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ilustraciones, fotografías, gráficas, tablas El agua utilizada para riego en Distrito Hidráulico La Ramada en la sabana de Bogotá posee características microbiológicas que representan un riesgo de salud pública, estas aguas son usadas en cultivos de hortalizas de consumo directo y poseen promedios consultados de concentraciones de coliformes totales de 6,5E+04 NMP/100ml y E. coli de 5,0E+10 NMP/100ml. En este documento se proponen y se diseñan unidades de tratamiento del agua por galerías filtrantes y filtración lenta de arena, se dimensionan para las condiciones del entorno rural de La Ramada teniendo como base el caudal de 0.84 L/min. Se hace también una aplicación teórica de un modelo de la filtración lenta de arena para determinar las remociones de E. coli que se producirían con diferentes condiciones operativas y se definen las que aplicarían para La Ramada, se hacen pruebas con los parámetros para ver su influencia en las remociones obtenidas con el modelo y se calculan las concentraciones del efluente de E. Coli para el filtro diseñado obteniendo remociones del 90% desde el tercer día de operación. (Texto tomado de la fuente). The water used for irrigation in La Ramada hydraulic system from the Bogotá savanna has microbiologic qualities that carry a risk for public health, it is used for irrigation of vegetable crops for direct consumption and have an average found of total coliform concentration of 6,5E+04 MPN/100ml and an E. coli concentration of 5,0E+10 MPN/100ml. In this paper a Slow sand filter (SSF) and a filtration well are suggested and designed for water treatment, their dimensions are defined for La Ramada rural environment by adopting a gaining flow of 0.84 L/min. A Slow sand filtration model is used for the calculations of the E. coli removals resulting from numerous operating conditions and the ones adopted for La Ramada are defined, other tests are made to see the influence of the model parameters in the removals obtained and a simulation for the designed SSF is calculated resulting in an E. coli removal of 90% from the third day of the run. Incluye anexos Maestría Magíster en Ingeniería - Recursos Hidráulicos Tratamiento del agua

Raw hospital wastewater is a source of excessive heavy metals and pharmaceutical pollutants. In water-stressed countries such as Pakistan, the practice of unsafe reuse by local farmers for crop irrigation is of major concern. In our previous work, we developed a low-cost bacterial consortium wastewater treatment method. Here, in a two-part study, we first aimed to find what physico-chemical parameters were the most important for differentiating consortium-treated and untreated wastewater for its safe reuse. This was achieved using a Kruskal–Wallis test on a suite of physico-chemical measurements to find those parameters which were differentially abundant between consortium-treated and untreated wastewater. The differentially abundant parameters were then input to a Random Forest classifier. The classifier showed that ‘turbidity’ was the most influential parameter for predicting biotreatment. In the second part of our study, we wanted to know if the consortium-treated wastewater was safe for crop irrigation. We therefore carried out a plant growth experiment using a range of popular crop plants in Pakistan (Radish, Cauliflower, Hot pepper, Rice and Wheat), which were grown using irrigation from consortium-treated and untreated hospital wastewater at a range of dilutions (turbidity levels) and performed a phytotoxicity assessment. Our results showed an increasing trend in germination indices and a decreasing one in phytotoxicity indices in plants after irrigation with consortium-treated hospital wastewater (at each dilution/turbidity measure). The comparative study of growth between plants showed the following trend: Cauliflower > Radish > Wheat > Rice > Hot pepper. Cauliflower was the most adaptive plant (PI: −0.28, −0.13, −0.16, −0.06) for the treated hospital wastewater, while hot pepper was susceptible for reuse; hence, we conclude that bacterial consortium-treated hospital wastewater is safe for reuse for the irrigation of cauliflower, radish, wheat and rice. We further conclude that turbidity is the most influential parameter for predicting bio-treatment efficiency prior to water reuse. This method, therefore, could represent a low-cost, low-tech and safe means for farmers to grow crops in water stressed areas.

