INTERACTIONS INTERACTIONS BETWEEN LAND USE AND FLOOD MANAGEMENT IN THE CHI RIVER BASIN BETWEEN LAND USE AND FLOOD MANAGEMENT IN THE CHI RIVER BASIN The Chi River Basin, Thailand, cannot handle the regularly occurring floods. Consequently, flooding of the low-lying areas occurs on a regular basis. Therefore, an integrated flood management framework needs to be developed to minimize the negative effects of floods of different magnitude. In response, a hydrological model (SWAT) and a hydraulic model (1D/2D SOBEK) were integrated to simulate river flows and inundated areas, and to analyse the current system. The developed modelling framework enables to analyse the impacts of different structural measures such as river normalisation, green river (bypass), and retention basin. In addition, non-structural measures including reservoir operation and land use planning were assessed in their capability to protect people and valuable infrastructure. For each measure, several possible scenarios were tested and evaluated based on financial and technical efficiency criteria. An ‘optimum’ combination of aforesaid measures was chosen since it could reduce flood extent and its damage more considerably than stand-alone solutions. Finally, the study illustrates the effects of land use changes on floods, which indicated little or no significant potential impact on flood regime at river basin level, but rather at sub-basin scale. This is important for a better understanding of the scale and | direction of impacts of developments in the future. KITTIWET KUNTIYAWICHAI kittiwet kuntiyawichai PHD_COVER_KUNTIYAWICHAI_vs140312-rug13,5mm.indd 1 24-03-12 16:34 INTERACTIONS BETWEEN LAND USE AND FLOOD MANAGEMENT IN THE CHI RIVER BASIN Kittiwet Kuntiyawichai Thesis committee Thesis supervisors Prof. dr. ir. E. Schultz Professor of Land and Water Development UNESCO-IHE Institute for Water Education Delft, the Netherlands Prof. dr. S. Uhlenbrook Professor of Hydrology UNESCO-IHE Institute for Water Education Delft University of Technology Delft, the Netherlands Other members Prof. dr. ir. R. Uijlenhoet Wageningen University Wageningen, the Netherlands Prof. dr. ir. N.C. van de Giesen Delft University of Technology Delft, the Netherlands Prof. dr. T. Tingsanchali Nakhon Pathom Rajabhat University Nakhon Pathom, Thailand Dr. N.E.M. Asselman Deltares Delft, the Netherlands INTERACTIONS BETWEEN LAND USE AND FLOOD MANAGEMENT IN THE CHI RIVER BASIN Thesis submitted in fulfilment of the requirements of the Academic Board of Wageningen University and the Academic Board of the UNESCO-IHE Institute for Water Education for the degree of doctor to be defended in public on Friday, 11 May 2012 at 3 p.m. in Delft, the Netherlands by Kittiwet Kuntiyawichai Born in Buriram, Thailand CRC Press/Balkema is an imprint of the Taylor & Francis Group, an informa business © 2012, Kittiwet Kuntiyawichai All rights reserved. No part of this publication or the information contained herein may be replaced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, by photocopying, recording or otherwise, without written prior permission from the publishers. Although care is taken to ensure the integrity and quality of this publication and the information therein, no responsibility is assumed by the publishers nor the author for any damage to property or persons as a result of operation or use of this publication and/or the information contained herein. Published by CRC Press/Balkema PO Box 447, 2300 AK Leiden, the Netherlands e-mail: [email protected] www.crcpress.com - www.taylorandfrancis.co.uk - www.ba.balkema.nl ISBN 978-0-415-63124-2 (Taylor & Francis Group) ISBN 978-94-6173-249-1 (Wageningen University) Table of contents Acknowledgement ......................................................................................................... IX Summary ....................................................................................................................... XI 1 Introduction .................................................................................................................. 1 1.1 General .................................................................................................................. 1 1.2 Problem description .............................................................................................. 2 1.3 Objective and methodology .................................................................................. 3 1.3.1 Research questions ........................................................................................ 3 1.3.2 Scope of the thesis ......................................................................................... 4 1.3.3 Hypotheses .................................................................................................... 4 1.3.4 Research objectives ....................................................................................... 5 1.3.5 Methodology ................................................................................................. 6 1.4 Structure of the thesis ........................................................................................... 6 2 Background ................................................................................................................... 9 2.1 General overview of Thailand .............................................................................. 9 2.1.1 Introduction ................................................................................................... 9 2.1.2 General climatic conditions ......................................................................... 10 2.1.3 Surface temperature .................................................................................... 11 2.1.4 Rainfall ........................................................................................................ 11 2.1.5 Relative humidity ........................................................................................ 12 2.1.6 Land and water resources ............................................................................ 12 2.1.7 Land and water development ...................................................................... 17 2.2 Brief description of the study area ...................................................................... 19 2.2.1 Chi River Basin ........................................................................................... 19 2.2.2 Characteristics of the study area .................................................................. 19 2.3 Developments in the Chi River Basin ................................................................. 26 2.3.1 Past developments ....................................................................................... 26 2.3.2 Present and future developments ................................................................. 28 3 Water resources and land use pattern in the Chi River Basin ..................................... 33 3.1 Land and water resources .................................................................................... 33 3.1.1 Land resources ............................................................................................ 33 3.1.2 Water resources ........................................................................................... 36 3.2 Hydrology ........................................................................................................... 38 3.2.1 Climate and rainfall ..................................................................................... 38 3.2.2 River system ................................................................................................ 39 3.3 Water management and flood protection schemes .............................................. 40 3.3.1 Opening ....................................................................................................... 40 3.3.2 Water management and land use under different water use practices ......... 40 3.4 Flood management and irrigation systems .......................................................... 43 3.4.1 Preface ......................................................................................................... 43 3.4.2 Flood prone zone ......................................................................................... 44 3.4.3 Types of flood management ........................................................................ 45 3.4.4 Types of irrigation systems ......................................................................... 47 3.5 Institutional arrangements with respect to water management and flood protection .................................................................................................................. 48 3.5.1 Institutional arrangements for water management in Thailand ................... 49 3.5.2 Agencies involved ....................................................................................... 49 3.5.3 Problems of water resources management in Thailand ............................... 51 VI Interactions between land use and flood management in the Chi River Basin ______________________________________________________________________________________________________________________ 3.5.4 Institutional arrangements for flood protection in Thailand ........................ 51 4 Impact assessment of land use on flooding conditions ............................................... 55 4.1 Beginning ...........................................................................................................