grain size analysis at mdu rohtak

Date: 19th Dec 2015Venue: Manav Rachna University, Delhi

Workshop On

WATER CONSERSATION AND POLLUTION

Organized byTHE INDIAN NATIONAL COMMITTEE OF INTERNATIONAL ASSOCIATION OF HYDROGEOLOGISTS(INC-IAH).&MANAV RACHNA UNIVERSITY.

Research paper:Jyoti Sharma, President, FORCEVidyyut Sharma, Geology(hon.) 3rd yr.

Grain Size Analysis at MDU Rohtak

Observations and Issues Raised

1. Established as Rohtak University, came into existence by Act No. 25 of 1975 of the Haryana Legislative Assembly.

2. Objective of promoting inter disciplinary higher education and research in the fields of environmental, ecological and life sciences.

3. Rechristened as Maharishi Dayananda University in 1977 after the name of the great visionary and reformer – Maharishi Dayanand.

4. The university is about 75 km from Delhi on the Delhi Hisar National Highway (NH-10).

5. MDU also administers programs through its Indira Gandhi PG Regional Centre, Meerput and the University Institute of Law and Management Studies, Gurgaon.

The purpose of the study is :

1. To help determine potential zones for recharging groundwater.

2. To find the cause of the chronic water logging issue in the area

The study of the area was carried out in the following way :

Test well of 32 meters depth dug

Samples taken at regular intervals of 2 meters

Samples were sun dried

Grain size analysis conducted

Observation inferred

Three major physical properties that are studied are :

1.Density – affected by weathering and packing of grains.

2.Porosity – it is the void spaces available between grains in a formation.

3.Permeability – ability to let fluids pass through the formation.

DENSITY

High density Low density

Percentage of pore spaces in a formation is the porosity of the formation.

POROSITY

Average soil formations have a porosity of about 50%.

%porosity = [1- (BD)/(PD)]*100

here; BD = Bulk Density PD = Particle Density

Sands have larger pores but less total pore space than clays.

Permeability is the ease with which fluids like water and can pass through a formation.

PERMEABILITY

Determined by the inter-connectivity of pore spaces.

A crude comparison of permeability between 3 major soil types

PERMEABILITY

POROSITY AND PERMEABILITY

A Sieve Test was conducted for the purpose of Grain Size Analysis.

Sieve Test consists of shaking the sample through a set of sieves with progressively smaller openings.The sieve with largest opening is on top and the one with smallest opening is at bottom.

S.No ASTM Grain size (in mm) Grain Size (in µm)

1 10 2 2000

2 18 1 1000

3 35 0.5 500

4 60 0.25 250

5 120 0.125 125

6 230 0.063 63

7 270 0.053 53

8 > 270 <0.053 <53

The following mesh sizes were used for the purpose of conducting the Experiment.

Chart showing measurement of different grains in different scales.

Labeling was done as follows.S.No Sample Code Depth (in mbgl)

1 VSRS 1 1

2 VSRS 3 3

3 VSRS 5 5

4 VSRS 7 7

5 VSRS 10 10

6 VSRS 12 12

7 VSRS 15 15

8 VSRS 17 17

9 VSRS 20 20

10 VSRS 22 22

11 VSRS 25 25

12 VSRS 27 27

13 VSRS 29 29

14 VSRS 32 32

1. From each sample 100g were taken and put through the Sieve Test. 2. A reading of amount left at each mesh was taken and percentage calculated.

S. No DEPTH 2mm 1mm 500 microns 250 microns 125 microns 63 microns 53 microns 53 microns Total

1 1 0% 0.00% 14.96% 14.29% 7.89% 38.66% 24.20% 0.00% 100%

2 3 0% 16.93% 32.14% 17.74% 8.86% 14.06% 9.43% 0.84%100%

3 5 0% 45.94% 20.44% 11.72% 5.33% 10.95% 5.09% 0.53%100%

4 7 0% 1% 1.02% 0.46% 9.86% 77.62% 6.36% 3.68%100%

5 10 0% 12.41% 23.56% 12.93% 12.17% 33.59% 4.95% 0.39%100%

6 12 1.07% 6.10% 11.67% 7.17% 10.28% 43.05% 14.65% 6.01%100%

7 15 0% 8.17% 10.55% 10.91% 14.74% 40.35% 10.90% 4.38%100%

8 17 11.49% 25.22% 19.35% 8.08% 5.88% 14.40% 10.68% 4.90%100%

9 20 4.34% 29.36% 20.41% 10.97% 6.08% 12.62% 13.95% 2.27%100%

10 22 45.28% 20.64% 9.73% 3.50% 3.75% 6.92% 6.93% 3.26%100%

11 25 0.65% 13.95% 16.72% 9.64% 5.89% 10.97% 29.08% 13.10%100%

12 27 0% 24.86% 33.86% 19.81% 8.76% 6.30% 5.32% 1.09%100%

13 29 13% 7.21% 7.01% 6.93% 7.69% 26.51% 21.07% 10.72%100%

14 32 0.42% 5.65% 11.41% 8.76% 8.26% 29.52% 27.09% 8.89%100%

Table showing percentages of grain sizes in each sample

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Best aquifers are those layers that have:

1. Majority of grains that are > 500 microns.

2. Very few grain smaller than 63 microns.

Based on Graph 1, three potential aquifer layers have been identified in the area:

Layer between 3mbgl-5mbglLayers between 17mbgl-22mbgl

A thin water lens at 27mbgl

The results observed also give a good reason for the chronic water logging and presence of saline water.

WATER LOGGING

SALINITY

Graph 1 clearly shows that the top layer of soil is clay dominant.

This layer is impermeable and hence does not allow water to percolate easily.

This causes the problem of water logging that is experienced in the area.

The issue of salinity is also linked to presence of clay dominant formation near the top.

Due to a clayey formation near the top, increased evapo-transpiration from the shallow water table takes place.

Thus salts start to accumulate and the water becomes saline.

1.Upto 15 m bgl there are thin alternating layers of aquifers and clayey strata.

2.After 15 m there is a relatively larger aquifer followed again by alternating strata.

ISSUESDoes this have any implications for water logging in the area?

Does this hold any potential for finding a solution to water logging?

Despite high industrialization, is the apparent high water table responsible for creating an artificial feeling of water adequacy ?

The results also raise some issues

HOW TO HANDLE WATER LOGGING

Is artificial recharge to groundwater a solution to water logging ?

We have tried this in Rohtak – we have made recharge wells that feed the 15-22 m bgl aquifer. They are functioning very well.

Should this be replicated?

Should policy makers consider:a) Encouraging shallow, non motorized dugwells as a source of waterb) Ban the use of canal water by industry ? Instead promote

concurrent groundwater extraction and recharge ?

Thank You