Extreme Flooding Events Assessment Using Remote

Sensing and GIS.

MS ThesisRemote Sensing and GIS

Presented BySyed Hammad ShabbirCIIT\FA13-RRG-010\ISB

Supervisor: Dr Aqeel Ahmed Kidwai

COMSATS Institute Of Information Technology Islamabad

Sequence of Presentation

IntroductionMethodologyResult DiscussionConclusionRecommendations

Introduction

To provide an assessment of extreme flood events inPakistan under predicted climate change scenarios

The severe flooding and its impact on social and economicconditions of people living around the vulnerable areasaround Indus Basin.

To examine different flood events and their potentialimpact on the floodplains

Defining Indus Basin and its catchment area, sub basinswithin the boundaries of Pakistan

Floodplain mapping and inundation maps

Study Area Indus River Historically known as Sindhu,

Sindhi also called Mehran in Sanskrit and Tibetan language.

One of the longest river of the world.

It is ranked as the twelfth largest river basin on Earth

Passing through the Himalayan, Karakorum and Hindu Kush ranges it has total length of 3200 Km

The drainage area is about 1,165,000 sq km.

The 453,000 square km area of basin is in the Himalayas Ranges, the Hindu Kush, and the Karakoram Range

The other part is in the plains of Pakistan

Indus River (Study Area) The annual flow of the river is around

243 cubic km

Geological history shows that 50 to 45 million years ago Indus River Delta emerged as a delta and the river in fifty million years has twice changed its course and direction.

Upper Indus Basin (UIB) has approximately 220,000 square kilometer (km2) surface area.

Major tributaries of Indus Basin are Chenab, Jhelum, Ravi, Sutlej and Kabul River

Glaciers runoff contributes approximately 19.6 million acre-feet (MAF) to the total annual flow of the UIB. 14.1 MAF from the Karakorum, 2.3 MAF from western Himalayas and 3.2 from the Hindu Kush.

18 percent of the total flow of 110 million acre-feet (MAF) from the mountain headwaters of Indus River and the 82 percent is from melt water from winter snow.

http://earthobservatory.nasa.gov/NaturalHazards/view.php?id=46369

Climate change and the Indus River Pictures

The most vulnerable people affected with climate change will be the poorest people of developing countries.

Indus River have been affected by frequent and high intensity floods in recent years.

Historical patterns and trends in temperature and precipitation indicate increasing hydro climatic risks in Pakistan over the coming years.

By the 2020s the temperature is expected to rise by about 2°C in northern Pakistan, 1.5°C in the central parts of the country, and 1°C in the coastal areas.

Have negative affect over the glaciers of UIB which will increase the rate of snow melting, increased frequency and intensity of floods.

AFP/ Getty Images

Sequence and Damages from flood events in Pakistan

Damages from July 2010 flood event

In 2010 Pakistan experienced catastrophic monsoon and extraordinary rainfall in mid-July to September 2010 resulting in unprecedented floods affecting the entire country.

This was the second worst event in terms of devastation since 1929.

Rains and floods affected over 20 million people, destroying the properties, housing, infrastructure and crops. The estimated cost was 10 billion US$ for reconstruction.

AFP/ Getty Images

METHODOLOGY

Defining the catchment area of Indus Basin with watershed delineation analysis.

Hydraulics modeling using geometric input data for modeling.

Historical extreme flood events modelling.

Flood modeling of 22 July 1958 for Dera Ghazi Khan Division

Flood modeling of 02 August 2010 for Dera Ghazi Khan Division

Flood modeling of 15 August 1976 for Sukkur, Larkana and Nasirabad Divisions

Flood modeling of 08 August 2010 Sukkur, Larkana and Nasirabad Divisions

METHODOLOGY Defining Indus Basin

By using the Arc Hydro tools define the catchment area of Indus River, its floodplains and streams network.

The points used for the delineation are of major barrages of Pakistan.

Watershed delineation analysis for

Tarbella Dam

Mangla Dam

Chashma Barrage

Taunsa Barrage

Trimmu Jehlum Link

Trimmu Chenab Link

Panjnad Barrage

Guddu Barrage

Kotri Barrage

Indus Basin Drainage Analysis

To perform drainage analysis digital elevation model (DEM) of Global Multi-resolution Terrain Elevation Data 2010 (GMTED2010) 15 arc-seconds is used.

For the hydrologic modeling the break line layers were used; the breaklineemphasis products are recommended layers for hydrology projects.

The images were mosaicked in Erdas Imagine 2011, Pakistan was extracted from the mosaic image using ArcMap spatial analyst tool.

Project to projected coordinate system UTM using project tool in ArcMap.

