energy storage

This paper presents a methodology to assess the technical and economic viability of grid-tied battery energy storage for a student residence under a time-of-use tariff structure. Battery as a storage medium can take advantage of the price arbitrage between peak and off-peak period under favourable conditions. To investigate the impact of different pricing regimes, summer rate was implemented, and the results were compared with that of winter rate on yearly basis. At base case conditions, neither a prevailing summer nor winter pricing tariff favours the use of battery energy storage. A 0.4656 R/kWh price differential between peak and off-peak period for a summer pricing regime was not sufficient for the battery energy storage system to break even. Implementing a year-round winter pricing regime with a price differential of 2.1171 R/kWh between peak and off-peak period requires a minimum of 866 battery cycle life to break even. Probabilistic analysis using Monte Carlo simulation indicated that to make battery energy storage system attractive, at least 110% increase in the peak price of electricity for summer is needed. The study concluded that the price differential among the different time-of-use tariff regimes impact on the extent of profitability of using battery energy storage.     

Considering groundwater use to improve the assessment of groundwater pumping for irrigation in North Africa

Groundwater resources in semi-arid areas and especially in the Mediterranean face a growing demand for irrigated agriculture and, to a lesser extent, for domestic uses. Consequently, groundwater reserves are affected and water-table drops are widely observed. This leads to strong constraints on groundwater access for farmers, while managers worry about the future evolution of the water resources. A common problem for building proper groundwater management plans is the difficulty in assessing individual groundwater withdrawals at regional scale. Predicting future trends of these groundwater withdrawals is even more challenging. The basic question is how to assess the water budget variables and their evolution when they are deeply linked to human activities, themselves driven by countless factors (access to natural resources, public policies, market, etc.). This study provides some possible answers by focusing on the assessment of groundwater withdrawals for irrigated agriculture at three sites in North Africa (Morocco, Tunisia and Algeria). Efforts were made to understand the different features that influence irrigation practices, and an adaptive user-oriented methodology was used to monitor groundwater withdrawals. For each site, different key factors affecting the regional groundwater abstraction and its past evolution were identified by involving farmers’ knowledge. Factors such as farmer access to land and groundwater or development of public infrastructures (electrical distribution network) are crucial to decode the results of well inventories and assess the regional groundwater abstraction and its future trend. This leads one to look with caution at the number of wells cited in the literature, which could be oversimplified.     

Study of the water saving potential of an irrigation area based on a remote sensing evapotranspiration model

To estimate the water saving potential of an irrigation area and create a scientific water saving plan, the irrigation water use efficiency and water productivity of the Hulanhe irrigation area for 2007–2014 were calculated, and the water saving potentials of different water saving plans were determined from the perspectives of engineering and crop water saving. The results showed that the evapotranspiration calculated from the surface energy balance algorithm for land model (SEBAL) agreed well with the measured results. The irrigation water use efficiency in the Hulanhe irrigation area was positively correlated with precipitation of irrigated land and was negatively correlated with the net irrigation water volume. The engineering water saving potential ranges for periods of 5, 8, 11, and 15 years were (1.702?×?10⁸, 5.103?×?10⁸) m³, (1.783?×?10⁸, 5.184?×?10⁸) m³, (1.865?×?10⁸, 5.266?×?10⁸) m³, and (2.301?×?10⁸, 5.702?×?10⁸) m³, respectively, and the water saving potential increased year over year. Low amounts of precipitation of irrigated land corresponded with small amounts of net irrigation water and greater water saving potential. Based on the cumulative frequency of the water productivity calculated for the Hulanhe irrigation area from 2007 to 2014, the target water productivity for short (50% of the multi-year average cumulative water productivity) and long (70% of the multi-year average cumulative water productivity) terms were 1.03 kg/m³ and 1.22 kg/m³, respectively, and the cumulative crop water saving potentials for short and long terms were 1.18?×?10⁸ and 2.74?×?10⁸ m³, respectively. These results provided a theoretical reference for creating water saving plans for irrigation areas.     

