喷头不同组合模式下水量分布和喷灌均匀度的田间试验及数值模拟

利用三次样条两次插值叠加法并结合单喷头水量分布可计算得到多喷头组合水量分布。为验证该方法的适用性及探究变间距条件下喷灌均匀度的变化情况,通过田间试验,得到ZY-2型单喷头水量分布及多喷头18 m×18 m组合形式下水量分布,计算了喷灌均匀度。利用MATLAB软件构建了喷头组合条件下水量分布的数值模拟模型,计算出不同组合模式下水量分布和组合喷灌均匀度。结果表明:模拟与实测喷灌水深的相对误差(RE)和均方根误差(RMSE)分别为8.49%和3.17 mm,组合喷灌均匀度的相对误差为1.85%,表明构建的模型能较准确地模拟不同喷头组合条件下的水量分布和组合均匀度; ZY-2型喷头在正方形21 m×21 m布置形式下,喷灌均匀度达到最高(0.873);在变喷头间距和变支管间距两种矩形布置时,喷灌均匀度整体上随着支管间距的增加而逐渐降低,但喷头间距增加时喷灌均匀度降低的幅度更大。研究结果可为优化喷头布置形式提供技术支撑。     

Modeling the Effect of Cistern Size,Soil Type,and Irrigation Scheduling on Rainwater Harvesting as a Stormwater Control Measure

Urban stormwater runoff could have negative impacts on water resources and the environment. Rainwater Harvesting (RWH) can serve both as a stormwater control and water conservation measure. Cistern size and irrigation scheduling are two of the factors that directly impact the total runoff from a residential unit with a RWH system and the amount of potable water used for irrigation. The effectiveness of RWH was evaluated for four soil types; Sand, Sandy Loam, Loamy Sand, and Silty Clay, with a root zone of 15.2 cm using three irrigation scheduling methods (Evapotranspiration (ET)-based, soil moisture-based, and time-based), and five cistern sizes. Total runoff volumes and total supplemental potable water used were compared among the three irrigation scheduling systems and a control treatment without RWH. A model was developed to simulate the daily water balance for the treatments. Irrigation and runoff volumes were compared for the various scenarios. Silty clay soil resulted with 83 % more runoff than Sandy soil, while Sandy soil required on average 58 % more supplemental water than Silty Clay soil. On average, the 833 L cistern resulted with 41 % savings in water supply and 45 % reduction in total runoff. Results showed that the greatest volumes of runoff predicted were for the silty clay soil Control Treatment using a time-based irrigation scheduling method, while the least volumes calculated were for the sandy loam soil time-based irrigation scheduling treatment with 833 L cistern size. The greatest volumes of total supplemental water predicted were for sandy loam soil Control Treatment, while the least volumes were for silty clay soil ET-based irrigation scheduling treatment with 833 L cistern size. Regression equations were developed to allow for users to select a RWH cistern size based on the amount of water they want to save or runoff to reduce.     

GIS Based Estimation of Sediment Discharge and Areas of Soil Erosion and Deposition for the Torrential Lukovska River Catchment in Serbia

In the present study the SHETRAN river basin modelling system was used in conjunction with Geographic Information System (GIS) to estimate potential erosion and deposition rates within the catchment and the concentrations of sediment in a flow at the catchment outlet on the example of the 114.31 km² mountainous torrential Lukovska River catchment in Serbia. The streams in the Lukovska River catchment are short, steep and often produce hazardous torrential floods as a consequence of strong rainfall of short duration. The soil erosion and sediment discharge were analysed in view of the catchment response to physical characteristics of the catchment. Considering that the most of total annual sediment discharge in watersheds of torrential character is achieved during storm events, the SHETRAN modelling system was calibrated on the example of a storm event in 1986 and validated for three other storm events in 1974, 1976 and 1979. The simulated results of discharges and sediment concentrations at the catchment outlet for both calibration and validation events were compared with the observed data and found to be reasonable. The changes of erosion and deposition rates within the catchment and in the course of time were estimated for the calibration event in 1986. The simulated erosion rates were within the range of 1 to 10.5 t/ha and corresponded to the observed rates of erosion in Europe during extreme rain events. The presented methodology is useful in identifying the erosion vulnerable regions in a catchment where erosion control measures should be implemented.     