Non-Contact Resonant Ultrasound Spectroscopy (NC-RUS) has emerged as a powerful tool to determine plant water status in a non-destructive, non-invasive and rapid way. In this study, ultrasonic parameters directly obtained from experimental measurements in the field using NC-RUS - such as resonant frequency (fres), velocity (v) and Q-factor - were evaluated as potential water stress indicators in Citrus plants. The experiments were carried out in two-year-old mandarin trees (Citrus clementina Hort. ex Tan. ‘Clemenules’) grown in pots in an open greenhouse where two different groups of plants were tested: a Control group (full irrigation) and a Drought Stress group (DS) whose irrigation was withdrawn during 7 days, followed by a 16 days recovery period. Soil water content, leaf water potential (Ψleaf) and the considered ultrasonic parameters were measured in the same leaves. fres detected changes between control and DS at day 7 without irrigation. Conversely, v showed differences after day 3, which were statistically significant at day 7, enabling discrimination between C and DS groups. Hence, Q-factor was the ultrasonic parameter that showed statistically significant differences between C and DS groups at days 3 and 7. Consequently, Signal Intensity in Q during the drought treatment showed a similar evolution to Ψleaf, although with slightly lower performance. However, Q-factor sensitivity excels Ψleaf at each day studied. Finally, a linear correlation (R2=0.57) between Ψleaf and Q-factor of all experimental data measured in DS group plants along the drought treatment was found. In conclusion, the ultrasonic parameters obtained using NC-RUS and in particular the Q-factor, demonstrated to be potential new water stress indicators in Citrus trees, with the novelty of being non-destructive, non-invasive and rapid. Future work should explore its suitability for its use in irrigation scheduling for Citrus trees.

In semi-arid regions that are characterized by large agricultural activities, a high volume of water is needed to cover the water requirements for agricultural production. Due to low precipitation and the associated limited availability of surface water, aquifers often represent the main source of irrigation water in these regions. Especially in coastal aquifers, high groundwater abstraction rates may change the flow dynamics of the aquifer and may lead to saltwater intrusion. In this study, within the framework of German–Moroccan international cooperation, the agricultural areas for the summer period 2019 of the Chtouka coastal aquifer in southern Morocco are classified using optical and multi-spectral Sentinel 2 data. Based on the developed land use maps, the groundwater abstraction for irrigation is then quantified by referring to local farmers’ irrigation practices. Following this approach, the total amount of groundwater abstraction is estimated at 157 million m3 for the summer period 2019 in the Chtouka aquifer.

International audience; We consider a simple crop irrigation model and study the optimal control which consists of maximizing the biomass production at harvesting time. A specificity of this work is to impose a quota on the water used for irrigation, in a context of limited resources. The model is written as a 2d non-autonomous dynamical system with a state constraint, and a non-smooth right member given by threshold-based soil and crop water stress functions. We show that when the water quota is below the threshold giving the largest possible production, the optimal strategy consists of irrigating once. We then show that the optimal solution can have one or several singular arcs, and therefore be better than simple bang-bang controls, as commonly used. The gains over the best bang-bang controls are illustrated on numerical simulations. These new feedback controls that we obtain are a promising first step towards the concrete application of control theory to the problem of optimal irrigation scheduling under water scarcity.

International audience; We propose a new simplified crop irrigation model and study the optimal control which consists in maximizing the biomass production at harvesting time, under a constraint on the total amount of water used. Under water scarcity, we show that a strategy with a singular arc can be better than a simple bang-bang control as commonly used. The gain is illustrated on numerical simulations. This result is a promising first step towards the application of control theory to the problem of optimal irrigation scheduling.

The increasing shortage of water for crop irrigation in arid and semiarid regions is encouraging the use of non-conventional resources. In the last decade, seawater desalination has consolidated its position as an alternative source to increase the supply for agricultural irrigation in Spain and Israel, where the farmers&rsquo, acceptance is progressively rising, despite the supply price being much higher than that of other conventional water sources. This article describes the current situation of desalinated seawater production and supply to agriculture in the southeast of Spain, and analyzes key questions such as its role in regional water planning, the infrastructure needed for conveyance and distribution, the energy requirements, the production and distribution costs, and the final price to farmers. The study is based on descriptive and quantitative data collected from desalination plants and irrigation district managers through technical questionnaires and personal interviews. The results show how seawater desalination is effectively alleviating the regional constraints in the irrigated agriculture supply, and why it is becoming strategic to maintaining food production and socioeconomic development. However, the high-energy requirements and associated costs in comparison with other water sources limit a more widespread use for agriculture, and for this reason desalinated water still only plays a complementary role in most irrigation districts.

We propose a new simplified crop irrigation model and study the optimal control which consists in maximizing the biomass production at harvesting time, under a constraint on the total amount of water used. Under water scarcity, we show that the optimal strategy could have a singular arc and therefore can be better than a simple bang-bang control as commonly used. The gain is illustrated on numerical simulations. This result is a promising rst step towards the application of control theory to the problem of optimal irrigation scheduling.

