A VERY BRIEF INTRODUCTION TO REMOTE SENSING!

 

There were many definitions of remote sensing and a simple way to know that is to do a google search.

Then what is the purpose of this paper?

For those who seek a simple understanding of remote sensing with out jargon or confusing terms !

Remote sensing is not a concept so alien to humanity rather it is what we actually do when we see objects that surround us or hear sounds emanating around us.

How do we do this?

Through sense objects such as eyes or ears and an interpreter named brain or mind.

This is exactly the process or the concept followed in the science of remote sensing.

Instead of the sense organs, special equipment named ‘sensors’ are used for remote sensing.

To understand how sensors work we need to understand what we do with our eyes or ears?

What we do with our eyes and ears?

With eyes we see and with ears we hear.

Fine how we see?

We see the light coming from the objects with eyes.

We see objects having different colours.

We see objects having different shapes and structures.

We not only see the objects but also how they are arranged, in addition, we see their shadows too, if the objects are in sun light.

In fact, it is not the eyes rather the brain interprets the images as objects. Some time the brain or mind do commit some mistakes while interpreting the image it sees through eyes, as in the case of ‘mirage’.

Similarly, we hear the sound, it do have patterns as in the case of music and noise.

So far , we understand how we see and hear. 

Seeing and hearing are simply the process of remote sensing we human beings use to gather information from the surroundings we live.

During the course of evolution human beings invented many new gadgets and instruments to make their life simple, beautiful and useful.  For example a ‘crane’, it is a mechanical device exactly does the work of a hand or a leg. But the crane is capable of lifting or throwing objects that far exceed the human limitations.

Similarly the ‘remote sensors’ are the electro- mechanical devices do the work of eyes. They see from a distance exceeding the limitations of the human eyes!

For instance, certain types of remote sensors are capable of seeing objects from a distance of 34,000Kms!

Thus ‘remote sensing is a process of seeing or observing earthen objects from a distance through sensors’.

From what we understood so far, we knew that remote sensors will only see and record the earthen objects like a camera or more precisely a digital camera but only the human beings can decode or interpret the recorded information. In addition, there may be ample possibilities of noises being recorded in the place of information and there would also be possibilities for misinterpretation.

An Evaluation of the interactions of outgoing long wave radiation (OLR) with Vegetation, Non-vegetated and snow covered areas in India
-.M.Pavalavanni, Hydrabad, India-
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The outgoing long wave radiation (OLR) is one of the most important components in the global energy balance for the Earth-Atmosphere system. Both spatial and temporal variations of long wave radiation have direct implications on the climate. This study aims to evaluate the interactions of OLR with vegetation, non-vegetated and snow covered areas in India. For this purpose OLR data derived from KALPANA-1 and Sea WiFs  satellite products has been used.

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  The response of Outgoing Long wave Radiation with vegetation, non-vegetated and snow covered area is evaluated through observations made out of Normalized Difference Vegetation Index calculated for the entire stretch of India from SewWiFS data. 

The period of observation is the monthly average of OLR and NDVI observed during 2009. The results indicate that ‘the non vegetated open land and ‘tar’ desert has a high OLR, consistent with dry, cloud free and warm conditions. From the study it is observed that the vegetation cover and OLR response are indirectly related.  Further, it is clear from the study that the wetness in the soil affects the interactions of OLR. Lower the wetness higher will be the OLR.  The snow surface and ice interaction is so unique with OLR. Though wet the ice and snow have high albedo and so high OLR response.

Average Outgoing   Long wave Radiation Across Indian States

  

The graph shows the average out going long wave Radiation (OLR) in different states.  From the graph it is clear that Gujarat and Rajasthan has the maximum LOR, where the condition of desert is prevalent.  The areas where non-vegetated land is high such as Madhya Pradesh, Maharastra, the  OLR is high.  In states like Kerala, Utranchal, Meghalaya, Sikkim and Nagaland where vegetative area is very high the OLR is low. Very low OLR is observed especially in north eastern states such as Arunachal Pradesh, Assam, Manipur and Mizoram where they receive very heavy rainfall.  A moderate OLR is registered in Himachal and Jammu and Kashmir where snow covered peaks are prevalent.

Results


From the study the following conclusions are derived as conclusion:

• High OLR is observed in Thar Desert of Rajasthan and low OLR is observed in Jammu Kashmir.
• The OLR distribution is strongly influenced by seasons such as summer, winter, spring and autumn.
• In summer due to  less dense seasonal crops and plantation canopy, dry soil and more non vegetated area induce high OLR.
• The dense forest vegetation canopy maintain soil moisture even in summer season, thus in these areas OLR is in medium category.
•  Snow covered areas have low OLR.
•  In monsoon season, the rainfall is more that provide wet soils with very dense vegetation canopy results in low OLR.
•  In spring season, haze and mist particles strongly absorb Long wave Radiation and thus acts as barrier for OLR.
• The observations of OLR  reveals that the vegetation is not the single most controlling factor for OLR,  rather it is a controlling factor when the soil moisture is high.

