chapter-5 : baseline environmental scenario · mizoram state road project –ii lunglei –...

Mizoram State Road Project –II

Lunglei – Tlabung-Kawrpuichhuah Road (km 0.0 to km 87.830)

4- 1 PWD Mizoram

CHAPTER-5 : BASELINE ENVIRONMENTAL SCENARIO

This chapter assesses the nature, type and dimensions of the study area with specific focus

on the project roads and their relevant physical and biological environmental components.

The database on the environmental components relevant to decisions about project location,

design and operation have been assembled from various secondary sources and primary

surveys conducted during project preparation.

5.1 METEOROLOGICAL BASELINE

The study of Meteorological and micro meteorological parameters is significant in a road

project as these parameters regulate transport and diffusion of pollutants released into the

atmosphere.

Mizoram represents three distinct climatic zones. The lower altitudes in the foothills and

valleys of Mizoram have a typical tropical climate whereas in the mid-region, sub-tropical

moist climate prevails. In the upper reaches, temperate climate is experienced. On the

whole, Mizoram has a pleasant climate. The summers are generally warm and wet, but

winters are cool and dry. Pre monsoon rains occur during March-April, whereas regular

monsoon commences from June and continues till October. Three seasons may be

recognised in the state, viz.,

Winter extending from November to February

Summer from March to May

Rainy season from May to October

The climate of the district is characterized by tropical humid climate with cool summer

and cold winter. Winter temperature varies from 110

to 130

C in general. The winter season



4- 2 PWD Mizoram

is however, without snow. The district receives heavy rainfall during May to late September

with an average annual rainfall of 2,200 mm under the influence of southwest monsoon.

Relative humidity in the dry season is 60 –70% and in the monsoon period is about 90%.

During southwest monsoon, February to April is comparatively dry when humidity is

between 60 –70%.

Average wind speed during site visit around 10.2km/hr and the Sunshine duration about <15

hours during August 2013

5.2 NATURAL AND BIOPHYSICAL ENVIRONMENT

.

5.2.1 Land use

About 65% length of the road passes through land owned/developed by individuals land

holders under periodic patta and village council pass. This land will be available free of cost

whereas compensation for plantations, crops etc. within the required corridor is paid to each

individuals. About 35% passes through forest area. The road passes through nine villages,

i.e. Lunglei ,Hauruang ,Pachang ,Phairuang, Routlang, Lungsen, Sihphir, Tuichawng &

Tlabung.

The list of the habitats along the project road is as follows:

S.No From km To km, Village Name

1.00 0.00 2.90 Lunglei

2.00 12.90 25.43 Hauruang

3.00 25.43 35.45 Pachang

4.00 35.45 43.53 Phairuang

5.00 43.53 44.34 Rotlang

6.00 44.34 60.43 Lungsen



4- 3 PWD Mizoram

7.00 60.43 60.62 Sihphir

8.00 60.62 80.25 Tuichawng

9.00 80.25 94.40 Tlabung

The settlements are all along the road. The forest have been cleared to give way for the

cultivation of crops but the percentage of land cover used for the agricultural purposes is

still very small. The clearing of the jungle and vegetation covers for settlements, agriculture,

transport and communication lines and consequent disappearance of the wild life have yet to

take its toll in the region.

Percentage Distribution of Land use

Sl

No

Land Use Percentage

1 Settlements 10 %

2 Agriculture 50 %

3 Forest 35 %

4 Others 5 %

.

