The UAE is not the only country to make use of cloud seeding. US ski resorts in Colorado reportedly use the method to induce heavier snowfall. China also used rain dispersal technology to ensure dry weather during the opening of the Beijing Olympics.
[PDF] Silage Harvesting , Storing , and Feeding 1 - Semantic Scholar
Earlier this year, a Dh Five-part documentary series takes viewers on a journey across various protected areas. You can manage them any time by clicking on the notification icon. Tuesday, July 9, UAE Environment. Not all seeded clouds produce rainfall, but it happens often, Newman said. Efforts to boost cloud seeding programme Earlier this year, a Dh More From Environment. UAE teen, 16, wins Diana award Amiteash Paul helped install recycling bins in offices, factories and labour camps.
New documentary series to showcase UAE ecosystem. Reader story. Sharjah shuts down restaurant after viral video. Air India bans Zamzam on two flights. The source of water was a series of laboratory models. This was to enhance the biodegradation rate of the hydrocarbons. The pot trial investigation showed that where the effluent water could be used for irrigation the excess nutrients provided distinct advantages to the growing plants [ 25 ].
In all cases, the plants irrigated with effluent grew much better than those irrigated with tap water. In effect, the system was being used for fertigation. In , an investigation was initiated [ 26 ] on an MPPS installed as a prison car park in Scotland. Samples were analysed for a wide range of determinants. For the heavy metals, all results were below the most stringent of irrigation water limits.
For TPH, the irrigation limits that were adopted are dependent on the solubility of the various carbon chain fractions except for C 9 —C 14 where a limit of 1. Since no measurements of TPH ever exceeded 1. Examining the major cation concentrations, it was shown that calcium, magnesium and potassium were low compared to any irrigation water limits and most authors would expect that at least magnesium and potassium would need to be supplemented for optimum plant growth.
It was concluded that if water is to be stored for irrigation purposes it would be necessary to divert the meltwater and the rainwater falling onto a salt contaminated pavement away from the storage tanks during the winter months after filling them as much as possible during October and November and then topping them up in April and May before the need for irrigation is established in the summer.
If the worst of the salt contaminated water can be diverted, the direct effect on plants will be minimized. Another issue from this particular site was the pH that was higher than optimal, but this was due to the limestone used in the subbase and would have been much lower if a granite subbase had been chosen.
Adjustment of pH with addition of calcium sulphate was proposed as a potential solution, but species selection for high pH tolerance would be an alternative. Pot trial experiments were carried out using both ryegrass and tomato plants using the experimental protocol previously proposed by Nnadi [ 21 ] irrigated with effluent collected from this pavement in September with initial results being reported to the SuDSnet conference in [ 29 ] and continued experiments and tissue analysis have shown that at this site, the water is perfectly suitable for irrigation, if harvested before the salt application.
Hence, further work in this area is required and this provides a good research opportunity for anyone interested in this area of study. One problem with block paving surfaced PPS is that they can become a habitat for weeds and chemical methods of weed control still dominate as the most preferred in the United Kingdom [ 30 ] and most European cities [ 31 , 32 ]. Recent work on the impact of GCH on pollution attenuation and biodegradation in a PPS indicated that GCH is not retained in the PPS structure and is subject to rapid wash through in response to water movement thus increasing the potential risk of reaching receiving environments [ 36 ].
Hence, not only does one need to consider the herbicide itself, but the breakdown of other pollutants such as hydrocarbons within the PPS can be potentially affected [ 35 ] with potential impact on the quality of irrigation water. In a recent study to determine the suitability of stormwater harvested from PPS for reuse purposes in conditions where GCH was applied as part of PPS maintenance procedure, Mbanaso et al. They, however, indicated that high dosage of the herbicide could lead to an elevated electrical conductivity of the recycled water.
Further work needs to be done on establishing the lifetime of such compounds in both the PPS and the stored irrigation water. As well as the need to control rapid water runoff in urban areas, there are several other problems to which SuDS can make a contribution. The urban heat island effect [ 38 , 39 ] and reduction in green space with associated loss of both amenity and biodiversity [ 40 ] are important issues.