Optimization of Irrigation Scheduling Using Soil Water Balance and Genetic Algorithms

In arid and semi-arid countries, the use of irrigation is essential to ensure agricultural production. Irrigation water use is expected to increase in the near future due to several factors such as the growing demand of food and biofuel under a probable climate change scenario. For this reason, the improvement of irrigation water use efficiency has been one of the main drivers of the upgrading process of irrigation systems in countries like Spain, where irrigation water use is around 70 % of its total water use. Pressurized networks have replaced the obsolete open-channel distribution systems and on farm irrigation systems have been also upgraded incorporating more efficient water emitters like drippers or sprinklers. Although pressurized networks have significant energy requirements, increasing operational costs. In these circumstances farmers may be unable to afford such expense if their production is devoted to low-value crops. Thus, in this work, a new approach of sustainable management of pressurized irrigation networks has been developed using multiobjective genetic algorithms. The model establishes the optimal sectoring operation during the irrigation season that maximize farmer’s profit and minimize energy cost at the pumping station whilst satisfying water demand of crops at hydrant level taking into account the soil water balance at farm scale. This methodology has been applied to a real irrigation network in Southern Spain. The results show that it is possible to reduce energy cost and improve water use efficiency simultaneously by a comprehensive irrigation management leading, in the studied case, to energy cost savings close to 15 % without significant reduction of crop yield.     

井灌区喷灌与管灌的技术经济的效益分析

随着首都经济的发展及日益严重的水资源危机，研究确定适宜的节水灌溉方式十分重要。在详细探讨喷灌和管灌系统技术经济性能的基础上，对喷灌和管灌系统技术经济性能指标进行了全面综合的分析和比较，提出了移动式和半固定式喷灌是北京市井灌区大田作物主推节水灌溉方式。     

指针式喷灌在广西甘蔗灌溉中的应用探讨

为探求指针式喷灌对广西甘蔗的影响,选择在南宁市宾阳县廖平农场高效节水工程开展大田试验,试验设置指针式喷灌3个处理和无灌溉(CK)1个对比。试验结果表明:采用指针式喷灌能提高糖料蔗的单产,有灌溉设施的蔗区单量6.37 t/亩,比无灌溉蔗区4.02 t/亩多2.35 t/亩;有灌溉设施的蔗区平均含糖分为14.04%,比无灌溉的蔗区14.29%低0.25%。     

Coefficients of heat and mass transfer of current-technology sprinklers for process computations of cooling towers

Analysis of formulas for computing coefficients of heat and mass transfer derived on the basis of results of laboratory tests of 22 sprinklers is used to show that the classification of sprinklers into film and drop ones can be based on a physically grounded parameter m, i.e., the exponent in the formula for the evaporation number K _ev = A _pλ^m (or for the Merkel number Me = A _xλ^m). Ageneralized formula describing the dependence of the coefficients of heat and mass transfer on the height of the sprinkler is derived, which makes it possible to determine the optimum sprinkler height in cooling tower design. The accuracy of the formulas for computing the coefficients is confirmed by a comparison of experimental and computed values of the temperature of cooled water in the cooling tower of the Novo-Ryazanskaya cogeneration plant. __________ Translated from élektricheskie Stantsii, No. 2, February 2006, pp. 24–30.     

Design of Sprinkler Irrigation Subunit of Minimum Cost with Proper Operation. Application at Corn Crop in Spain

MATLAB^? software named PRESUD (Pressurized Subunit Design) was developed to identify the optimum solid set sprinkler irrigation subunit design with a criterion of minimizing the annual water application cost (C_T). This C_T is defined as the cost per cubic meter of water applied to the soil for crop use. In this study, only rectangular subunits are considered, using an iterative method for calculating the lateral and manifold pipelines. The results indicate that water cost (C_w)_, which includes the investment and operation costs for pumping water from the source to the subunit inlet, makes up 75 % of C_T. Another important factor is energy cost, which comprises 14 % of C_T. The remaining variables, such as sprinkler spacing and layout, or application rate (AR_a), have a lower impact on C_T. In cases of use groundwater, the proportion of energy cost in C_W can reach 40 %; thus, energy is an important part of C_T. Results shows that the criterion of limiting the maximum difference in pressure heads in the irrigation subunit (Δh?T, and the use of tools such as PRESUD can help obtain better solutions.     

