A VISIT TO YELLOWSTONE NATIONAL PARK-A GEOLOGIST'S PERSPECTIVE

 VISIT TO YELLOWSTONE NATIONAL  PARK USA-A GEOLOGIST’S PERSPECTIVE

C SATYANARAYANA                                                                                         

INTRODUCTION

The National Yellowstone Park is located in Wyoming,Montana and Idaho states of USA and situated in an vast area of 8983 Sq.Km. This park is famous for Wild Life, Geothermal features

and Sub-alpine forest.

Yellowstone Lake is one of the largest high elevation lakes and is centered over the Yellowstone 

Caldera or Craton the largest super volcano.

Yellowstone Park itself is a Volcano and one of its most spectacular eruptions occurred

640000 years ago. During the eruption, the land collapsed and left a large depression in 

the earth-the yellowstone Caldera or Crater. Within the past 2.1 million years three major

eruptions occurred in yellowstone and volcano is still active.

This Caldera filled with lava flows over hundreds of years creating the volcanic Plateau

that comprises much of the central part of the Park. Surprisingly, many of the Park’s Geysers

Hot springs,Mudpots and Fumaroles are also found near or within the Caldera.

Plate tectonics played an important role in the creation of Volcanic terrain in Yellowstone

Park. North America Plate and Pacific Plate collided along the western margin of North 

America. As the collision progressed North American Plate began to ride over the oceanic plate

which the oceanic plate was pushed down(Subducted) deep into the hot earth where it began to 

melt.This molten magma is the source for chain of Volcanoes.

Magma generated above the subducting slab(Pacific ocean plate) rose into North American

Continental crust about 300 to 500 Km. inland. Great arc-shaped volcanic mountain ranges grew  as lava and ash spewed out of dozens of individual volcanoes.                                                                                                                                                                                                                                                

North America plate scrapped against the top of the oceanic plate and peeled off layers of

Sediments. During the last half of Mesozoic Era, much of todays California,British Columbia,

Oregon and Washington were added to North America.

About 200 million years ago, the Plate motions adjusted,as the Pacific plate shifted to north

westerly course and shift transformed the head on collision to more of a glancing,sliding margin

became what is referred as the San Andreas Fault which includes many fault lands west of the 

San Andreas Fault system are part of Pacific plate those to the east belong to the North America.

THREE MAIN  LOCATIONS IN YELLOW STONE PARK

1 Noris Geyser Basin and Old Faithful

2 Mammoth Hot Springs

3 Mud Volcan

Before discussing above locations first let’s find out the meaning of Geyser,Hotspring,Mud volcano and Fumaroles.

Geyser- Geyser’s form if the fractures through which heated water flows contain constrictions.

Between eruptions, temperatures in the super heated pressurized water beneath the constriction buildup creating increasing amount of steam. Eventually, the steam pushes water

out of the constriction, water pressure deep in the system drops instantaneously and the Geyser

erupts. 

Hot Springs- Hot springs are features with no constriction unlike Geysers. Super heated water

cools slightly, as it reaches the surface and is replaced by hotter water from deeper source.This

sets up a pattern of water circulation which prevent the chain reaction leading to an eruption.

Fumaroles- (Steam vents) Hottest surface features. Their underground channel systems penetrate hot rock but are generally dry. When little water ( rain or melting snow) drain into the fumarole’s channel(fractures) converts instantly to steam and reaches the surface.

Mud Pots- Form when acid decomposes surrounding rock into clay.The clay mixes with water to form mud of varying consistency and color. Gas bubble burst through the mud and

 and create bubbles. 

1. NORIS GEYSER BASIN.

      2.1 million years old Caldera or Crator. Caldera is the place where volcanic eruption took 

place. It is acidic Geyser(PH is less than 5). It is one of the hottest and acidic Geyser in Yellow

Stone National Park’s hydrothermal area. Many hot springs and Fumaroles here have temperature
 near the boiling point(93 degree centigrade). Earth Quakes often changes the                                                                                                                           

features. Noris Geyser area is near the intersection of two major faults. One runs from the North

another runs from West. These two faults intersect with a ring fracture from the yellowstone Caldera eruption
 640000 years ago. Each year at Noris, new hot springs and geysers appear and others become dormant.

