Runoff: Surface and Overland Water Runoff

When rain falls onto the earth, it just doesn’t sit there, it starts moving according to the laws of gravity. A portion of the precipitation seeps into the ground to replenish Earth’s groundwater. Most of it flows downhill as runoff. Runoff is extremely important in that not only does it keep rivers and lakes full of water, but it also changes the landscape by the action of erosion. Flowing water has tremendous power it can move boulders and carve out canyons; check out the Grand Canyon!

Runoff of course occurs during storms, and much more water flows in rivers (and as runoff) during storms. For example, in 2001 during a major storm at Peachtree Creek in Atlanta, Georgia, the amount of water that flowed in the river in one day was 7 percent of all the streamflow for the year.

Some definitions of runoff:.                               

1. That part of the precipitation, snow melt, or irrigation water that appears in uncontrolled (not regulated by a dam upstream) surface streams, rivers, drains or sewers. Runoff may be classified according to speed of appearance after rainfall or melting snow as direct runoff or base runoff, and according to source as surface runoff, storm interflow, or groundwater runoff.

2. The sum of total discharges described in (1), above, during a specified period of time.

3. The depth to which a watershed (drainage area) would be covered if all of the runoff for a given period of time were uniformly distributed over it.

Meteorological factors affecting runoff:

Type of precipitation (rain, snow, sleet, etc.)
* Rainfall intensity
* Rainfall amount
* Rainfall duration
* Distribution of rainfall over the watersheds
* Direction of storm movement
Antecedent precipitation and resulting soil moisture
*Other meteorological and climatic conditions that affect evapotranspiration, such as temperature, wind, relative humidity, and season.

Physical characteristics affecting runoff:

* Land use
* Vegetation
* Soil type
* Drainage area
* Basin shape
* Elevation
* Slope
* Topography
* Direction of orientation
* Drainage network patterns
* Ponds, lakes, reservoirs, sinks, etc. in the basin, which prevent or alter runoff from continuing downstream

Runoff and water quality :

A significant portion of rainfall in forested watersheds is absorbed into soils (infiltration), is stored as groundwater, and is slowly discharged to streams through seeps and springs. Flooding is less significant in these more natural conditions because some of the runoff during a storm is absorbed into the ground, thus lessening the amount of runoff into a stream during the storm.

As watersheds are urbanized, much of the vegetation is replaced by impervious surfaces, thus reducing the area where infiltration to groundwater can occur. Thus, more stormwater runoff occurs—runoff that must be collected by extensive drainage systems that combine curbs, storm sewers (as shown in this picture), and ditches to carry stormwater runoff directly to streams. More simply, in a developed watershed, much more water arrives into a stream much more quickly, resulting in an increased likelihood of more frequent and more severe flooding.

What if the street you live on had only a curb built around it, with no stormwater intake such as the one pictured here. Any low points in your street would collect water when it rained. And if your street was surrounded by houses with yards sloping uphill, then all the runoff from those yards and driveways would collect in a lake at the bottom of the street.

A storm sewer intake such as the one in this picture is a common site on almost all streets. Rainfall runoff, and sometimes small kids’ toys left out in the rain, are collected by these drains and the water is delivered via the street curb or drainage ditch alongside the street to the storm-sewer drain to pipes that help to move runoff to nearby creeks and streams. ; storm sewers help to prevent flooding on neighborhood streets.

Drainage ditches to carry stormwater runoff to storage ponds are often built to hold runoff and collect excess sediment in order to keep it out of streams.

Runoff from agricultural land (and even our own yards) can carry excess nutrients, such as nitrogen and phosphorus into streams, lakes, and groundwater supplies. These excess nutrients have the potential to degrade water quality.

Why might stormwater runoff be a problem?