考虑全寿命周期成本的供水管网优化设计

针对城市管网的传统优化设计中仅考虑初始投资而没有考虑运行过程中维修管理成本的问题,提出了基于全寿命周期成本(LCC)的管网优化模型和计算方法。通过对管网建造成本及运行阶段维修管理成本的定量分析,建立了以全寿命周期总费用最低为目标的优化模型,并利用PSO算法对管径进行优化设计。通过实例分析,分别得到两种常用管材的最优管径,并基于寿命周期成本对比分析为管网设计阶段的方案选择和优化设计提供了依据。     

Irrigation energy use and related greenhouse gas emissions of maize production in Mexico

Maize is the most important crop grown in Mexico, with more than one-third of total production coming from irrigated fields. We compute irrigation energy use and associated greenhouse gas emissions of different irrigated maize systems in Mexico. Calculations were based on National Agriculture and Forestry Census 2007 microdata, irrigation water requirements estimated from state-level climate data, and energy and emission coefficients from the literature. Weighted average irrigation energy and related emissions are in the range of 1.0–31.6 GJ/ha and 62.0–2,019.9 kg CO₂e/ha, respectively, while country-scale estimates amount to 4.8 PJ and 305.2 Gg CO₂e.     

Optimizing Reservoir Operation Policy Using Chance Constraint Nonlinear Programming for Koga Irrigation Dam,Ethiopia

One of typical problems in water resources system modeling is derivation of optimal operating policy for reservoir to ensure water is used more efficiently. This paper introduces optimization analysis to determine monthly reservoir operating policies for five scenarios of predetermined cropping patterns for Koga irrigation scheme, Ethiopia. The objective function of the model was set to minimize the sum of squared deviation (SSD) from the desired targeted supply. Reservoir operation under different water availability and thresholds of irrigation demands has been analyzed by running a chance constraint nonlinear programming model based on uncertain inflow data. The model was optimized using Microsoft Excel Solver. The lowest SSD and vulnerability, and the highest volumetric reliability were gained at irrigation deficit thresholds of 20 % under scenario I, 30 % under scenario II, III and V, and at 40 % under scenario IV when compensation release is permitted for downstream environment. These thresholds of deficits could be reduced by 10 % for all scenarios if compensation release is not permitted. In conclusion the reservoir water is not sufficient enough to meet 100 % irrigation demand for design command areas of 7,000 ha. The developed model could be used for real time reservoir operation decision making for similar reservoir irrigation systems. In this specific case study system, attempt should be made to evaluate the technical performance of the scheme and introduce a regulated deficit irrigation application.     

Site Selection of Different Irrigation Systems Using an Analytical Hierarchy Process Integrated with GIS in a Semi-Arid Region

Site selection of different irrigation systems can lead to higher water productivity in drought conditions. The present study intends to evaluate suitable regions along the Izeh plain (Iran) for different pressurized and gravitational irrigation systems using Analytical Hierarchy Process (AHP) based on Geographic Information System (GIS). To that end, a variety of inputs such as climate, topography, skilled labor and system costs, etc. were identified and classified into two main categories of socio-economic and environmental criteria. Each criterion was subdivided into several criteria to make the site selection more specific. A matrix of the pair-wise comparison was, in turn, used to compare these criteria and sub-criteria, and to evaluate them based on their relative importance based on the region’s suitability for different irrigation system alternatives. Geographical layers were then obtained for each sub-criterion to select the most suitable sites for different irrigation systems in the study area. Pressurized irrigation systems including wheel move irrigation system, drip irrigation system and solid-set sprinkler irrigation system, together with gravitational irrigation systems consisting of surface irrigation system, and low-pressure irrigation system were considered as irrigation system alternatives during the site selection process in this study. The result map of site selection for different alternatives showed that surface irrigation, drip irrigation and low pressure systems were the best irrigation system alternatives for the region studied.