Geologic events trigger many of these changes. Even small earth quakes can alter hydrothermal behavior.
 Different colors found in Noris are evidence of thermophiles( heat loving microorganisms) and their activity

These colors are yellow-due to sulphur, Dark brown due to Iron Oxide, Emerald green due to chlorophyll

-a green pigment, Dark blackish green due to algae called Zygogonium

Geyser in Noris basin-    All of Yellowstone’s hydrothermal areas are heated by magma(partially molten rock)
 exist approximately 5 to 13 Kms below the earth’s surface in this area. Beneath  the Park, this partially molten magma

 heat water percolating down from the surface along fractures and faults. This superheated water rises back toward the
 surface collecting into larger channel focr each hydrothermal feature.

Old Faithful- Upper Geyser basin home of old faithful. The  majority of the world’s active Geyser’s are in the upper 
Geyser basin. Rangers forecast the eruption times of five Geysers here-

Old faithful

Castle Geyser

Grand Geyser

Daisy Geyser

River side Geyser

Within the past 2.1 million years, three major eruptions occurred in yellowstone and the 

volcano is still active. Partially molten rock or magma may be as close as 5-13Kms

underground. This magma produce first ingredient for thermal features. 

Second ingredient -water-Rain and Snow supply water. The water seeps down several thousand feet(one kilometer)
 below the surface where it is heated.Third ingredient-underground fractures(cracks)form third

 ingredient a natural plumbing system

Hot water rises through the plumbing (fractures) to produce Hotsprings if there is no constriction

in fractures and Geysers when there is constriction in fracture. In Geyser constriction in the fractures prevent
 water from circulating freely to the surface when heat would escape.

The deepest water can almost reach the boiling point of 93 degrees centigrade.

Pressurized water beneath the constriction buildup creating increasing amount of steam.

Eventually the steam pushes water out of constriction, water pressure deep in the system drops     

instantaneously  and the Geyser erupts.

The eruption stops when the reservoir is exhausted drained of water or heat. Old Faithful erupts more frequently than any of other big geysers although it is not the largest or most regular Geyser in the Park.Its average interval between eruption is about 90 minutes varying from 50-127 Minutes.                                       

 An eruption lasts 1.5 to 5 minutes expels(discharge)3700-8400 gallons(14000-32000 litres)of boiling water and reaches a height of 106-184 feet(32-56 meter). 

                                              

                                                     

                                                                                                                      

                                       

Hot Spring

Low Faithful Geyser

Low Faithful Geyser

                             

                                

2. Mammoth Hot Spring-

Terraces of Mammoth Hot Springs —At Mammoth, network of fractures and fissures form the 

plumbing systems that allows hot water from underground to reach the surface. The water comes  from rain and snow falling on the surrounding mountains and seeping deep into he earth where it is heated. Small earthquakes may keep the plumbing open.

Limestone occurs in the subsurface provides the final ingredient. Hot water(due to contact of percolated water with molten magma)with dissolved carbon dioxide makes a solution of weak carbonic acid. As the solution rises through rock  it dissolves calcium carbonate the primary compound in Limestone.

At the surface, the calcium carbonate is deposited in the form of travertine(is a form of Limestone deposited by mineral springs), the rock that forms the terraces of Mammoth Hot Springs. The Thermophiles(heat loving microorganisms)create tapestries of color where hot water flows among the terranes. Colorless and yellow thermophiles grow in the hottest water. orange,brown and green thermophiles thrive in cooler waters. Colors also changes with the seasons due to differing amount of sunlight.

The features are always changed, but the over all, activity of the entire area and the volume of water discharge  remain relatively constant.Different types of terraces existing in the Park.

Opal terrace

Main terrace

New high land terrace

white elephant back terrace

Angel terrace.