Much of this is being exacerbated by climate change. A contribution to the mitigation of such problems is to apply green SuDS techniques and foremost amongst these is the attempt to utilise the roof spaces of buildings to create green roofs. The potential of green roofs to contribute to the mitigation of rainwater runoff is well established, see Refs. What is less often stressed, however, are the problems in certain climates associated with the fact that after a heavy rainstorm, the water in the saturated substrate can take a considerable time to drain or evaporate and a subsequent storm will be offered significantly reduced attenuation.
The capability of green roofs to contribute to the cooling of buildings and combating the heat island effect has been widely reported [ 45 — 50 ]. Green roofs can also play a role in improving biodiversity within urban areas [ 40 , 51 ] and, the aesthetic value of a green roof can often be a dominant factor in its adoption [ 52 ] even though aesthetic planting schemes can come into conflict with biodiversity aims [ 53 ]. Particularly where the green roof is intended to be accessible and provide, in part, the function, for example, of an urban park, it is important that the provision of water, to maintain adequate growing conditions for a wide range of plants , during dry periods is recognised.
This helps to enhance the amenity value. One of the factors is the maintenance of adequate soil moisture content. An alternative to storing the water solely within the substrate is to drain the water into a cistern to allow the water to be used to irrigate the roof during dry periods and, if correctly sized, can offer temporary storage during storms occurring when the substrate is close to saturation.
A green roof with a cistern for reuse was the subject of a modelling study by Hardin et al. Their system included a green roof with its drainage system connected to a cistern which in turn supplied irrigation water to the roof via a pump. A supplemental water source is also connected to the cistern to provide water should there not be sufficient water to perform the irrigation event. It was proposed that the irrigation should be managed via a controller, similar to what is widely used for home lawn irrigation, which only irrigates on the prescribed times unless sufficient rain has fallen within 24 h of the intended irrigation event.
Green roofs. However, without a separate cistern, the volume available for storage will be relatively small unless special steps are taken. One such approach has been developed in the Netherlands [ 56 ]. This modified green roof stores the water directly under the substrate within modified load bearing plastic void formers originally developed for pervious pavement applications. This is a remarkable installation which has transform the former rooftop bus station vacant for some time after it being moved to ground level into a popular public park area with a resulting increase in economic development into the form of many additional rooms constructed in adjacent hotels.
The roof park built on the former Orlyplein Bus Station deck, before, during and after construction. The system of capillary irrigation outlined above has also found application in ground level applications. Zuidas is a very densely build urban area and therefore prone to urban flooding during intense rain events. The strip is deeper than its surroundings, making it a natural water collection point in the street design. This planting strip is designed to be dry throughout the year, but is allowed to flood during rain events. Planting species are selected to be able to withstand occasional flooding.
Innovative in the design is the mm high water attenuation system 40 cm below the planting, which is fed with water from the roofs. The improved water availability for plants maintains their evapotranspiration rates at close to the potential evapotranspiration generated by the local weather, improving their urban cooling capacity. Surplus of water can drain freely to ground water level alongside the water drainage and capillary irrigation system.
To prevent the Green Stream from overflowing onto the sidewalk, extra emergency overflows are created at the maximum fill level, connected to the conventional sewer. Left to right: Schematic of the green stream system, under construction and on the day of completion. Another application of this technology has been on sports surfaces such as football pitches both on rooftops and at ground level.
The system provides water to the growing grass turf, while the void space can be made sufficiently deep to satisfy the most stringent stormwater attenuation requirements for new stadium construction. Even if supplemental water has to be used to maintain the playing surface in very hot dry countries, the application of water from below by capillary action is more efficient than spray irrigation from above.
Currently, trials are underway in preparation for the soccer world cup in Qatar. Novel below ground water storage options provide a significant opportunity for the reliable delivery of acceptable water to trees in the urban environment.
Low retention rates of applied water, where water evaporates or percolates away from tree roots before uptake. Tree removal or inappropriate management resulting in damage to trees if land use changes regard existing trees as an obstacle.
Thus, water supply considerations provide some of the major challenges faced by urban trees and depending on the tree species, a mature tree with a mm trunk diameter could require l of water to be provided for survival and normal function during drought conditions. It is important to acknowledge the local hydrological benefits of urban trees in times of intense and or prolonged rainfall where the drainage system may be at capacity.
