基于SHAW模型的河套灌区秋浇渠系优化配水模型研究

河套秋浇是为满足来年春播作物水盐需求而进行的保墒淋盐灌溉。针对传统基于作物需水预测成果进行渠系配水存在的预报依赖性强和中长期预报精度低问题,本文提出了一种不需要作物需水预测成果的渠系优化配水模型框架,该框架依据春播初期作物水盐要求,将SHAW模型嵌入优化配水模型,确定秋浇配水计划。河套灌区永济灌域2016年秋浇配水计划编制实例研究表明:与传统基于需水预测的配水方法相比,新方法得到的配水计划可以在不增加渠首引水量及渠道输水损失总量基础上显著提升淋盐效果,使春播初期0～40 cm土层水盐状态更加适宜于作物播种,春播初期土壤0～40 cm土层平均盐分超标由60%以上降低至5%以下,同时配水公平性也得到提升。     

Pond and Irrigation Model (PIM): a Tool for Simultaneously Evaluating Pond Water Availability and Crop Irrigation Demand

Agricultural ponds are an important alternative source of water for crop irrigation to conserve surface and ground water resources. In recent years more such ponds have been constructed in Mississippi and around the world. There is currently, however, a lack of a tool to simultaneously estimate crop irrigation demand and pond water availability. In this study, a Pond-Irrigation Model (PIM) was developed to meet this need using STELLA (Structural Thinking, Experiential Learning Laboratory with Animation) software. PIM simulated crop land and agricultural pond hydrological processes such as surface runoff, soil drainage, and evapotranspiration as well as crop irrigation demand and pond water availability. More importantly, PIM was able to decide when to conduct crop irrigation based on management allowable depletion (MAD) root zone soil water content and to determine optimal ratios of agricultural pond size to crop land with sufficient pond water available for crop irrigation. As a case demonstration, the model was applied to concomitantly estimate row crops (i.e., corn, cotton, and soybeans) water irrigation demand and pond water availability in a farm located at East-central Mississippi. Simulations revealed that corn used more soil water for growth than soybeans, whereas soybeans needed more irrigation water than corn and occurred due to less rainwater available for soybeans growth. We also found that there was one time for corn, zero time for cotton, and two times for soybeans when the pond water level was drawn to near zero for irrigation from 2005 to 2014. PIM developed in this study is a useful tool for estimating crop irrigation demand and pond water availability simultaneously.     

宁夏汉延渠灌区灌溉水利用系数测算分析与评价

农田灌溉水利用系数表示从水源引水被农作物吸收利用的过程,是反应灌区灌溉用水效率的一项指标。本文以汉延渠灌区为例,综合考虑宁夏的气候环境、土壤类型、灌溉制度及作物种植结构等因素,选取典型渠段和样点灌区,分别采用"连乘法"和"首尾法"计算宁夏汉延渠灌区2018—2019年的灌溉水利用系数,并对其进行对比分析评价,从而确定灌区适宜的计算方法。     

A Numerical Simulation Model for Conjunctive Water Use in Basin Irrigated Canal Command Areas

Basin irrigation is a common practice for growing water intensive crops like paddy. Irrigation water, when supplied through a network of canal, is often found to be inadequate to meet the crop water requirement uniformly throughout the irrigated command area. The most deprived are the cultivators of the lower end of the command, who resort to supplementing the crop water requirement by extractions from the ground. This practice is noticeable in irrigation system without a proper canal water distribution schedule and often result in water logging in the upper command regions contrasted with excessively depleted groundwater table in the lower commands. The present contribution attempts to model the conjunctive water use of such a canal irrigated command using physically based numerical sub-models for simulating surface flow, groundwater flow and the interlinking process of moisture movement through the unsaturated zone for a given quantum of supplied water and crop water demand. Individual models are validated to demonstrate their applicability in an integrated framework. Various plausible conjunctive water use scenarios are tested on a hypothetical command area practising basin irrigation to identify the best possible water distribution strategy under given constraints.     

