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کیا اس سال سیلاب آئے گا؟

سنہ2017 کی ایک عالمی رپورٹ کے مطابق موسمیاتی تبدیلیوں سے شدیدمتا ثر ہونے والے  ملکوں میں بنگلہ دیش پہلے  پاکستان     16ویں جبکہ  چین 49 ویں نمبرپر ہے اور ناروے سب سے کم متاثرہ ہونے کی وجہ سے 170 ویں نمبر پر ہے۔ پاکستان ان شدید  موسمیاتی تبدیلیوں کی وجہ   سےسیلاب، خشک سالی، زلزلوں جیسی قدرتی آفات کی زد میں رہتا ہے۔  پاکستان میں سیلاب کی تاریخ کافی پرانی ہے۔ وفاقی سیلابی ادارے  کی ایک رپورٹ کے مطابق پچھلے 68 سالوںمیں  سیلاب سے ہونے والے نقصان کا تخمینہ تقریبا 38 بلین ڈالر ہے   جبکہ اسی رقم سے 3 دیامیر بھاشا ڈیم تعمیر کیے جاسکتے ہیں۔ پاکستان کی حالیہ تاریخ میں 1952، 1973، 1976، 1978، 1988، 1992، 1997 اور 2010 کے سیلاب شدید ترین نوعیت کے تھے۔  صرف 2010 کے سیلاب سے 2000 اموات واقع ہوئی  اور 0.16 ملین زرخیز زمین زیر آب آ گئی۔ پاکستان میں کل سیلابی نقصان کا 42 فیصد 210-2015 کے دوران وقوع پزیر ہونے والے سیلابوں  کی کارستانی ہے۔ اقوام متحدہ کے ایک محتاط اندازے کے مطابق 2010 کے سیلاب میں 18 ملین افراد متاثر ہوئے جس میں آبادی کے لحاظ سے صوبہ سندھ اور اموات کے لحاظ سے  صوبہ خیبر پختونخوا سب سے زیادہ متاثر ہوئے۔

Flood 2010

سنہ 2017 میں پاکستان میں مون سون سے سیلاب کے خطرے کی جانچ کیلئے پاکستان کے موسمیاتی ادارے کی 14 جون2017 کو شائع ہونے والی رپورٹ کا جائزہ از حد ضروری ہے۔ اس موسمی پیش گوئی کی رپورٹ کے مطابق   اس سال پاکستان میں مون سون بارشیں جولائی میں نارمل ہوں گی اور اگست اور ستمبر میں یہ نارمل سے بھی کم ہوں گی۔پاکستان کے جنوبی علاقوں میں بارش کی کمی کی وجہ سے خشک سالی کا بھی خطرہ  ہو سکتا ہے۔ اس کے ساتھ یہ بھی امکاں ہے کی پہاڑی اور نیم  پہاڑی علاقوں میں سیلابی ریلوں کے خطرات موجود رہیں۔

سیلاب کی صورتحال کی عکاسی کے لیئے  پاکستان میں موجود دریاوں کے خدوخال کی وضاحت ضروری ہے۔ پاکستان میں سیلابی پانی کو ذخیرہ کرنے کیلئے صرف دو ڈیم  تربیلا اور منگلا ہیں جن میں ایک خاص حد تک پانی ذخیرہ کیا جا سکتا ہے،  جبکہ باقی تین دریاوں ستلج، راوی اور چناب پر کوئی پانی ذخیرہ کرنے کی سہولت میسر نہیں ہے۔ سیلابی پانی سے آبادی کو بچانے کیلئےدریاوں کے ساتھ سیلابی پشتے تعمیر کیے جاتے ہیں اور ان پشتوں کے اندرونی علاقے بیٹ یا کچا کے علاقے کہلاتے ہیں جہان مستقل تعمیرات کی اجازت نہی۔ان علاقوں میں مون سون کے دنوں میں عموماٰ ان علاقوں سیلابی پانی آسانی سے داخل ہو جاتا ہے اور وہاں کے رہائشی اس موسم میں نقل مکانی کے عادی ہیں۔ سیلابی صورتحال اس وقت گھمبیر ہو جاتی ہے جب پانی ان پشتوں سے باہر نقل کر آبادی اور زرخیز زمینوں میں داخل ہوتاہے اور جانی ومالی نقصان کا باعث بنتا ہے۔