5.2.2 Physiography and Geomorphology

Physiographically, the district is a mountainous terrain with prominent relief. The

hills have ranges running from North to South. Mostly anticlinal longitudinal parallel to sub

parallel hill ranges and synclinal narrow valleys create deep gorges in between North- South

hill ranges. Basically, these are structural hills. The denudation and weathering is still under

going in response to various physicochemical processes. One of the dominant processes of

the formation of such land form is running water. Based upon relief, drainage, lithology and



4- 4 PWD Mizoram

structural pattern, the district has been divided into two major units i.e. a) Denudation

Structural Hills and b) Valleys.

a) Denudation Structural Hills

The district is mostly occupied by denudation structural hills which is predominantly

argillaceous comprising shale, siltstone and mudstone, fine grained and compact sandstone

with occasional limestone. The processes of denudation have not yet obliterated the

structural features such as dip facets and strike trend, anticline and syncline. This major

form has been further divided as follows.

i) Low linear ridges

These are low elevated hills and occupy outer flank of structural folds. They have gentle to

moderate slopes and possess gully erosion. The main drainage is controlled by strike of the

formations and shows slight meandering pattern. The main rock types are mixture of

arenoargillaceous assemblages, comprising shale and fine to medium grained, friable

sandstone. The units occur in the western part of the district.

ii) Moderate linear ridges

Mostly moderate linear ridges occupy about 90% of the district. The main constituents are

hard and compact sandstone, shale and siltstone, alterations of Bhutan formation. The

ridges show serrated top and hogback pattern, which are highly dissected and separated by

intervening ‘V’, shaped narrow valleys.

b) Valleys

The valleys have limited areal extent and occur mostly in the western part of the

district adjacent to Bangladesh border.



4- 5 PWD Mizoram

i) Linear rolling valley

These valleys are found in the structural depressions in between low linear ridges of

fine to medium grained, friable sandstone with subordinate shale of Bhuban group of rocks

and siltstone, shale, mudstone with subordinate sandstone of Bokabil group of rocks.

5.2.3 Soil Types

The soils of the district, in general, have been derived from parent rock such as

ferruginous sandstone, shale, alluvial and colluvial materials. In general, the soil formations

have been categorized into following groups.

i) Hill Soil: It includes colluvial soil, formed along the steep side slopes because of

accumulation of material on slope surface.

ii) Valley Soil: Occurs as a mixture of colluvial and alluvial materials. It is

restricted to the rolling valleys along the river courses.

iii) Terrace Soil: These are the remnants of deposits of cobbles and pebbles which

make it excessively drained.

5.2.4 Terrain

The project road is located in Mizoram, one of the most variegated hilly terrains in eastern

part of India. The hills are undulating and are separated by rivers, which flow either to the

north or south creating deep gorges between the hill ranges.



4- 6 PWD Mizoram

The classification of the terrain is normally done by means of cross slope to the country viz.

slope approximately perpendicular to the center line of the highway location.

Terrain Classification as per IRC: SP-48-1998

Sl no Terrain Classification % Cross slope of country

1 Plain 0 to 10

2 Rolling Greater than 10 upto 25

3 Hilly Greater than 25 upto 60

4 Steep Greater than 60

The road mostly is in the hilly to steep terrain.

5.2.5 Surface water

The project road traverses through mountainous and steep terrains with several natural

drainages such as deep gorges, depressions, etc., where perennial water and rain water

runoff are collected. Sometimes the storm runoff is accompanied by large quantities of

debris from upstream side of the nallahs.

List of Rivers/Nullahs on the project road are tabulated below:

Sl.No. Location in Km Name of River

1 27.00 Nullah

2 33.510 Phairuang River

3 35.130 Nullah



4- 7 PWD Mizoram

4 67.015 Tuichang River

5 70.212 Nullah

5.2.6 Geology

Predominant geological formation is lower tertiary formations of miocene.

The project area represent Barail Group of rocks which comprises a monotonous

sequence of shale interbedded with siltstone and hard compact, thinly bedded, grey to

khaki, fine grained sandstone. Locally, a few hard, dark grey compact, medium to fine

grained quartzwacke bands are present.

