#12: groundwater (hydrogeology) -...

dwzwy-geologi-2010

#12: Groundwater

(Hydrogeology)

Assoc. Prof. Dr. Wan Zuhairi Yaacob

Program Geologi

UKM

110/20/2010

dwzwy-geologi-2010

• Hidrogeologi

– Kajian air di bawah

permukaan

– Geologi

– Hidrogeologist

• Hidrologi

– Kajian air permukaan

sahaja

– Kejuruteraan awam dan

environmental scientist

2

2 jenis bidang kajian air

10/20/2010

Istilah

• Groundwater

• Hydrogeology

• Hidrogeologi

• Air bawah tanah

• Air tanah

• Air bumi

• Air bawah permukaan

• Air telaga

• Air sumur

• ―Mata air‖ 10/20/2010 dwzwy-geologi-2010 3

Air adalah pelarut istimewa kerana:

– Molekul air tertarik antara satu

sama lain secara ikatan hidrogen

– Air adalah dwi-polar (iaitu

mempunyai dua cas)

– Molekul air tertarik pada

permukaan pepejal yang bercas

positif dan negatif

– Air adalah bahan pepejal yang

lebih ringan daripada bahan

cecair

10/20/2010 dwzwy-geologi-2010 4

Water as a Unique Liquid

Air dan agama

• Islam– Air Zam Zam

– Air sembahyang

– Air ―tawar‖

• Hindu– Sungai Ganges

• Kristian– Air suci ―holy water‖

10/20/2010 5dwzwy-geologi-2010

dwzwy-geologi-2010

Kitaran air

6

Surah Ar-Rum: 48 (KITARAN AIR)

Surah Al-Waqiah : 68-70 (HUJAN)

Air bawah tanah

(hujan)

(pemejalwapan)

(evapo-transpirasi)

(resapan)(aliran bawah tanah))

10/20/2010

Taburan air di bumi


Slide from Mohd Hatta Abd. Karim (JMG)

b m3 = billion cubic meter

m m3 = million cubic meter

MLD = million liter per day

MGD = million gallon per day

Japan International Cooperation Agency (JICA)


Water resources in Malaysia

33

5

62

Groundwater utilization by sector

Industrial

Agricultural

Domestic

3

97

Water use by source

Groundwater

Surface water


dwzwy-geologi-2010

GROUNDWATER

Groundwater is water located beneath the ground

surface in soil pore spaces and in the fractures of

lithologic formations.

Geologists

Hydrologists

Soil scientistsgeographers

Ecologists

Geotech Engineers

Mining engineerssanitary engineers

Petroleum reservoir analysts

Groundwater

1010/20/2010

dwzwy-geologi-2010 1110/20/2010

Groundwater to mining engineer (eg. Penjom Gold Mine)

drwzwy::2010_2011

Istilah air bawah tanah (1)

• Akuifer

– Unit telap geologi tepu air yang boleh mengalirkan air

– eg. Batu pasir, gravel, batuan retak —akuifer yg baik

• Akuiklude

– Unit geologi tepu air yang tidak boleh mengalirkan sejumlahkuantiti air

– Zon bahan bumi yang mampu menakung air tetapi tidakberupaya untuk mengalirkan air cukup banyak untuk dipamkeluar

– Akuifer yang tidak bagus (shale atau lempung padat)

• Akuitard

– Lapisan tidak telap air dalam lapisan stratigrafi

– Lempung (clay) dan batu padat (dense rock)

10/20/2010

drwzwy::2010_2011


• Zon tepu air (saturated)– Rongga tanah diisi sepenuhnya oleh air

• Zon tak tepu air (unsaturated) – Vadose zone– Rongga tanah yang tidak diisi sepenuhnya oleh air

