Impact of Climate Change on tarbela dam water reservior and water resources

                       INTRODUCTION TO OUR FYP  CLIMATE CHANGE: ?Climate Change is a change in the pattern of weather , and related changes in oceans , land surfaces and ice she

Project Title

Impact of Climate Change on tarbela dam water reservior and water resources

Project Area of Specialization

Shared Economy

Project Summary

                       INTRODUCTION TO OUR FYP 

CLIMATE CHANGE:

ØClimate Change is a change in the pattern of weather , and related changes in oceans , land surfaces and ice sheets , occurring over time scales of decades or longer.

ØA change of climate is attributed directly or indirectly to human activity that alters the composition of global atmosphere.

ØPakistan lies in temperature climate zone , which itself contributes very little to Green house gases , yet it remains one of most hitted country in world by global warming.

Hindukush-Karakoram-Himalaya (HKH):

ØHindukush-Karakoram-Himalaya (HKH) region is actually a global asset. HKH area is the biggest reserve of ice and snow other than the Polar Regions.

ØThis area comprises about 54,000 glaciers having 6,000 km3 ice volume; 60,000 km2 area, while the cover of snow in this area is about 0.76 million km2 .

ØDue to global warming, there is rapid shrinkage in solid state water leading to increase in melt water causing flash floods and flow variations.

ØIt has been observed in the HKH region, that during past few decades that over the Himalayan high mountain belt, in the east specifically, there is an increase in the monsoon precipitation.

TARBELA DAM:        

ØTarbela dam is the largest earth filled dam of the world , Which became operational from the year 1970.

ØThe primary objective was to supply water for irrigation by storing flow during monsoon period and hydropower generation.

Ø Its hydroelectric power capacity is 4888MW and expected to be increased to 6298MW.

Ø Tarbela dam reservoir is 80km long and surface area is of 250km² and storage capacity of 11.6MAF and live storage is of 9.7MAF.

PROBLEM STATEMENT

ØWith passing time the climate is changing globally and regionally with an unexpected rate due to which the glaciers are melting as a result effecting the water flow of rivers , causing excessive sedimentation in dams, while abnormal rain cycles  causes flood and drought in different regions.

ØIndus river basin play’s a significant role to the economy of Pakistan by contributing 32% out of 36% electricity and 44% available water  for irrigation of crops and stabilization of eco system .                        

ØOver the past 38 years live storage capacity of Tarbela dam reservoir has declined by 33.5% from 6.434 MAF against its original capacity of 9.679MAF .

ØConsidering the above statistics , we are determined to use new Hydrological Models and Software's to predict the impact of climate change on tarbela dam water reservoir and flow variability.

SEDIMENTATION AT TARBELA DAM

Tarbela reservoir has experienced severe sedimentation, leading to the loss of one third of its total volume due to the accumulated sediment deposits.

 In addition to losing the volume and thus capacity to regulate the flow for irrigation, the advancing sediment deposits potentially present a threat to the operation of the dam.

 An important part of the project was dedicated to the collection of new field data, particularly regarding sediments.

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Project Objectives

Potential Outcomes / Practical Applications :

1)Our study will assess spatial and temporal flow variability to identify drought and flood periods using flow data from Indus river.

2) To maximize hydraulic outflow  for the purpose of controlling the flooding downstream of Tarbela.

3)To ensure an increase in sustainability and resilience to future uncertainties of climate and irrigation and hydropower demand.

4)Potential change in life span of the dam due to sediment transport

Due to excessive sedimentation , the storage capacity of Tarbela dam is decreasing rapidly which is a matter of serious concern.This ultimately effects the  Agriculture , Hydropower Energy generation and Flood control by conserving snow melt and monsoons flows of Indus River.

 Tarbela reservoir has experienced severe sedimentation, leading to the loss of one third of its total volume due to the accumulated sediment deposits. In addition to losing the volume and thus capacity to regulate the flow for irrigation, the advancing sediment deposits potentially present a threat to the operation of the dam. Rising sediment levels near the dam may block the low-level outlets and impede their continual operation. Sand-sized sediment are starting to pass into the hydropower intakes and this will cause abrasion of turbine blades, leading to increasing cost of maintenance and time when the turbines are out of operation.

Project Implementation Method

 MAIN CONSIDERATIONS (RESEARCH METHADOLOGY) 

 1) Key informant analysis – which aimed to identify who is doing what in the area of climate change and hydrology in Pakistan.

 2)  Water supply analysis – the most significant portion of the project, this component involved preparing a synthesis of the current state of knowledge regarding how water flow levels in the Indus River Basin may or may not change in the future, based on a systematic review of existing literature.

 3)  Water demand analysis – which aimed to summarize current understanding of projected changes in water demand in Pakistan, providing a basis of comparison with projected changes in water supply.

 4)  What are the implications of a changing climate for three key sectors—energy, agriculture and health—based on the outcomes of the water supply and demand assessments?

 5) What are the main research gaps related to the projected changes in water supply and what interventions are needed to address these gaps and strengthen capacity?