Arc Hydro tools are useful in hydrologic modeling

Steps in Drainage Analysis

Fill Sinks

Flow Direction

Flow Accumulation

Stream Definition

Stream Segmentation

Catchment Grid Delineation

Catchment Polygon Processing

Drainage Line Processing

Adjoint Catchment Processing

Drainage Point Processing

Longest Flow Path for Catchments

Longest Flow Path for AdjointCatchments

Slope

Batch Watershed Delineation

Drainage Area Centroid

Longest Flow Path

Construct 3D Line

Smooth 3D Line

Hydro Network Generation

Node/Link Schema Generation

Compute Local Parameters

Generate Report

Steps

Watershed Maps

Hydraulic Analysis

Define the floodplains of the Indus Basin and to create flood inundation maps.

Areas are selected for the hydraulic analysis

Dera Ghazi Khan Division

Sukkur Division

Larkana Division

Nasirabad Division

Demographics

Rahim Yar Khan, Muzaffargarh, D.G.Khan and Rajanpur are classified in the high deprived category.

Kashmore, Jaccobabad, Jamshoro, Tando Muhammad Khan, Umer Kot, Badin, Thatta and Tharparkar for the Sindh province are high level of deprivations magnitude of overall Index of multiple deprivations according to the Districts’ Indices of Multiple Deprivations

A research study conducted by Plan International suggested based on fourteen different parameters that Dera Ghazi Khan Division, Sukkur Division and Larkana Divisions are amongst the most vulnerable and insecure regions for the flooding (Neighboring Risk 2010).

Hydraulic Modeling and Floodplain Mapping with HEC-GeoRAS and HEC-RAS

HEC-GeoRAS is software developed by US Army Corps of Engineers Institute for Water Resources as an extension for ArcGIS. The tools are used to build geometric data for river analysis. The geometric files are exported to HEC –RAS and then imported back for Inundation maps.

HEC – RAS is software developed by US Army Corps of Engineers Institute for Water Resources.

The Hydrologic Engineering Centers River Analysis System (HEC-RAS) is developed to perform one-dimensional steady flow analysis it also perform unsteady flow analysis, sediment transport computations, and water temperature modeling. (USACE, 2002 b).

Process flow diagram of HEC-RAS Analysis

Start an ArcGIS Project

Prepare Geometric Data

TIN

Stream Center Line

Bank Lines

Flowpath Lines

Extract Elevation Data

Export RAS DataStart RAS Project

Import Geometric Data

Cross Section Review

Enter Flow Data

Create Profiles for Steady Flow Analysis

Export GIS File

ArcGIS Project

Import RAS Results

Create Flood profile maps

Inundation Maps

Spatial Data preparation

DEM Dera Ghazi Khan Division and TIN Dera Ghazi Khan Division

Spatial Data preparation

DEM Nasirabad – Larkana - Sukkur Division & TIN Nasirabad – Larkana - Sukkur Division

Importing Geometry data into HEC-RAS

The geometric file created in HEC-Geo RAS is now imported into HEC – RAS as GIS import file

HEC-RAS can perform steady and unsteady flow water surface profile calculations, sediment transport computations, and water temperature analysis (USACE, 2002 b).

Modeling in HEC-RAS

Subcritical analysis was used to perform floodplain and inundation mapping.

Flow Data and boundary conditions.

The historical flow data of past extreme flood events were collected from the Federal Flood Commission Report 2010.

The flow data used to perform this analysis was from Tanusa Barrage data i.e. 7,88,646 for 22 July 1958 and 9,59,991 cusecs for 02 August 2010 was considered for Dera Ghazi Khan Division and Guddu Barrage i.e. 11,99,672 cusecs for 15 August 1976 and 11,31,000 cusecs for 08 August 2010 for the Sukkur, Larkana and Nasirabad Divisions.

Normal depth was used for the boundary condition.

Modeling in HEC-RAS

Two plans of flow data entered for the Dera Ghazi Khan Division first was historical flow data of 22 July 1958 i.e. 7,88,646 cusecs and 9,59,991 cusecs for 02 August 2010 for Tanusa Barrage.

For the second analysis the historical flow data of 15 August 1976 i.e. 11,99,672 cusecs and 11,31,000 cusecs for 09 August 2010 for the Guddu Barrage.

The cusecs were converted into cubic meter/second as a requirement of the SI units.

Steady Flow Analysis

Subcritical flow regime was selected for this analysis.

The RAS file was exported as GIS data with all the computed profiles to be used for flood inundation mapping.

Flood inundation mapping

RESULTS

The areas severely affect by these results are Layyah, Kot Addu, Muzaffargarh and Jampur. Rajanpur was not included in the final result because the analysis was done up till the divisional boundaries of the river.