Climate change is a proven fact. In the report of 2007 from IPCC, one can read that global warming is an issue to be dealt with urgently. In many parts of the world, the estimated rise of temperature (in a very near future) is significant. One of the most affected regions is the Iberian Peninsula, where the increasing need for water will very soon be a problem. Therefore, it is necessary that decision makers are able to decide on all issues related to water management. In this paper, we show a couple of mathematical models that can aid the decision making in the management of an agricultural field at a given location. Having a field, in which different crops can be produced, the solution of the first model indicates the area that should be used for each crop so that the profit is as large as possible, while the water spent is the smallest possible guaranteeing the water requirements of each crop. Using known data for these crops in Portugal, including costs of labour, machines, energy and water, as well as the estimated value of the products obtained, the first mathematical model developed, via optimal control theory, obtains the best management solution. It allows creating different scenarios, thus it can be a valuable tool to help the farmer/decision maker decide the crop and its area to be cultivated. A second mathematical model was developed. It improves the first one, in the sense that it allows considering that water from the rainfall can be collected in a reservoir with a given capacity. The contribution of the collected water from the rainfall in the profit obtained for some different scenarios is also shown., The authors were supported by POCI-01-0145-FEDER-006933-SYSTEC, PTDC/EEI-AUT/2933/2014, POCI-01-0145–FEDER-016858 TOCCATTA and POCI-01-0145-FEDER-028247 To Chair–funded by FEDER funds through COMPETE2020—Programa Operacional Competitividade e Internacionalizaça˜ o (POCI) and by national funds (PIDDAC) through FCT/MCTES, which is gratefully acknowledged. Financial support from the Portuguese Foundation for Science and Technology (FCT) in the framework of the Strategic Financing UID/FIS/04650/2013 is also acknowledged. The authors also thank SMARTEGOV Project (P2020 NORTE-45-2015-23) Harnessing EGOV for smart governance. Acknowledgments The authors acknowledge the Department of Mathematics, the Centre of Physics, INESC TEC, from the University of Minho, Systec—Research Center for Systems and Technologies, from the University of Porto, UNU-EGOV Portugal and LEMA-ISEP, Instituto Politécnico do Porto., info:eu-repo/semantics/publishedVersion

Предложено описание математической модели водоудерживающей способности почвы с учетом гистерезиса. На основе модели разработана компьютерная программа «Hysteresis». Программа предназначена для идентификации параметров модели методом точечной аппроксимации опытных данных, а также для выполнения прогнозных расчетов и графического представления ветвей петли гистерезиса. Проведены вычислительные эксперименты для проверки: (i) возможности идентификации параметров математической модели по данным о главных (граничных) ветвях иссушения и увлажнения почвы; (ii) точности прогнозных расчетов сканирующих ветвей петли гистерезиса. Использованы литературные данные о четырех почвах. Представлено сравнение полученных результатов с результатами исследований предшественников. Достигнута достаточно высокая точность прогнозирования сканирующих ветвей. Практическая значимость предложенной модели заключается в обеспечении расчета прецизионных норм орошения сельскохозяйственных культур. Применение таких норм позволит предотвратить сток избытка влаги за пределы корнеобитаемого слоя почвы и минимизировать потери поливной воды, удобрений, мелиорантов и средств защиты растений, а также понизить уровень риска загрязнения грунтовых вод агрохимикатами и эвтрофикации водных объектов., A description of the mathematical model for the water-retention capacity of the soil, taking into account hysteresis, is proposed. The computer program called "Hysteresis" is developed on the basis of this model. The program is designed to identify the model parameters using the method of dot-approximation (fitting) of the experimental data as well as to perform predictive calculations and graphical presentations of the branches of the hysteresis loop. Computational experiments were carried out to verify: (i) the possibility of identify based on data on the main (boundary) branches of soil drying and wetting and (ii) the accuracy of predictive calculations of the scanning branches of the hysteresis loop. Data on four soils taken from literature were used. A comparison between the results obtained here and the results of studies available from literature is presented. A sufficiently high accuracy of the prediction of the scanning branches has been achieved. The practical significance of the proposed model is to ensure the calculation of irrigation precise rates. The use of such calculated irrigation rates will prevent excessively percolation beyond the root zone, will minimize the losses of irrigation water, fertilizers, ameliorants and plant protection products and will reduce the risk degree for groundwater contamination with agrochemicals as well for water bodies’ eutrophication.