     

南方季节性缺水灌区旱地节水灌溉技术设备适应性示范研究

南方季节性缺水灌区灌水次数少,建设一套节水灌溉系统加上运行维护管理费用经济效益往往难以体现,但若不建,干旱又造成作物减产甚至绝收.经过节水示范区建设研究认为,南方季节性缺水灌区适宜建立移动式的节水灌溉系统,适宜建设联合运用的小型水利工程及中低压喷灌、移动式机喷、大流道微喷等节水灌溉技术和灌水器.     

Adoption of More Technically Efficient Irrigation Systems as a Drought Response

Adoption of technically efficient irrigation systems can mitigate the effects of drought by allowing irrigators to maintain water consumption with reduced applications. This paper uses survey data from the worst drought in Colorado's history to examine how drought conditions affect the choice of irrigation system by irrigators. Results indicate that drought conditions did significantly increase the percentage of farms using more efficient sprinkler systems relative to gravity systems. The key factors affecting the decision were land tenure, farm scale and available water supply, suggesting that those enterprises with the most owned land, the highest number of acres and the most reliable water supplies are most likely to invest in more efficient irrigation systems during severe droughts.     

Effect of Various On-Farm Water Management Scenarios on Equity and Productivity in Irrigation Networks

This research investigated the optimum on-farm water management methods for a summer crop (Maize). Water equity and productivity were optimized simultaneously by using genetic algorithms in Doroodzan Irrigation Network. Increase in water reduction fraction (WRF) (0.0 to 0.8) has the incremental effect on water equity (on average 19.4 %), however by increasing WRF, water productivity initially increased (on average 25.3 % at WRF?=?0.4) and then decreased. With increasing irrigation application efficiency (E_a) (40 to 90 %), the values of water equity and productivity increased by on average 52.8 and 91.5 %, respectively. Increment of conveyance efficiency of channels (E_c) (70 to 90 %) resulted in minimum incremental effect on water equity and productivity (on average 18.5 and 11.9 %, respectively). Furthermore, the values of performance measure decreased from wet water year to drought water year. Tape irrigation system was considered as the best choice at low quantities of WRF (<=0.4), however for higher values of WRF (>?=?0.6), sprinkler irrigation system was considered as the best choice for achieving higher values of water equity and productivity. Meanwhile, when equity and productivity were considered together for a specific method of deficit irrigation scheduling, under specified quantity of irrigation water, with increasing equity the water productivity reduction was negligible.     

Feasibility Evaluation of Pressurized Irrigation in Canal Commands

India has one of the largest and most ambitious irrigation programme in the world with net irrigated area exceeding 47 million hectares. However, the overall project efficiency from the headwork to the farmer’s field has been quite low which leads to not only poor utilization of irrigation potential created at huge cost, but also aggravates the degradation of soil and water resources and thereby endangers the sustainability of agricultural production system. As the cost of creating additional irrigation potential in terms of financial, human and environmental aspects has increased tremendously, need of the hour is to increase the irrigation efficiency of existing projects and use saved water for irrigating new areas or meeting the demand of non-agricultural sector. The contribution of application efficiency to poor irrigation efficiency is quite high and therefore increasing application efficiency by a shift in application method from surface to pressurized system has potential of vastly improving irrigation efficiency. To evaluate feasibility of this concept, a pilot study was initiated at Water Technology Centre for Eastern Region, Bhubaneswar, on one outlet of a minor irrigation command. The system has been designed in such a way that it provides pipe conveyance and surface irrigation for rice cultivation during monsoon season and pressurized irrigation during post monsoon period through a hybrid system of sprinkler and drip with four outlets for sprinkler irrigating 2.8 ha area and two outlets for drip irrigating 1.9 ha area. The system is also capable of providing irrigation through drip to part of a command during summer for third crop using water stored in service reservoir after the canal is closed in first week of April. To take care of sediment in the canal water, there are three stages of filtration: first by hydrocyclone filter which filters heavy suspended materials viz. sand, silt, etc., then by the sand filter and finally by the screen filter. The filtration at three stages reduces the turbidity to the desired level. It has been found that three-stage filtration reduced the turbidity to two NTU which is within permissible limit. Considering the cost of water saved, a benefit-cost ratio of the system was found out to be 1.126. This B: C ratio can be further increased by increasing the productivity of the fish and papaya in service reservoir area and better crop management during summer season.     

