典型灌溉模式下灌溉水利用效率尺度变化模拟

为探讨灌区水分利用效率的尺度特征以及适宜的灌溉模式,以湖北漳河灌区为背景,基于改进的分布式水文模型,模拟得到"间歇"灌溉和"薄浅湿晒"灌溉模式下不同尺度水平衡要素和作物产量分布.结果表明,2种灌溉模式下的灌溉水分生产率和毛入流水分生产率在小于一临界尺度时,都随尺度增大而增大,当大于此临界尺度后,则处于平缓甚至有下降趋势."薄浅湿晒"模式比"间歇"模式节约灌溉水量19%左右,而灌溉水分生产率提高约1 kg/m3.因此对于漳河灌区,"薄浅湿晒"是一种值得推广的节水灌溉模式.     

莫索湾灌区1998—2007年地下水埋深变化及影响因素

依据玛纳斯河中游莫索湾灌区1998—2007年(共120个月)的地下水位监测资料,分析地下水埋深年际变化情况,采用主成分分析法对灌区地下水埋深变化的影响因素进行分析.结果表明:地下水埋深年际变化持续或波动下降;灌水量和抽水量是影响地下水埋深的主要因子,其荷载分别为0.801和0.769,埋深随灌水量的减少、抽水量的增加而增大;蒸发量仅次于灌水量和抽水量,也是影响地下水埋深的重要因子;而降雨量对地下水埋深没有显著的影响,其贡献率只有15%.分析了主要影响因素与地下水埋深变化动态的关系,认为灌区地下水埋深在自然因素和人为活动的交互影响下年内季节变化明显.     

河北石津灌区水循环组份特征及用水水平分析

选择河北省石津灌区作为研究区,利用收集的灌区资料分析灌区2004~2006年水循环组份特征,发现灌区水资源组成结构中灌溉和降雨所占比例为42%,潜水补给所占比例为16.5%,灌域降水量、潜水位和作物腾发量年内变化皆表现出了一定的规律性.选择渠系水利用系数、灌溉效率以及3个水分生产率指标计算了2004~2007年冬小麦生育期内灌区用水水平,结果表明渠系水利用系数和灌溉水利用系数2004~2007年平均值分别为0.51和0.4,而考虑了水资源在时间上的重复利用后,得到灌溉效率为0.66,通过计算灌域不同尺度水分生产率,发现该指标随着尺度的增大而减小,说明水平回归水很少.     

内蒙古河套灌区节水对区域水盐平衡的影响分析

内蒙古河套灌区实施大型节水改造以来,渠系衬砌、田间节水和种植结构调整等节水措施影响了该区域原有的水盐平衡。通过比对灌区节水措施从1990年到2013年的实施历程和灌区引水量、排水量和耗水量等水盐循环要素在同时期的演进情况发现,随着节水措施的实施,多年平均引黄水量从1998年之前的49.7亿m3减少到1999—2013年的45.3亿m3;进一步分析了灌区地下水位和盐分变化情况,发现年平均地下水埋深从1990—1994年的1.70 m下降到2010—2013年的2.09 m;灌区长期处在积盐状态,但积盐量呈下降趋势。分析结果表明:节水最直接的结果是导致灌区水循环通量减少;随着节水措施的不断加强,地下水埋深不断增大;节水导致灌区引盐量减少、排盐量增加;节水对灌区生态的影响还有待进一步研究。     

宁夏中部干旱带枸杞痕量灌溉试验研究

为探究痕量灌溉不同灌水量设置对枸杞大面积种植区土壤含水规律及产量的影响,选取宁夏中部干旱带枸杞大面积典型种植区,通过设置生育期不同灌水量,开展多年生枸杞、一年生枸杞痕量灌溉技术同多年生枸杞滴灌技术进行灌水量、土壤含水规律及产量对比分析试验。结果表明:当痕量灌溉管埋深为25 cm,痕量灌溉比滴灌能够更好地补充枸杞生长所需的水分,尽可能减少了土壤蒸发和深层渗漏,达到节水目标;痕量灌溉生育期灌水量对作物产量的影响与滴灌相似,在保持产量相同水平情况下,痕量灌溉较滴灌能够减少用水量16%左右;试验得出枸杞采用痕量灌溉技术全年灌水8～11次,年灌水量2 250～2 775 m~3/hm~2,生育期灌水量1 650～2 175 m~3/hm~2。     

基于Modflow的灌区地下水管理策略——以柳园口灌区为例

根据开封市柳园口灌区的水文地质条件,运用地下水数值模拟软件Visual Modflow,建立了地下水三维非稳定流模型.用1986-1998年的资料进行率定,1999-2003年的资料进行验证,结果表明模型的模拟结果与实际情况较吻合,模型可以对该灌区的地下水动态进行模拟和预测.拟定不同的地下水开采量、不同的地表引黄水分配以及不同的作物种植结构等方案,对灌区地下水系统对各方案的响应进行模拟.结果表明,与种植结构的调整及控制地下水开采量相比,灌区采用井渠联合应用模式可以更加有效地减少潜水蒸发和控制适宜的地下水位埋深.模拟分析结果为灌区合理开采地下水及提高灌区水利用率提供了科学的水管理依据.     