Water use and the cost of water are key factors when considering the net value of urban agriculture (UA). This systematic review critically evaluates past and recent UA yield research from the perspective of water use efficiency. A systematic literature search was conducted using the databases Scopus, ProQuest Agriculture and Environment, and Web of Science for references from1975 to 2018, with 25 articles meeting the inclusion criteria. Of these, only five articles had actively collected UA water use data, all on purpose-built experimental gardens. Considering the scarcity of UA water use efficiency and water measurement literature, South Australia is presented as a case study to demonstrate the considerable diversity of water pricing, water sources and irrigation methods available to urban food growers. The practical challenges of garden placement and the wide variety of cultivation techniques, water sources and irrigation methods are reviewed. Four equations to calculate the water use efficiency (WUE) of UA are proposed and demonstrated. Collection of additional UA water use data would support more robust evaluations of the water use efficiency and economic implications of different cultivation techniques. Further work in this field will enable a realistic understanding of the current and future contribution of UA to our society. Refereed/Peer-reviewed

As espécies da família Cyperaceae incluem-se entre as principais plantas daninhas que infestam as lavouras de arroz irrigado no Rio Grande do Sul. Objetivou-se com este trabalho avaliar o controle de Cyperus esculentus, a seletividade e a produtividade de grãos de arroz, cultivar Qualimax 1, em função de épocas de início da irrigação por inundação, épocas de aplicação e doses do herbicida penoxsulam. O experimento foi instalado em campo, no ano agrícola 2005/06. Utilizou-se o delineamento experimental de blocos ao acaso com parcelas subsubdivididas, com quatro repetições. Os tratamentos constaram de duas épocas de aplicação (precoce e tardia) do penoxsulam, três épocas de início da irrigação (1, 15 e 30 dias após a aplicação dos tratamentos - DAT) e doses do herbicida (0, 24, 36, 48 e 60 g ha-1). Observou-se que o penoxsulam apresentou seletividade à cultura do arroz irrigado, independentemente da associação dos tratamentos testados. A aplicação do penoxsulam, associado à entrada de água até 15 dias após a aplicação dos tratamentos, mostrou eficiente controle de C. esculentus. A maior produtividade foi obtida pela aplicação do penoxsulam em doses iguais ou superiores a 36 g ha-1, independentemente da época de aplicação e quando a irrigação foi realizada nas épocas iniciais.The Cyperaceae family include the most important weeds found in the state of Rio Grande do Sul rice fields. The objective of this work was to evaluate Cyperus esculentus control and rice cv. Qualimax 1 selectivity and grain yield in function of the irrigation starting times, application times and penoxsulam rates. The trial was set up under field conditions in the agricultural year of 2005/2006 and was arranged in a completely randomized block design with split plots and four replications. Treatments were in a factorial scheme (2 x 3 x 5) and consisted of two herbicide application times (early and late), three irrigation starting times (1, 15 and 30 days after treatment), and herbicide rates (0, 24, 36, 48 and 60 g ha-1 ). The herbicide penoxsulam showed selectivity to the rice culture regardless of the association between the evaluated treatments. The application of penoxsulam, combined with irrigation starting 15 days after herbicide application promoted efficient control of C. esculentus. Highest grain yield was obtained by applying penoxsulam at the rates of 36 g ha-1 or above, regardless of the application time, and when early irrigation was carried out.

The report uses a theoretical model of a typical drainage basin, but the approach could be applied to many of the drainage basins managed by the holding company for water and wastewater in Egypt. This study set out to assess the relative health impacts of different wastewater management strategies on health in the Nile delta region using an approach similar to that used in the Ghana. The ultimate objective was to develop a framework for long-term investment planning based on monitoring of health and productivity impacts of proposed Bank operations which could be included in project Monitoring and Evaluation (M&E) systems. This will equip task teams to assess the risks and opportunities which arise due to the proposed shift from on-site to networked sanitation in four governorates where the Bank has wastewater operations. A secondary objective was to assess the extent to which existing legislation supports health riskbased planning. The conclusions of the study provide an indication of how such methods could increasingly be used to enable the selection of cost-effective and appropriate wastewater management strategies.

In Iraq, water shortages and drought, especially during the hot summer months, necessitates that municipal authorities adopt water reuse projects like reusing treated domestic wastewater for crop irrigation. This work gives the conceptual and basic design elements for the necessary steps of filtration, UV irradiation and chlorination to make such a wastewater fit for agricultural use. A typical rural community of 50,000 people is considered as an example case for which functionality and relative simplicity of the proposed designs are prime factors. The objectives are 1) to show what is required and 2) that the presented information may be utilized to embark on the following phases of detailed design and execution of such projects.

