كليدواژه :
پهنه بندي , پتانسيل اقليمي , گندم ديم , استان زنجان , سيستم اطلاعات جغرافيايي
چكيده فارسي :
شناخت اقليم و بررسي نيازهاي اقليم شناختي گياهان زراعي از مهمترين عوامل موثر در توليد است. با بررسي هاي هواشناسي كشاورزي مي توان امكانات بالقوه اقليمي را در مناطق مختلف مشخص و از آن ها حداكثر بهره برداري را نمود. در اين تحقيق براي بدست آوردن نقشه پتانسيل اقليمي استان زنجان از داده هاي اقليمي مربوط به ايستگاه هاي كليماتولوژي و سينوپتيك واقع در محدوده استان زنجان طي دوره آمري (2010-1986) استفاده گرديد. بعد از بدست آوردن تاريخ آغاز بارش هاي پاييزي در سطح استان، براي هر منطقه از استان براي هر منطقه از استان تاريخ كاشتي مشخص گرديد. در ادامه از عنصر بارش، نقسه هاي هم ارزش اقليمي بارش سالانه، بارش در دوره جوانه زني، بارش در دوره گل دهي و بارش پر شدن دانه استخراج گرديد. همچنين با توجه به عنصر دما نيز نقشه هاي هم ارزش اقليمي دماي مناسب جوانه زني، تنش هاي دمايي در طول دوره گل دهي و پر شدن دانه در سطح استان تهيه شد. در نهايت با تلفيق اين نقشه ها در محيط GIS نقشه پهنه بندي اقليمي كشت گندم ديم استخراج گرديد. نقشه بدست آمده شامل چهار پهنه بسيار مناسب، مناسب، متوسط و ضعيف ترسيم شد اين نقشه ها نشان داد كه عمده مناطق مناسب براي كشت گندم ديم در استان در ناحيه جنوبي و مركزي استان قرار دارند و شامل نواحي جنوبي شهرستان زنجان، نواحي غربي شهرستان ابهر و بيش تر قسمت هاي شهرستان هاي خرمدره و خدابنده مي باشد. در مقابل مناطق واقع در شمال استان در محدوده استان هاي طارم و ماهنشان و مناطق مرتفع و پرشيب رشته كوه هاي البرز داراي وضعيت متوسط و ضعيف از لحاظ كشت گندم مي باشند.
چكيده لاتين :
Introduction
Agriculture is commonly considered as one of the important sections of economics
and economic progress depends strongly on the agricultural crops. Nowadays, it is
applicable to achieve an improved and scientific agriculture based on doing precise
scientific researches and to identify the environmental potentials of each region. To a
knowledge the climatic parameters and their effects on the farming plants one of the
most important effective factors in increasing performance and production, and
especially such condition is consideration of dry farming.
Because of the cultivation of crops in most parts of the country based on traditional
experiences, their climate-agricultural potential is not well-known. This paper aims to
interpolate the regions regarding wheat production based on climatic potentials of
Zanjan Province through temperature and precipitation analyses. It is possible to
present a crop performance enhancement and utilize the climatic conditions by
identifying the appropriate areas to cultivate. The results of this study will help to
agricultural planning in the Zanjan province.
Various studies been done on the impact of climate factors on the growth of dry
farming products. Zang (1994) has done many researches on the winter wheat
growth to determine the effects of temperature and precipitation changes in China.
In his research, Norwood (2000) investigated the effects of climatic parameters on
the wheat dry-farming cultivation in Great Plains of Kansas State in the United States,
and came to the conclusion that evaporation and precipitation play the most
significant role in wheat' dry-farming growth process compared to the other climatic
elements. In West Azerbaijan, Zarrin (2000) investigated the effect of climatic
parameters on performance of the amount of dry-farming crop. He finally
represented a pattern for the dry-farming wheat crop's forecasting in the region.
Materials and Methods
In this paper, the daily maximum, minimum, average temperatures, and annual
precipitation data records for nine synoptic and climatology stations in the Zanjan
province in the 30-year period (1976-2005) were received from the Meteorological
Organization. Then subtraction and ratio methods have been used for filling some
gaps of temperature and precipitation data records.
In the next step, an attempt was made to derive the precipitation variables (annual
precipitation and germinating/ blooming/ full-grown precipitations), as well as
temperature variables (proper temperature of germinating, temperatures less than
9°C in blooming, temperatures more than 25°C in blooming period, and temperatures
less than 9 °( in full-grown, and temperatures more than 30°C in full-grown period).
Appropriate condition for wintertime wheat cultivation is depending on two variables
of precipitation and temperature. At the present research, as regards of the region
and importance of precipitation in dry farming, the following definition applied to
compute the date of cultivation: The first date of rainfall occurrence and more than
5mm took place for one or two consecutive days with a probability of 75% in fall
season. Proper temperatures for this period were also determined to be between
l2°C to 20°C. In continuation, concerning the thermal requirements of wheat during
various growing phases, the beginning and ending time of growth sensitive steps
(germinating/ blooming/ full-grown) were determined. Finally, the interpolation
maps related to these parameters provided and then categorized by using GIS.
Discussion
The results of the geographic distribution regionalization of the province's
precipitation showed that the amount of precipitation is noticeability in a poor
condition (less than 250mm) in a small part of the northwest and west of the
province in which is an obstacle for economical cultivation of wheat dry farming (Fig.
4). The results obtained from Fig (6) indicate that the amount of autumn's
precipitation is more than annual figuers in the northeast and east of the province,
and the autumn precipitation amount is decreasing towards the south and west.
Concerning that the western Coasts of Caspian Sea receive the most precipitation in
the Fall season, in neighboring with such a rainy area, that is the reason why the
northwest of the Zanjan Province receives a high amount of precipitation in Fall
season.
It was defined four classes for each layer, after deriving the required parameters for
all the stations and transferring them to GIS based on the scientific resources as well
as the climatic conditions of the study area. In addition, each region was given a
digital weight between one to four to make the same scale for the layers for overlying
process, based on the climatic proper condition of the dry farming wheat {table 2). All
of the layers related to the climatic parameters of temperature and precipitation
were integrated using GIS by utilizing the overlying method of "classified weight". In
the next step, the high steep heights and forest regions as inappropriate regions with
the view of wheat cultivation were overlie with the map of obtained from the climatic
parameters, and finally the regionalization map of areas for dry-farming wheat was
produced for the Zanjan province (Fig. 16).
Conclusions
Special geographic situation of Zanjan Province and its natural capabilities throughout
the history has led to forming a series of agricultural activities. The paper's objectives
were to identify the abilities and limitations caused by climate in the region, in other
words, and to regionalize agro-climatology of wheat dry farming using climatic
elements by GIS. To do so, the former background studies regarding the climatic
potentials of dry-farming wheat cultivation were investigated first, and then agroclimatology
map of wheat dry farming was produced for Zanjan Province by using the
precipitation and temperature data and overlying method by GIS. The results showed
that some central parts of the province such as Khodabandeh and Southwest Zan jan
city were recognized as the best locations to cultivate the dry-farming wheat. Other
equivalent important results of the paper was to utilize the capabilities and abilities
of Geographic Information System (GIS) in overlaying and producing the spatial
information with non-spatial data, which can be very useful for managers and
planners to access the information.