As it flows over the land surface, stormwater picks up potential pollutants that may include sediment, nutrients (from lawn fertilizers), bacteria (from animal and human waste), pesticides (from lawn and garden chemicals), metals (from rooftops and roadways), and petroleum by-products (from leaking vehicles). Pollution originating over a large land area without a single point of origin and generally carried by stormwater is considered non-point pollution. In contrast, point sources of pollution originate from a single point, such as a municipal or industrial discharge pipe. Polluted stormwater runoff can be harmful to plants, animals, and people.

Runoff can carry a lot of sediment

When storms hit and streamflows increase, the sediment moved into the river by runoff can end up being seen from hundreds of miles up by satellites. The right-side pictures shows the aftermath of Hurricane Irene in Florida in October 1999. Sediment-filled rivers are dumping tremendous amounts of suspended sediment into the Atlantic Ocean. The sediment being dumped into the oceans has an effect on the ecology of the oceans, both in a good and bad way. And, this is one of the ways that the oceans have become what they are: salty.

Florida, Oct. 14, 1999. When Hurricane Irene passed over Florida in 1999, the heavy rainfall over land caused extensive amounts of runoff that first entered Florida’s rivers which then dumped the runoff water, containing lots of sediment, into the Atlantic Ocean.

Florida, Dec. 16, 2002. The east coast of Florida is mostly clear of sediment from runoff. The shallow coastal waters to the west of Florida are very turbid (sediment-filled), perhaps from a storm that passed over a few days earlier.

The end.….

CHANDRAYAAN-1India’s First Lunar Exploration Mission. Moon Mineralogy Mapper observations point to possibility of water on the Moon!

Chandrayaan-1, India’s first mission to Moon, was launched successfully on October 22, 2008 from SDSC SHAR, Sriharikota. The spacecraft was orbiting around the Moon at a height of 100 km from the lunar surface for chemical, mineralogical and photo-geologic mapping of the Moon. The spacecraft carried 11 scientific instruments built in India, USA, UK, Germany, Sweden and Bulgaria.

After the successful completion of all the major mission objectives, the orbit has been raised to 200 km during May 2009. The satellite made more than 3400 orbits around the moon and the mission was concluded when the communication with the spacecraft was lost on August 29, 2009.

The idea of undertaking an Indian scientific mission to Moon was initially mooted in a meeting of the Indian Academy of Sciences in 1999 that was followed up by discussions in the Astronautical Society of India in 2000.

Based on the recommendations made by the learned members of these forums, a National Lunar Mission Task Force was constituted by the Indian Space Research Organisation (ISRO). Leading Indian scientists and technologists participated in the deliberations of the Task Force that provided an assessment on the feasibility of an Indian Mission to the Moon as well as dwelt on the focus of such a mission and its possible configuration.

After detailed discussions, it was unanimously recommended that India should undertake the Mission to Moon, particularly in view of the renewed international interest in moon with several exciting missions planned for the new millennium. In addition, such a mission could provide the needed thrust to basic science and engineering research in the country including new challenges to ISRO to go beyond the Geostationary Orbit. Further, such a project could also help bringing in young talents to the arena of fundamental research. The academia would also find participation in such a project intellectually rewarding.

Subsequently, Government of India approved ISRO’s proposal for the first Indian Moon Mission, called Chandrayaan-1 in November 2003.

The Chandrayaan-1 mission performed high-resolution remote sensing of the moon in visible, near infrared (NIR), low energy X-rays and high-energy X-ray regions. One of the objectives was to prepare a three-dimensional atlas (with high spatial and altitude resolution) of both near and far side of the moon. It aimed at conducting chemical and mineralogical mapping of the entire lunar surface for distribution of mineral and chemical elements such as Magnesium, Aluminium, Silicon, Calcium, Iron and Titanium as well as high atomic number elements such as Radon, Uranium & Thorium with high spatial resolution.

Various mission planning and management objectives were also met. The mission goal of harnessing the science payloads, lunar craft and the launch vehicle with suitable ground support systems including Deep Space Network (DSN) station were realised, which were helpful for future explorations like the Mars Orbiter Mission. Mission goals like spacecraft integration and testing, launching and achieving lunar polar orbit of about 100 km, in-orbit operation of experiments, communication/ telecommand, telemetry data reception, quick look data and archival for scientific utilisation by scientists were also met.

