Interpolation of vulnerability level and degree of drought in rural areas (The farmer's perspective)
Abstract:
Introduction
Drought is a deficiency in precipitation over an extended period, usually a season or more, resulting in a water shortage causing adverse impacts on vegetation, animals, and/or people. It is a normal, recurrent feature of climate that occurs in virtually all climate zones, from very wet to very dry. Drought is a temporary aberration from normal climatic conditions, thus it can vary significantly from one region to another. Drought is different than aridity, which is a permanent feature of climate in regions where low precipitation is the norm, as in a desert. Human factors, such as water demand and water management, can exacerbate the impact that drought has on a region. Because of the interplay between a natural drought event and various human factors, drought means different things to different people. In practice, drought is defined in a number of ways that reflect various perspectives and interests. Drought is difficult to define precisely, but operational definitions often help define the onset, severity, and end of droughts. No single operational definition of drought works in all circumstances, and this is a big part of why policy makers, resource planners and others have more trouble recognizing and planning for drought than for other natural disasters. In fact, most drought planners now rely on mathematic indices to decide when to start implementing water conservation or measures in response to drought. In this study, the drought can be defined such: Agricultural drought links various characteristics of meteorological (or hydrological) drought to agricultural impacts, focusing on precipitation shortages, soil water deficits, reduced ground water or reservoir levels needed for irrigation, and so forth. Drought is not a disaster for nature itself, the disaster occurs when we consider the demand people place on their water supply. Human beings often increase the impact of drought because of high use of water which cannot be supported when the natural supply decreases. Droughts occur in both developing and developed countries and can result in economic and environmental impacts and personal hardships. All societies are vulnerable to this natural hazard.
Methodology
Agricultural drought occurs when there isnt enough soil moisture to meet the needs of a particular crop at a particular time. Agricultural drought happens after meteorological drought but before hydrological drought. Agriculture is usually the first economic sector to be affected by drought. In this study, vulnerability of drought in rural communities was investigated as a problem for agriculture. In this regard, Socio-economic drought is what happens when physical water shortage starts to affect people, individually and collectively. Or, in more abstract terms, most socioeconomic definitions of drought associate it with the supply and demand of an economic good. For achieve the goals, literature review and field survey methods have been used. Sulduz rural district in west Azarbaijan was the statistical society of the study. Therefore ten villages were selected as samples. This selection was carried out considering the criteria such as information of township disasters, type of agriculture land and population. According to Cochran formula, 300 questionnaires were filled randomly. In order to, drought interpolation in rural areas, at the beginning the levels of vulnerability have been studied in the selected villages. Data were analyzed using different statistical methods such as comparison of averages and Analysis Of Variance in SPSS software. Interpolation of drought severity and vulnerability in rural areas has been done by Spline method in GIS.
Results And Discussion
There are many methods of interpolating randomly spaced point data. Some of these methods are global while others are local. Global methods utilize all the known values to evaluate an unknown value, while in local methods only a specified number of nearest neighbors are used to evaluate an unknown value. The Spline tool uses an interpolation method that estimates values using a mathematical function that minimizes overall surface curvature, resulting in a smooth surface that passes exactly through the input points. The Spline with Barriers tool uses a method similar to the technique used in the Spline tool, with the major difference being that this tool honors discontinuities encoded in both the input barriers and the input point data. This study investigated drought intensity and vulnerability in Sulduz rural district by drought evaluation of the farmers’ point of view and finally, villages of studied were classified based on the data obtained of the field survey. The results of present study showed that villages have difference in the levels of vulnerability. Therefore, drought impacts will reduce in vulnerable rural through awareness of drought vulnerability levels. In Sulduz rural district, villages were classified in the five ranges from very low to very high. In order to, higher risk villages are identified; finally Quick and Helbi were recognized as the most vulnerable villages.
Conclusion
Drought is different from tornadoes, hurricanes, and floods. It can be more difficult to detect and it can last much longer than other weather events. We don’t have watches or warnings for drought like we do for other natural hazards. But just because drought is different from the other natural disasters doesn’t mean we can’t plan for it and take steps to help protect ourselves from the effects of drought. The social and economic costs of drought require decision makers to improve planning, mitigation, and adaptation strategies to deal with this hazard. The spatial interpolation methods were developed either for specific disciplines or even for specific variables based on the data properties modeled. Each method has its specific assumptions and features. These features, such as global versus local, exact versus inexact, deterministic versus stochastic, and gradual versus abrupt, are discussed. As geographic information systems (GIS) and modeling techniques are becoming powerful tools in natural resource management and biological conservation, spatial continuous data of environmental variables are increasingly required.
Language:
Persian
Published:
Human Geography Research Quarterly, Volume:48 Issue: 95, 2016
Pages:
19 - 31
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