The ridge area of the project is formed by Sandstone which are fine to very fine

grained, not too bluish grey to light brown in colour, compact and hard, thinly bedded,

rarely yellowish brown, medium grained and friable. The low structural hill is formed

by Siltstone and Shale which are dark grey to grey in colour and are usually

splintery.(refer map 4.2 ) (Source: Geological survey of India)

5.2.7 Ground water / Hydrogeology

Geologically, the district is occupied by shale, siltstone, and sandstone of Surma

formation of Miocene age. Ground water stored in the hill slopes emanates in the form of

springs which are used as a source of water supply. From quality point of view, most of the

chemical constituents present in ground water are within the permissible limit.

The estimated gross annual dynamic groundwater resource is 5.53 mcm while net

ground water availability for future irrigation development is 4.97 mcm. The stage of

development is 1.22%. Future provision for domestic and industrial use is 0.1 mcm.

The present ground water utilization is for domestic and to some extent for agriculture

purpose as there is no major industry in the district.



4- 8 PWD Mizoram

As per earlier field investigation reports, it is found that water samples collected

from springs indicate pH value ranges from 6.9 to 8.3. Electrical conductivity of spring

water is found to vary from 31 to 249 micromhos/cm at 25O

C except at few places. The

concentration of bicarbonate ranges from 12 to 158 ppm. The concentration of Calcium

varies from 4 to 22 ppm and that of Magnesium varies from 1 to 10 ppm respectively.

Concentration of Iron ranges from 0.02 to 0.3 ppm and is within the permissible limit of 0.3

ppm.

In general, the chemical quality of ground water in the district is fresh and potable and is

suitable for domestic and industrial purposes.

In spite of good rainfall, there is acute shortage of water especially during the summer.

5.2.8 Rain Water Harvesting Structures constructed under Central Sponsored

Scheme

Village wise volume of water used and number of persons benefited are given below

. Sl.

No.

Name of District/ Block Name of

Village

Volume of

Water Used

(liters)

No. of

Persons

Benefited

1. Lunglei/ Hnahthial R.D.

Block

Thingsai 15,800 3,316

2. Lunglei R.D.Block Sekhum 15,800 250

3. --do-- Chengpui 15,800 300

4. --do-- Farm Veng 15,800 2,300

5. --do-- Salem Veng 15,800 2,302

6. Lungsen R.D.Block Thangte 15,800 291



4- 9 PWD Mizoram

7. Bunghmun R.D. Block Sertlangpui 15,800 946

5.2.9 Drainage condition

The major drainage pattern having different bifurcation ratios follow the N-S trending

depressions and gorges in the low level topography, separated by highland topography in

between them. The depressions and gorges, in most cases, are the physiographic

manifestations of the faults and other structural trends. The tributaries and streamlets

forming ‘angular’, ‘sub-parallel’ to ‘parallel’ and ‘dendritic’ drainage pattern. The drainage

gradient in general is moderate.

The hills are steep and separated by rivers which flow either to the north or south,

creating deep gorges between the hill ranges. There are innumerable rivers, streams and

brooks in the state. In the north, the Tlawng (Dhaleswari), the Tuirail (Sonai) and the

Tuivawl start from the middle of Mizoram and flowing north fall in the Barak River in

Cachar district. In the south, the Karnafuli flows north from the southern tip of the state and

from near Tlabung in West Central Mizoram, it flows to Bangladesh where it is being

tapped for a huge hydel project. The Koladyne River enters Mizoram from Burma and near

Lunglei it takes a U turn and re-enters Burma again. River Tiau is the main drainage channel

of the project area.

5.2.10 Forest resources and ecological sensitive locations

The proposed alignment is not passing through any wild life sanctuary, biosphere reserve,

national park etc. but it passes through rivirine forest area .