Results in Tabular format and Graphical Profiles

Flood 22 July 1958 Profile 1 X-Y-Z Perspective RAS ModelingFlood 22 July 1958 Profile 1 Output Table, RAS Modeling

Results in Tabular format and Graphical Profiles

Flood 22 July 1958 Profile 2 Output Table, RAS Modeling Flood 2010Profile 2 X-Y-Z Perspective RAS Modeling

Flood inundation mapping

Flood 22 July 1958 Floodplain Map RAS Modeling Flood 22 July 1958 Depth Map RAS Modeling

Flood inundation mapping

Flood 02 August 2010 Depth Map RAS ModelingFlood 02 August 2010 RAS Modeling

Flood inundation mapping

Flood 15 August 1976 RAS ModelingFlood 08 August 2010 RAS Modeling

Results comparison

Dera Ghazi Khan Flood 02 August 2010 Landsat Image 12 August 2010 Flood 2010 UNDP Shapefile

Results comparison

Floodplain extent 2010 RAS Modeling Rivers and Canals System Sukkur, Nasirabad and Larkana Divisions

Conclusion The most vulnerable districts to be affected by the floods every year are the most

poorest districts of Pakistan.

The social and economic conditions in these districts are at lowest level.

The Human development Index of these districts are among the lowest.

The chances to recover from floods for these districts are very low without external help.

Catchments, sub catchments with drainage lines of stream network with delineation points helps to work on specific floodplain.

The final results can be used for the hazard mapping and mitigation purpose.

The velocity, power, shear and depth of the flood is calculated in the final results.

ArcGIS and River Analysis Systematic Tools provided the prospect to complete this study by using historical data of the floods.

Model historical extreme or predicted flood event by using these tools.

Meteorological data can be added to create time series floodplain mapping

Limitations

Cross section data

TIN data

Bridges and Culverts data

Ineffective flow areas

Obstructions

Boundary Conditions

Levees and embankment data

Comparison Maps

RECOMMENDATIONS

Geo-referenced surveyed data for the cross section can improve the quality and accuracy of the final results.

LiDAR data for the TIN creation is recommended for the analysis as LiDAR data is more accurate and detailed than the Digital Elevation Models.

Bridges data with their heights and width as input for geometric data preprocessing can improve the results.

Obstructions and other blocked areas including lakes and canal data can also impact the final results of the analysis.

Similarly the embankments on the river sides can also impact the results the height and width of these embankments can affect the results.

Flow change locations and factors like time series data, precipitation data at the time of flood in particular catchment area can also improve the final results of floodplain mapping.

REFERENCES Arshad, R.R. (2010). Pakistan Floods 2010. Preliminary Damage and Needs Assessment

Dragan, S., Slobodan P. S. (2009). Vulnerability of Infrastructure to Climate Change, Background Report 2 - Hydraulic Modeling and Floodplain Mapping. City of London.

EM – DAT: CRED International Disaster Database, http://www.emdat.be, 2015.

Eum, H.I., Simonovic. S. P. (2009). Vulnerability of Infrastructure to Climate Change, Background Report 1 – Climate and Hydrologic Modeling. The City of London.

FFC (2010). Federal Flood Commission Annual Flood Report 2010.

Jie, Y., Ronald, D.T., Bahram, D. (2006). Applying the HEC-RAS model and GIS techniques in river network floodplain delineation

Khadija, Z., Anna, C. (2014). How the people of Pakistan live with climate change and what communication can do. The ClimateAsia Report 2014.

Meyer, S., Olivera, F. (2007). “Floodplain Mapping & Hydraulic Analysis with HEC-GeoRAS 4.1.1 and ArcGIS 9.1.” Retrieved from: https://ceprofs.civil.tamu.edu/.../GeoRAS411/

Nasser, M. (2010). Malevolent Floods of Pakistan 2010-2012. SPO

NATIONAL CLIMATE CHANGE POLICY. GOVERNMENT OF PAKISTAN, Ministry of Environment. Draft National Climate Change Policy, 2011.

USACE (2005). HEC-GeoRAS, GIS Tools for support of HEC-RAS using ArcGIS, User’s Manual, Version 4. United States Army Corps of Engineers, Hydrologic Engineering Centre, Davis, California.

USACE (2006). HEC-RAS, River Analysis System, User’s Manual, Version 4.0. United States Army Corps of Engineers, Hydrologic Engineering Centre, Davis, California.

Winston, Y., Yi-Chen, Y., Andre, S., Donald, A., Casey, B., James, W., Dario, D., Sherman, R. (2010). The Indus Basin of Pakistan. The Impacts of Climate Risks on Water and Agriculture.

Young, W.P. (2013). The Environment and Climate Change Outlook of Pakistan. UNEP 2013.