Estimation of field irrigation water demand based on lumped kinematic wave model considering soil moisture balance

An estimation model of farm field irrigation water demand is developed. The model is based on the lumped kinematic wave model considering soil water balance. The lumped model approach reduces the computational load in rainfall-runoff analysis and allows application to large river basins. Evapotranspiration is estimated on hourly basis by the improvement of FAO’s method. Not only water volume necessary for farm field irrigation but also the number of the water charge and its interval can be estimated by the combined use of the lumped runoff model and the hourly evapotranspiration model.     

鄱阳湖环湖灌区枯季缺水量分析及对策建议

近年来,在以三峡大坝为代表的一系列流域人类活动作用下,鄱阳湖出现了枯水期延长、水位提前消落的现象,导致了一系列生态环境和民生问题.本文从环湖灌溉缺水入手,采用11种概率分布分析1953-2018年星子站水位,进行比较优选后选择Wakeby分布作为理论分布,得到90％保证率下的湖泊年平均水位及枯季9月至翌年2月月平均水位...     

塔里木灌区香梨树腐烂病害发生成因

本文根据2001～2011年对塔里木灌区香梨树腐烂病害的观测调查情况,结合当地农业气候条件进行对比分析,找出香梨树腐烂病害加重形成的因素。通过连续11年的跟踪观测、调查资料结合对灌区香梨树腐烂病害的发生规律进行研究分析,香梨树腐烂病害的发生、发展与气候、土壤、虫害、田间管理等有密切关系。本文针对各种不同情况香梨树腐烂病害的发生、发展,提出相应的预防对策措施,为今后灌区香梨树腐烂病害的防治提供有利依据。     

A rapid loess flowslide triggered by irrigation in China

A loess landslide occurred in the morning of October 6, 2006, in Gaolou district of Daming town, Hua country, Shaanxi, China. The landslide originated from a valley side slope of the loess ‘yuan’ (dissected loess plateau), below which many houses are densely located. The displaced materials smashed several houses and killed 12 persons, after traveling down a long but gentle valley channel. Field surveys revealed that the displaced materials were highly fluidized. Because there was no rainfall before this event, the leakage of irrigation water from the canal on the top of the slope may be the reason for the initiation. To investigate the possible mechanisms underlying the initiation and movement of this landslide, laboratory tests on the loess samples from the source area were performed. Some preliminary research results are presented in this report.     

Groundwater quality in the lower Varuna River basin,Varanasi district,Uttar Pradesh

The lower Varuna River basin in Varanasi district situated in the central Ganga plain is a highly productive agricultural area, and is also one of the fast growing urban areas in India. The agricultural and urbanization activities have a lot of impact on the groundwater quality of the study area. The river basin is underlain by Quaternary alluvial sediments consisting of clay, silt, sand and gravel of various grades. The hydrogeochemical study was undertaken by randomly collecting 75 groundwater samples from dug wells and hand pumps covering the entire basin in order to understand the sources of dissolved ions, and to assess the chemical quality of the groundwater through analysis of major ions. Based on the total dissolved solids, two groundwater samples are considered unsuitable for drinking purpose, but all samples are useful for irrigation. Graphical treatment of major ion chemistry by Piper diagram helps in identifying hydro-geochemical facies of groundwaters and the dominant hydrochemical facies is Ca-Mg-HCO₃ with appreciable percentage of the water having mixed facies. As per Wilcox’s diagram and US Salinity laboratory classification, most of the groundwater samples are suitable for irrigation except two samples (No’s 30 and 68) which are unsuitable due to the presence of high salinity and medium sodium hazard. Irrigation waters classified based on residual sodium carbonate, have revealed that all groundwaters are in general safe for irrigation except one sample (No. 27), which needs treatment before use. Permeability index indicates that the groundwater samples are suitable for irrigation purpose. Although the general quality of groundwater of the lower Varuna River basin is suitable for irrigation purpose, fifty seven percent of the samples are found having nitrate content more than permissible limit (>45 mg/l) which is not good for human consumption. Application of N-Fertilizers on agricultural land as crop nutrients along the Varuna River course may be responsible for nitrate pollution in the groundwater due to leaching by applied irrigation water. The other potential sources of high nitrate concentration in extreme northern, southern and southwestern parts of study area are poor sewerage and drainage facilities, leakage of human excreta from very old septic tanks, and sanitary landfills. The high fluoride contamination (>1.5 mg/l) in some of the samples may be due to the dissolution of micaceous content in the alluvium. Nitrate and fluoride contamination of groundwater is a serious problem for its domestic use. Hence an immediate protective measure must be put into action in the study area.     