Upgradation of existing road is going to pass through following forest stretches :



4- 10 PWD Mizoram

(A) Riverine Reserved Forest (RRF) :

Phairuang RRF Area (29.700Km to 35.100Km) = 6.48 Ha

Tuichawng RRF Area (60.800Km to 63.700) = 4.68 Ha

Khawthlang Tuipui RRF (74.00Km to 77.900Km & 85.600Km to 87.842Km) = 7.37 Ha

(B) Forest Plantations :

At Ch 20.830Km to 21.750Km = 1.10 Ha

At Ch 44.000Km to 44.430Km = 0.52 Ha

At Ch 63.940Km to 65.970Km = 2.44 Ha

Total B = 4.06 Ha

Total A = 18.53Ha

Forest Clearance Required for (A + B)= 22.59 Ha

5.2.11 Slope Stability

In the project road in general the hill slopes are stable. Potential major landslide areas

were not noticed /reported in the project road..Enginnering as well as bioengineering

techniques are proposed to satbilised the soil and slopes.

5.2.12 Mineral resources

No major mineral deposits of economic importance have been reported so far in the

state. However, in course of systematic geological mapping, occurrence of shell

limestone, coal, hard sandstone bands (suitable as building material), saline springs

and a few gas seepage have been located.

5.2.13 Seismic characteristics

In Mizoram, lie the southern most end of the Purbachal Himalayan range. Their folded

structure is a synclinorium consisting of broad synclines and tight-faulted anticlines.

Earthquakes in this region are generally shallow, though a few quakes of intermediate

depth have occured. The seismic hazard map of India was updated in 2000 by the

Bureau of Indian Standards (BIS). States of Mizoram lie entirely in Zone V i.e.

highest risk of earthquake. (Refer map)

5.2.14 Natural hazards and Vulnerability of the sub-project area



4- 11 PWD Mizoram

Due to its geo-climatic condition, the entire state is one of the most hazard prone

states in the country. The state is annually swept by cyclonic storms, cloudbursts,

hailstorms and landslides. To make matters worse, the State falls under Seismic Zone

V, and thus liable to be hit by strong earthquakes. Small tremors are felt every now

and then in and around the state. Although the State is enjoying abundance of rainfall

during monsoon period, the dry spell during non-monsoon period is really hard for the

people. Due to the steepness of the hillsides, underground water retention is minimal,

causing perennial water sources to dry up during this period. This had been aggravated

by the tradition custom of jhum cultivation, commonly known as slash and burn. The

habit of felling trees and foliage of forests and burning them really destroy natural

vegetation, thus causing ecological imbalances. Moreover, this usually led to

unwanted spread of fire to forests.

As per State Action Plan for Climate Change (SAPCC) for 2010 -2015 indicate the

fact that - A recent report on climate change impact in India highlights that “extreme

precipitation events may increase by 5-10 days in all the regions in the Mizoram , the

rise in temperature with respect to the 1970s ranges from 1.8°C to 2.1°C. Also, the

number of rainy days is likely to increase by 1-10 days with intensity of rainfall in the

region to increase by 1-6 mm/day. This may cause wide alarm in the state as many

parts of the state are prone to landslides and flash floods which are only aggravated by

heavy rainfall due to steep gradient. Flash floods leave very little scope for

preparedness and also render, crop and pastureland useless. In this context, the state

climate change action preparation has been initiated.

5.2.15 Air Quality

Being an industrially backward state with no major polluting sources, in terms of air

quality, the ambient air quality in Mizoram is generally pristine. Low traffic volumes

along the existing roads also point to lower pollutant concentrations even when close

to the roads.

The results of air quality monitoring indicate that the ambient air quality is within the

acceptable limits along the corridor. Table below shows the concentrations of the

major pollutants of interest in settlement along the upgradation corridor and compares



4- 12 PWD Mizoram

it with the applicable standards for rural and residential areas shows that all results are

below the NAQQS standard.