اگر چہ محکمہ موسمیات کی پیشین گوئی کو مد نظر رکھا جائے تو اس سال سیلاب کے امکانات کم ہیں،  تاہم مون سون کے غیر معمولی برتاو کی وجہ سے سیلاب کے خطرہ کو یکسر مسترد نہیں کیا جاسکتا۔  اس کی ایک وجہ  یہ  ہے کہ مون سون کی بارشیں کسی ایک وقت میں کم اور دوسرے وقت میں زیادہ ہوں اور بحیثیت مجموعی ان کا    رویہ نارمل ہو۔اسی ضمن میں اگر 2010 کے سیلاب کی صورتحال کو مد نظر رکھا جائے تو مندرجہ ذیل حقیقت واضح ہوتی ہے: جولائی 2010 میں شمالی علاقہ جات میں نارمل سے چار گنا زیادہ بارشیں ہوئیں اور ان بارشوں کی شدت 36 گھنٹوں میں 300 ملی میٹر تک ریکارڈ کی  گئی۔ایک قلیل وقت میں اتنی زیادہ مقدار میں پانی کو سنبھالے کی استعداد  اور سکت ہماری انتظامی مشینری میں نہیں تھی جس کا نتیجہ 2010 کے سیلاب کی صورت میں بھگتنا پڑا۔ اقوام متحدہ نے 2010 کے سیلاب کو  موجودہ تاریخ کا بدترین انسانی بحران قرار دیا اور اس وقت سیکریٹری بان کی مون بذات خود پاکستان میں صورتحال کا جا ئزہ لینےکیلئے تشریف لائے۔ موجودہ چیف جسٹس لاہور ہائی کورٹ جسٹس منصور علی شاہ کی قیادت میں2010 میں بننے والے سیلابی کمیشن نے یہ نتیجہ اخذ کیا تھا کہ سیلاب سے نمٹنے کیلے متعلقہ محکموں کےپاس  نہ ہی درکار استعداد تھی اور  نہ ہی منظم فیصلہ سازی کی صلاحیت تھی۔ اس کے علاوہ   سرکاری اہل کاروں  کی غفلت اور سیلابی پشتوں کی  غیر مناسب دیکھ بھال اور تعمیر میں ناقص مواد کا استعمال بڑی تباہی کا باعث بنے۔

سیلاب سے نمٹنے کیلے ضروری ہے  ملک میں نئے ڈیم تعمیر کیے جائیں، اداروں کی استعداد کار میں اضافہ کیا جائے، سیلابی پشتوں کی مناسب دیکھ بھال کا  شفاف نظام وضع کیا جائے اور جدید مہارتوں کے استعمال سے نقصانات کو کم سے کم سطح پر لایا جائے۔

Imagery Downlinked from Satellite to Ground in 6 Minutes

Some months ago, I had written about the EDRS SpaceDataHighway and real-time provision of Sentinel-1 satellite imagery through laser link and satellite relay. Now, ESA has done an experiment with Sentinel-2B to deliver imagery to the ground moments after it was capture by the satellite. The captured image strip was downlinked in just 6 minutes. This experiment brings us closer to the amazing future when we would be able to access satellite imagery as non-defence / non-strategic users in near-real-time.

See more details here:

http://www.esa.int/Our_Activities/Observing_the_Earth/Copernicus/Sentinel-2/First_Sentinel-2B_images_delivered_by_laser

Aperture Synthesis and Azimuth Resolution in Synthetic Aperture Radar – Lecture Notes

Teaching the fundamentals of Synthetic Aperture Radar (SAR) system design and imaging mechanism to remote sensing students / professionals is always a difficult task. Remote sensing students / professionals generally do not have an in-depth background of signal processing and radar system design, and as an instructor, I always have to think over how much I need to tell them about SAR system design, without diving into the detailed mathematics of signal processing and imaging mechanism. Normally, I go in-depth towards the imaging geometry and an understanding of the Doppler history curve, and briefly go over the signal-processing heavy concepts like pulse compression and matched filtering. A good fundamental understanding of the SAR system design, imaging geometry, and image formation is essential for remote sensing students / professionals to have a background context knowledge when they select SAR data and process / analyze it for different remote sensing applications.