PSLV-C11, chosen to launch Chandrayaan-1 spacecraft, was an updated version of ISRO’s Polar Satellite Launch Vehicle standard configuration. Weighing 320 tonne at lift-off, the vehicle used larger strap-on motors (PSOM-XL) to achieve higher payload capability.

PSLV is the trusted workhorse launch Vehicle of ISRO. During September 1993- April 2008 period, PSLV had twelve consecutively successful launches carrying satellites to Sun Synchronous, Low Earth and Geosynchronous Transfer Orbits. On October 22, 2008, its fourteenth flight launched Chandrayaan-1 spacecraft.

By mid 2008, PSLV had repeatedly proved its reliability and versatility by launching 29 satellites into a variety of orbits. Of these, ten remote sensing satellites of India, an Indian satellite for amateur radio communications, a recoverable Space Capsule (SRE-1) and fourteen satellites from abroad were put into polar Sun Synchronous Orbits (SSO) of 550-820 km heights. Besides, PSLV has launched two satellites from abroad into Low Earth Orbits of low or medium inclinations. This apart, PSLV has launched KALPANA-1, a weather satellite of India, into Geosynchronous Transfer Orbit (GTO).

PSLV was initially designed by ISRO to place 1,000 kg class Indian Remote Sensing (IRS) satellites into 900 km polar SunSynchronous Orbits. Since the first successful flight in October 1994, the capability of PSLV was successively enhanced from 850 kg to 1,600 kg. In its ninth flight on May 5, 2005 from the Second Launch Pad (SLP), PSLV launched ISRO’s remote sensing satellite,1,560 kg CARTOSAT-1 and the 42 kg Amateur Radio satellite, HAMSAT, into a 620 km polar Sun Synchronous Orbit. The improvement in the capability over successive flights has been achieved through several means. They include increased propellant loading in the stage motors, employing composite material for the satellite mounting structure and changing the sequence of firing of the strap-on motors.

Vikram Sarabhai Space Centre (VSSC), Thiruvananthapuram, designed and developed PSLV-C11. ISRO Inertial Systems Unit (IISU) at Thiruvananthapuram developed the inertial systems for the vehicle. Liquid Propulsion Systems Centre (LPSC), also at Thiruvananthapuram, developed the liquid propulsion stages for the second and fourth stages of PSLV-C11 as well as reaction control systems. SDSC SHAR processed the solid motors and carries out launch operations. ISRO Telemetry, Tracking and Command Network (ISTRAC) provide telemetry, tracking and command support during PSLV-C11’s flight

Who can submit a Proposal?

Proposals could be submitted by individuals or a group of scientists and academicians belonging to recognized institutions, universities, planetaria and government organisations of India. Only those having at least a minimum remaining service of four years before superannuation are eligible to lead the project as PI/Co-PI. The proposals must be forwarded through the Head of the Institution, with appropriate assurance for providing necessary facilities for carrying out the projects under this AO programme. The end….


A lunar eclipse occurs when the Moon moves into the Earth’s shadow.This can occur only when the Sun, Earth, and Moon are exactly or very closely aligned (in syzygy) with Earth between the other two, and only on the night of a full moon. The type and length of a lunar eclipse depend on the Moon’s proximity to either node of its orbit.

Totality during the lunar eclipse of 21 January 2019. Direct sunlight is being blocked by the Earth, and the only light reaching it is sunlight refracted by Earth’s atmosphere, producing a reddish color.

Latter phases of the partial lunar eclipse on 17 July 2019 taken from GloucestershireUnited Kingdom.

A totally eclipsed Moon is sometimes called a blood moon for its reddish color, which is caused by Earth completely blocking direct sunlight from reaching the Moon. The only light reflected from the lunar surface has been refracted by Earth’s atmosphere. This light appears reddish for the same reason that a sunset or sunrise does: the Rayleigh scattering of bluer light.

