Chronology Of Developments

Attempts to relate agricultural production to weather go back at least 2,000 years and are still evolving. The twentieth century can be termed a very progressive and fertile one in respect to meteorology and agrometeo-rology (Fleming, 1996). Qualitative studies in the nineteenth century were followed by statistical analyses, then by microclimatic measurements, and most recently by modeling (Decker, 1994 Monteith, 2000). Quantification of Crop-Weather Relationships Visual observations of the...

Drought Monitoring and Planning for Mitigation

Drought is a climatic hazard that occurs in almost every region of the world. It causes physical suffering, economic losses, and degradation of the environment. A drought is a creeping phenomenon, and it is very difficult to determine when a dry spell becomes a drought or when a severe drought becomes an exceptional drought. It is slower and less dramatic than other natural disasters, but its effects are long lasting and widespread. The cost and misery suffered from a drought are more than...

Drought Monitoring In Australia

There may be few countries in the world where drought occurrence is more frequent than in Australia. Every state has developed its own procedures to identify and monitor the drought situation. AGROMETEOROLOGY TABLE 5.8. Crop Moisture Index (CMI) CMI values when index increased or CMI values when index did not change from previous week decreased from previous week CMI values when index increased or CMI values when index did not change from previous week...

Solar Radiation Interception By Plants

Three aspects of solar radiation are biologically significant. The first is the intensity of radiation, the amount of radiant energy falling on a unit of surface area in a unit of time. The second is the spectral distribution of radiation that governs the photochemical process of photosynthesis. The third aspect is the radiation distribution in time, which is important for photo-periodic phenomenon. Quantification of intensity and spectral distribution of radiation within crop canopies is...

Remotesensing Applications

Some examples of the use of remote sensing for agricultural applications are discussed in this section. Many of the examples have been taken from the Australian situation. Additional information is available in White, Tupper, and Mavi (1999). Vegetation Cover and Drought Monitoring Vegetation cover is important as an indicator of available fodder and to protect the soil resource from erosion. Cover can be estimated using remote sensing, field measurements, pasture and crop models, and farm...

Role Of Weather And Climate

Weather is the most important factor that determines the geographical distribution and periodic abundance of crop insect pests and parasites of animals. Weather controls the development rate, survival, fitness, and level of activity of individual insects the phenology, distribution, size, and continuity of insect populations migration and their establishment and the initiation of insect outbreaks (Pedgley, 1990 Drake and Farrow, 1988). Weather influence can be immediate, cumulative, direct,...

Remote Sensors And Instruments

All remote-sensing systems designed to monitor the earth's surface rely on energy that is either diffusely reflected by or emitted from surface features. Current remote-sensing systems fall into three categories on the basis of the source of the EMR and the relevant interactions of that energy with the surface. These sensor systems detect solar radiation that has been diffusely reflected (scattered) upward from surface features. The wavelength ranges that provide useful information include the...

Climatological Methods forManaging Farm Water Resources

Almost all of the water available on the earth, 97 percent, occurs as saltwater in the oceans. Of the remaining 3 percent, 66 percent occurs as snow and ice in polar and mountainous regions, which leaves only about 1 percent of the global water as liquid freshwater. More than 98 percent of freshwater occurs as groundwater, while less than 2 percent occurs in rivers and lakes. Groundwater is formed by excess rainfall (total precipitation minus surface runoff and evapotranspiration) that...

Practical Utility

The dangers to the natural resource base, crops, and livestock that have a meteorological component include pollution of soil and air soil erosion from wind or water the incidence and effects of drought crop growth animal production the incidence and extent of pests and diseases the inci dence, frequency, and extent of frost the dangers of forest or bush fires losses during storage and transport and all farm operations. Agrometeo-rology offers practical solutions for harnessing climate...

Drought Exceptional Circumstances

Drought conditions of some magnitude are present almost every year in some part of Australia because of its vast size and semiarid to arid climate. Such occurrences are a part of normal life and are not of major concern at the national level. Sustained droughts, usually lasting one to two years, possibly for three years, and extending across large tracts of the country have created great disasters. These are of relatively less frequent occurrence, and each of them has different spatial,...

Meteorological Indicators Of Drought

Drought conditions are basically due to a deficit of water supply in time and or space. The deficit may be in precipitation, stream flow, or accumulated water in storage reservoirs, ground aquifers, and soil moisture reserves. In describing a drought situation, it is important to understand its duration, spatial extent, severity, initiation, and termination. Depending on the areal extent, a drought can be referred to as a point drought, small-area drought, or a continental drought. The point...

Simulation Models Relevant To Australian Farming Systems

During the twentieth century, world agriculture passed through three revolutionary eras. The first was the mechanical (1930-1950), the second, seed-fertilizer (1960-1970), and the third, information technology (in the closing decades of the century). Within the span of the last two decades of the century, several thousand computer-based plant and animal dynamical models were developed worldwide which have expanded scientific insight into the complex interactions between environmental and...

Making Effective Use Of Rainfall

Hand Brakes For Carts

An inadequate and variable water supply and extremes of temperatures are the two universal environmental risks in agricultural production. High temperatures in tropical climates limit the production of crops native to temperate latitudes, and low winter temperatures in high latitudes are a check on growing crops native to tropical areas. Inadequate and variable water supply, however, has a negative impact on crop production in every climatic region. The problem is more pronounced in tropical...

Remote Sensing

Remote sensing is defined as the science of obtaining and interpreting information from a distance, using sensors that are not in physical contact with the object being observed. Animals (including people) use remote sensing via a variety of body components to obtain information about their environment. The eyes detect electromagnetic energy in the form of visible light. The ears detect acoustic (sound) energy, and the nose contains sensitive chemical receptors that respond to minute amounts of...

Definition Of Drought

The definition of drought is not very simple, and the question What is drought continues to pose a problem (Sivakumar, 1991). This is because drought could mean different things to different people, and there are probably as many definitions of drought as there are users of water. In general, a drought is when a shortfall in precipitation creates a shortage of water, whether it is for crops, utilities, municipal water supply, recreation, wildlife, or other purposes. According to a WMO...

Impact Of Climate Change On Hydrology And Water Resources

One of the major impacts of global warming is likely to be on hydrology and water resources, which in turn will have a significant impact across many sectors of the economy, society, and environment (Figures 11.2 and 11.3). Characteristics of many ecosystems are heavily influenced by water availability. Water is fundamental for human life and many activities, in- FIGURE 11.2. Impact of climate change on water resources and agriculture FIGURE 11.2. Impact of climate change on water resources and...

Dinajpur Watcher

Arachchi, D.H.M., Naylor, R.E.L., and Bingham, I.J. 1999 . A thermal time analysis of ageing of maize Zea mays L. seed can account for reduced germination in hot moist soil. Field Crops Research 63 159-167. Atta-Aly, M.A. and Brecht, J.K. 1995 . Effect of postharvest high temperature on tomato fruit ripening and quality. In Ait-Oubahou, A. and El-Otmani, M. Eds. , Postharvest Physiology, Pathology and Technologies for Horticultural Commodities Recent Advances. Proceedings of the International...