基于干旱区的大豆高效节水灌溉制度制定

大豆属于需水较多的旱作物,对土壤水分的要求比较严格,土壤水分充足与否,对大豆各生育阶段的发育及产量形成,都有较大的影响。文章对大豆不同生育期的土壤水分,制定出干旱区大豆的节水灌溉制度。     

A Modified Constrained State Formulation of Stochastic Soil Moisture for Crop Water Allocation

In response to uncertainty in crop water allocation, several methodologies have been proposed in the literature, most of them considering rainfall as a stochastic variable affecting soil moisture. A methodology considering uncertainties both in irrigation depth and soil moisture is more realistic for irrigated crops as developed here using an explicit stochastic optimization model. This new work is based on an earlier constrained state formulation which did not consider the irrigation depth as stochastic. In constrained state formulation methods, the first and second moments of state variables are developed considering the uncertainties which are then used as constraints in an optimization model. In contrast to alternative methods that are dynamic programming-based, the proposed optimization method can be solved using standard nonlinear optimization tools. Performance of the proposed model is evaluated for the case of two different crops, winter wheat and barley. Model verification is performed by comparing the results with simulation results. The model is quite acceptable and shows considerable improvement over analogous models.     

GIS-Integrated Rice Irrigation Management Information System for a River-Fed Scheme

The Tanjung Karang Irrigation Scheme is one of the large rice granaries in Malaysia. Irrigation management for rice irrigation is difficult because of different planting schedules, variability in soil and crop conditions and unreliable intake of water in the main canal due to the absence of storage reservoir and their uneven distribution to tertiary canals. In view of this concern, the scheme needs the daily estimation of the available water for irrigation and its equitable allocation among tertiary canals to cater trade-offs in water use for the scheme. Easy access of these spatially and temporally distributed data helps to make management system simpler. A GIS-integrated tool known as RIMIS was developed for equitable irrigation supply to tertiary canals and the characterization of their irrigation delivery performance as the season advances. RIMIS dynamically links a field irrigation demand prediction model for the area irrigated by a canal network in GIS. The system can correctly simulate and evaluate recommended irrigation supplies among tertiary canals that match the available discharge at the system head with the crop water demand for the actual field conditions. The user-interface was developed using ArcObjects and Visual Basic for Application (VBA) programming languages in ArcGIS software. RIMIS can give information on the uniformity of water distribution and the shortfall or excess and what decisions to adopt for the next day. It ensures equal sharing of water for the tail-end users. The system helps to keep input and output databases always updated with respect to the real field conditions. The results are displayed on the computer screen together with colour-coded maps, graphs and tables in a comprehensible form. This will help irrigation managers to enhance decision-making in the management and operation of the irrigation system. The development of the overall system and procedures is illustrated with data from a study area.     

作物需水量与灌溉制度模拟

从作物需水量的基本概念出发，以水量平衡原理为基础，建立了模拟农田根层土壤水循环的计算机模型-ISAREG.这一模型具有多种功能，可模拟根层土壤水分变化，评价给定的灌溉制度，计算作物需水量和灌溉需水量，也可用以制订多种供水限制条件下的优化灌溉制度．用望都灌溉试验站的小麦、玉米、棉花3种作物两年的试验观测资料对上述模型进行了验证．     

再生水灌溉研究进展

从再生水灌溉对土壤、作物、地下水和土壤斥水性4个方面简述国内外再生水灌溉的发展概况和研究进展。已有研究表明：再生水灌溉对土壤肥力和土壤酶活性的影响尚未有定论;再生水对农作物生长的影响尚有分歧;再生水灌溉对地下水水质具有一定的影响,并显著影响地下水水环境;长期的再生水灌溉会引发土壤斥水性的产生,且土壤斥水持续时间与土壤有机质质量分数呈正相关。目前存在的问题有：再生水灌溉对土壤和农作物的影响研究不一致,如何消除再生水灌水对地下水和土壤斥水性的影响。认为由于再生水中含有作物正常生长的必要营养元素,若能克服再生水灌溉存在的问题,可缓解淡水资源的压力和减少化肥的使用,避免环境的污染。     

Methods to estimate irrigated reference crop evapotranspiration - a review

Efficient water management of crops requires accurate irrigation scheduling which, in turn, requires the accurate measurement of crop water requirement. Irrigation is applied to replenish depleted moisture for optimum plant growth. Reference evapotranspiration plays an important role for the determination of water requirements for crops and irrigation scheduling. Various models/approaches varying from empirical to physically base distributed are available for the estimation of reference evapotranspiration. Mathematical models are useful tools to estimate the evapotranspiration and water requirement of crops, which is essential information required to design or choose best water management practices. In this paper the most commonly used models/approaches, which are suitable for the estimation of daily water requirement for agricultural crops grown in different agro-climatic regions, are reviewed. Further, an effort has been made to compare the accuracy of various widely used methods under different climatic conditions.     