The positive impacts of trees include rainfall detention, retention and uptake, which may remove significant volumes of water from runoff totals, or delay local peak discharge in comparison with a location without trees [ 60 ]. In theory, it would be acceptable to deliberately divert stormwater from a new development to supplement existing urban trees to meet the total water need. This could include disconnection of downpipes into soil and conveyance to areas where trees are located. However, this retrofit option could result in standing water in the case of intense events if infiltration and percolation are not sufficient and a bypassing of the tree if the water is not retained by the soil.
Hence, solutions are required that provide the required volume of water, but allow this to be retained close to the roots and provide useful water. In practice, this is necessarily targeted at new developments and is usually provided by tree pits, where a selected soil medium is placed into a structural chamber.
This material also has the potential for water transfer to woody plants. The use of engineered materials, including allochthonous soils, in providing water to trees has not been proven to fully replicate the functioning of the biological component of mature natural soils, nor have an equivalent of the nutrient recycling and regeneration of soil.
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However, it has been established that drainage systems that include trees and soil can improve water quality in sustainable drainage applications, including the absorption and retention of heavy metals, nitrogen and phosphorus [ 62 ]. The understanding of the requirements for successful irrigation of urban trees has improved in recent years, particularly as the recognition of the full range of benefits provided by urban trees has become apparent and the use of trees in the urban landscape has been more readily encouraged.
As shown in the plates in this section, care must be taken to prevent waterlogging of supporting soils, partly due to the confined nature of tree pits and also the provision of water in excess from large impermeable areas, which may exclude the air that is found in natural soils and may, if serious enough, lead to anoxic conditions and the production of greenhouse gases.
Consideration of aeration and an under drain in design should prevent this, alongside a consideration of local rainfall totals and the nearby landscape conditions. SuDS elements, by their nature, store water but it is not always simple to either make a SuDS system provide a suitable supply of irrigation water or to make a water harvesting system contribute to stormwater source control. Where the prime aim is to harvest a good quality of water such as on a roof, whether this is used directly to irrigate plants on the roof or is collected for offline irrigation sizing of tanks needs to allow enough excess storage to deal with storm events and the tanks need to be managed to ensure such volume is routinely available.
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Built by scientists, for scientists. Our readership spans scientists, professors, researchers, librarians, and students, as well as business professionals. Downloaded: Abstract While urbanization and increasing population has put much pressure on natural drainage channels and resulted in increase in flooding, there is increased pressure on available water resources due to climate change, reduction in frequency of rainfall events and drought. Introduction Urbanization can initiate undesirable local modifications to the water cycle.
Device Quantity issues Quality issues Underground and above ground barrels, tanks and cisterns harvesting roof water only The sizing of the system needs to be done carefully and the usage of the water be well established if both stormwater attenuation and water harvesting are to be achieved in the same system.
With modern computer control the sizing can be reduced by actively draining tanks in response to predicted rain events.
The quality of water will be affected mainly by atmospheric fallout and the nature of materials used in roof construction. While this is not really considered an issue new UK guidance requires that even roof water should have some treatment before discharge to a watercourse Underground and above ground storage harvesting both surface runoff and roof water The additional resource will require a greater storage volume for it to be utilisable. If there is attenuation available upstream of the storage tanks this can be minimized as a problem Surface water will generally be of much poorer quality than roof water alone see above but provided the system is correctly designed to retain day to day pollutant releases it will generally only be an issue if major pollutants releases overcome the pollution attenuation mechanisms.
Salt applications in temperate zones can be a problem. Pervious pavements and similar without off line additional storage Unless taking runoff from impervious surfaces too the total inputs are limited to the water falling on the surface. Unless designed with extra storage capacity even an attenuation based system will have limited capacity to store water for more than short periods of time Input of potentially harmful organisms from faecal contamination and chemical pollutants from atmospheric fallout.
If exposed to traffic there will also be day to day input of automotive based pollutants and if not provided with upstream protection the water can be subject to contamination from the very rare losses of engine oil and fuel. Irrigation water resource potential of a range of hard SuDS devices. Storage needs to take into account sufficient temporary storage to provide stormwater source control when substrate is close to saturated.
If fertiliser is used on the roof, then recycling the water via the roof will retain the nutrients where they are needed.
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