Irrigated Agriculture

One of the most significant sources of water wastage in Australia is loss from small storage dams, either by seepage or evaporation. Over much of Australia, evaporative demand routinely exceeds precipitation. This paper outlines first, methodologies and measurement techniques to quantify the rate of evaporative loss from fresh water storages. These encompass high-accuracy water balance monitoring; determination of the validity of alternative estimation equations, in particular the FAO56 Penman-Monteith ETo methodology; and the commencement of CFD modeling to determine a ‘dam factor ’ in relation to practical atmospheric measurement techniques. Second, because the application of chemical monolayers is the only feasible alternative to the high cost of physically covering the storages to retard evaporation, the use of cetyl alcohol-based monolayers is reviewed, and preliminary research on their degradation by photolytic action, by wind break-up and by microbial degradation reported. Si...

Video supports for facilitating the dialogue around water management in large irrigation schemes. Rural Morocco is profoundly restructured following the redefinition of the role of the state and the local stakeholders in agricultural development. The orientations of the structural adjustment programmes aim at reducing the state intervention. The rural societies are urged to participate in local development programmes and to

The socio-economic pressure for improvements in irrigation efficiencies is increasing due to intense competition for water between agricultural, domestic and industrial users as well as demands for compliance with environmental regulations. Precision irrigation technology involving less irrigation water and uniform application across the field is therefore important. In the context of declining water allocation for irrigation and the variations in weather and drought patterns attributed to global climate change, efficient and precise applications are necessity. Traditional irrigation methods such as furrow, flood and sprinkler are neither efficient nor environmentally benign. Precision irrigation methods such as drip and subsurface drip irrigation are advocated because they are more water use efficient and because they offer a possible approach to meet projected food demand, a doubling by the 2050. In spite of greater water use efficiency afforded by minimal soil surface evaporation and deep drainage, and ease of automation, wide scale adoption of surface and subsurface drip irrigation technology is limited. This is due to their high investment cost for installation. They often lack a significant yield benefit when compared to conventional irrigation practice. Reasons are probably linked to a sustained wetting front around emitters. These emitters impose a condition of low oxygen content in the root-dense rhizosphere surrounding emitters that impede root respiration, and negatively impact on plant uptake of water and nutrients, leading to constrained yield performance. Here we review aspects of soil oxygen dynamics during irrigation and present evidence for sustained hypoxia in the wetting fronts associated with drip and subsurface drip irrigation. This condition of low oxygen content in the ­rhizosphere conditioned by the drip irrigation we term as the irrigation paradox. At dissolved oxygen concentrations one half of that at saturation root respiration and function start to decline. The pros and cons of different approaches to maintain aeration of the crop root zone are reviewed and we suggest that the best approach to overcome hypoxia is through aeration of the irrigation water stream, a practice known as oxygation. This conclusion is based on the evidence derived from a number of controlled environment experiments and field trials on crops where consistent increases of 10–30% in yield and water use efficiency were reported with aerated irrigation water. Aerated drip delivery of irrigation also allows for the simultaneous application of agro-chemicals directly into the crop root zone. We define this approach of delivering multiple agro-chemicals with aerated drip irrigation as multigation. Delivering nutrients and other chemicals with irrigation water according to the crop requirements reduces the cost of application and improves input use efficiencies and becomes increasingly ­practical with adoption of automation using dosing equipment. The dynamics and fate of agrochemicals in the soil with aerated water irrigation differs from those of non-aerated water irrigation, e.g. oxygen provided greater salt exclusion by roots compared to non-aerated treatments. Opportunities also exists for improving the use of treated effluent water for irrigation with multigation as treated effluent water has high biological oxygen demand and often record poor dissolved ­oxygen concentration causing hypoxia upon crop irrigation. Review of previous research and modelling suggests that the behaviour of multiphase components in aerated irrigation water streams, and subsequently in the soil, and their interaction with plant roots influences the dynamics of salt, nutrients and pesticides and therefore provides opportunity for the sustainable management of these inputs for irrigated agriculture.

Based on predicted changes in the magnitude and distribution of global precipitation, temperature and river flow under the IPCC SRES A1B and A2 scenarios, this study assesses the potential impacts of climate change and CO2 fertilization on global agriculture. The analysis uses the new version of the GTAP-W model, which distinguishes between rainfed and irrigated agriculture and implements water as

This article evaluates irrigated agriculture sector response and resultant economic impacts of climate change for a part of the Murray Darling Basin in Australia. A water balance model is used to predict reduced basin inflows for mild, moderate and severe climate change scenarios involving 1, 2 and 4°C warming, and predict 13, 38 and 63% reduced inflows. Impact on irrigated agricultural production and profitability are estimated with a mathematical programming model using a two-stage approach that simultaneously estimates short and long-run adjustments. The model accounts for a range of adaptive responses including: deficit irrigation, temporarily following of some areas, permanently reducing the irrigated area and changing the mix of crops. The results suggest that relatively low cost adaptation strategies are available for a moderate reduction in water availability and thus costs of such a reduction are likely to be relatively small. In more severe climate change scenarios greater costs are estimated. Adaptations predicted include a reduction in total area irrigated and investments in efficient irrigation. A shift away from perennial to annual crops is also predicted as the latter can be managed more profitably when water allocations in some years are very low.

