Irrigated Agriculture

ORIGINAL ARTICLE Groundwater salinization processes in shallow coastal aquifer of Djeffara plain of Medenine, Southeastern Tunisia Rim Trabelsi • Kamel Abid • Kamel Zouari • Houcine Yahyaoui Received: 3 March 2010 / Accepted: 23 July 2011 Ó Springer-Verlag 2011 ...

SUMMARY - It is nowadays widely accepted that the increasing concentration of the so-called greenhouse gases in the atmosphere is altering the Earth's radiation balance and causing the temperature to rise. This process in turn provides the context for a chain of events which leads to changes in the different components of the hydrological cycle, such as evapotranspiration rate, intensity

Desertification is the process that turns productive deserts into non-productive deserts as a result of poor land-management. Desertification reduces the ability of land to support life, affecting wild species, domestic animals, agricultural crops and humans. The reduction in plant cover that accompanies desertification leads to accelerated soil erosion by wind and water. South Africa is losing approximately 300–400 million tons of topsoil every year. As vegetation cover and soil layer are reduced, rain fall impact and run-off increases. This paper discusses the extent of desertification, its potential threat to sustained irrigated agriculture and possible measures adopted to control ongoing desertification processes to minimize the loss of agricultural productivity in an arid country such as the Kingdom of Saudi Arabia.

Water for irrigation is a major limitation to agricultural production in many parts of the world. Use of waters with elevated levels of salinity is one likely option to meet the supply of increased demands. The sources of these waters include drainage water generated by irrigated agriculture, municipal wastewater, and poor quality groundwater. Soil salinity leaching requirements that were established

The dramatic increase of poppy cultivation and opium production in Afghanistan has led to a serious drug addiction problem in te world. The rising heroin use, because of needle sharing, may lead to a much higher incidence of HIV infection and AIDS in Afghanistan in the future. We organized two expeditions into Afghanistan itself, one through the capital, Kabul and

Increasing economic pressures on water resources are causing countries to (re)consider various mechanisms to improve water use efficiency. This is especially true for irrigation agriculture, a major consumer of water. “Getting prices right” is seen as one way to allocate water, but how to accomplish this remains a debatable issue. Methods of allocating water are sensitive to physical, social, institutional

ABSTRACT ABSTRACT The Lower Jordan River Valley is a place of extreme water scarcity and constitutes an overexploited closed river basin. No surface runoff currently leaves the area and the water level of the Dead Sea, as the final sink, has already dropped by more than 20 m over the past fifty years as a result. This demonstrates, that even apart from water quality considerations, total inflows into the system do not match outflows, resulting in a continuous depletion of the available storage, i.e. all available water is already utilised. The only means of providing additional volumes of water to the area are water imports or reduction of evaporation from open water bodies or reduction of evapotranspiration from irrigated agriculture. Wastewater reuse and desalinisation would increase the amount of water fit for human demand but not affect the water balance in total. Increasing the amount of managed aquifer recharge (MAR) would be beneficial to the water availability of the region ...

