Onset Date for Rice Cultivation over Yom Basin in Thailand
Mr. SAMAN PRAKARNRATTHAI METEOROLOGICAL DEPARTMET (TMD)BANGKOK THAILAND Tel. 662 3992387 e-mail saman@metnet.tmd.go.thAbstract
A study of Onset date for rice cultivation over Yom Basin in Thailand using Backward and Forward Rainfall
accumulation method. In this publication used daily rainfall data from 104 rainfall stations over Yom Basin during 1976 to2000. The result shown that the onset date for rice cultivation over Yom Basin in Thailand started on 8 th May until 9th Junealong the upper of Yom Basin though the lower of Yom Basin. The Ending date of cultivation over the upper Yom Basinlies on 29th September though the lower of Yom Basin on 21st October.

1. Introduction
There are 25 major river basins in Thailand.
There are 7, 3, 5, 3 and 7 basins in the Northern,Northeastern, Central, Eastern and Southern part. Yombasin was selected to study which was in northern part ofThailand. Many people who lived in this basin are farmer,
mainly paddy field, horticulture and field crops. Farmers
therefore traditionally grow only rainfed wetland rice crop,so amount and distribution of rainfall is the important. If
we know the onset date for cultivation over Yom basin, it
will be the best. Fig 1 showed landuse map

2.

Materials and method

2.1 Site and description and data collection
Fig 2 showed the location of rainfall stations
involved in the network of 104 stations over Yom basin in
Thailand. Daily rainfall were selected due to theircontinuity and quality during the period 1976 to 2000.

2.2

Model description

Backward and forward accumulation method ispresented to determine the onset and termination of the wet
season, base on daily rainfall data. Morris and Zandstra(1972) choose 200 mm. accumulated rainfall for initiationof puddling-wet land preparation of rice fields. Someconclusions can be drawn from this graphicalrepresentation. The onset of the rainy season in Khon kaen,
Thailand is much more gradual compared to the end of therainy season. The termination date is chose 100mm. backward accumulation rainfall.

2.3

Data analysis

2.3.1

Forward accumulation rainfall

The datasets were in rows and column . The datecolumn is Julian-day. Accumulate rainfall since 1st January
forward until equal or more than 200 mm.. then stop.
Record number of Julian-day for each year and average
number of Julian-day
2.3.2

Backward accumulation rainfall

Accumulate rainfall since 31st December backward
until equal or more than 100 mm.. then stop. Record
number of Julian-day for each year and average number ofJulian-day
2.3.3 GIS program
Julian-days were analyzed contour lines using
Sufer program version 8.0. Export contour lines from Sufer
program and import to ArcInfo program. Build topology
for this map into Geographic Information System (GIS).

10099NMae Suai99Chiang KhamPa DaetChiang Dao

NChun

Muang Phayao
Wang Nua
Dokkhamtai

Mae Taeng

Pong

#Pua
Tha Wang Pha

Phrao
N

#

#

Chae Hom

San Khamphang

Doi Saket##San Khamphang#Mae Tha

Na NoiWiang Sa#

18

Soem Ngam

Mae Mo##

LiThoen

Tron#Mae Phrik

Si Nakhon
Sawan Khalok

Si Satchanalai

Si Samrong

Thung Saliam#

Wat Bot

17##
Chat Trakan

Phi# Chai#Wat Bot

Phrom Phiram

Muang Sukhothai Thani

17
Wang Thong

Muang Tak

Bang Krathum

Lan Krabu

LanduseSai NgamKing Amphoe Thung Sai

Urban

Chondaeng

99Muang Nakhon Sawan

100

Khanu WoralaksaburiBanphot Phi Sai#Phai Sali

Ban Rai King Amphoe MaeWong101

3. Result and discussion
The result of this study found that the onset dateover Yom Basin on 28th April to 9th June for the each area
The onset date started on the upper of Yom Basin though
the lower of Yom Basin. (Fig 3 ) The onset date ismeaning that there was enough moisture in the ground forwetland rice . So the farmer can prepare their rice fieldand select the date to cultivation. The ending date ofcultivation lies on 29th September to 21st October thesedate showed that the farmer cannot prepare rice field forcultivation ( Fig 4 )This case study used only daily rainfall to analyze.
The area are shown the onset date and ending date for ricecultivation over Yom Basin in Thailand (Fig 3 & Fig 4 )would be help the user’s planning. The user must be
consider dry spell, crop water requirement, actual water
consumption of crop, frequency and duration of rainfall
and disaster .