• Paras air tanah (water table) – Meja air?– Satu lapisan yang terletak diantara zon tepu air dan

zon tak tepu air

– Memisahkan kedua-dua lapisan

– Tekanan air pada paras ini = tekanan atmosphere

10/20/2010

drwzwy::2010_2011

• Recharge air tanah• Sebarang proses yang

menambah air dalam

akuifer

• Air masuk ke zon tepu

samada dari air hujan atau

salji yg cair

• Discharge air tanah• Sebarang proses yang

mengeluarkan air dari zon

tepu air


10/20/2010

drwzwy::2010_2011

• Perched water table • aquifer that occurs above the regional water table, in

the vadose zone


10/20/2010

drwzwy::2010_2011

2 jenis akuifer:-

1. Tak terkekang (unconfined)

• Tiada lapisan penindih yang menindih zon akuifer tersebut

2. Terkekang (confined)

• Ada lapisan tak telap air yang menindih lapisan tersebut

• Air berasa di bawah tekanan(artesian)

• Bila digali pada zon ini, air akankeluar ke permukaan dengansendiri tanpa di pam (flowing artesian)

Jenis akuifer

10/20/2010

dwzwy-geologi-2010

Groundwater

1710/20/2010

Perkaitan air permukaan dan air bawah

tanah• Influent streams

– Water in stream moves down

to the water table

– Water pollution in the stream

may pollute the groundwater

• Effluent streams

– Groundwater seeps into the

channel, maintaining stream

flow

10/20/2010 dwzwy-geologi-2010 18

Gaining stream

Losing stream

10/20/2010 dwzwy-geologi-2010 19

Groundwater movement

Darcy’s Law:

10/20/2010 dwzwy-geologi-2010 20

Q = K.I.A ; I = h/ᶩ

Q/A = K.I

V (Darcy velocity) = K.I

Q = discharge

I = hydraulic gradient

K = hydraulic conductivity

V = Darcy velocity

A = Cross sectional area

V = Vs.n

Vs = V / n

V = Darcy velocity

Vs = seepage velocity;

n = effective porosity

manometer

Hukum Darcy

10/20/2010 dwzwy-geologi-2010 21

http://www.easycalculation.com/physics/fluid-mechanics/darcy-hydraulic-

gradient.php

10/20/2010 dwzwy-geologi-2010 22

Field application of Darcy’s Law

Pumping test

Piezometer / borehole

Example of Darcy’s LawA confined aquifer has a source of recharge. K for

the aquifer is 50 m/day, and n is 0.2. The

piezometric head in two wells 1000 m apart is 55

m and 50 m respectively, from a common datum.

The average thickness of the aquifer is 30 m, and

the average width is 5 km.

Calculate:

(a) the rate of flow through the aquifer

(b) the time of travel from the head of the

aquifer to a point 4 km downstream

The solution:Cross-Sectional area (A) =

30(5)(1000) = 15 x 104

m2

Hydraulic gradient (i) = (55-50)/1000

= 5 x 10-3

a) Rate of Flow for K = 50 m/dayQ = (50 m/day) (75 x 10

1 m2)

= 37,500 m3/day

Darcy Velocity:

V = Q/A = (37,500m3/day) / (15 x 104

m2) = 0.25m/day

Q = KiA

And…• Seepage Velocity:

Vs = V/n = (0.25) / (0.2) =

1.25 m/day (about 4.1 ft/day)

• Time to travel 4 km downstream:

T = 4(1000m) / (1.25m/day) =

3200 days or 8.77 years

This example shows that water moves

very slowly underground !!.

Arah pergerakan air bawah tanah

10/20/2010 dwzwy-geologi-2010 28

Well 1

Well 2

Well 3

10/20/2010 dwzwy-geologi-2010 29

Well 1

Well 2

Well 3

Arah pergerakan air bawah tanah

Groundwater flows at right

angle to water table contours

Water table contours

Berapa bilangan telaga minima yang diperlukan untuk menentukan arah

pergerakan air bawah tanah??

LDK 4

1. Membuat garis kontur air

bawah tanah

2. Menentukan arah

pergerakan air bawah

tanah

10/20/2010 dwzwy-geologi-2010 31

dwzwy-geologi-2010

Sumber air tanah

• Faktor akuifer yang baik?

– Kuantiti

– Kualiti

• Sumber air tanah terbaik di

dunia ialah air zam-zam

3210/20/2010

Apa yang mengawal kuantiti?

1. Porositi (rongga)• menentukan jumlah air yang boleh disimpan

2. Saiz akuifer• ketebalan dan keluasan

3. Ketertelapan (permeability @ hydraulic conductivity)

• Keupayaan sesuatu medium tanah untuk mengalirkanair melaluinya

• mempengaruhi kadar recharge dan keupayaan untukdipam.