For semi-arid regions, methods of assessing aquifer recharge usually consider the potential evapotranspiration. Actual evapotranspiration rates can be below potential rates for long periods of time, even in irrigated systems. Accurate estimations of aquifer recharge in semi-arid areas under irrigated agriculture are essential for sustainable water-resources management. A method to estimate aquifer recharge from irrigated farmland has been tested. The water-balance-modelling approach was based on VisualBALAN v. 2.0, a computer code that simulates water balance in the soil, vadose zone and aquifer. The study was carried out in the Campo de Cartagena (SE Spain) in the period 1999–2008 for three different groups of crops: annual row crops (lettuce and melon), perennial vegetables (artichoke) and fruit trees (citrus). Computed mean-annual-recharge values (from irrigation+precipitation) during the study period were 397 mm for annual row crops, 201 mm for perennial vegetables and 194 mm for fruit trees: 31.4, 20.7 and 20.5% of the total applied water, respectively. The effects of rainfall events on the final recharge were clearly observed, due to the continuously high water content in soil which facilitated the infiltration process. A sensitivity analysis to assess the reliability and uncertainty of recharge estimations was carried out. En régions semi-arides, les méthodes d’estimation de la recharge des aquifères prennent généralement en compte l’évapotranspiration potentielle. Les taux d’évapotranspiration actuels peuvent être inférieurs aux taux potentiels sur une longue période de temps même sous systèmes irrigués. Une estimation précise de la recharge des aquifère en zone semi-aride avec une agriculture irriguée est essentielle à la gestion adéquate de la ressource en eau. Une méthode pour estimer la recharge d’un aquifère sous terrains agricoles irrigués a été testée. La modélisation du bilan hydrique se base sur l’utilisation de VisualBALAN v. 2.0, un code informatique qui simule le bilan hydrique du sol, de la zone vadose et de l’aquifère. L’étude a été menée sur le Campo de Cartagena (SE de l’Espagne) durant la période 1999–2008 et sur trois types différents de cultures : culture annuelle en rang (salade et melon), végétaux vivaces (artichaut) et arbres fruitiers (agrumes). Les recharges moyennes annuelles calculées (irrigation+précipitation) durant la période d’étude sont de 397 mm pour les cultures en rang, 201 mm pour les végétaux vivaces et 194 mm pour les arbres fruitiers: respectivement 31.4, 20.7 et 20.5% de l’apport en eau total. Les effets des évènements pluvieux sur la recharge finale sont clairement observés, du fait d’une teneur en eau des sols continuellement élevée qui facilite les processus d’infiltration. Une analyse de sensibilité a été effectuée afin d’estimer la fiabilité et l’incertitude des estimations de recharge. Los métodos para evaluar la recarga de acuíferos en las regiones semiáridas habitualmente consideran la evapotranspiración potencial. Los ritmos de evapotranspiración real pueden estar por debajo de la evapotranspiración potencial para largos períodos de tiempo, aún en sistemas irrigados. Las estimaciones precisas de la recarga de un acuífero en áreas semiáridas bajo agricultura irrigada son esenciales para el manejo sustentable de los recursos de agua. Se ha probado un método para estimar la recarga del acuífero a partir de tierras de granjas irrigadas. La aproximación del modelado del balance de agua se basó en VisualBALAN v. 2.0, un programa de computación que simula un balance de agua en el suelo, la zona vadosa y el acuífero. El estudio fue llevado a cabo en el Campo de Cartagena (SE de España) en el período 1999–2008 para tres grupos diferentes de cultivos: cultivos anuales en filas (lechuga y melón), hortalizas perennes (alcachofa) y árboles frutales (citrus). Los valores computados de recarga anual media (a partir de irrigación + precipitación) durante el período de estudio fueron 397 mm para cultivos anuales en filas, 201 mm para hortalizas perennes y 194 mm para árboles frutales: 31.4, 20.7 y 20.5% del agua total utilizada, respectivamente. Se observaron claramente los efectos de los eventos de la precipitación en la recarga final, debido a un permanente alto contenido de agua en el suelo lo que facilitó los procesos de infiltración. Se llevó a cabo un análisis de sensibilidad para evaluar la confiabilidad e incerteza de las estimaciones de la recarga. 对半干旱区含水层补给量评估的方法往往考虑潜在蒸散发. 即使在灌溉区, 实际蒸散发率也可能低于长期的潜在蒸发.在半干旱的灌溉农业区, 含水层补给量的精确估计对可持续水资源的管理是必不可少的.一种评估灌溉农业区含水层补给量的方法通过测试.这种水均衡模拟方法以模拟土壤, 包气带, 含水层中的水量均衡的电脑程序VisualBALAN v. 2.0为基础. 从1999到2008年, 在Campo de Cartagena (西班牙东南部) 选取三种不同类型的作物: 一年生行间作物 (生菜和甜瓜), 多年生蔬菜 (朝鲜蓟) 和果树 (柑橘) 进行研究. 计算整个模拟期的年平均补给量 (来自灌溉和降水), 一年生中耕作物为397 mm,多年生蔬菜为201 mm,果树为194 mm, 分别占总可利用水量的31.4, 20.7 ,20.5%.因为土壤中连续不断的高含水量促进了渗透过程,降雨量对最终补给量的影响清晰可见. 对补给量可靠性及不确定性进行了灵敏度分析. Em regiões semi-áridas, os métodos de análise da recarga de aquíferos geralmente consideram a evapotranspiração potencial. O valor de evapotranspiração real pode ser inferior ao potencial por longos períodos de tempo, mesmo em sistemas irrigados. Estimativas precisas da recarga de aquíferos em zonas semi-áridas irrigadas para fins agrícolas são essenciais para uma gestão sustentável dos recursos hídricos. Testou-se um método para estimar a recarga de aquíferos em parcelas agrícolas irrigadas. O modelo de balanço hídrico utilizado foi baseado no VisualBALAN v. 2.0, um código numérico que simula o balanço hídrico no solo, zona vadosa e aquífero. O estudo foi desenvolvido em Campo de Cartagena (SE de Espanha) no período entre 1999–2008, para três tipos de culturas diferentes: culturas anuais (alface e melão), culturas de hortícolas perenes (alcachofra) e árvores de fruto. Os valores médios anuais de recarga anual estimados (da irrigação+precipitação) para o período de estudo foram 397 mm para as culturas anuais, 201 mm para as hortícolas perenes e 194 mm para as árvores de fruto; correspondem a 31.4, 20.7 e 20.5% do volume total de água aplicado, respectivamente. Os efeitos dos eventos de precipitação na recarga final foram claramente observados, devido ao valor continuamente elevado de água no solo que facilitou o processo de infiltração. Desenvolveu-se uma análise de sensibilidade para caracterizar a fiabilidade e a incerteza dos valores de recarga estimados.