برآورد زمانی فضایی بارش با استفاده از داده‌های ماهواره‌ی gpm در حوضه‌ی آبریز جازموریان

بارش به عنوان مهم ترین متغیر در چرخه ی هیدرولوژیکی تامین کننده ی آب، نقش مهمی در تداوم حیات سیاره ی زمین ایفا می کند. پایداری اکوسیستم های مختلف گیاهی و جانوری در حوضه ی آبریز جازموریان وابستگی بسیار زیادی به مقدار بارش دارد. تغییرپذیری بالای بارش، تاب آوری این حوضه را با چالشی جدی روبرو نموده است. با توجه به کمبود ایستگاه های زمینی و پراکنش نامناسب آن ها در این حوضه، در تحقیق حاضر به واکاوی تغییرات زمانی فضایی بارش طی دوره ی (2019-2001) با استفاده از داده های ماهواره ی سنجش جهانی بارش (gpm) پرداخته ‌شد. در ابتدا داده های بارش مورد نیاز با تفکیک فضایی 0.1 × 0.1 درجه و تفکیک زمانی ماهانه، فصلی و سالانه فراهم گردید. پس از انجام پیش پردازش های لازم در محیط نرم افزارهای گرافیکی و آماری، با استفاده از روش های زمین آماری نرم افزار gis به پهنه بندی توزیع فضایی بارش اقدام و در نهایت به تفسیر خروجی های مربوطه پرداخته شد. براساس نتایج، توزیع فضایی بارش حوضه ی آبریز جازموریان در دوره ی آماری مورد مطالعه از 232-83 میلی متر متغیر بوده است. بیشینه ی بارش در بخش های شمالی و غربی و کمینه ی آن در نواحی مرکزی و شرقی حوضه رخ داده است. به لحاظ توزیع فصلی، مقدار بارش در زمستان 73، بهار 47، تابستان 12 و پاییز نیز 12 میلی متر برآورد گردید. واکاوی بارش ماهانه نیز بیان گر رخداد بیش ترین مقدار بارش در ماه های مارس (33 میلی متر) و فوریه (32 میلی متر) و کم ترین آن در ماه های سپتامبر (1 میلی متر) و می، ژوئن و اکتبر (3 میلی متر) است. به طور کلی، نتایج حاکی از تغییر پذیری بالای بارش و حاکمیت شرایط خشک در حوضه ی آبریز جازموریان است.

Spatiotemporal Estimation of Precipitation Using GPM Satellite Data in Jazmourian Catchment

Introduction Precipitation is the most important element of water level that recognizing its temporalspatial characteristics at different scales is an important step towards better understanding and modeling of the hydrological cycle and related phenomena such as floods. Drought, landslides, snow and climate change are on a regional and global scale. Despite the large number of studies conducted in this field, there is still a lot of research need in many parts of the world for reasons such as lack of weather stations to access ground observation data and the nonuniform spatial distribution of these stations. Nowadays, with significant technological advances, including the advent of various satellites, access to a variety of precipitation data has been greatly facilitated. Among the latest precipitation products of various satellites, we can refer to the Global Precipitation Measurement (GPM) satellite data. Related to the subject of the present study, it is stated that most of the studies on rainfall in the Jazmourian catchment area have been based on station data, which due to the poor distribution of meteorological stations; it is not possible to estimate the temporalspatial distribution of precipitation in the study basin. In this study, the temporalspatial analysis of precipitation using GPM satellite precipitation products as one of the most important climatic parameters in the basin Due to the undeniable importance of rainfall in this basin, it seems that the analysis of variable rainfall can provide valuable climatic information to researchers and planners. To pave the way for new study platforms.Materials and Methods In this study, satellite data (GPM) with a spatial resolution of 0.1 × 0.1 degrees from January 2001 to December 2019 have been used for spatiotemporal analysis of precipitation in the Jazmourian catchment. The GPM satellite provides more accurate and realistic estimates than other TRMM satellites. In this study, a calibrated precipitation product of level 3 of 6 GPM satellite versions was used. Relevant data are in NCDF format and have UTM image system with WGS84 datum, which after quality control and preprocessing, by specialized software (ENVI, ArcGIS and EXCELL) is converted into network data and data tables and the necessary outputs based on the geographical boundary of the catchment was extracted. The average monthly rainfall was extracted from the average daily rainfall belonging to each month and the seasonal average was extracted from the average of three months related to each season. Spatially, the values of each pixel are the conditions of the average amount of precipitation related to each time series (monthly, seasonal and annual) during the statistical period.Results and Discussion Based on the results, the average rainfall in the Jazmourian catchment was estimated as 144 mm, the spatial distribution of which ranged from 83 to 232 mm. The maximum rainfall occurred in the northern and western parts and the minimum occurred in the central and eastern parts of the basin. Furthermore; based on the annual distribution of rainfall during the statistical period under study, the highest rainfall was in 2019 with 239 mm and the lowest with 53 mm in 2001. In terms of seasonal distribution, winter and spring with values of 118 and 88 mm, respectively, showed the highest and autumn and summer with values of 22 and 45 mm, showed the lowest values of precipitation. Also, during the statistical period under study, winter 2005 with 193 mm had the highest and autumn 2003 with 1 mm had the lowest seasonal rainfall in the basin. In addition, an interesting point is the spatial displacement of highpressure nuclei in different seasons of the year; so that these nuclei are observed in the cold seasons of the year in the northern and western parts and in the warm seasons of the year in the southwestern and southeastern parts of the basin. The spatial distribution of monthly precipitation indicates the occurrence of the highest monthly precipitation in February and March and the lowest in May and September. Also, the monthly rainfall time series indicates the maximum incidence of precipitation in February 2001 (94 mm) and it’s minimum in January 2001 (no precipitation).Conclusion Precipitation as a source of fresh water on Earth is one of the most important hydrological parameters, the importance of which is undeniable in the survival of human communities and natural ecosystems. Due to the large temporalspatial variations of precipitation, its study seems necessary. But one of the main challenges for studying this phenomenon is the lack of ground stations as well as their improper distribution. Today, with advancement of technology and remote sensing, a diverse range of satellite data has become available to environmental scientists. In this regard, in the present study, using GPM satellite data and in the statistical period 20012019, the temporalspatial distribution of precipitation in the Jazmourian catchment area in southeastern Iran has been investigated. In general, the high variability of rainfall in Jazmourian catchment in different months and seasons of the year, shows the dominance of arid and low climate in this basin. Therefore, due to the rainfall situation and its high fluctuations under climate change conditions, in the near future, this basin will face serious challenges and crises in water resources management and the sustainability of natural ecosystems. The GPM satellite data used in this study showed appropriate and expected results from the spatialtemporal distribution of precipitation in the Jazmourian catchment and showed a good correlation with meteorological stations. In general, the use of GPM satellite data in the present study is appropriate, which due to its appropriate spatiotemporal separation, gives reliable and satisfactory results. On the other hand, inadequate spatial coverage of meteorological stations and their large statistical vacuum in such a relatively large basin justify the use of this valuable and useful satellite data.