For the past few years, I have been teaching a graduate course in Radar Remote Sensing and also run an annual Summer School on Earth Remote Sensing with SAR at our research group GREL. One of the core issues in understanding the aperture synthesis process is the requirement for enhancement of the azimuth / along-track resolution. It is always interesting to discuss in class how in normal imaging radar the azimuth resolution depends inversely on the antenna along-track length, while in fully-focussed SAR the azimuth resolution becomes half of the antenna along-track length. This is a significant reversal: In normal imaging radar, we need a bigger antenna in along-track dimension to get better azimuth resolution, while in SAR, the smaller the antenna in the along-track dimension, the better the azimuth resolution.

AzimuthResolutionSAR

To explain how aperture synthesis changes the azimuth resolution to half of the along-track antenna length, I have made some detailed notes for my ongoing graduate class on Radar Remote Sensing. These notes require just basic knowledge of geometry, algebra, and sum series in mathematics. I would like to share them with the wider scientific audience, please access the PDF notes here: Aperture Synthesis and Azimuth Resolution.

ApertureSynthesis

The synthetic aperture length is defined in the figure above. The azimuth resolution in fully-focussed SAR becomes half of the antenna along-track dimension.

I have taken the help of two excellent resources on SAR remote sensing in developing these notes:

For more in-depth understanding and analysis of how SAR is used for remote sensing, you can consider attending the next Summer School on Earth Remote Sensing with SAR, which I will be offering this summer. The summer school is coming up in July, 2018, and it will be open for international participants; formal dates will be announced soon. Keep watching the GREL website for updates.

Big Earth Data Documentary

Recently I ran into this wonderful documentary about how scientists are handling the huge amounts of remote sensing and earth science data being collected in the current age.

The documentary spends a lot of time talking about how remote sensing is used for oceanography and marine security monitoring, looking at concerns like monster waves, oil spills, surface ice content, ship routing through polar oceans, etc.

The EarthServer project is mentioned, which establishes “big earth data analytics, rapid ad-hoc processing and filtering on massive geodata.” Satellite images are shown to be useful also for automatic counting of houses or camps, and for disaster damage assessment. The use of GRACE satellite system for Earth gravimetry and water content measurement is mentioned.

For background information regarding the documentary, go here.

 

GUEST POST: Time to Map and Monitor Pakistan’s Forests at the National Scale – Transparency and Accuracy

In Pakistan, too often, forested lands are treated as “free wastelands”. Deforestation and forest degradation is occurring primarily due to institutional negligence. An eye-opening example is massive deforestation in just four months observed in National Zoo-cum Park & Botanical Garden, Bani Gala, right in the capital territory of Islamabad. (see Fig. 1).

Figure1

Figure 1: A massive deforestation in four months (May-Oct, 2016) in National Zoo-cum Park & Botanical Garden, Bani Gala, Islamabad (Source of satellite images: Google Earth)

In Pakistan, many people consider real estate as the best investment, and this gives incentives for encroachers to intrude on state-owned land. Forested lands, due to their natural beauty and as a source of a double benefit, i.e., timber and land, are especially threatened by illegal land grabbers. Another example of forest degradation in Murree, Galliat region can be seen in Fig. 2, where 7.58 km2 of forest land was destroyed by  housing societies.

Figure2

Figure 2: Illegal encroachments in state-owned forests from 2005 to 2011: Bahria Golf City (Above) and OGDC Housing Society (Below). (Source of satellite images: Google Earth). See more detail in this published research article.

On the bright side, in recent years Pakistan has taken gigantic steps towards tree plantation under national (Green Pakistan Programme) and provincial (Billion Tree Tsunami in Khyber Pakhtunkhwa) initiates. These initiates have been well received and recognised globally. As an example, in 2009, Pakistan received a certificate from Guinness Book of World Records in acknowledgment of planting 541,176 mangrove plants in a single day in Keti Bunder (Indus Delta), Thatta district, Sindh province (see Fig. 3).

Figure3

Figure 3: Monitoring mangrove plantations: Repeat terrestrial photographs taken on May 2010 and May 2015 (left) and satellite images showing afforestation and conversion of mudflats into new mangroves (right). (Source of photographs: WWF-Pakistan; source of satellite images: Google Earth).