In this paper we assess the economic impact of evaporation losses from great dams (GDs) and on-farm agricultural water reservoirs (AWRs) in the semi-arid Segura River basin, SE Spain. Evaporation losses from water reservoirs reduce the high water use efficiency reached in agriculture by means of other techniques such as well-built water pipes or drip irrigation and have a substantial economic impact. Evaporation losses have been calculated using Class-A pan evaporation data and pan coefficients, whereas their economic impact has been assessed using an economic mathematical programming model that simulates land and water allocation in the different irrigated areas of the basin. Our results show that annual evaporation from GDs and AWRs represents 8.7% of the water currently available for irrigation in the Segura basin. The economic impact of such losses has been estimated in a reduction of 6.3% of the value of agricultural production and 5.4% of the farm net margin. As less water is effectively available for farmers the basin’s irrigated area is reduced in a 7.5%. This impact is greater, in both absolute and relative terms, in the areas accommodating the most intensive and profitable irrigated agriculture. The applied methodology and results could be useful to regional water agencies and collective irrigation schemes for future planning and management, including the assessment of alternatives for reducing evaporation from reservoirs.

Abstract: It is well-documented that energy and energy systems have a central role in social and economic development and human welfare at all scales, from household and community to regional and national (41). Among its various welfare effects, energy is closely linked with people s ...

There are two aims of this work focused across northern Australia (north of the tropic of Capricorn). First is to identify adaptive strategies to deal with climate change in each jurisdiction. Second the work identifies issues for adaptation in water resource management across the region in light of potential impacts and local conditions. Over half of Australia‘s annual runoff occurs

Agricultural production is heavily dependent on water availability in Turkey, where half the crop production relies on irrigation. Irrigated agriculture consumes about 75 percent of total water used, which is about 30 percent of renewable water availability. This study analyzes the likely effects of increased competition for water resources and changes in the Turkish economy. The analysis uses an economy-wide

This study uses a hydro-economic model to examine the role of water trading, and the economic impacts of climate change and reduced surface water availability in the Murray–Darling Basin. The results show that losses to irrigated agriculture under a median climate change scenario are modest, but under a 'mod-ified 2030 dry extreme scenario' there would be substantial reductions in water use, irrigated land use and profits. Nevertheless, the Basin-wide proportional economic impacts would be less than the percentage decline in water use. A comparison of model results with and without interregional water trade shows that interregional water trade in periods of much reduced water availability mitigates the on-farm impacts of climate change. Given that agricultural production in the Basin is likely to be affected by climate change, the development of drought-tolerant crops and cultivars along with learning and extension of best farming practices to reduced water use could also assist irrigated agriculture adapt to climate change within the Basin.

Malaria in Sri Lanka is unstable and epidemic, with large spatial and temporal differences in transmission dynamics. The disease is of great public health significance and identification of underlying risk factors is important in order to use the limited resources in a cost-effective way. The International Water Management Institute (IWMI) recently launched a project of GIS-based malaria risk mapping in Sri Lanka, to investigate whether this tool could be used for epidemic forecasting and for the planning of malaria control activities. This paper presents results for the Uda Walawe region in southern Sri Lanka, an irrigated agricultural area where malaria cases were mapped at the smallest administrative level for each month over a 10-year period. Malaria incidence rates were related to land- and water-use patterns, socio-economic features, and data on malaria control interventions in a multivariate analysis. Areas of high malaria risk were characterized by: (i) higher than average rainfall, (ii) greater forest coverage; (iii) slash and burn cultivation as a predominant agricultural activity; (iv) presence of many abandoned irrigation reservoirs; and (v) poor socio-economic status. Irrigated rice cultivation areas had a lower risk of malaria than non-irrigated areas. This difference could be due to socio-economic factors related to irrigation development and/or transmission dynamics related to vector density or species composition. Our findings call for malaria control strategies that are readily adapted to different ecological and epidemiological settings. Malaria risk maps are a convenient tool for discussing targeted and cost-effective interventions with disease control personnel.