淮北平原基于水文气象多因子的土壤水分动态预测

为研究土壤水分动态变化,利用五道沟水文实验站1989-2015年水文气象和大田土壤水实测资料,采用灰色关联度和线性回归分析,建立了冬小麦各生长阶段不同土层土壤水分预测模型。结果表明:不同土层土壤水分与气象因子的关联度一致;不同生长阶段土壤水分与气温和地下水埋深关联度最强,分别达0. 92和0. 95;分蘖-越冬期,土壤水分与地下水埋深和日照时数关联度最强,其他生长阶段,土壤水分与气温和地下水埋深关联度最强。通过水文气象因子模拟土壤水分拟合度较高,R~2达0. 94。不同生长阶段不同土层,土壤水分计算模型均具有良好的预测能力,R~2达0. 80。成果为实施作物不同生长阶段的灌溉计划提供科学依据。     

An Empirical Assessment of On-Farm Water Productivity using Groundwater in a Semi-Arid Indian Watershed

Realistic estimation of irrigation volume applied to any crop at farm level generally requires information on event based discharge rates and corresponding periods of irrigation application. Use of mean seasonal discharge rates leads to erroneous estimation of volume due to unaccounted seasonal fluctuations in the water table, upon which the discharge rate of tube well is dependent. In the absence of such information, an alternative approach of estimating farm level water application based upon water table fluctuation data has been adopted in this study. The total actual water extracted during each irrigation event from the watershed was distributed among the farms irrigating crops in proportion to the product of irrigation time and the pump capacity (h_p). Volume of water withdrawal concurrent to an irrigation event was computed based on the water level fluctuations in the wells in conjunction with potential recharge contribution from the surface storage structures to the groundwater aquifer. A production function approach was used to estimate the marginal productivity of water for selected crops at various stages of plant growth. Water, as an input in the production function, encompassed either in-situ soil moisture storage from rainfall or irrigation from groundwater or both. The inter-season as well as intra-season groundwater use, and the consequent groundwater withdrawals were analyzed based on the marginal value and output elasticity of water at different crop growth stages during the season. The cotton crop realized marginal value product of water, ranging from Rs. 1.03/m³ to Rs. 10.43/m³ at different crop growth stages in cotton. Castor crop had the marginal value product ranging from Rs. 2.89/m³ to Rs. 6.81/m³. The availability and use of water, including soil moisture, in the two seasons, coupled with the local harvest prices received, yielded the differential marginal values of water.     

SIMETAW# - a Model for Agricultural Water Demand Planning

A successful water management scheme for irrigated crops requires an integrated approach, which accounts for water, soil, and crop management. SIMETAW# is a user friendly soil water balance model that assesses crop water use, irrigation requirements, and generates hypothetical irrigation schedules for a wide range of crops experiencing full or deficit irrigation. SIMETAW# calculates reference evapotranspiration (ET_o), and it computes potential crop evapotranspiration (ET_c), and the evapotranspiration of applied water (ET_aw), which is the amount of irrigation water needed to match losses from the effective soil root zone due to ET_c that are not replaced by precipitation and other sources. Using input information on crop and soil characteristics and the distribution uniformity of infiltrated irrigation applications in full or deficit conditions, the model estimates the mean depth of infiltrated water (IW) into each quarter of the field. The impact of deficit irrigation on the actual crop evapotranspiration (ET_a) is computed separately for each of the four quarters of the cropped field. SIMETAW# simulation adjusts ET_o estimates for projected future CO₂ concentration, and hence the model can assess climate change impacts on future irrigation demand allowing the user to propose adaptation strategies that potentially lead to a more sustainable water use. This paper discusses the SIMETAW# model and evaluates its performance on estimating ET_c, ET_a, and ET_aw for three case studies.     

减少蒸发蒸腾 促进水资源可持续利用——以河北省馆陶县为例

依据馆陶县世行节水灌溉项目和GEF海河项目的测定数据,对项目区和对照区的不同作物及同一作物在不同耕作方式下的ET值进行计算分析.提出了在缺水区可通过调整种植结构和采用节水灌溉、保水保墒等措施来有效减少ET值;减少水的无效蒸发,从而达到节约用水,减少地下水开采量,实现水资源可持续利用的目的.     

Farm location and farmers’ performance on the Hamza minor canal

A sample of 36 tenant farmers, at varying locations along the Hamza Minor Canal of the Sudan Gezira Scheme, were surveyed in 1986/7, the purpose being to estimate locational variation in irrigation water supplies and. tenancy income levels. Results show that for the main crop, cotton, there are declines in water balance, crop yields and net returns between head, middle and tail end of the canal. However, in middle and tail‐end locations groundnuts yield a substantially higher net return per hectare than the main crops, cotton and wheat, which suggests that changes in crop rotations would be profitable.     