MAMMOTH TERRACES

 MAMMOTH TERRACES

 MAMMOTH TERRACES

                                  

 MAMMOTH TERRACES

    

GRAND CANYON OF THE YELLOWSTONE PARK

About 640000 years ago, a huge volcanic eruption occurred in Yellowstone park emptying a large underground chamber of Magma(partially molten rock). Volcanic ash spread for thousands of miles.

The roof of this chamber slowly collapsed forming a giant Caldera or Crator 45 Km across 75 Km long. The Caldera began to fill with lava flows continued for hundreds and thousands of  years. Scientists of the opinion that  the oldest Canyon of Yellowstone formed 160000 to 140000  year ago.This paleo crater was not as deep as the Canyon you see now.

Past and current hydrothermal activity weakened the Rhyolite(volcanic rock)lmaking the rocks softer. The yellowstone river eroded these weakened rocks to deepen and widen the Canyon a process that continues today. The current canyon begins at Lower  Falls and ends downstream from Tower falls.

The 308 feet(93m)lower falls may have formed because the river flows over volcanic rock more resistant to erosion than the downstream rocks which are hydrothermally altered. The 109 feet (33m) upper falls flows over similar rocks

The large rocks upstream from upper falls are remnants of a lava flows resistant to erosion.

The multi-hued rocks of the Canyon result from the hydrothermally altered rhyolite and sediments. The active hydrothermal features of colored rhyolites with dark orange brown and green areas near the river are seen. The Canyon can be viewed from south rim and 

north rim(in the map rims are shown).

WATER  FALLS IN CANYON

 RHYOLITE ALTERED DUE TO THERMAL WATERS AND GASES.

Waterfalls in RHYOLITE rock

   MUD VOLCANO-

 One of the most acidic features in the Park.Sulphur Caldron is located

here. The pungent odor of rotten egg is caused by hydrogen sulphide gas. Located near

the greatest uplift and sinking of the Caldera floor. Many faults converge here and Earth 

Quakes are common.

Here at mud volcano you are close to one of the resurgent domes. Resurgent domes are areas

of active ground deformation where the land moves up or down with the fluctuation of the magma chamber below. Scientists monitor these domes closely for information about ongoing       

volcanic activity.

                                                                                                                                                                                                                                                                                

The fascinating and mysterious mud features found here are some of the most acidic in the Park. This acidity plays a part in making them different from most hot springs and geysers.

Hydrogen sulphide gas is present deep in the earth at mud volcano.

Some microorganisms use the gas as an energy source. They help convert the gas to 

sulphuric acid which breaks down rock to clay. Listen to the sounds,notice the smell

and observing the colors of the mud volcano area. Much of what you sense comes from 

sulphur.

Dragon’s mouth springs has captured imaginations for centuries. In 1999, dramatic changes 

occurred. The water temperature dropped ten degrees and the color changed from green to 

chalky white.

MUD VOLCANO

MUD VOLCANO

.

REFERENCES

1.TRAIL GUIDES OF NATIONAL PARK SERVICE

2.GEOLOGY OF USA-WIKIPEDIA.

WATERSHED DEVELOPMENT AND OTHER METHODS IN TACKLING OVER DRAFT GROUNDWATER CONDITONS.

 NATIONAL SEMINAR ON PUMP SET ENENGISATION AND GROUND WATER RESOURCE MANAGEMENT, CIRE, HYDERABAD, P.117-123, FEB 1999.

C.SATYANARAYANA

ABSTRACT    

The enthusiasm shown towards exploitation of Groundwater through agricultural pump set energisation program lacking in simultaneous formulation of artificial groundwater recharge schemes and generation of additional power. This has led to steep decline of water table and power crisis in certain parts of the country. From groundwater point of view, water shed wise development projects in critical areas to reduce soil erosion, run-off and to increase groundwater recharge from annual rainfall are the suitable measures to tackle over-exploitation of groundwater.

INTRODUCTION

 The recurrence of droughts highlighted the importance of groundwater exploitation.

After 1970, large scale construction of irrigation wells started and with the introduction of SPA participative programs since 1978, the pace of ground water exploitation has increased manifold.  Desired results of increased food production and establishment of ancillary units in rural areas were achieved in a satisfactory manner.

