zoning by using GIS and RS techniques. Anam Munawar Assistant - - PowerPoint PPT Presentation

Flood prone area’s mapping, modeling and zoning by using GIS and RS techniques.

Anam Munawar

Assistant Manager GIS The Urban Unit

M.Phil. Space Sciences

Department of Space Science

University of the Punjab.

 Basic Essentials of research Work  Introduction to study area  Methodology/flowchart  Input Data  Outcomes/Findings  Results & conclusions  Recommendations

Presentation Scheme

Basic Essentials of Research work

Theme of Research work: This Research focuses on practical

applications of GIS tools for flood hazard mapping and resource management.

Emphasized Field: This research visibly illustrates how to use GIS

and RS to make flood hazard assessment and management easier

to do and increase productivity while addressing water, floodwater and storm water systems.

Introduction to Flooding..

When the amount of water level rises up to a certain level, after which the capacity of that particular water body ends, it results in overflow of water in the surrounding land. This phenomenon is termed as “flooding”.

 Flash Floods:

Floods that can occur in a very short period of time due to heavy amount of rainfall associated with a thunderstorm. Flash floods lasts for may be a few minutes or some hours. It is difficult to be monitored and processed because of its shorter duration and localized nature.

 Coastal floods: Floods that can me be resulted due to flash flooding or tidal

surges.

 Riverine Floods: Floods that occur when amount of water rises due to heavy

rainfall or melting of ice.

 Dam Failure floods:

The worst form of flood occurs, when a dam fails working, as the strong speedily moving downward water destroys everything that comes across.

FLOOD MANAGEMENT TECHNIQUES STRUCTURAL METHODS need more

budget and physical developments to take place for protection measures before/during or after the exposure of floods.

NONSTRUCTURAL METHODS involves

preprocessor alarms, future forecasts and planning before flood comes for fewer damages to occur. That’s why; non structural techniques are being more preferred in recent many decades as these are cheap and effective.

Non-

Study AREA

District Muzaffargarh, Pakistan.



stripped between River Indus and River Chenab



In case of any disturbance in the water level of these rivers or their tributaries, there will be a direct impact on the study area.



Major area of the district is composed of barren land and sand dunes.

Technical Requirements …

Below is the list of soft wares, which were used during different phases of this research work:

 ArcMap 9.3  ERDAS IMAGINE 9.2  HEC_RAS 4.0  Google earth pro 4.2

Input Datasets/Sources…

For flood mapping, all flood data layers was provided by THE URBAN UNIT. The last 20 years Rain fall data and other metrological data was retrieved from Pakistan Metrological department, Lahore. Hydrological data was obtained from Punjab irrigation department. DEM with 15m resolution and Satellite image

• f Landsat ETM Plus with 30m resolution were

downloaded from the website www.glcf.com.

Research workflow chart

Flood zones are the

land areas that are defined as less or more hazardous

• n the basis of future risk

levels.

Flood zonation

is found to be fundamental line

• f

attack for suitable development and for investigation of the ecological and environmental consequences.

Raster processing based mapping

This RS based land use Map is showing that vegetation has the maximum area covered in District Muzaffargarh. Water and Urban infrastructures are also capturing large significant area.

Irrigation Network

Vector Data based mapping

Flood Affected Areas(2014)

HYDRAULIC MODELS routes the runoff to determine the surface

water profile via stream channels at particular locations along the stream network. GIS based hydraulic models can apply/use different data layers containing different land parameters like land use and drainage network etc. but the basic component of all hydraulic models is DEM with the help of which we can determine stream channel network, water level depth, slope, aspect and many other characteristics of water channels.

Floodplain models are mainly of two types: Hydrologic models Hydraulic Models Hydrologic model identifies the peak flood flows.

All hydraulic model development is completed in following three steps.

 Pre-processing of data  Model execution  Post-processing of model

 Collection of necessary data for the floodplain analysis can be

• rganized as:

a) Topographic data b) Obstructions data c) Hydrologic data Topographic data involves Cross Sections Data for the given Rivers and streams and reach length etc. Obstruction data involves bridges and culverts of cross sections. However, the hydrologic data involves the discharge rates for the storm of interest.

Data for Flood Plain Modeling

 Data has been collected from the following departments:  Pakistan Meteorological Department  Irrigation and Power Department WAPDA  Internet Resources

For HEC RAS modeling following data was collected.