Energy demand and economic consequences of transport policy

Transport sector is a major consumer of energy. Concern of energy scarcity and price fluctuations enhanced significance of transport sector in national planning. This paper analyses energy demand for transport services in Bangladesh for different policy scenarios. Aggregate transport demand model is integrated into Long-range Energy Alternatives Planning model to forecast consequences of transport policy on energy demand and economy. Demand for imported energy for transport sector is observed to increase from 1.7 million ton of oil equivalent (Mtoe) in 2005 to 11.8 Mtoe in 2030 for business-as-usual scenario. In increased fuel price scenario, cost of importing fuel for transport sector is projected to increase from 1.37 to more than 14.9 % of Gross Domestic Product during the same period. Country’s energy demand may be reduced by 2 and 4 Mtoe in 2030 by improvement of waterway and railway, respectively. Moreover, by using compressed natural gas in motor vehicles cost of importing fuel may be reduced by US $5 billion annually in 2030 and a further reduction of transport sector energy demand by 9 % can be achieved through eliminating subsidy on fuel.     

Two-dimensional modelling of hydrodynamics and water quality of a stratified dam reservoir in the southern side of the Mediterranean Sea

A vertical two-dimensional, laterally averaged hydrodynamic and water quality model CE-QUAL-W2 was used to simulate water temperature, dissolved oxygen, electrical conductivity, chlorophyll a, total suspended solids, alkalinity, ammonium, phosphate, and total iron in the Sejnane Dam (North Tunisia) in response to external forcings that characterize main features of climate in the southern side of the Mediterranean Sea. The hydrodynamic modelling results show that the model is able to reproduce accurately the measured water surface elevation, spatio-temporal patterns of temperature, dissolved oxygen and other state of variables and to capture most of the seasonal changes in the reservoir. Three scenarios involving the impacts of severe drought season, summer rainfall and total suspended solids load on hydrodynamics and water quality are analyzed. Severe drought reduces the thickness of hypoxic waters from 10 to 2–4 m and shifts the temperature of the entire water column up to 5 °C during summer and about 1.2 °C in winter. The thermocline takes place 1 month before that of the reference and sinks to the bottom faster by 1–2 m per month. Summer rainfall dilutes the first waves of the autumn rains and disrupts the thermal gradient in the water column, which may show complex thermal structures. TSS load has the most negative effects on water quality in that it shifts the phosphorus concentration by 1–3 mg/l and promotes an early warming of surface water in spring and an early cooling since late summer by up to 1 °C. During summer stratification, it contributes to the cooling of the metalimnion by 2 °C on average, which may alter its structure and dynamics as an aquatic biotope.     

既地下水采补平衡又冬小麦稳产的探讨

河北省太行山山前平原浅层地下水位持续下降,问题十分突出,然而,该区域又是我国优质冬小麦的重要产区。能否实现在浅层地下水采补平衡的同时做到冬小麦稳产,是该区域水资源保护和农业生产管理工作中亟待回答的重要问题。基于分布式水文模型的模拟结果表明:在该区域若要实现地下水位止降回升这一压采目标,仅利用浅层地下水进行灌溉,冬小麦的产量会减少40%以上。考虑到南水北调中线工程的引水线路自南向北贯穿河北省太行山山前平原,建议在冬小麦关键需水期的灌溉中采用“一水用浅层地下水另一水用南水北调水”的“修改的春浇两水”模式。基于模拟结果的估算表明:在这种限水灌溉模式下有望实现浅层地下水采补基本平衡且冬小麦基本稳产。值得注意的是,这种“修改的春浇两水”模式,需要南水北调中线引水工程每年提供的灌溉水量大约为8.6×108 m3,灌溉成本较纯井灌至少增加562.5～1282.5元/hm2。本研究可为我国最典型的浅层地下水超采区——河北省太行山山前平原探索保产量与节水并举的新路径提供定量化的参考。     

跨地区调水对水成本的影响分析:一个类比

就跨区域调水引起的水价问题按照全成本定价的划分项目进行定性分析,通过将跨区域调水和排污权交易中的泡泡法进行类比,为详细考察提供了一个经济分析方面具有一般性的框架。分析表明,跨区域调水对相关区域的每项水资源成本都发生影响,在合适的调水量之下,两地水资源成本互相趋近而总成本减少,与排污权交易导致的污染治理成本变化类似。跨地区调水建立的地区水资源联系打破了原来水资源成本项目的划分,使调出区原来过剩的水因为存在与调入区交易的可能而产生机会成本,并因调水后水供给与两地水需求更一致而提高了水资源的周转率,等同于增加了可用水资源量并因此降低了水成本。在此显示了水资源价值中时间因素的影响。分析证明水资源潜在的产权因为跨地区调水工程而变成可交易更完整的产权之后,提高了水资源配置效率,这与科斯定理完全一致。调入区的获益在短期和长期内有所不同。