The pump set energisation programme is so fast particularly in few states covered by hard rock terrain like Maharashtra, Andhra Pradesh, TamilNadu, parts of Karnataka, Gujarat and Madhya Pradesh that the ground water draft exceeded the safe yield resulting in decline of water levels.

The initiation and enthusiasm shown for exploitation of ground water through energisation of agricultural pump sets were missing towards the artificial recharge of groundwater projects and additional generation projects to meet the growing demand.  As a result, a number of white area blocks were transforming into grey blocks and grey into dark area from groundwater point of view and severe power crisis developed in many states.  However, still there is a lot of demand for agricultural connections in these areas.

 *Sr.Hydrogeologist, Rural Electrification Corporation Limited, Project Office, Chennai.

ONGOING STUDIES: 

As the Groundwater related Departments were also established after 1970, taluk wise and district wise groundwater assessment studies were carried out taking some of the norms on Adhoc basis.  After acquiring some field data and experience now modified norms are being adopted for assessment of groundwater particularly in areas where exploitation of groundwater exceeds safe Yields. The methods include 1) Watershed wise assessment of groundwater 2) Water level fluctuation and specific yield method.

WHAT IS WATERSHED.                           

Watershed is a drainage basin or catchment with natural stream outlet and is separated from another watershed by topographic ridge and slope.  The catchment of bigger river like Ganga, Godavari, Krishna are called basin, the catchment of tributaries of bigger rivers are called sub Basin and the catchment of smaller stream is watershed. The groundwater assessment is done taking watershed as a unit which covers catchment of a small stream, covering about 12 to 15 villages.  Even micro-watersheds comprising the area under the jurisdiction of one village is also suggested as this help in grouping the people in one co-operative society.  These schemes depend mainly on the co-operation of people as multiple activities are involved.(Basin and Water Shed map enclosed)

The advantages of watershed approach are:

  1). The entire rain fall experienced by a watershed could be accounted easily as the total Rainfall, evaporation, surface run-off and soil moisture are confined to the catchment of water shed only.

  2). There is a specific entry point and outlet and a spread area in the form of catchment is available in watershed.  Hence the budgeting of groundwater is possible with certain degree of accuracy than the assessment made on administrative boundaries like taluk/block.

IMPORTANCE OF WATERSHEDWISE DEVELOPMENT IN TACKLING OVER   EXPLOITATION OF GROUNDWATER.

There are three important components in the assessment of groundwater.

1). Recharge of groundwater basin.

2). Surface run-off.

3). Evaporation and Transpiration.           

 It is estimated that in our country, 47% of rainfall goes as surface run-off, 30 to 35% as evaporation and 15 to 25% to groundwater recharge. The groundwater recharge depends on the nature of soil, rock formation and topography etc., if any watershed becomes dark or grey category due to overexploitation, the alternate methods to increase groundwater recharge are - to reduce surface run-off and evaporation.

  The following watershed wise methods enable to increase the groundwater recharge from rainfall.

1.    Gully plugging in minor streams.

2.    Sub-surface dykes or percolation tanks along stream.

3.    Contour bunding.

4.    Trenching along hill slopes.

5.    Farm ponds in the foot hill zone.

6.    Check dam cum minor irrigation on the main stream.

7.    Land leveling (terracing)

8.    A forestation.

 The above methods check the erosion of soil, reduce surface run-off and increase groundwater recharge.

PRESENT STATUS OF WATERSHED PROJECTS:

The methods like bunding, land leveling, afforestation and other soil conservation measures were already taken up in most of the states.  Construction of percolation tanks and assessment of groundwater by watershed method was taken up by Maharashtra government from 1973 onwards.  About 7000 percolation tanks were constructed in Maharashtra state. Evaluation studies on selected percolation tanks in DPAP areas indicated that groundwater recharge has increased up to 50% of its gross storage.  Under normal conditions the groundwater recharge from rainfall is 10 to 15% in hard rocks. With other artificial recharge projects like trenching at nala bed, contour trenching, flooding nala has increased the recharge to Groundwater from 30 to 40% of gross storage of projects.          