基于水文-作物耦合模型和CWAPI指数的农业干旱评估

基于模拟土壤含水量构建的干旱指数可反映农业干旱的时空发展过程,已被广泛用于大范围农业干旱评估中。当前模拟用于干旱评估的土壤含水量时,常采用水文模型进行模拟。然而,水文模型常过于简化作物模块甚至缺少作物模拟方案,无法模拟作物需水量,因此仅基于土壤含水量构建的土壤干旱指数因忽略作物需水而难以准确评估实际的农业干旱情况。研究构建了考虑灌溉过程影响的水文-作物耦合模型VIC-EPIC（Variable Infiltration Capacity-Environmental Policy Integrated Climate）,提出了基于VIC-EPIC模拟作物需耗水过程的作物缺水距平指数CWAPI（Crop Water Anomaly Percentage Index）,在青口河流域开展了区域农业干旱评估方法研究。验证分析表明,构建的CWAPI因考虑作物需水影响可直接反映作物的缺水状态和缺水对作物生长的累积影响;由于在干旱评估中引入了作物种植比例、轮作类型和灌溉的影响,CWAPI能够较SMAPI（Soil Moisture Anomaly Percentage Index）更客观地反映区域作物旱情。因此评估农业干旱时,需要考虑作物种植比例、轮作和灌溉过程的影响。     

Assessing Options to Increase Water Productivity in Irrigated River Basins Using Remote Sensing and Modelling Tools

In regions where water is more scarce than land, the water productivity concept (e.g. crop yield per unit of water utilized) provides a useful framework to analyse crop production increase or water savings in irrigated agriculture. Generic crop and soil models were applied at field and regional scale, together with geographical and satellite data to analyse water productivity in Sirsa District (India). In this district certain parts show a serious decline in groundwater levels and water shortage, while other parts experience a serious rise of groundwater levels, causing waterlogging and salinization. The regional analysis showed a large spatial variability of water productivity, net groundwater recharge and salinization. Scenario analysis showed that improved crop husbandry, reallocation of canal water from fresh to saline groundwater areas and reduction of seepage losses in saline groundwater areas are effective measures to increase the overall water productivity and to attain sustainable irrigation in Sirsa District.     

干旱缺水地区根系分区交替灌溉技术探讨

干旱缺水地区的科学合理灌溉模式不仅能为作物提供适宜的水分,降低ET损耗,还能使土壤中的水、气、热维持在良好状态,给作物生长发育带来良性刺激,有利于提高作物产量.本文探讨干旱缺水地区地表滴灌与地下滴灌相结合的作物根系分区交替灌溉模式,包括两种布置方式:1)滴灌带单行直线布置;2)滴灌带双行直线布置.两种布置方式有其不同的适用性,但地表及地下滴灌带单行铺设易于在生产实际中得到推广.地表灌溉与地下灌溉相结合的灌溉模式对于干旱缺水地区推广精准灌溉,发展现代农业具有重要的意义.     

河北平原井灌区冬小麦灌水定额的计算分析

根据华北半湿润偏旱井灌区节水农业综合技术示范区的建设实践,在河北平原三河井灌区,通过实时监测冬小麦田间土壤含水率,计算出其田间土壤含水量与田间持水量之差即为灌水定额;当实时监测的田间土壤含水率低于冬小麦适宜生长含水率高于凋谢系数时,便对监测地块进行灌溉。采用移动式管道喷灌或支管退行式畦灌模式进行冬小麦灌溉,使灌水定额控制在750m^3／hm^2以内,达到节水增产增收的目的,促进农业又好又快发展。     

Using SWAT for Strategic Planning of Basin Scale Irrigation Control Policies: a Case Study from a Humid Region in Northern Germany

The eco-hydrological model SWAT is used worldwide for simulating hydrology and water quality of agricultural catchments. One of the main water uses is irrigation, predominantly in arid and semi-arid regions. Climate impact simulations show that a future increase of irrigation demand can be expected for humid regions. Options for adaptation include the improvement of irrigation techniques and the modification of crop patterns. In our study we investigate the application of SWAT for the development of water saving irrigation control strategies in a humid river catchment in Northern Germany. We developed different scenarios using both soil moisture deficit control and plant water demand control. The results show plausible changes of irrigation amounts when changing the trigger points of both control methods. By deficit control strategies, the water consumption could be reduced with only a moderate decrease of crop yield. Differences between soil characteristics were well shown in the SWAT simulations, but the model consistently overestimated irrigation values. Furthermore we found a high variability of the model errors between the different years, even if the long term average values are considered acceptable. Future research is needed to improve the model accuracy in automatic irrigation control.