We should not forget that since 2011, Pakistan is part of UN-REDD (United National- Reducing Emission from Deforestation and Forest Degradation) program. Under the REDD program, developing countries receive performance-based incentives (payments) for reducing emissions of greenhouse gasses from forestlands. National Forest Monitoring System (NFMS) and Forest Reference Emission Level (FREL) / Forest Reference Level (FRL) systems are mandatory elements for REDD reporting system to get the financial benefits. Accurate and up-to-date information about the size, distribution, composition, and condition of forests and woodlands is essential for developing and monitoring policies and guidance to support their sustainable management. Although, in Pakistan, many independent researchers and organizations are conducting a number of scattered and local studies (e.g. Mapping Deforestation and Forest Degradation Patterns in Western Himalaya, Pakistan), however, a fundamental question remains:

How can we, in a systematic and transparent manner, map and monitor wall to wall Pakistan land cover and forest areas at the national scale?

Over the years, the use of satellite remote sensing data has become most popular among researchers and policy makers, for both smaller and larger scales. Consistent time series medium resolution freely available remote sensing data (e.g. Landsat, Sentinel-2 etc.) provide frequent, synoptic, and accurate measurements, monitoring, and simulation of earth surface features, especially forests. Unbiased ground information (field surveys, photographs, forest inventory, etc.) are very much necessary for the accuracy and evaluation of any product derived from satellite images. Under the REDD program, for FREL/FRL construction and reporting, Pakistan has to follow the guidance and guidelines of IPCC and the UNFCCC. For reporting to international bodies, Pakistan has to combine remote sensing and ground-based forest carbon inventory approaches for estimating, as appropriate, anthropogenic forest-related greenhouse gas emissions by sources and removals by sinks, forest carbon stocks, and forest area changes.

So, in my view, without further delay, Pakistan needs to take five steps for better forest management and policy formulations on the national scale:

  1. To operationalize satellite-based annual forest monitoring system for spatial quantification of deforestation, forest degradation, and afforestation
  2. To conduct comprehensive forest inventories for accuracy assessment, current forest stock, and greenhouse gas inventory
  3. To assess satellite-based land cover and land use changes at 5 years interval as an activity data for FRL reporting
  4. To map forest type and biomass/carbon stocks through integration of satellite and forest inventory data for spatial identification and quantification of habitats of tree species
  5. To develop a web-based visualization and dissemination tool using geospatial and socio-economic data for transparency and consistency

Conflicts of Interest: The findings reported stand as scientific study and observations of the author and do not necessarily reflect as the views of author’s organizations.

About this post: This is a guest post by Hammad Gilani. Learn more about this blog’s authors here.

Summary: ISNET / NARSS Workshop on SAR Remote Sensing, 27th Nov. – 1st Dec., 2016

The Inter-Islamic Network on Space Sciences & Technology (ISNET), in collaboration with National Authority for Remote Sensing & Space Sciences (NARSS), held a 5-day Workshop on “Earth Remote Sensing with Synthetic Aperture Radar (SAR)” from 27 November – 1st Dec 2016 at NARSS premises, Cairo, Egypt. This workshop was supported by the OIC Ministerial Standing Committee for Scientific and Technological Cooperation (COMSTECH) and the Islamic Development Bank (IDB).

Teaching complex numbers NARSS SAR workshop

Reviewing complex numbers, which form the basis of SAR imaging.

The initial part of the workshop comprised of seminar and research presentations on SAR remote sensing applications. This was followed by 2.5 days of extensive tutorial modules on SAR fundamentals, and hands-on training workshop sessions on different softwares and tools that are required for SAR remote sensing applications. The tutorial and workshop sessions were led by me, and I was honoured to be invited by ISNET and NARSS to conduct these sessions.

Group picture NARSS SAR workshop

Participants of the hands-on training workshop sessions.

The hands-on workshop modules were conducted with actual SAR remote sensing imagery to give experience to participants on processing and analysis of SAR data. Open-source software tools specifically made for SAR data processing, such as ESA Sentinel Applications Platform (SNAP) and ASF MapReady, were utilized for this workshop to ensure large no. of participants and to make the hands-on workshop modules accessible to all participants. The hands-on modules covered topics like identifying errors in SAR imagery (topographic, radiometric, geometric), data pre-processing, SAR sub-surface imaging and SAR-optical data fusion, interpreting SAR data over the ocean, understanding complex SAR data, and basics of interferometry.

Overall, more than 60 participants took part in the training workshop. Although I teach a graduate course on Radar Remote Sensing and also conduct a SAR Remote Sensing summer school since the last 2 years at our research group, yet this was a first experience for me to conduct a international SAR workshop. I got great feedback, and more motivation to continue forward on my SAR journey.