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 Author : Mr.M.Pavalavanni, Core Logic, Hydrabad, India

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Mullai Periyar Dam :A Spatial Perspective and some Reading Between the Lines

Dr.R.Narayanakumar, GIS Expert,Chennai
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This is one of the burning issues of spatial origin, would compel any geographer to comment. This article traces the fear psyche of recent agitations against the presence of an old dam at Tamil Nadu, Keral Border through 'Google images' and 'wiki tables' for comprehension and intellectual evaluation.
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This is one of the burning issues of spatial origin, would compel any geographer to comment. When i think over it and Googled, i am able to get some glimpses of the problems and came out with my own interpretations.

The popular opinions and people psyche have largely changed after 'Fukushima'.  The problem starved 25 and odd TV News channels in India want problems, if not to solve but to be discussed. This creates a greater awareness to people. This enhanced awareness combined with the fear psyche add fuel to many such problems. Let us get into the issue:
The River:   
Periyar meaning big river, is one of the many perennial rivers originating in the Western Ghats. Running across idukki and Thekkadi districts of Kerala have a length of 244 kms. 
The Dam:

The Mullaperiyar Dam was constructed during 1887-1895 across Periyar River in the then Travancore state (now Kerala) territory after said indenture. The Periyar Dam with full reservoir level of 152 ft. provides for diversion of water from the reservoir through a tunnel to Vaigai basin in Tamil Nadu for irrigation benefits in 68558 ha. On 29-10-1886 a lease indenture for 999 years was made between Maharaja of Travancore and Secretary of State for India for Periyar irrigation works by another agreement in 1970, Tamil Nadu was permitted to generate power also.

Source : Ministry of Water Resources, India

The Issues:

Why Tamil Nadu Need the Dam?

- To avoid drought and immigration  and  Increased Agricultural Productivity 

The above Map shows Tamil Nadu Region and Kerala.  Compare the greenery on Tamil Nadu Side and Kerala. Tamil Nadu is the rain shadow region of the western ghats. While Kerala enjoys the rain, Tamil Nadu  suffers the shadow.  The picture bellow shows the green Kerala from Mullai Periyar - the far side is the Arabian Sea.

Why Kerala Hate the Dam?

The fear of Dam Failure

Fear of Natural Calamity Post Fukushima.  The root for all the agitations witnessed in Kerala related to Mullai periyar dam and in Tamil nadu related to kudankulam atomic power station are same - The fear of failiure against natural catastrophes. The psyche of somebody in Kerala is not strange because somebody in Tamil Nadu is also doing the same against atomic power stations. 

Let us look at this fear of dam burst little clearly from the historical evidences. A deeper look into the details reveals that many such dam bursts resulted in high mortality due to its proximity with the habitations.

Look into the following dam locations and compare it with the location of Mullai Periyar.

Hope Mills Dam : North Carolina, United States (Sinkhole caused dam failure)

Banqiao and Shimantan Dams at China

Situ Gintung Dam Indonesia ( Failed in 2009)

Before Failiure:

After Failiure:

Compare these satellite images with the bellow one showing mullai periyar dam location. The settlements are not much like the above one. It is a blessing that in Kerala the settlements are not  of a conglomerate type rather dispersed. So the impact won't be as imagined or feared.

The following chart and table has been prepared from the list of dam failiures listed in Wikipedia (http://en.wikipedia.org/wiki/Dam_failure)

From the listed 37 dam failures from Wiki  it could be deduced that the failures are mainly due to unanticipated Heavy rain. Earth quake and associated geological stability causes 3 out of 37 dam bursts including 'Fukushima'. 

Cost Benefit Analysis

Benefit:

High TRP Rating for TV Channels and sales for news papers.

Politicians

Movies  & Theatres

Cost:

Pending projects

Retarded GDP

More cases for already strained judiciary

The following may be a broad line of solution

•       Raising against failure psyche

•       Addressing the real fear

•       Infusing confidence through technology

•       Pro developmental attitude

Disclaimer: I author tried his level best to be impartial. The intention of the author is not to prove some thing in favor of some one but make the geographical facts vivid for any one's clarification.

Author: Dr.R.Narayanakumar, Chennai

Safety during non-peak traffic hours 
 (O.M.Murali , Chennai,India)
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There are two types of road accidents categorised based on the time of occurrence - peak and non-peak hour accidents. More accidents with fatal cases, in reality, happen during non-peak hours. This article explores especially this aspect in detail and suggest ways to overcome this hurdle.

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Road accidents can be categorised based on the time of occurrence - peak and non-peak hour accidents.

As far as peak hour accidents are concerned, the Chennai City Traffic Police have gained more control and are comfortable in bringing them down further. On the other hand, attention is needed towards non-peak hour accidents which happen in the absence of any control mechanism like traffic signals, and traffic police.