Changes in soil quality indicators under long-term sewage irrigation in a sub-tropical environment

Though irrigation with sewage water has potential benefits of meeting the water requirements, the sewage irrigation may mess up to harm the soil health. To assess the potential impacts of long-term sewage irrigation on soil health and to identify sensitive soil indicators, soil samples were collected from crop fields that have been irrigated with sewage water for more than 20 years. An adjacent rain-fed Leucaena leucocephala plantation system was used as a reference to compare the impact of sewage irrigation on soil qualities. Soils were analyzed for different physical, chemical, biological and biochemical parameters. Results have shown that use of sewage for irrigation improved the clay content to 18–22.7%, organic carbon to 0.51–0.86% and fertility status of soils. Build up in total N was up to 2,713 kg ha⁻¹, available N (397 kg ha⁻¹), available P (128 kg ha⁻¹), available K (524 kg ha⁻¹) and available S (65.5 kg ha⁻¹) in the surface (0.15 m) soil. Long-term sewage irrigation has also resulted a significant build-up of DTPA extractable Zn (314%), Cu (102%), Fe (715%), Mn (197.2), Cd (203%), Ni (1358%) and Pb (15.2%) when compared with the adjacent rain-fed reference soil. Soils irrigated with sewage exhibited a significant decrease in microbial biomass carbon (−78.2%), soil respiration (−82.3%), phosphatase activity (−59.12%) and dehydrogenase activity (−59.4%). An attempt was also made to identify the sensitive soil indicators under sewage irrigation, where microbial biomass carbon was singled out as the most sensitive indicator.     

Pricing China's irrigation water

Many development agencies and other actors are advocating that China adopt a system of water markets or of high water prices in order to resolve the inefficiencies of irrigation agriculture and to supply sufficient water for growing urban and industrial uses. We argue that this proposal rests on a series of propositions: that the price of water is too low to encourage farmers to be efficient; that farmers are not charged volumetric prices and so are not encouraged to conserve water; that water is scarce largely because farmers are profligate in their use of water; and that proper pricing of water will not affect equity. None of these contentions is true. Farmers have to pay not only the official charges for water but also the much higher costs of pumping it onto their fields. Once pumping is included, farmers are paying prices that are volumetric. Furthermore, the inefficiency of farmers arises in large part from the manner in which water is delivered to them: the system offers no rewards for care in the use of water and instead rewards greed. And, finally, although it might be true that higher prices do not affect equity within a village, in fact they would have substantial effects on inter-sectoral equity, with farmers becoming worse off in comparison to urban dwellers. The paper concludes by sketching a more appropriate scheme for raising the efficiency of use of irrigation water.     

Joint venture schemes in Limpopo Province and their outcomes on smallholder farmers livelihoods

Joint Venture schemes based on the floppy irrigation technology are being promoted in the post-Apartheid South Africa's Limpopo Province. Access to land and water resources in South Africa are largely viewed as a mechanism for re-dressing the Apartheid injustices. This research was part of a broader applied research to help inform irrigation practise in the Limpopo Province. The research used literature review, key informant interviews and a questionnaire survey. The overall research question sought to understand how the Joint Venture Schemes had benefited the smallholder farmers. This paper argues that the joint venture partnership created a new injustice. Firstly, the Joint Venture Scheme design is fundamentally a bad idea which disempower farmers not only to water access but also land as well. The choice of the ‘efficient’ floppy irrigation technology was made by the state and entailed that land had to be managed as a single unit. In order to make more effective use of this highly sophisticated new technology, the smallholder farmers also needed to go into a joint venture partnership with a white commercial farmer. By virtue of signing the Joint Venture agreement the farmers were also forfeiting their land and water rights to be used for crop production. The smallholder farmers lost access to their water and land resources and were largely relegated to sharing profits – when they exist - with hardly any skills development despite what was initially envisaged in the Joint Venture partnership. Secondly, the implementation of the JVS has been skewed from the start which explains the bad results. This paper further shows how the negative outcomes affected women in particular. As the smallholder farmers argue the technological options chosen by the state have excluded both male and female farmers from accessing and utilising their land and water resources in order to improve their livelihoods; it has entrenched the role of the state and the private interests at the expense of the smallholder male and female farmers in whose name the irrigation funding was justified. The paper concludes by offering recommendations on how joint venture schemes can be genuinely participatory and meaningfully address the rural livelihoods.     

抽水灌溉对宝鸡地电阻率观测的影响

在陕西省宝鸡台地电阻率测区内进行了短期的人工抽水和灌溉实验,并对测区内大面积、长期抽水和灌溉活动对该台地电阻率观测的影响进行了研究。结果显示短期、局部范围的抽水活动对地电阻率观测没有明显影响;而持续性的大量抽水、灌溉活动明显影响了地电阻率观测结果。讨论了这种现象的可能原因。此结果为地震监测、预报中地电阻率观测资料的有效应用提供了参考依据。     

甘肃景电灌区水资源利用现状分析

对甘肃省景泰川引黄灌溉工程水资源利用进行研究.对景泰川电力提灌工程及灌区的现状进行分析,根据对灌区水资源的分析,通过计算灌区内来水及用水情况,对灌区进行水量的平衡分析,明确提出灌区在水资源利用上存在的主要问题.在当前水资源匮乏的现实情况下,要积极采取相应的节水措施,开展灌区的水资源保护工作.