850农场地下水资源可持续开采利用研究

850农场是三江平原地下水开采强度最大农场之一,井灌面积占平原面积57.7%,现地下水埋深约5 m,处理想埋深中,地下水用量约405 m^3/hm^2·a,产量还略高于本场渠灌稻。本地区井灌面积达2.07×104hm^2,只要在节水灌溉上下功夫,可达采补平衡。若在雨洪资源化上下功夫,“西水东调”和建河滩“漏水库”,还可发展水田,水田比例由现0.577上升到0.60以上,故此850农场地下水可持续开采利用。     

黄河南岸灌区土壤盐分运动及模拟

以鄂尔多斯黄河南岸灌区为研究区域,在分析其土壤盐分运动规律及影响因素的基础上,采用BP神经网络模型对耕作期浅层土壤盐分变化进行了模拟与预测。结果表明:同期降雨后不同区域可呈现不同的脱盐或积盐过程,降雨对土壤盐分的影响主要集中在土壤深度60 cm以内的浅层区域,减小灌溉强度可能造成土壤表层反盐;土壤盐分运动受到地下水埋深、土壤初始含盐量及灌溉水质等因素的影响,地下水埋深大于2 m后,地下水对土壤盐分的影响逐渐消失。BP神经网络模型对土壤盐分运动具有良好的模拟精度,减小灌溉强度后耕作层土壤呈弱积盐状态,4个灌溉周期后耕作层土壤盐分将上升4.7%。     

降雨对浅埋地下水补给的初步探讨

的我国北方平原地区,降雨对地下水补给是地区地下水资源主要补给水源。研究降雨对地下水补给对地区地下水资源评价和合理开发利用地下水有着十分重要的意义。本文根据饱和——非饱和水分运动微分方程和初边值条件模拟浅埋地下水位在降雨入渗补给下有关土壤水和地下水问题。探讨降雨强度对地下水补给的影响;地下水位埋深对降雨补给的影响,以及土壤剖面含水量对降雨补给的影响,最后通过实例模拟蒸发——降雨条件下土壤水和地下水运动问题。     

黑龙江省浅井灌溉与节约保护水资源

对发展浅井灌溉在实现水资源优化配置、合理利用以及节约与保护水资源中的作用进行了论述,认为浅井灌溉可增加渗漏回归,减少损失;适当降低地下水位,可以减少地下水无效蒸发,增加降雨入渗,减少地下水污染;沿江发展井灌有利于雨洪资源化;对三江平原弱承压区,适当降低地下水位,可增加江河的补给量。在充分认识浅井灌溉优势的基础上,要合理开发利用,进行水资源优化配置,提高水资源利用率,实现可持续发展。     

基于改进SWAT模型的区域蒸发蒸腾量模拟

运用改进的SWAT模型,以漳河灌区三干渠内杨树垱小流域为研究对象,针对"间歇灌溉"、"淹灌"、"薄浅湿晒"3种不同灌溉模式下的流域内ET模拟分析,结果表明该区域ET从大到小的顺序依次为"淹灌"、"间歇灌溉"、"薄浅湿晒",同种灌溉模式下ET随水稻种植面积比的增加而增大.对3种灌溉模式下的稻田ET分项(植株蒸腾、稻田水面蒸发、稻田土壤蒸发)模拟分析表明,3种模式下植株蒸腾比较稳定,维持在37%~40%;"间歇灌溉"和"淹灌"模式下的稻田水面蒸发占稻田ET的55%以上,而土壤蒸发只占6%和0.4%;"薄浅湿晒"灌溉模式下稻田水面蒸发和土壤蒸发分别占33%和27%.     

Remote sensing and census based assessment and scope for improvement of rice and wheat water productivity in the Indo-Gangetic Basin

Understanding of crop water productivity (WP) over large scale, e.g., river basin, has significant implications for sustainable basin development planning. This paper presents a simplified approach to combine remote sensing, census and weather data to analyze basin rice and wheat WP in Indo-Gangetic River Basin, South Asia. A crop dominance map is synthesized from ground truth data and three existing LULC maps. National statistics on crop area and production information are collected and the yield is interpolated to pixel level using moderate resolution imaging spectroradiometer (MODIS) normalized difference vegetation index (NDVI). Crop evapotranspiration is mapped using simplified surface energy balance (SSEB) model with MODIS land surface temperature products and meteorological data collected from 56 weather stations. The average ET by rice and wheat is 368 mm and 210 mm respectively, accounting for only 69% and 65% of potential ET, and 67% and 338% of rainfall of the crop growth period measured from Tropical Rainfall Measurement Mission (TRMM). Average WP for rice and wheat is 0.84 and 1.36 kg/m³ respectively. WP variability generally follows the same trend as shown by crop yield disregarding climate and topography changes. Sum of rice-wheat water productivity, however, exhibits different variability leading to better understanding of irrigation water management as wheat heavily relies on irrigation. Causes for variations and scope for improvement are also analyzed.     