In reality, more accidents with fatal cases happen during non-peak hours due to varied reasons like:

Driving  with lack of sleep, driving with lack of driving experience ( which people attempt during non-peak hours to learn driving), absence of signals, joy of speedy and rash driving  and last and the very important - absence of traffic-calming structures in black spot areas.

Unfortunately, the duration of non-peak hours extend more than 15 hours of the actual 24 hours. It is a matter of fact that having a monitoring system by means of manpower round the clock is practically impossible. Under such circumstances, two remedial measures can be considered by the traffic police.

·         One way is by enforcing temporary traffic calming engineering structures (median, speed bump, curb extension, etc.) within city limits; especially at intersections and other important accident-prone areas during non-peak hours.

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·         Secondly, there is a need to create long term awareness among the road-users (children to aged persons and women of all ages) to strictly obey the road rules in the absence of any control mechanisms. Outside the city limit, there is no marked difference between peak and non-peak hour vehicular movement. 

     But extra care from individuals makes all the difference in ensuring accident-free roads.

    

     The most important thing to be considered during non-peak hour accident is the hit-and-run case.    It is very common when there is no one to notice the dangerous impact and the accused always try to escape from the scene. Here, it is very essential to know the vulnerable accident locations and probable place where   people will disobey road rules, and then such hit-and-run cases can be greatly reduced by implementing traffic calming structures. Head-on-collision can be avoided only when the medians are implemented.

   Common knowledge of traffic rules are very essential which should be cultivated right from the school age. Educating the people on traffic rules alone can reduce road accidents. Children are taught road rules and safety aspects in their school curriculum. As part of exposure, students must be encouraged to participate in regulating traffic during peak hours near their schools. Such initiatives will cultivate a positive attitude in children and also make them more responsible in society. Because of the type of upbringing, men and women will have different perception when they are on the road, their time of travel, preference of places of travel, locations preferred to cross the road, and the overall adherence to traffic rules. These parameters will decide the location and severity of road accidents if less attention is paid.

   The role of the media should be used rightly. Periodic documentary on aspects of road safety should be featured. In the rural areas where awareness will be the lowest, much needs to be done through TV, posters, booklets and banners. More and more articles should be published by police officials and professors on various issues relating to traffic. Such initiatives will generate awareness among the common man.

   To support the traffic police to continue their task uninterrupted due to shortage of funds, IT companies/ Schools and Colleges should come forward in supporting the laying of traffic-calming structures close to their office/school/college premises and at important junctions. One way, it improves road safety and in another, it gives opportunity for private companies and education enterprises to actively involve in community development.

    From the traffic police point of view, they should ensure that roads are safer for all age groups. Accordingly, many proactive measures need to be initiated by traffic police jointly in collaboration with other prospective and willing agencies. The following steps need to be initiated by traffic police:

  1.      Identification and monitoring of accident spots using GIS

  2.      Permanent removal of encroachments on arterial roads

  3.      Enforcing strict rules to those who violate road rules during non-peak hours

  4.      Assured 6 hours of sleep to long-distance travellers, particularly those engaged in travel and heavy vehicle useage

  5.      Implementation of traffic-calming measures to reduce head-on collision within city limits

  6.      Encouraging the public to join hands with traffic police to regulate traffic during peak and non-peak hours

  7.      Creating awareness on road safety to underprivileged people

  8.      To ensure the safety of cyclists and pedestrians during peak and non-peak hours

  9.      To encourage more tie-ups with prospective companies to initiate research and development on traffic   management

  10.  using technologies like GIS and Global Positioning System (GPS)

  11.  When such proactive approach is adopted by the traffic police, then the day is not far off where all road-users will travel safely and happily without worrying about tragic incidents like road accidents.

Author : O.M.Murali (Ph.D), WTI, Chennai, India

Tracking Cyclone ‘Thane‘

Date : 28/12/11

A severe cyclonic storm named ‘Thane’ is expected tomorrow, it is reported that the cyclonic storm is 500 kms away from Chennai and would reach Chennai in less than 24 hours.

An orange message is given in this respect.

Heavy rains with high speed wind  reaching up to 100 kmph is expected

Cyclone behavior:

As expected by the meteorology department the cyclonic storm THANE was stationary and intensified into a severe cyclonic storm about 500 km east-southeast of Chennai (Tamilnadu). 

The system is likely to move west-northwestwards (see the cloud motion Vector) , intensify in the next 24 hrs and cross north Tamil Nadu and south Andhra Pradesh coasts between Cuddalore and Sriharikota, close to south of Chennai around morning of 30th December 2011. 

However, as the cyclonic storm will come further close to coast after 24 hours, there is probability of slight weakening before landfall.

Expected Wind Speed during the Storm :

 

Anticipated Impacts:

Districts wise storm effect:

Useful Indian Meteorology Department  Links:
Animation of IR images for the Last Three Hours
 Radar Readings

(Compiled and Reported  : Dr.Narayanakumar, GIS Expert, Chennai)