1) Though large numbers of watershed development projects are now being taken up in several parts of the country, the results of these projects are not available to other agencies who are engaged in the same field.

2). The details of water level data, discharge of wells, run-off data, evapotranspiration data, soil/fertility cropping pattern before taking up watershed programme and collection of similar data after completion of project is necessary so that benefit due to watershed development programme could be quantified.

The publications of such results are very useful as it could act as a guide to other areas where similar programs are likely to be taken up.

OTHER METHODS TO TACKLE OVER-EXPLOITED AREAS

 As the watershed projects involves long gestation period and involve lot of financial commitment, it is very difficult to cover even small number of watersheds in the coming 5 to 10 year period. Hence the alternative methods are to be searched to tackle the over draft conditions. Some of the alternatives are given below;-

a)    Even in the dark category watersheds also, the groundwater conditions near the tanks, ponds, valley-fill areas, flood plains, natural levees, meandering courses of rivers, streams etc. palaeo channels, and foot -hill zones are some of the groundwater potential zones to be taken up for groundwater extraction.  These areas can be delineated utilizing aerial photos and satellite imageries.  Already several groundwater departments brought out district wise groundwater reports where the maps depicting the above aspects are demarcated.

b)    In hard rock terrain where deep water level conditions are existing and deep bore wells are the only groundwater abstraction structures, the ‘deep fractured aquifers should be utilized for meeting the drinking water needs only. Drilling of bore wells for irrigation purpose in such areas should be discouraged as the groundwater potential in deep fractured terrain is limited.

c)    Desilting of tanks and ponds should be carried out to increase the recharge of groundwater. During the dry seasons, farmers may be allowed to collect the silt/clay material accumulated at the bottom of the tanks. This will enable the farmers to put the silt in their agricultural fields to enhance the fertility of the soil. This program can enhance the recharge to groundwater from tanks and ponds. Desilting not only increase the discharge of wells but also reduce the total head of agricultural pump sets to Pump out water.  This in turn will cause lot of savings in consumption of power in agricultural pumping systems.  As the ultimate beneficiary for watershed development is power sector, SEB’s can associate with schemes formulated for watershed development in association with financial institutions, NABARD and minor irrigation departments.

d)    At present both state and Central Groundwater Departments are carrying out monitoring of National Network observation wells periodically. Under the programme, monitoring of water level fluctuation and changes in quality of groundwater were carried out. But it is also advisable to establish some piezometers in representative areas in grey and white blocks particularly in hard rock terrain and carry out step drawdown test to monitor:

·         Changes in efficiency of wells.

·         Changes in Discharge, water levels and Drawdown of wells etc.

The collection of above data enables us to watch the groundwater system and can take                                       preventive measures in case the aquifers are leading for overdraft conditions.

   e). Artificial recharge of groundwater by channel spreading, induced recharge and injection               some of the important methods to tackle over draft conditions.  Few artificial recharge projects were taken already by CGWB and state GWD’s. But the studies are in preliminary stage only and projects are to be taken up to cover major portion of over exploited area.

CONCLUSIONS  

  Large scale groundwater exploitation through pump set energisation has taken up mostly in the   States covered by hard rock terrain, like Maharashtra, Andhra Pradesh, Tamil Nadu, part of Gujarat, Madhya Pradesh and Karnataka etc., In some districts of these states, large scale exploitation of groundwater caused decline of water levels which involves lot of money in deepening of existing wells, construction of bore wells and requirement of additional power to meet the enhanced connected load which was caused due to increase in total head. The decline of water levels increased the total head and high density of irrigation wells reduces the discharge rate.  These factors added to the high consumption of power.  This has lot of impact on the existing power systems in the way of erecting additional distribution transformers, substations and generation of additional power.

For the above problems, watershed development projects to enhance the groundwater recharge are one of the important solutions besides artificial recharge of groundwater by several methods which are in vogue.