Table 5-2 : Air Quality Data and Comparison with National Standards

Pollutants

Average

monitoring

Time

(Hours)

Monitoring

at Start

Point(3

Gate)

Monitoring

at Lungsen

village

Monitoring

at Tlabung

village

Standard*

SO2 24 3.5 μg/m3 2.7 μg/m3 4.5 μg/m3 80 μg/m3

NO2 24 11.5 μg/m3 16.5 μg/m3 10.5 μg/m3 80 μg/m3

PM 10 24 70.5 μg/m3g 71.0 μg/m3 78.0 μg/m3 100 μg/m3

PM2.5 24 31.5 μg/m3 34.5 μg/m3 37.0 μg/m3 60 μg/m3

CO 1 2.5 mg/m3 1.7 mg/m3 2.0 mg/m3 4.0 mg/ m3

* As per CPCB Publication: Ambient Air Quality Status and trends in Delhi (2009)

5.2.16 Noise Environment

Ambient noise level was measured by “Noise Level Meter”. Noise was measured at eight

locations during day and night time for average. , maximum and minimum levels in

dB(A)Leq .The day time average is 58.0 dB(A)Leq and night time average is 42.0

dB(A)Leq.

5.2.16 Fauna

There is no unique faunal community within the core and buffer zone of the project area,

except most common ones like toad, frog, crow, sparrow and myna, Loris, etc. In

addition to insects (including moths, stick insects, dragonflies, beetles, cockroaches,

grasshoppers, ) lizards are noted.



4- 13 PWD Mizoram

5.2.17 Tuichang River Marsh: The following organisms were observed to inhabit and use

the marshy ecosystem as breeding place at Tiau marsh:

Sl. No

Common Name Scientific Name

Identifying

Character/Colour

1 Algae Rodophyceae sp. brown

2 Green Algae Chlorphyceae sp. Dark Green

3 Dragon fly Macromia sp purple

4 Damsefly

Enallagma sp. fluorescent blue

5 Dragon fly Macromia sp scarlet

6 Dragon fly Macromia sp. red small

7 Dragon fly Sympetrum corruptum Yellow

8 Tadpoles Rana sp Dark brown

9 Planktons Nektons, Neuston Dark green

10 Surface swimmers Brachionus s., etc Swimmers

Some of the birds and animals reported to be spotted by visual observation

during the visit, and through local informants are (local names given in

parenthesis):



4- 14 PWD Mizoram

Sl No Common/Local Name Zoological name

1 Wild cat (Sanghar) - Felis spp.

2 Partridges (Ram parva) - Columba sp.

3 Lizard - Laiking Caleotes vesicular

4 Squirrels (Thehlei) Callos ciurus macclellandi

5 Sazaw type Felis sp.

5.2.17 Cultural and Heritage resources

A fine blending of different shades of culture is noticeable in the festivals observed

through out the district. Almost all the festivals are associated with the underlying

principle of the anthropomorphizing of the divinity and the ascriptions of human

conduct and affection to it.

No heritage site has been observed near the project corridor .

5.2.18 Socio-economic Characteristics of the Project Influence Area

Lunglei District, the biggest District in Mizoram is bounded on the nort h by Mamit

and Serchhip Districts, on the south by Lawngtlai and Saiha Districts, on the east by

Myanmar and on the west by Bangladesh. It has area of 4,538 Sq.kms with a

population of 154,094 (2011 census) and 186 villages. There are three Civil Sub-

Divisions namely – Lunglei Sadar Sub-Division, Tlabung and Hnahthial Civil Sub-

Divisions. The District is also divided into four Rural Development Blocks –

Lunglei, Hnahthial, Lungsen and Bunghmun.



4- 15 PWD Mizoram



4- 16 PWD Mizoram

Map 5.2 – Geology of project area Map 5.1 – Physiography of project area



4- 17 PWD Mizoram

Map 5.3 – Drainage pattern of the project area Map 5.4 – Seismic zonation of the project area

5-18

Starting Point at Lunglei (Three Gate)

5-19

Phairuang Village (Pipeline along the road)

Tuichwang Riverine forest area

5-20

Tlabung : Solid waste on the road

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