99

Taphan#Hin

Pho Thale##Kao Lieo
10 0 1020304050
Kilometers
LatyaoNong BuaTha Tako

Fig 1 Landuse over Yom Basin#
Pho Prathapchang

Khlong Khlung

Um Phang

Chum Saeng

King Amphoe Thung Sai#

100#Wang Pong#

Thap Khlo##Chondaeng#Bang Munnak

#

#Chum
# SaengMuang Nakhon Sawan#

Noen Maprang#

16

Bang Munnak

Kao Lieo
10 0 1020304050
Kilometers
LatyaoBang#
Krathum
Sam Ngam#Muang Phichit

King Amphoe Bung Samakkee

Pho Thale

Khanu WoralaksaburiBanphot Phi Sai

Ban Rai King Amphoe MaeWong

Khlong Lan

16

Khlong Khlung

Sai NgamWang Pong
Thap Khlo#

Bang Rakum#

Taphan Hin

Nakhon Thai## # Wang Thong #Lan Krabu
Muang Kamphang Phet

Pho Prathapchang

King Amphoe Bung Samakkee##Muang# Phitsanulok

Phran Kratai

Noen Maprang

Sam NgamMuang Phichit

Miscellaneous land

Phrom Phiram#Kong Krai Lat
Khili Ma#t

Muang Phitsanulok
Bang Rakum

Muang Kamphang Phet
Agriculral land#M#
# #Thaniuang Sukhothai

17

Khili Mat
Phran Kratai

Ban Dan Lan Hoi

Ban Tak

Kong Krai Lat

16

Si Nakhon##
Sawan Khalok

Si Samrong #Nakhon ThaiBan Dan Lan Hoi#Nam Pat

Tron

Chat Trakan

Phi Chai##Tha Pla#Muang Uttaradit ##Lap Lae##Khan# Thong Saen##

Thong Saen Khan

Fak Tha

Denchai#Nam Pat

Si Satchanalai

Mae Phrik

King Amphoe Na Mun
Muang Phrae
Sungmen#Long

Wang Chin

Muang Uttaradit
Lap LaeThung Saliam

Mae Tha

Sop Prap

Tha PlaLiThoen

Ko KhaSoem Ngam

18

Wang Chin

#i
Na No

18

Sop Prap## Rong Kwang###

Fak Tha

Denchai####Hang Chat# Muang Lamphang

King Amphoe Na Mun
Muang Phrae
SungmenLong#Song##Ko Kha#Muang Nan

Ngao

King Amphoe Maeon

Mae MoRong Kwang

Water bodyPua
Tha Wang Pha##

Chae HomMuang Lamphun

Um Phang

Pong#

Chiang Muan
# Ban Luang#Wiang SaHang Chat
Muang Lamphang

Khlong Lan

Chiang Klang #Muang#Phayao#
Wang Nua
Dokkhamtai

Mae Taeng19

Muang NanSong

Forest land

N

#Chun

Muang Phan

Muang Lamphun

LanduseKing Amphoe Song Khae

Mae Chai#Wiang Pa Pao

Ngao

King Amphoe Maeon

Muang Tak

Chiang Kham

19

Chiang Muan
Ban Luang

Muang Phan

Ban Tak

101##Thoeng#Pa Daet#Doi Saket

19#PhanChiang Dao

Chiang Klang

Wiang Pa Pao100#Mae Suai

NKing Amphoe Song Khae

Mae ChaiPhrao
N101

ThoengPhan

Nong BuaTha TakoPhai Sali

101

Fig 2 Rainfall Stations over Yom Basin

4. Conclusions
Rice is the significant commodity for Thai’seconomy. It is the country’s stable food, by-products of riceis also importance for human and animal consumption.
Farmers enjoy their earning from selling rice as well as thecountry gains a large amount of foreign exchange fromexporting of rice. Generally the rice in Thailand isharvested after the fields become dry at the end of the rainyseason ( September – October ). Typical result of the study
will give the farmers who lived in Yom Basin to knows thesystem to study appropriate timing for cultivation rice. Ihoped that the informations in this document will not only
give some ideas for planning to cultivate rice but will also
encourage more detailed of the method of GIS and applyfor another rainfed areas in the world.

