Heavy rainfall

A critical situation arises in summer when the tank is heated by strong radiation, then cooled by sudden rainfall. Heavy rainfall results in a rapid drop in ambient temperature and the formation of a rainwater nlm that flows on the top of the tank and down the tank wall. The wall and, with a certain lag, the gas in the tank are cooled, and air must flow into the tank to prevent a significant pressure difference from arising between the inside and outside of the tank. If vapors in the tank are condensed, more air must flow into the tank. 

A problem of many sewage treatment works in the UK is that urban drainage is included with domestic sewage in the sewage collection systems. The resulting storm-water discharges, at times of heavy rainfall, lead to continuing phosphorus export to the river. Correction of this problem requires considerable investment in separate systems. 

Fig. 9.1. Rain falls when the water droplets in clouds turn to ice. This con only happen if the clouds are below 0°C to begin with. If the droplets are clean, ice can form only in the unlikely event that the clouds cool down to the homogeneous nucleation temperature of -40°C. When dust particles are present they can catalyse nucleation at temperatures quite close to 0°C. This is why there is often heavy rainfall downwind of factory chimneys.

First evidences of the impact of heavy rainfall on the epidemiology of enteric pathogens were obtained from studies on the presence of various faecal organisms, both pathogens and indicators in water. Increased numbers of pathogens and indicators in different water bodies, including drinking water, had been reported after heavy rains. 

Auld H, Maclver D, Klaassen J (2004) Heavy rainfall and waterborne disease outbreaks the Walkerton example. J Toxicol Environ Health A 67 1879-1887... 

Significant levels of herbicides have also been detected in rivers, although these are usually transitory. Heavy rainfall can move herbicides from agricultural land to nearby ditches and streams due to runoff, and in soils that are high in clay, percolation of water occurs through deep fissures with consequent movement into neighboring water courses. Such events under extreme weather conditions are likely to have contributed to the pulses of herbicide contamination observed in some rivers. Questions have been asked about possible effects of such episodic pollution on populations of aquatic plants. 

Williams, R.J. et al. (1996). Report of the Rosemaund Study—Describes the movement of herbicides through cracks and fissures in heavy soil into neighboring water courses following heavy rainfall. 

On the basis of evidence presented herein, this author conservatively estimates that, in terms of total carbofuran in water, damage is possible to aquatic invertebrates at >2.5 pg/L and to teleosts at >15 pg/L. These levels could be attained during a heavy rainfall shortly after carbofuran treatment of adjacent fields. Among sensitive species of warm-blooded animals, dietary concentrations as low as 10 pg/kg ration have demonstrable effects, which were measurable only after extended periods postingestion. For comparison, this level is about 1/5 that allowed in meat by-products for... 

Flood Heavy rainfall, soil has poor drainage system... 

Red spider mite epidemics at periods of excessive dry weather in areas of heavy rainfall may be serious, but, so far, the duration of the invasions has been short in banana farms. Weather and natural enemies have, to date, quickly brought this pest under control. 

Pentachlorophenol(PCP) is a versatile pesticide widely used as an insecticide, herbicide or fungicide. In Japan, PCP was produced approximately 15,000 ton/year from 1962 to 1970 and used mostly in the summer-time as a herbicide in paddyfields which were filled with water at a depth of few inches. The PCP applied to paddyfields easily flowed out of the fields to rivers and coastal area due to unexpected heavy rainfalls, resulting in a high mortality of fish and shellfish. The use of PCP in Japan was restricted in 1971 by the Government because of its high toxicity to fish. 

Density stratification in coastal waters can result from increased freshwater flows from land due to heavy rainfall, and from seasonal surfece warming. Changes in winds and currents alter upwelling conditions that can also affect stratification, while concurrently affecting nutrient resupply to the surface waters. These changing environmental... 

Despite new trends for decking and patios, a lawn remains a garden essential for many of us. Wildlife certainly gains more benefit from a lawn than from any hard surface, and it acts as a good soakaway for heavy rainfall. From perfect turf to hard-wearing play area, all types of lawn can be managed organically. 

Prolonged or heavy rainfall may produce erosion, moving the surface soil to other locations. It will almost certainly produce runoff that carries dissolved... 

Irrigation water is susceptible from direct contamination from sewage or manure spills. In the course of heavy rainfall, contamination associated with manure heaps can leach into water courses (Heaton and Jones, 2008 Lazarova and Savoys, 2004 Ottoson and Stenstrom, 2003). The level of contamination from these sources varies significantly. General population levels of E. coli in variety of potential contamination sources are presented in Table 4.3. 

Enteric viruses can persist for up to 4 months in subsurface soil layers. In contrast, viruses on the surface are typically inactivated within days by the antimicrobial effects of UV (Gerba et al, 2002 Moll and Vestal, 1992). Under heavy rainfall, viruses can be spread over wide areas (>150 m) especially when introduced into water courses (Santamaria and Toranzos,... 

Movement of pathogens from manure storages or manure or biosolids-fertilized cropland to surface or groundwater can be a significant source of contamination of water that may be used for irrigation purposes (Berry et al., 2007 Hill et al., 2005 Muirhead et al., 2006). This can occur as the result of over application of liquid manures or biosolids, but more commonly occurs in response to heavy rainfall shortly following manure or biosolids application (Muirhead et al., 2006). Potential also exists for rainfall-induced surface transport from treated cropland directly to fruit and vegetable fields. 

ISCOR technology is most applicable to aquifers with hydraulic conductivities greater than 10 " cm/sec. Vertical and horizontal heterogeneities within the aquifer will affect the oxidant s path and distribution rate through the aquifer. Heavy rainfall can back up water in the injection wells or trip the leak detectors and shut down the ISCOR system. Suspended solids from the precipitation of manganese(IV) oxide, undissolved oxidant, or other sources can cause clogging in the injection and extraction wells and uneven distribution of the oxidant. 

Discharges from this lysimeter only occurred after heavy rainfall and lasted for short periods. 

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