Unlike a solar eclipse, which can only be viewed from a relatively small area of the world, a lunar eclipse may be viewed from anywhere on the night side of Earth. A total lunar eclipse can last up to nearly 2 hours, while a total solar eclipse lasts only up to a few minutes at any given place, because the Moon’s shadow is smaller. Also unlike solar eclipses, lunar eclipses are safe to view without any eye protection or special precautions, as they are dimmer than the full Moon.

Types of Lunar Eclipse:

A schematic diagram of the shadow cast by Earth. Within the umbra, the central region, the planet totally shields direct sunlight. In contrast, within the penumbra, the outer portion, the sunlight is only partially blocked. (Neither the Sun, Moon, and Earth sizes nor the distances between the bodies are to scale.)

A total penumbral lunar eclipse dims the Moon in direct proportion to the area of the Sun’s disk covered by Earth. This comparison of the Moon (within the southern part of Earth’s shadow) during the penumbral lunar eclipse of January 1999 (left) and the Moon outside the shadow (right) shows this slight darkening.

Penumbral Lunar Eclipse

This occurs when the Moon passes through Earth’s penumbra. The penumbra causes a subtle dimming of the lunar surface, which is only visible to the naked eye when about 70% of the Moon’s diameter has immersed into Earth’s penumbra.A special type of penumbral eclipse is a total penumbral lunar eclipse, during which the Moon lies exclusively within Earth’s penumbra. Total penumbral eclipses are rare, and when these occur, the portion of the Moon closest to the umbra may appear slightly darker than the rest of the lunar disk.

Partial lunar eclipse

This occurs when only a portion of the Moon enters Earth’s umbra, while a total lunar eclipse occurs when the entire Moon enters the planet’s umbra. The Moon’s average orbital speed is about 1.03 km/s (2,300 mph), or a little more than its diameter per hour, so totality may last up to nearly 107 minutes. Nevertheless, the total time between the first and the last contacts of the Moon’s limb with Earth’s shadow is much longer and could last up to 236 minutes.

Total lunar eclipse

This occurs when the moon falls entirely within the earth’s umbra. Just prior to complete entry, the brightness of the lunar limb– the curved edge of the moon still being hit by direct sunlight– will cause the rest of the moon to appear comparatively dim. The moment the moon enters a complete eclipse, the entire surface will become more or less uniformly bright. Later, as the moon’s opposite limb is struck by sunlight, the overall disk will again become obscured.

This is because as viewed from the Earth, the brightness of a lunar limb is generally greater than that of the rest of the surface due to reflections from the many surface irregularities within the limb: sunlight striking these irregularities is always reflected back in greater quantities than that striking more central parts, and is why the edges of full moons generally appear brighter than the rest of the lunar surface.

Central lunar eclipse

This is a total lunar eclipse during which the Moon passes through the centre of Earth’s shadow, contacting the antisolar point. This type of lunar eclipse is relatively rare.

The relative distance of the Moon from Earth at the time of an eclipse can affect the eclipse’s duration. In particular, when the Moon is near apogee, the farthest point from Earth in its orbit, its orbital speed is the slowest. The diameter of Earth’s umbra does not decrease appreciably within the changes in the Moon’s orbital distance. Thus, the concurrence of a totally eclipsed Moon near apogee will lengthen the duration of totality.


A selenelion or selenehelion, also called a horizontal eclipse, occurs where and when both the Sun and an eclipsed Moon can be observed at the same time. The event can only be observed just before sunset or just after sunrise, when both bodies will appear just above opposite horizons at nearly opposite points in the sky. A selenelion occurs during every total lunar eclipse it is an experience of the observer, not a planetary event separate from the lunar eclipse itself. Typically, observers on Earth located on high mountain ridges undergoing false sunrise or false sunset at the same moment of a total lunar eclipse will be able to experience it. Although during selenelion the Moon is completely within the Earth’s umbra, both it and the Sun can be observed in the sky because atmospheric refraction causes each body to appear higher (i.e., more central) in the sky than its true geometric planetary position.