气候变化对水稻灌溉需水量的影响——以高邮灌区为例

采用FAO56推荐的方法计算了江苏省高邮灌区1955~2007年的水稻灌溉需水量,并通过Mann-Kendall检验对其长期变化趋势进行分析,结合气象因素的变化趋势,分析了气候变化对高邮灌区水稻灌溉需水量的影响.结果表明,由于气温上升和相对湿度下降,在过去的50余年中高邮灌区水稻生育期的参考作物腾发量呈显著上升趋势,在降雨基本无变化的情况下,灌溉需水量有上升的趋势.在不减少灌区水稻种植面积的条件下,应通过节水措施减少水量损失和提高水分利用效率,尽可能地满足灌溉需水要求,降低气候变化对水稻生产的影响.研究结果可为提高水稻灌溉管理水平、应对气候变化的策略研究提供理论依据.     

Modeling the crop transpiration using an optimality-based approach

Evapotranspiration constitutes more than 80% of the long-term water balance in Northern China. In this area, crop transpiration due to large areas of agriculture and irrigation is responsible for the majority of evapotranspiration. A model for crop transpiration is therefore essential for estimating the agricultural water consumption and understanding its feedback to the environment. However, most existing hydrological models usually calculate transpiration by relying on parameter calibration against local observations, and do not take into account crop feedback to the ambient environment. This study presents an optimality-based ecohydrology model that couples an ecological hypothesis, the photosynthetic process, stomatal movement, water balance, root water uptake and crop senescence, with the aim of predicting crop characteristics, CO₂ assimilation and water balance based only on given meteorological data. Field experiments were conducted in the Weishan Irrigation District of Northern China to evaluate performance of the model. Agreement between simulation and measurement was achieved for CO₂ assimilation, evapotranspiration and soil moisture content. The vegetation optimality was proven valid for crops and the model was applicable for both C ₃ and C ₄ plants. Due to the simple scheme of the optimality-based approach as well as its capability for modeling dynamic interactions between crops and the water cycle without prior vegetation information, this methodology is potentially useful to couple with the distributed hydrological model for application at the watershed scale.     

Modeling the crop transpiration using an optimality-based approach

Evapotranspiration constitutes more than 80% of the long-term water balance in Northern China. In this area, crop transpiration due to large areas of agriculture and irrigation is responsible for the majority of evapotranspiration. A model for crop transpiration is therefore essential for estimating the agricultural water consumption and understanding its feedback to the environment. However, most existing hydrological models usually calculate transpiration by relying on parameter calibration against local observations, and do not take into account crop feedback to the ambient environment. This study presents an optimality-based ecohydrology model that couples an ecological hypothesis, the photosynthetic process, stomatal movement, water balance, root water uptake and crop senescence, with the aim of predicting crop characteristics, CO₂ assimilation and water balance based only on given meteorological data. Field experiments were conducted in the Weishan Irrigation District of Northern China to evaluate performance of the model. Agreement between simulation and measurement was achieved for CO₂ assimilation, evapotranspiration and soil moisture content. The vegetation optimality was proven valid for crops and the model was applicable for both C ₃ and C ₄ plants. Due to the simple scheme of the optimality-based approach as well as its capability for modeling dynamic interactions between crops and the water cycle without prior vegetation information, this methodology is potentially useful to couple with the distributed hydrological model for application at the watershed scale.

     

Effects of irrigation efficiency on chemical transport processes

Irrigation practices greatly affect sustainable agriculture development. In this study, we investigated the effects of irrigation efficiency on water flow and chemical transport in soils, which had significant impact on the environment. Field dye staining experiments were conducted at different soils with various irrigation amount. Image analysis was conducted to study the heterogeneous flow patterns and their relationships with the irrigation efficiency. Irrigation efficiency and its environmental effects were evaluated using various indictors, including application efficiency, deep percolation ratio, storage efficiency, and uniformity. Under the same irrigation condition, soil chemical distributions were more heterogeneous than soil water distributions. The distributions were mainly affected by soil texture, initial soil water content, and irrigation amount. Storage efficiency, irrigation uniformity, and deep percolation ratio increased with irrigation amount. Since the chemical distribution uniformity was lower than the water uniformity, the amount of chemical leaching increased sharply with decrease of irrigation uniformity, which resulted in high environmental risks of groundwater pollution.     

水稻田灌溉用水的一个预测公式

从水稻田水量平衡公式出发，推导出水稻灌溉用水预测公式，利用历史实测灌溉用水及同期降雨资料率定有关参数，根据降雨预测灌溉用水量。公式适用于种植结构不明的灌区。     

人民胜利渠灌区多水源优化调配研究

针对人民胜利渠灌区水资源优化调配中存在的问题,为实现引黄水、地下水、有效降雨等水源的综合利用效益最大,建立了灌区缺水量最小和作物产量最大的人民胜利渠灌区多水源多目标优化模型,采用引力搜索算法求解模型,得出了不同水平年多水源在灌区不同用水部门及作物不同生育阶段的优化调配方案.