 River cross sections  Recorded peak flood data (Long Term)  Peak flood data 2010  DEM of the area

DEM for the Study area

Watershed Delineation

After DEM has been preprocessed to be used for the watershed delineation, by using Hydrology tools in Arc map, flow direction and flow accumulation were investigated to delineate watershed. Major DEM applications include (USGS, 2000):

• Delineating watershed boundaries

and streams

• Developing parameters for

hydrologic models

• Modeling terrain gravity data for use

in locating energy resources

• Determining the volume of proposed

reservoirs

• Calculating the amount of material

removed during strip mining

• Determining landslide probability

Flow Length

Flow length is the distance travelled

from a given cell to the outlet along with the surface flow network. It is helpful for identifying areas that are closer to headwater or near the stream outlets. Flow Length

Watershed basin

Digital Elevation Model is the main part for flood model building in Hec-Ras as all the watershed information and other important hydraulic parameters are derived from DEM. All hydraulic model development is completed in following three steps. 1.Pre-processing of data 2.Model execution 3.Post-processing of model HEC_GeoRaS is an extension of the arc map that was used for pre-processing of the GIS data Using different functions and applications of HEC_GeoRAS, the GIS data can be obtained in a format which is required for input to the HEC RAS. HEC-GeoRas toolbar contains the following menus:

Ras Geometry

Ras Geometry menu contains functions for pre processing of the GIS data and makes layers in a format that can be imported in Hec-Ras directly.

RAS Mapping

Flood inundation mapping is done by using functions of RAS Mapping that is used for post processing of the HECRAS processed output data. It also contains the functionality for data visualization

ApUtiliteis

ApUtilities contains data management tools.

Help

The Help menu is self explanatory. It provides help for any kid of issues relevant to data handling and management in HEC_GeoRAS.

UPSTREAM AND DOWNSTREAM DISCHARGE AT TARBELA DAM (2011)

The figure is showing the water discharge flow at Tarbela dam for the year of

• 2011. Results have shown that downstream discharge flow values are two times

greater than that of the upstream discharge flow values.

Maximum Discharge peaks at Chashma, Tounsa and Marala barrages for the last 20 years. [SOURCE: PAKISTAN METROLOGICAL OFFICE, LAHORE.]

RIVER X SECTIONS

The data for river cross sections were taken from Irrigation and Power Department. River sections are drawn and shown in the figures shown below.

Indus River Cross Section RD 137,000 Indus River

Indus River Cross Section RD 147,000 with Cross Section RD 160,000

With the help of DEM data catchment delineation was carried out and shown in the following Figures:

Flood Frequency Analysis (Source: Wenner 2010)

Catchment Delineation

SherShah-Punjnad 400 390 380 370 360.19 350.20 340.21 330.22 320.23 310.24 300.25 280.27 260.29 250.30 240.31 220.33 210.34 C hen ab R i ve r Tounsa-Muzgrh 100 90 80 70 60.17 50.18 40.19 30.20 20.21 10.1 9.5 9.1 I n d us R i ver Low er Reach 50.1 40.2 Junction

HEC GEORAS MODELING RESULTS

• Schematic diagram

developed for HEC- RAS modeling.

• extent of flooded

area is shown in the next following Figures:

CONCLUSIONS…

 Peak floods in Muzaffargarh area can cause severe damage in the district due to

location of the area in between two rivers vs Indus and Chenab. Due to peak floods from Indus River, maximum flood water surface elevation may reach upto 414 feet from sea level. Therefore the area lying below this elevation will be flooded.

 Due to peak floods from Chenab River, maximum flood water surface elevation may

reach upto 402 feet from sea level. Therefore the area lying below this elevation will be flooded.

 Wheat, sugarcane and cotton are the main crops grown in the district. Rice, jawar,

bajra, moong, mash, masoor, ground nuts, maize and oil seeds such as rape / mustard and sunflower are also grown in minor quantities in the district. Mangoes, dates, citrus and pomegranate are the main fruits grown in the district. Onions, carrots, cauliflower and peas are the main vegetables grown in the district. These will be damaged due to flooding.

 An area of 100,864 acres is forested in the district. There is also linear plantation of 1250

A.V. mile the roads/rails/canals in the district.The district's major industries include cotton ginning and pressing, flour mills, jute textile, oil mills, paper/paperboard articles, petroleum products, polypropylene bags, power generation, readymade garments, solvent extraction, sugar, textile composite and textile spinning. These will be damaged due to flooding if measures are not taken up.

 Lal Pir Thermal Power station, the most efficient power plant in Pakistan. is located in

• Muzaffargarh. The Thermal Power Station TPS is also located in Muzaffargarh. These

areas are also under threat for flooding.

RECOMMENDATIONS…

Results of this research work present critical implications for the flood damage deduction in the study area. This will be highly beneficial to lessen the economical losses to the country that it has to suffer almost every year due to flooding. Land use planning on the basis of flood risk zones is a proposition for all the decision makers. According to the conception of this study, flood losses can be reduced by building land use development in a systematized manner. Once the flood prone areas have been identified precisely then secure utilization of this land should be developed accordingly.