The timing of total lunar eclipses is determined by what are known as its “contacts” (moments of contact with Earth’s shadow)

P1 (First contact): Beginning of the penumbral eclipse. Earth’s penumbra touches the Moon’s outer limb.
U1 (Second contact): Beginning of the partial eclipse. Earth’s umbra touches the Moon’s outer limb.
U2 (Third contact): Beginning of the total eclipse. The Moon’s surface is entirely within Earth’s umbra.
Greatest eclipse: The peak stage of the total eclipse. The Moon is at its closest to the center of Earth’s umbra.
U3 (Fourth contact): End of the total eclipse. The Moon’s outer limb exits Earth’s umbra.
U4 (Fifth contact): End of the partial eclipse. Earth’s umbra leaves the Moon’s surface.
P4 (Sixth contact): End of the penumbral eclipse. Earth’s penumbra no longer makes contact with the Moon.

Danjon scale:

L = 0: Very dark eclipse. Moon almost invisible, especially at mid-totality.
L = 1: Dark eclipse, gray or brownish in coloration. Details distinguishable only with difficulty.
L = 2: Deep red or rust-colored eclipse. Very dark central shadow, while outer edge of umbra is relatively bright.
L = 3: Brick-red eclipse. Umbral shadow usually has a bright or yellow rim.
L = 4: Very bright copper-red or orange eclipse. Umbral shadow is bluish and has a very bright rim.


Chandrayaan2 is India’s second lunar probe, and its first attempt to make a soft landing on the Moon. It has an Orbiter, which will go around the Moon for a year in an orbit of 100 km from the surface, and a Lander and a Rover that will land on the Moon. Once there, the Rover will separate from the Lander, and will move around on the lunar surface. Both the Lander and the Rover are expected to be active for one month.

CHANDRAYAAN BEGUN ITS JOURNEY: Chandrayaan-2 satellite had begun its journey towards the moon leaving the earth’s orbit in the dark hours on August 14, after a crucial maneuver called Trans Lunar Insertion (TLI) that was carried out by Isro to place the spacecraft on “Lunar Transfer Trajectory”

India’s Moon mission: Chandrayaan-2 will be a ground-breaking mission to the south pole of the moon and should land on a high plain between two craters, Manzinus C and Simpelius N, which are around 70° south.

India’s Geosynchronous Satellite Launch Vehicle, GSLV MkIII-M1 had successfully launched the 3,840-kg Chandrayaan-2 spacecraft into the earth’s orbit on July 22.

In a major milestone for India’s second Moon mission, the Chandrayaan-2 spacecraft had successfully entered the lunar orbit on August 20 by performing Lunar Orbit Insertion (LOI) maneuver. On August 22, Isro released the first image of the moon captured by Chandrayaan-2. On September 2,Vikram’ successfully separated from the orbiter, following which two de-orbiting manoeuvres were performed to bring the lander closer to the Moon.

Vikram’ and ‘Pragyan’

As India attempted a soft landing on the lunar surface on September 7, all eyes were on the lander ‘Vikram’ and rover ‘Pragyan’.

The 1,471-kg ‘Vikram‘, named after Vikram Sarabhai, father of the Indian space programme, was designed to execute a soft landing on the lunar surface, and to function for one lunar day, which is equivalent to about 14 earth days.

Chandrayaan, which means “moon vehicle” in Sanskrit, exemplifies the resurgence of international interest in space. The US, China and private corporations are among those racing to explore everything from resource mining to extraterrestrial colonies on the moon and even Mars.

LAUNCHED IN: India’s second mission to the Moon, Chandrayaan-2 was launched on 22nd July 2019 from Satish Dhawan Space Center, Sriharikota. The Orbiter which was injected into a lunar orbit on 2nd Sept 2019, carries 8 experiments to address many open questions on lunar science.