100
Mae SuaiN

Mae Chai
Phrao

NPong

Muang Phan
Chae HomKing Amphoe Song Khae
Mae ChaiPhraoNSongPong

Chiang Muan
Ban Luang

Muang Phan

Sa20Wiang
May

Chae HomKing Amphoe Maeon
SongMae Mo

28 May1 Oct

Soem Ngam

20 May16 MaySop Prap

King Amphoe Na Mun
Muang PhraeSungmen

12 May16 MayDenchaiWang Chin

Ko Kha19Li Oct

Sawan Khalok
Si Samrong

17Thung Saliam

Sawan Khalok

28 MayKhili Mat
Phran Kratai

17Wang Thong

13 Oct30 MayMuang Phitsanulok

Lan Krabu

Muang Kamphang Phet

Sai NgamKing Amphoe Thung Sai

King Amphoe Bung Samakkee

16Khlong Khlung

Um Phang

Khlong Lan

100

Noen Maprang

Sam NgamMuang Phichit

Khlong Khlung

Um Phang

Nong BuaTha TakoReferences
L.R. Oldman & M. Frere : A Study of the Agroclimatologyof the Humid Tropics of Southeast Asia, Technical
Report FAO / UNESCO / WMO Interagency projecton Agroclimatology. Rome , 1982
Somchai Baimoung ,1992 (in Thai) : Length of theGrowing Season in Thailand, Meteorological
Department, Bangkok, Thailand.
Department of Land Development, RTSD : Thailand on aDisc, 1996.
Thai Meteorological Department : Rainfall data from1976 - 2000

Chondaeng

Pho ThaleBang Munnak

Chum Saeng101

Fig 3 Onset Date for Rice Cultivation
over Yom Basin in Thailand

Thap KhloTaphan Hin

Khanu WoralaksaburiBanphot Phi Sai

Kao Lieo
10 0 1020304050
Kilometers
LatyaoPhai Sali

Wang Pong

Pho Prathapchang

King Amphoe Bung Samakkee

Bang Munnak

Muang Nakhon Sawan

King Amphoe Thung Sai

Chondaeng

Chum Saeng

Ban Rai King Amphoe MaeWong

Sai NgamThap Khlo

Khanu WoralaksaburiBanphot Phi Sai

99

Bang Krathum

Lan Krabu

Muang Kamphang Phet

Taphan Hin

Pho Thale

Kao Lieo
10 0 1020304050
Kilometers
Latyao5 Oct Wang Thong

Muang Phitsanulok
Bang Rakum

11 OctWang Pong

Pho Prathapchang

Phran Kratai

Noen Maprang

3 JunSam Ngam
Muang Phichit

16Khlong Lan

Kong Krai Lat
Khili Mat

Muang Tak

Bang Krathum

Nakhon Thai

Phrom Phiram 7 Oct

Muang Sukhothai Thani

Bang Rakum

24 MayWat Bot

Ban Dan Lan Hoi

Ban Tak

Kong Krai Lat

Chat Trakan

Phi Chai9 Oct

Si Samrong

Muang Sukhothai Thani

Muang Tak

Si Nakhon

15 Oct

Nakhon Thai

Phrom Phiram

1 JunThong Saen KhanTron

17 OctChat Trakan

Wat Bot

Ban Dan Lan Hoi

Si Satchanalai

Mae Phrik

26 MayPhi Chai

Nam PatMuang Uttaradit
Lap LaeThoen

Si Nakhon

Thung Saliam

Tha Pla5 OctThong Saen Khan
Tron

Fak ThaDenchaiWang Chin

7 Jun

Mae Phrik

Ban Tak

Na Noi

3 Oct

King Amphoe Na Mun
Muang Phrae
SungmenLong

Sop Prap

Nam PatMuang Uttaradit
Lap Lae
Si Satchanalai

Mae ThaSoem Ngam

Fak ThaTha Pla24 MayLiThoenMae Mo18

Long

Wiang Sa

29 SepHang Chat
Muang Lamphang

Rong Kwang

26 MayMae Tha

Ko Kha18Noi
18NaMay

Rong Kwang

3 Oct

Muang Nan

Ngao

Muang Lamphun

Hang Chat
Muang Lamphang

Pua
Tha Wang Pha

5 Oct

Doi Saket

San Khamphang

Muang Lamphun

ChiangKlang
7 Oct

Muang Phayao
Wang NuaDokkhamtai

Mae Taeng

18 MayNgao

King Amphoe Maeon

NChun

9 Oct

Wiang Pa Pao

16 MayMuang Nan

Chiang KhamPa DaetChiang DaoPua
Tha Wang Pha

Chiang Muan
Ban Luang

101

ThoengPhan

N

Chiang Klang

14 MayDoi Saket

San Khamphang

100
Mae SuaiKing Amphoe Song Khae

12 MayChun

Muang Phayao
Wang Nua
Dokkhamtai

Mae Taeng

19NWiang Pa Pao

99

10 Chiang
MayKham

Pa DaetChiang Dao

101

ThoengPhan

1999

Ban Rai King Amphoe MaeWong

99

Muang Nakhon Sawan

100

Nong BuaTha TakoPhai Sali

101

Fig 4 Ending Date for Rice Cultivation
over Yom Basin in Thailand