An Original GIS and Remote Sensing Protocol to Detect Agricultural Drought Effects on Rainfed Agro Ecosystems in Semi-Arid Developing Regions: A Case Study for Central Mexico Andres Sierra-Soler Bioresource Engineering Faculty of Agricultural and Environmental Sciences McGill University, Montreal 2 A thesis submitted to McGill University in partial fulfillment of the requirements of the degree of Masters in Science ©2013 3 Contents Acknowledgements .........................................................................................................................8 Abstract............................................................................................................................................ 9 Chapter 1 .......................................................................................................................................12 1.1 Introduction .............................................................................................................................12 1.2 Objectives................................................................................................................................ 17 1.3 Thesis Outline.......................................................................................................................... 18 Chapter 2 .......................................................................................................................................21 Literature Review and Selection of Methods ................................................................................21 2.1 What is a Drought? ..................................................................................................................21 2.2 What Causes Drought? ............................................................................................................22 2.3 Classification of Droughts....................................................................................................... 24 2.4 Overview of Drought Indices ..................................................................................................25 2.4.1 Data driven drought indices .............................................................................................25 Palmer Drought Severity Index (PDSI)................................................................................. 26 Standardized Precipitation Index (SPI) .................................................................................26 Crop Moisture Index (CMI) ..................................................................................................27 PDSI vs. SPI ..........................................................................................................................28 2.4.2 Drought indices derived from Satellite Data. ...................................................................28 Normalized Difference Vegetation Index (NDVI) ................................................................28 Vegetation Condition Index (VCI) ........................................................................................30 The Normalized Difference Water Index (NDWI) ................................................................31 Tasseled Cap Transformation Wetness (TCW) .....................................................................32 Temperature Condition Index (TCI) ......................................................................................34 Vegetation Health Index (VHI) .............................................................................................35 Standardized Vegetation Index (SVI) ....................................................................................35 2.5 Comparing Drought Indices ....................................................................................................36 2.6 The Use of Land Use Land Cover (LULC) Maps for Detecting the Effects of Droughts ......38 2.7 Why Study Drought? Social Vulnerability to Drought ...........................................................39 2.7.1 Social vulnerability to drought .........................................................................................40 2.7.2 Droughts as a natural hazard ............................................................................................40 4 2.7.3 Droughts and human activity ...........................................................................................41 2.7.4 The importance of maize in Mexico. ................................................................................42 2.7.5 Overview of land tenure processes in Mexico .................................................................42 2.8 Selection of Methods............................................................................................................... 46 2.8.1 Meteorological Analysis................................................................................................... 46 2.8.2 Remotely Sensed Data...................................................................................................... 48 2.8.3 Land Use Land Cover Maps............................................................................................. 50 2.8.4 Spectral indices to detect agricultural drought .................................................................52 2.9 Summary and Conclusions...................................................................................................... 55 Preface to chapter 3 .......................................................................................................................55 Chapter 3 .......................................................................................................................................56 Assessing Agricultural Drought at a Regional Scale Using LULC Classification, Standardized Precipitation Index (SPI), and Vegetation Indices. ........................................................................56 Abstract .........................................................................................................................................56 1. Introduction ...............................................................................................................................57 1.1 Study Area ...............................................................................................................................62 1.1.1 Climate .............................................................................................................................63 1.1.2 Agriculture ........................................................................................................................63 2. Materials and Methods ..............................................................................................................64 2.1 Materials.................................................................................................................................. 64 2.1.1 Monthly Precipitation Data ..............................................................................................64 2.1.2 Open Access SPI software ‘SPI_SL_6.exe’: ....................................................................65 2.1.3 Satellite Imagery ..............................................................................................................65 2.1.4 Ground truth data.............................................................................................................. 67 2.1.5 Climatic and topographic maps ........................................................................................68 2.1.6 GIS software .....................................................................................................................68 2.1.7 Remote sensing software ..................................................................................................68 2.2 SPI Analysis ............................................................................................................................68 2.3 Land Use Land Cover (LULC) Classification ........................................................................70 5 2.3.1 Preprocessing images .......................................................................................................70 2.3.2 Extraction of training sampling locations ........................................................................71 2.3.3 Land Use Land Cover (LULC) Analysis: Saadat et al., (2011) simplified method .........72 2.3.4 Assessing accuracy in remotely sensed data ....................................................................74 2.4 Spectral Indices for Detecting Drought ...................................................................................75 2.4.1 The normalized difference vegetation index (NDVI) .......................................................75 2.4.2 The vegetation condition index (VCI) ..............................................................................78 2.5 Change Detection ....................................................................................................................79 2.5.1 Vegetation types and phenomenology ..............................................................................80 3. Results and Discussion ..............................................................................................................81 3.1 SPI Results ..............................................................................................................................81 3.2 LULC Maps............................................................................................................................