• Contoh: – Pasir – ketertelapan tinggi (2 x 10-2 m/sec)

– Lempung/lodak – ketertelapan rendah (1 x 10-9 m/sec)

10/20/2010 33dwzwy-geologi-2010

Hydraulic Conductivity

Permeability / ketertelapan

K represents a measure of the ability for flow through porous media:

• K is highest for gravels : 0.1 to 1 cm/sec

• K is high for sands : 10-2 to 10-3 cm/sec

• K is moderate for silts :10-4 to 10-5 cm/sec

• K is lowest for clays : 10-7 to 10-9 cm/sec

10/20/2010 dwzwy-geologi-2010 35

dwzwy-geologi-2010

Kualiti air

• Kualiti akuifer

– Air tanah mengandungi pelbagaijenis bahan kimia inorganikdalam pelbagai kepekatan

– Kimia air dipengaruhi oleh jenisbatuan atau akuifer yang menakung air tersebut

– Cth: air bawah tanah di kawasanbatu kapur berbeza dengan air tanah di kawasan granite

– Analisis kualiti air (water quality)

3610/20/2010

dwzwy-geologi-2010

Water quality parameters

3710/20/2010

1) Alkalinity

2) Ammonia (NH3)

3) Dissolved Oxygen (DO) BOD ; COD

4) Fecal Coliform Bacteria

5) Flow

6) Hardness

7) Nitrate (NO3)

8) Nitrite (NO2)

9. pH

10.Phosphorus

11.Specific Conductance

12.Temperature

13.Total Organic Carbon (TOC)

14.Total Dissolved Solids (TDS)

15.Total Suspended Solids (TSS)

16.Turbidity (kekeruhan)

• Groundwater solutes

– Major Ions (concentration > 1 mg/L)

– Minor ions (concentration < 1 mg/L)

10/20/2010 drwzwy

Groundwater quality plot

dwzwy-geologi-2010 40

Stiff Diagram Piper Diagram

10/20/2010

Semua unit dalam Meq/L

Parameter untuk plot rajah piper

Cations

– Ca

– Mg

– Na

Anions

– HCO3

– SO4

– Cl

10/20/2010 dwzwy-geologi-2010 41

Semua unit dalam Meq/L

National Guidelines for Raw Drinking Water Quality from the

Ministry of Health, MOH or KKM (Revised December 2000)

Parameter unit value

Sulphate mg/l 400

Hardness mg/l 500

Nitrate mg/l 10

Coliform MPN 10

Manganese mg/l 0.2

Chromium, hexavalent mg/l 0.05

Zinc mg/l 1.5

Arsenic mg/l 0.05

Selenium mg/l 0.01

Chloride mg/l 250

Phenols mg/l 0.002

TDS mg/l 1500

Iron mg/l 1

Copper mg/l 1

Lead mg/l 0.1

Cadmium mg/l 0.005

Mercury mg/l 0.001

Ministry of Health, Malaysiadwzwy-2009

dwzwy-geologi-2010

Multiparameter water quality meter

4310/20/2010

The YSI Multiparameter water quality

meter can provide data on:-

• Dissolved Oxygen (DO)

• Temperature

• Electrical Conductivity

• Salinity

• pH (acidity)

dwzwy-geologi-2010

Total Solids (residue)

• 1. Total suspended solids (TSS)

– filterable solids

– Silt, clay, metal oxides, sulfides, algae, bacteria, fungi

• 2. Total dissolved solids (TDS)

– nonfilterable solids

– Would pass through 0.45 um filter

– Dissolved minerals and salts

– Major contributors: carbonate, bicarbonate, chloride, sulfate, phosphate and nitrate salts.

