Autonomous real-time adaptive management of soil salinity using a receding horizon control algorithm: a pilot-scale demonstration

Soil salinization is a potentially negative side effect of irrigation with reclaimed water. While optimization schemes have been applied to soil salinity control, these have typically failed to take advantage of real-time sensor feedback. This study incorporates current soil observation technologies into the optimal feedback-control scheme known as Receding Horizon Control (RHC) to enable successful autonomous control of soil salinization. RHC uses real-time sensor measurements, physically-based state prediction models, and optimization algorithms to drive field conditions to a desired environmental state by manipulating application rate or irrigation duration/frequency. A simulation model including the Richards equation coupled to energy and solute transport equations is employed as a state estimator. Vertical multi-sensor arrays installed in the soil provide initial conditions and continuous feedback to the control scheme. An optimization algorithm determines the optimal irrigation rate or frequency subject to imposed constraints protective of soil salinization. A small-scale field test demonstrates that the RHC scheme is capable of autonomously maintaining specified salt levels at a prescribed soil depth. This finding suggests that, given an adequately structured and trained simulation model, sensor networks, and optimization algorithms can be integrated using RHC to autonomously achieve water reuse and agricultural objectives while managing soil salinization.     

Economic and financial analysis on rainwater harvesting for agricultural irrigation in the rural areas of Beijing

Since 2006, around 600 rainwater harvesting systems have been constructed for agricultural irrigation in Beijing. The financial and economic implications of using these systems are discussed less. It is important to understand the effectiveness of the investments spent on the rainwater harvesting systems. The paper aims to analyze economic and financial performance of the constructed rainwater harvesting systems in rural areas of Beijing through the method of cost benefit analysis. The economic analysis focuses on determining the contribution of rainwater harvesting systems to the development of society, carried out from the point of view of government. The financial analysis allows comparison of the financial implications of using groundwater with using rainwater for agricultural irrigation from the point of view of individual participant, namely the local farmers. The results show that the rainwater harvesting systems are economically feasible. This means rainwater harvesting have positive effects for society. However, the financial feasibility of rainwater harvesting systems depends on the charge for groundwater and on the size of the rainwater harvesting systems. If groundwater is not charged, the rainwater harvesting systems are not financially feasible. If groundwater is charged at 2 Yuan/m³, only large size systems are financially feasible while small and middle sizes systems are not financially feasible. Under these circumstances, only large systems can run smoothly, while farmers may not use the small and medium-size systems.     

宁夏灌区不同类型农田土壤氮素累积与迁移特征

在宁夏灌区选择设施菜田（n=4）和水旱轮作大田（n=4）,通过田间多点取样观测和室内分析的方法,研究了2种类型农田土壤氮素累积与分布特点,以及其迁移对浅层地下水的影响。结果表明,设施菜田0~150 cm土壤剖面溶解性总氮（TSN）、硝态氮（NO3--N）和溶解性有机氮（SON）含量都显著高于大田,前者分别是后者的1.5~5.6、1.5~3.4倍和1.6~9.8倍。设施菜田土壤氮素主要累积在0~5 cm和5~20 cm土层,而大田主要在40~100 cm土体。设施菜田和大田土壤溶解性总氮占全氮比例分别在5.4%~11.5%和2.2%~4.9%之间,前者的淋失风险较高。设施菜田各形态氮素累积量表现为SON＆gt;NO3--N＆gt;NH4＋-N,大田为NO3--N＆gt;SON＆gt;NH4＋-N。设施菜田浅层地下水中TSN、NO3--N和SON含量也都显著高于大田,前者平均含量分别是后者的9.5、13.8倍和7.0倍。因此,硝态氮和溶解性有机氮都是2种类型农田氮素累积的主要形态,也是浅层地下水污染的重要来源。     

From insight to action in reservoir management—lessons from Asia

The World Commission on Dams (WCD) has now presented its final report on the problems with large dams. Many dam projects were found to be underperforming, especially those built for irrigation purposes. WCD also reports that many projects fail to meet current standards of social equity. A reallocation of costs and benefits is needed, but entrenched interests make this a difficult task. This article identifies shortcomings in large Asian irrigation projects: why the problems emerged, and what could be done to improve the performance of existing projects. The article argues that Asian irrigation agencies take mainly an engineering perspective, focusing on the dam itself. In a large number of cases, it takes over 10 years for the infrastructure to be installed and for the water to be delivered to the fields of the command area. Agencies need to improve their competence in dealing with social and environmental issues. This article argues that social and economic infrastructure is often inadequate; there is a need for an integrated view of the role of agriculture in development. Furthermore, adaptive management practices and water user participation can often be critical elements. To be successful, participation needs to be gender sensitive, and stakeholders at all income levels need to be consulted. To bridge the gulf between rhetoric and action, there is also a need for independent evaluation of dam projects.     

地下回灌——污水回用的重要战略

介绍了污水资源化的重要技术方法——地下水回灌在战略上的重要性,并介绍了地下回灌的方法、方式、技术和国内外的现状、存在问题及发展前景。     

德州灌区地表水中溶解态痕量金属的空间分布及来源研究

以黄河下游德州引黄灌区主要水系为研究对象,采集了灌区内36个地表水样,分析了水体中溶解态痕量金属元素Ba、Fe、Li、Mn、Sr、Zn和非金属元素B的含量及其污染状况.借助于空间分析与相关性分析,探讨了其空间分布及来源.结果表明,这几种元素含量的大小顺序为:Sr﹥B﹥Ba﹥Mn﹥Li﹥Fe﹥Zn.根据国家生活饮用水卫生标准(GB5749—2006)和美国环境保护局(EPA)饮用水标准,B、Fe、Mn的超标率分别为50%、2.78%、27.78%.变异系数结果表明各元素都具有显著的空间差异性.漳卫新河B、Fe、Li、Mn含量均最高,重金属污染较为严重.相关性分析结果表明,Li-B、Li-Fe、Li-Mn及Fe-Mn之间呈显著相关,说明这几种元素污染源可能相同.本研究为评价痕量金属污染对地表水环境及人类健康的影响提供科学依据.     

沈抚灌区上游土壤中多环芳烃的含量分析

沈抚灌区是我国最大的石油类污灌区,文章采用气相色谱-质谱联机方法对灌区上游土壤进行了测定。结果表明,土壤中的多环芳烃含量在787~24570μg/kg,明显高于清水灌溉土壤。