 DATA AND METHADOLOGY / PROJECT IMPLEMENTATION METHOD:

 1) The daily inflow, demand, and physical data for reservoir inflow and release measurements shall be obtained from WAPDA or any other operating authority.

 2) The primary objective of the project is to assess the impact of different sediment management strategies, including flushing, at the reservoir and downstream infrastructure at the Indus River.This is however a practical step as we have to deal with sediment samples , their source and their measurements across the rivers.

 3)Use of GIS for Hydrologic and Hydraulic modelling.

Different softwares like ARC GIS shall be used for spatial data analysis and to determine the detailed impact of sediment releases on bed levels and sediment concentrations of two downstream impoundments: Ghazi Barotha, located 7 km downstream of the Tarbela dam, and Chashma, about 250 km downstream of the Tarbela dam. We have to visit both the sites for detailed inspection and collection of data.

4)Raster Map of Potential Extreme Peak Discharges: Potential  extreme peak discharges are estimates of the highest peak discharge expected to occur at a  certain location. Yhis chapter explains the process of generating a raster map (i.e., grid) of  the precomputed values of potential extreme peak discharges in GIS for a particular  watershed.

5) Flood Flow Calculator: the development of an ArcView extension that calculates watershed parameters, peak discharges, isochrone lines,  and runoff curve numbers using GIS.

6)Rainfall Runoff Model: This deals with the development of   a system of ArcView scripts and associated controls that extract topographic, topologic, and hydrologic information from digital spatial data of a hydrologic system.

7)Detailed Drone Surveys.

8)Soil censor sample experiments.

 

Benefits of the Project

1)We will be able to determine the life span of tarbela dam , which is of prime importance as our country Pakistan maybe facing water scarcity in the future according to current situation of Pakistan.

2)We would be able to suggest the ways that would tackle with issues of Agriculture as it would really give a rise to Pakistan's Economy.

3)Our research would suggest ways of increasing hydropower generation through tarbela dam as in current situation sedimentation has reduced one by third the capacity of reservior.

4)This research would suggest the ways to control floods which may take place in the future due to severe Climate Change.

5)Instantaneous collaboration through the cloud.

6)Improved decisions by gonernment officials.

7)Improved allocation of resources and planning.

Technical Details of Final Deliverable

Tarbela dam plays a vital role in Pakistan's economy as it is a major resource of irrigation water and electricity generation. Its reservoir has been rapidly filling since its start due to sediment transported and deposited by Indus River. In this study, a numerical model is realized taking in account different morphologic parameters and hydrodynamic processes to predict the evolution of sediment deposits due to river bed erosion and settling velocity in the reservoir

Globally the average annual loss of reservoir capacity is approximately 1%. Pakistan is confronting major issue of sedimentation which is continuously depleting the useful storage of reservoirs. GSTARS3 model was used to determine the rate of deposition and sediment pattern of Chashma Reservoir since its operation. The model was calibrated and validated for bathymetric survey of 2008 and 2012. The results of GSTARS3 shall be incorporated to a GIS software to visualize sediment accumulation in reservoir. The study reveals that sediment flushing of the Chashma Reservoir can be carried out during flood season at a pond level of 638.15 ft. (194.51 m). However, its negative impact if any on the hydropower generation needs to be analysed. 

Data collection

Following necessary data were collected and used for GSTARS3 sediment transport model:

Geometry data

Cross-sectional geometry was defined by X–Y coordinate which is a lateral location and bed elevation. Lateral locations (X) were given using a reference point for each cross section, and the coordinate pair was entered in order of increasing X coordinate, i.e. starting from the left-hand side of the cross section and marching towards the right-hand side (looking downstream).

Hydrological data

Hydrological data include water discharges, temperatures and water surface elevations. Daily discharge data for tarbela dam for the year 1971–2012 was collected from surface water hydrology project (SWHP), WAPDA.

Sediment data

Sediment data comprise of bed gradation data and sediment inflow hydrograph. Bed gradation data and suspended sediment load data for D/S of Jinnah Barrage was collected from WAPDA and sediment gradation curve for suspended load was plotted. Particle size distribution at D/S of Jinnah Barrage showed that suspended sediment load comprises of 18% clay, 75% silt and 7% of sand.

Calibration of model

The model shall be calibrated by simulating the observed sediment deposition from the year 1971 to 2008. By slightly adjusting the Manning’s “n” value and using eight-sediment transport function, a good agreement between measured and simulated values can be found.

Validation of model

The validation of model is done to evaluate its performance by using the parameters which were adjusted during calibration process.The validation of model is performed by using the bathymetry data for the year 2008 to 2012 using Yang’s 1973?+?84 sediment transport function. 

Final Deliverable of the Project

Software System

Core Industry

Energy

Other Industries

Agriculture , Food , Others

Core Technology

Shared Economy

Other Technologies

Others

Sustainable Development Goals

Affordable and Clean Energy, Decent Work and Economic Growth, Industry, Innovation and Infrastructure, Responsible Consumption and Production, Life on Land

Required Resources

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