India’s ambitious mission to land on the Moon failed. The Vikram lander, of the Chandrayaan 2 mission, crashed on the lunar surface on September 7, 2019, but it was only in December that scientists found it. Why did it take so long to find the lander?

There are quite a few technical reasons for that. Let’s start with a quick recap of what happened on the landing day.

who said three days after the landing day that they had spotted the lander. ISRO failed to show any pictures or provide location coordinates to the public despite the claims.

The statement is in fact only the third and the last time ISRO publicly spoke of the lander’s condition. However, it didn’t stop ISRO from coming out of the slumber and boasting that they found the lander first, i.e. before NASA did with help from Subramanian.

Going by the publicly available evidence, NASA found the Vikram lander on the Moon’s surface, not ISRO. And what does Chandrayaan 2’s landing failure mean for ISRO? Go back to the launch pad.

The end ..

Marine Pollution


Pollution in ocean is a major problem that is affecting the ocean and the rest of the Earth, too.Pollution in the ocean directly affects ocean organisms and indirectly affects human health and resources.Oil spills, toxic wastes, and dumping of other harmful materials are all major sources of pollution in the ocean.

Marine Pollution:

Marine pollution is a combination of chemicals and trash,most of which comes from land sources and is washed
or blown into the ocean.


Some of the main causes for the marine pollution is as follows

• Ocean dumping

Land runoff

• Oil spills

• Littering

• Ocean mining

• Noise pollution

Ocean dumping:

Deliberate disposal of hazardous wastes at sea from vessels, aircraft, platforms or other human-made structures.

Land runoff:

Eighty percent of marine pollution comes from land run off.

Oil spills:

Contamination of seawater due to an oil pour, as a result of an accident or human error, is termed an oil spill.


Marine litter is not only ugly it can harm ocean ecosystems wildlife, and humans. It can gure coral reels and bottom dwelling species and entangle or drown ocean wildlife. Some marine animals ingest smaller plastic particles and choke or starve

Ocean Mining (Deep Sea Mining):

Mining under the ocean for gold, silver, copper, cobalt,etc is another source for ocean pollution.Deep sea mining could even make climate change worse. The disruption caused by the machines may release carbon stored in deep sea sediments.

Noise Pollution in the ocean:

Ocean noise refers to sounds made by human activities that can interfere with or obscure the ability of marine animals to hear natural sounds in the ocean.

Devastating Effects of Ocean Pollution:

1. Effect of Toxic Wastes on Marine Animals:

The oil spilled in the ocean could get on to the gills and feathers of marine animals, which makes it difficult for them to move or fly properly or feed their children.

2. Disruption to the Cycle of Coral


Oil spill floats on the surface of the water and prevents sunlight from reaching to marine plants and affects the process of photosynthesis.

3. Depletes Oxygen Content in Water:

When oxygen levels go down, the chances of survival of marine animals like whales, turtles, sharks, dolphins, penguins for a long time also goes down.

4. Failure in the Reproductive System of Sea Animals

Chemicals from pesticides can accumulate in the fatty tissue of animals, leading to failure in their reproductive system.

5. Effect on Food Chain:

Chemicals used in industries are ingested into small animals in the ocean and are later eaten by large animals, which then affects the whole food chain.

6. Affects Human Health:

Animals from impacted food chain are then eaten by humans, which affects their health as toxins from these contaminated animals get deposited in the tissues of people and can lead to cancer, birth defects or long term health problems.

Solutions to Ocean Pollution:

1. Reducing the Use of Plastic Products

2. Use Reusable Bottles and Cutlery

3. Recycle Whatever You Can


4. Stop Littering the Beach, and Start

Cleaning It

5. Reducing the Use of Chemical Fertilize

6. Reducing the Energy Use


• We must help to stop ocean pollution, by recycling, using decomposable materials instead of plastic or glass to decrease our accumulating waste. Marine animals are suffering due to our actions, and if we do not put a halt to pollution soon, we too will suffer the consequences.