This paper provides an overview of major groundwater issues for Sub-Saharan Africa, with an assessment of their policy implications in terms of potential development and appropriate management. In terms of construction time, capital outlay and drought resilience, groundwater is the preferred source to meet most water-supply demands, despite hydro geological complexity, natural constraints on water well yields and quality, and institutional weaknesses. The 'new developmental agenda' relates to improving urban water-supply security and expanding irrigated agriculture to meet these challenges many countries need to undertake strategic assessment of their groundwater and prioritize investment on institutional strengthening so as to facilitate appropriately-managed groundwater development. Without effective use of available groundwater resources, improved livelihoods and climate-change adaptation will prove much more difficult to achieve.

The objective of this study is to improve understanding of the implications of climate change for the groundwater systems in coastal Bangladesh. This is achieved by: (a) obtaining available geologic, hydrologic, and geochemical information on coastal aquifers of Bangladesh; (b) developing groundwater flow and salt transport models representing general features and conditions along the coast of Bangladesh; and (c) simulating potential changes in the groundwater systems due to various aspects of human activity and climate change. The simulation analysis will focus on both the pattern and response time of the saltwater-freshwater distribution in subsurface aquifers, with a view towards sustainability of current and future water use under stress due to climate change. The study is aimed at understanding processes and rates of change for systems representative of a range of conditions in coastal Bangladesh, but it is expected that regional and local differences occur. Thus, only general conclusions and guidance should be drawn from this work.

The aim of this paper is to provide a strategic overview of a decade of experience in supporting public administrations in their efforts to confront excessive groundwater resource exploitation for agricultural irrigation. Special emphasis is put on a series of on-the-ground pilot projects mainly in South and East Asia and Latin America, which are profiled through a series of boxes introduced in the paper. In these pilots' appropriate packages of technical, economic, institutional and social measures, in the main selected through use of a 'pragmatic framework' for groundwater resource management, have been introduced with agreement of stakeholders in an attempt to promote more sustainable groundwater use in agricultural irrigation. They have achieved varying degrees of success but do provide hope and orientation for the future in this important aspect of water resource management.

As espécies da família Cyperaceae incluem-se entre as principais plantas daninhas que infestam as lavouras de arroz irrigado no Rio Grande do Sul. Objetivou-se com este trabalho avaliar o controle de Cyperus esculentus, a seletividade e a produtividade de grãos de arroz, cultivar Qualimax 1, em função de épocas de início da irrigação por inundação, épocas de aplicação e doses do herbicida penoxsulam. O experimento foi instalado em campo, no ano agrícola 2005/06. Utilizou-se o delineamento experimental de blocos ao acaso com parcelas subsubdivididas, com quatro repetições. Os tratamentos constaram de duas épocas de aplicação (precoce e tardia) do penoxsulam, três épocas de início da irrigação (1, 15 e 30 dias após a aplicação dos tratamentos - DAT) e doses do herbicida (0, 24, 36, 48 e 60 g ha-1). Observou-se que o penoxsulam apresentou seletividade à cultura do arroz irrigado, independentemente da associação dos tratamentos testados. A aplicação do penoxsulam, associado à entrada de água até 15 dias após a aplicação dos tratamentos, mostrou eficiente controle de C. esculentus. A maior produtividade foi obtida pela aplicação do penoxsulam em doses iguais ou superiores a 36 g ha-1, independentemente da época de aplicação e quando a irrigação foi realizada nas épocas iniciais. The Cyperaceae family include the most important weeds found in the state of Rio Grande do Sul rice fields. The objective of this work was to evaluate Cyperus esculentus control and rice cv. Qualimax 1 selectivity and grain yield in function of the irrigation starting times, application times and penoxsulam rates. The trial was set up under field conditions in the agricultural year of 2005/2006 and was arranged in a completely randomized block design with split plots and four replications. Treatments were in a factorial scheme (2 x 3 x 5) and consisted of two herbicide application times (early and late), three irrigation starting times (1, 15 and 30 days after treatment), and herbicide rates (0, 24, 36, 48 and 60 g ha-1 ). The herbicide penoxsulam showed selectivity to the rice culture regardless of the association between the evaluated treatments. The application of penoxsulam, combined with irrigation starting 15 days after herbicide application promoted efficient control of C. esculentus. Highest grain yield was obtained by applying penoxsulam at the rates of 36 g ha-1 or above, regardless of the application time, and when early irrigation was carried out.