– Taste problems – high TDS levels

• TDS ----- salinity ----- specific conductivity

4410/20/2010

TSS

dwzwy-geologi-2010

Jumlah Pepejal Terlarut

Total Dissolved Solids (TDS)

Simple groundwater classification based on TDS:

Category TDS (mg/l)

Fresh water 0-1000

Brackish water 1000-10,000

Saline water 10,000-100,000

Brine water >100,000

Note: water with 2000-3000 mg/l TDS – too salty to drink

4510/20/2010

dwzwy-geologi-2010

Biochemical oxygen demand (BOD)

• Biochemical oxygen demand (BOD)– The amount of oxygen used

for bacterial decomposition

– Measured as mg/l of O2

consumed over 5 days in the dark at 20oC (BOD5 test)

– High BOD; high level of decaying organic matter in water

4610/20/2010

Incubator

DO meter

BOD bottle

dwzwy-geologi-2010

BOD Level

(in ppm)Water Quality

1 - 2

Very Good

There will not be much organic

waste present in the water

supply.

3 - 5 Fair: Moderately Clean

6 - 9

Poor: Somewhat Polluted

Usually indicates organic matter

is present and bacteria are

decomposing this waste.

100 or greaterVery Poor: Very Polluted

Contains organic waste.

Biochemical oxygen demand (keperluan oksigen biokimia)

4710/20/2010

Chemical oxygen demand (COD)

• Digunakan untuk mengukur kandungan bahan

organik dalam air

• Salah satu parameter ukuran kualiti air

• Unit: mg/L (mass of O2 consumed per liter of

solution)

10/20/2010 dwzwy-geologi-2010 48

DO (dissolved oxygen) @ oksigen terlarut

• Kandungan oksigen yang larut dalam air

@ yang berada dalam air

– unit mg/L atau ppm (part per million)

• Oxygen gets into water by:

– Diffusion from the surrounding air

– Aeration (rapid movement), and

– Waste product of photosynthesis.

dwzwy-geologi-2010 4910/20/2010

dwzwy-geologi-2010

DO Level

(in ppm atau mg/L)Water Quality

0.0 - 4.0

Poor

Some fish and

macroinvertebrate populations

will begin to decline.

4.1 - 7.9 Fair

8.0 - 12.0 Good

12.0 +

Retest

Water may be artificially

aerated.

Water pollution; DO < 5mg/L

OKSIGEN TERLARUT (DISSOLVED OXYGEN)

5010/20/2010

dwzwy-geologi-2010 5110/20/2010

DO

Air Permukaan (surface water)

dwzwy-geologi-2010 5210/20/2010

Not so bad ??

dwzwy-geologi-2010 5410/20/2010

ASMA (Alam Sekitar Malaysia Sdn Bhd)

Langat Basin

dwzwy-geologi-201010/20/2010 55

Item No. Item Description Qty. Unit price (RM) Total Value (RM)

Manual Water Quality Data at:

1. Sungai Buloh (1B01), Sg Klang (1K02,1K05,1K06),Sg Damansara (1K13), 20 135 2700.00Sg Penchala (1K14), Sg Langat 1L01, 1L02), Sg Btg Labu (1L08),

Sg Semenyih(1L09), Sg Btag Benar (1L12,IL20),Sg Buan (1L21),

Sg Btg Nilai (1L22,1L23), Sg Jijan (1L25), Sg Air Hitam (1SR02),

Sg Btg Kali (1SR03), Sg Kerling (1SR06), Sg Sembah (1SR09)

Parameter: Complete

Period:2009

TOTAL 2700.00

Water Quality Index (WQI)

10/20/2010 dwzwy-geologi-2010 56

10/20/2010 dwzwy-geologi-2010 57

Water Quality Index (WQI)

10/20/2010 dwzwy-geologi-2010 58

Agensi berkaitan air di Malaysia

Pahang-Selangor Raw Water

Transfer (PPAMPS)

Interstate Water Transfer To

Meet Future Water Demand

For Selangor And Wilayah

Persekutuan Kuala Lumpur

10/20/2010 dwzwy-geologi-2010 59

JBA – Jabatan Bekalan Air

SPAN – suruhanjaya Perkhidmatan Air Negara

JPS – Jabatan Pengairan dan Saliran Malaysia

MWA – Malaysia Water Association

SYABAS - Syarikat Bekalan Air Selangor Sdn. Bhd.

NAHRIM - National Hydraulic Research Institute of Malaysia

DOE & ASMA

TAMAT

dwzwy-geologi-2010 6010/20/2010

#12: groundwater (hydrogeology) -...

Documents