Economic valuation of reduction in nitrogen outflow from a paddy field area equipped with a recycling irrigation facility.

We estimated the reduction in nitrogen outflow load from a paddy field that had a recycling irrigation facility and, by using a replacement cost method, evaluated the economic effect of nitrogen removal by the paddy field during the irrigation period in the Yoshinuma region of Tsukuba City, Japan. The recycling ratio of outflow water (proportion of outflow reused) was 13.5%. The nitrogen (N) outflow load was reduced by about 45 kg ha(-1) by the N removal function of the paddy field and by about 39 kg ha(-1) by the recycling irrigation facility. The paddy field equipped with a recycling irrigation facility as an N removal facility was valued at 32.6 million Japanese yen (JPY) ha(-1) and 0.72 million JPY ha(-1) per year, which compare it with the construction and maintenance costs, respectively, of a water quality improvement facility. The recycling irrigation facility was costed at 17.3 million JPY ha(-1) for construction and 0.21 million JPY ha(-1) for maintenance per year. The cost for constructing and maintaining a recycling irrigation facility was 53% of the value of the paddy field area equipped with a recycling irrigation facility as an N removal facility.     

现代灌溉水肥精量调控原理与应用

过去15年间,中国水利水电科学研究院水利研究所瞄准现代灌溉农业集约化和精量化发展目标,重点围绕不同生态区域、不同尺度农田的水肥施用与多过程综合调控中存在的问题,系统开展了现代灌溉水肥精量调控研究,取得了系列化的成果:考虑土壤空间变异和层状质地对水肥分布的影响,改进了微灌系统的设计方法;在干旱区和半湿润区等不同气候区,选取小麦、玉米、棉花和蔬菜等典型作物,全面考虑水力学参数、土壤水肥动态和淋失、环境参数以及作物产量和品质等因素对微灌均匀系数的响应机制进行研究,提出了微灌均匀系数分区标准;在国内率先开展了变量灌溉理论和控制技术的研究,发展了适用于缺水地区的非充分变量灌溉理论;从系统安全、环境安全和水肥高效利用出发,揭示了再生水滴灌对系统性能和环境的影响机制,定量评价了再生水中养分的有效性;研发了低压高均匀灌水器、多功能系列喷头和智能灌溉施肥机等装置,实现了灌水施肥性能的提升;形成了区域化的喷、微灌水肥高效利用模式。上述成果为进一步提高农田水肥利用率、推动喷、微灌理论和技术进步提供了支撑。     

坡地允许喷灌强度研究

本文在分析坡地降雨入渗机理的基础上，根据二维土壤水分运动方程，建立均匀坡地上不同土壤及其边界条件的均匀灌水入渗模型，研究模型的有限元数值解方法，得到了土壤非饱和情况下，坡地喷灌强度不需折减的结论。通过数值计算和实验验证，所得实验结果与数值分析结果基本吻合。     

Estimation of Groundwater Recharge from the Rainfall and Irrigation in an Arid Environment Using Inverse Modeling Approach and RS

Quantifying recharge from agricultural areas is important to sustain long-term groundwater use, make intelligent groundwater allocation decisions, and develop on-farm water management strategies. The scarcity of data in many arid regions, especially in the Middle East, has necessitated the use of combined mathematical models and field observations to estimate groundwater recharge. This study was designed to assess the recharge contribution to groundwater from rainfall and irrigation return flow in the Mosian plain, west of Iran. The Inverse modeling approach and remote sensing technology (RS) were used to quantify the groundwater recharge. The recharge for steady–state conditions was estimated using the Recharge Package of MODFLOW. The land-use map for the research area was produced using remote sensing and satellite images technology. According to results, groundwater recharge from the rainfall and irrigation return flow was at the rate of 0.15 mm/day. The recharge to the groundwater from rainfall was about 0.08 mm/day (10.8 % of total rainfall). The average of groundwater recharge contribution in the study area was about 0.39 mm/day that include 15.2 % of the total water used in the irrigated fields. We can conclude that irrigation water is the most important resource of groundwater recharge in this area, consequently, it should be integrated into relevant hydrological models as the main source of groundwater recharge.