Bu çalışma, Aşağı Seyhan Ovasında yer alan ve 9 495 ha alanı kaplayan Akarsu Sulama Birliği sahasında 2007 hidrolojik su yılında yürütülmüştür. Araştırmada su, tuz ve nitrat bütçesi elemanlarının Coğrafi Bilgi Sistemi (CBS) ortamında saptanması ve elde edilen sonuçların su kaynaklarının etkin kullanımı ve sulama yönetimi bağlamında irdelenmesi amaçlanmıştır. Su yılının başında ve sonunda 108 adet taban suyu gözlem kuyusunda derinlik ölçümleri ile birlikte su örnekleri de alınmıştır. Benzer şekilde, drenaj gözlem kuyularına yakın yerlerdeki 0-0.9 m derinlikteki toprak profilinden örnekler alınmış; örneklerin gravimetrik su içerikleri, tuzlulukları ve nitrat konsantrasyonları belirlenmiştir. Sulama ve drenaj kanalları üzerine toplam 8 adet akım gözlem istasyonu (AGİ) tesis edilmiş; giren ve çıkan akımlar AGİ’lerde bir saat aralıklarla ölçülmüştür. Kesitlerin “anahtar eğrileri” elde edilmiş; ölçülen su derinlikleri su debisine çevrilip kaydedilmiştir. Drenaj havzasının çıkış noktasındaki AGİ’den günde bir, diğer istasyonlardan haftada bir su örnekleri alınarak toplam tuzluluk ve nitrat konsantrasyonları laboratuvarda belirlenmiştir. Sekiz farklı noktaya piyezometre bataryaları tesis edilmiş; haftada bir kez olmak üzere derinlik ölçümleri yapılmış ve su örnekleri alınarak tuz ve nitrat içerikleri belirlenmiştir. Taban suyu derinlik, tuzluluk ve nitrat haritaları CBS ortamında çizilmiş; matematiksel işlemler harita katmanları üzerinde yapılmıştır. Bütçe hesabında, temel hidrolojik su bütçesi denklemi kullanılmıştır. 2007 su yılında, Akarsu sahasına 676 mm yağış düştüğü, 1014 mm net sulama suyu saptırıldığı ve 788 mm suyun havzadan drene olduğu belirlenmiştir. Su kullanım randımanının %39, drenaj fraksiyonunun ise %47 olduğu saptanmıştır. Su, tuz ve azot bütçeleri sırasıyla +180 mm, -12.8 ton ha-1 ve +13.73 kg N ha-1 hata ile saptanabilmiştir.

This paper illustrates the malleable boundaries that define nature. Personal construct theory is employed to examine the apparent contradiction of the human/nature binary posed by landscapes generated by domesticated agriculture and physical and biological processes. Specifically, the paper reports on how tourists to the Kimberley region of Australia discriminate between their perception of human artifacts as attractions (including Lake Argyle, the Argyle Dam, and irrigated agriculture) and the region’s gorges, rivers, billabongs, flora and fauna. Repertory grid analysis suggests that the Argyle Dam is perceived in a similar fashion to physical, geological, and biological attractions. However, the irrigated agriculture is perceived quite differently, as domesticated. Policy implications for the region’s nature based tourism are explored.Les lignes de démarcation du tourisme de la nature. Cet article illustre les frontières malléables qui définissent la «nature». On utilise la théorie de la construction personnelle pour examiner l’apparente contradiction du système binaire humain/nature, qui est représenté par des paysages générés par l’agriculture et les processus physiques et biologiques domestiqués. En particulier, l’article constitue un rapport sur la façon dont les touristes à la région du Kimberley, en Australie, font la distinction entre leur perception des attractions qui sont des constructions humanies (Lac Argyle, le barrage Argyle et l’agriculture irriguée) et celle des gorges, rivières, billabongs, flore et faune. Une analyse par grille de répertoire suggère que le barrage Argyle est perçu de la même façon que les attractions physiques, géologiques et biologiques. Par contre, l’agriculture irriguée est perçue comme apprivoisée. On examine les implications pour la politique du tourisme basé sur la nature de la région.

Human-made ecologic transformations have occurred at an unprecedented rate over the past 50 years. Prominent among them are water resource development projects. An estimated 40,000 large dams and 800,000 small dams have been built, and 272 million hectares of land are currently under irrigation worldwide. The establishment and operation of water projects has had a history of facilitating a change in the frequency and transmission dynamics of malaria, but analyses of these environmental risk factors are sparse. Here, we present a comprehensive review of studies that assessed the impact of irrigation and dam building on malaria prevalence or incidence, stratified by the World Health Organization's (WHO) sub-regions of the world, and link these studies with the latest statistics on disability adjusted life years, irrigated agriculture, and large dams. We also present estimates of the population at risk due to proximity to irrigation schemes and large dam reservoirs. In WHO sub-regi...

Summary The improvement of irrigated agriculture needs sound performance assessment based on economic principles. This is particularly relevant to design adequate policies in terms of water allocation. In this paper we endeavour to assess irrigation efficiency using a behavioural approach in which the cost function (shadow cost) is based on shadow prices of inputs. This approach is useful to derive

This research study identifies the types and estimates the quantity of pesticides used in selected Palestinian districts. A survey of farmers (n = 126) was conducted in five districts of the West Bank and Gaza Strip, where pesticides are mostly used on irrigated land cultivated with vegetables. Data analysis of received questionnaires (87%) revealed a total number of 217 pesticides including 13 soil sterilizers, while 134 kinds with different active ingredients (insecticides 62; fungicides 45; herbicides 20) were applied in all districts. Based on the total irrigated land cultivated, the rate of pesticides per dunum reached 0.77 L in Gaza strip and 0.18 L in the West Bank districts. Contrary to earlier published data, our results support a trend of general decrease in the use of agricultural pesticides in the districts under study further to recent efforts encouraging pest management practice.