Prof. M. S. Mohan Kumar and Usha Manohar Department of Civil Engineering and CiSTUP Indian Institute of Science - Bangalore

Transcription

1 Water and Water Distribution Networks in Urban Areas Prof. M. S. Mohan Kumar and Usha Manohar Department of Civil Engineering and CiSTUP Indian Institute of Science - Bangalore

2 Urban Water Supply Water is a precious natural resource and one of the most essential requirement of all living beings. Regions with the highest growth rate are not having access to water both in terms of quantity and quality. Indian cities receive intermittent water supply. Need is to understand Quantity is not sufficient and Quality is deteriorating 2

3 Major source of supply Piped water supply in cities Intermittent and erratic Pressure is not acceptable Inequalities in service provision between the rich and the poor High rate of water losses form the distribution systems. 3

4 Issues and Challenges Population growth and urbanization Growing urban water demand Infrastructure is aging and deteriorating Increased pollution from municipal and industrial discharges Overexploitation of water resources 4

5 Water Supply in Indian Cities Source: Central Pollution Control Board 5

6 Impact of Water on Living Conditions Inadequacy in the quantity and quality of drinking water unsafe water Inadequate infrastructure in the disposal of wastewater poor sanitation Unsafe water and poor sanitation leading to poor hygiene and water-related diseases 6

7 Capacity of Piped Water Supply in Bangalore city Source Established during (Year) Potential (MLD) Actual Supply (MLD) 1. Arkavathi River a) Hesaragatta b) T.G. Halli Cauvery River a) Stage I b) Stage II c) Stage III d) Stage - IV -Phase I e) Stage IV Phase II* 2011* 500* 500* Total * The Cauvery Water Supply Stage IV-Phase-II is under implementation and will be completed by 2011 ** The quantity from TG Halli (60 MLD) might be very less in these days 7

8 Supply and demand gap The supply cannot meet the demand. The Unaccounted For Water is about 35-40%. To meet the deficit other sources of water are tapped. BWSSB is also supplying water through its 6750 borewells and 22 water tankers. Comparison of Water Demand and Supply in Bangalore City (Source: Mallick and Vasudevan, 2008) 8

9 Groundwater Scenario in Bangalore City Groundwater plays an important role in the total water supply of the city. 40% of the population of Bangalore is dependent on groundwater. Number of borewells in the city is ranging from 200,000 to 400,000. Overexploitation and poor management have contributed to groundwater depletion and quality problems. 9

10 Present Scenario of Water Supply BWSSB has divided Bangalore in to six zones. Calculation of water consumption. Piped water supply population and per capita consumption in each zone. Groundwater - Assuming 50% of the borewells are dry, and the remaining borewells yielding about 1.5lit/sec, with a pumping of 2 hours duration per day. 10

11 Piped and Groundwater Supply Zone Surface Water (MLD) Groundwater (MLD) Central North West East South South East Total BWSSB Zonewise Piped Water Supply and Groundwater Consumption 11

12 Water Distribution Systems Includes water utility components pumps, valves, reservoirs, storage tanks, fittings to distribute finished water to consumers A major infrastructure and an asset of water supplies Designed to provide adequate water of acceptable quality 12

13 Water Distribution System Integrity Maintain physical barrier between distribution system interior and external environment physical Maintain desirable water flows, pressures, water age Maintain disinfectant residual, bio-stability, prevent contamination Hydraulic Quality 13

14 Integrated Approach to Manage WDS Integrity On-line real time monitoring program Data integration Analytical (modeling) methods Research and developmental strategies 14

15 Modeling Methods Models can be used for analysis of the existing system to improve the supply in terms of pressure / flows/ minimize leakage Design of new system to address issues regarding engineering / economics Models are very flexible - a variety of analysis, design solutions could be arrived at easily Models could also lead to real time operation of the water distribution system 15

16 Water Distribution System Modeling Water Distribution System Modeling Hydraulic Model Water Quality Model 16

17 Hydraulic Modeling Model the system to predict pressures / flows Representation of the system through mass conservation and energy conservation equations Node based / loop based approaches Model mimics the real system 17

18 Water Distribution Modeling Tools User friendly existing models EPANET Performs extended period simulation of hydraulic and water quality behaviour. Tracks the flow of water in each pipe, the pressure at each node, the height of water in each tank, and the concentration of a chemical species. Water age and source tracing can also be simulated. 18

19 Water Quality Models Models movement of non-reactive and reactive chemical species with time Tracks percent of flow from a source node to other nodes over time system operation can be based on both simple tank level or timer controls 19

20 Decision Support Systems Control Algorithms To maintain equitable distribution among different reservoirs To minimize leakage Automated throttling to achieve targeted flows Automated pump speeds to increase efficiency Automated chlorine / booster injection for uniform quality distribution 20

21 Controls in water supply systems To reach the targets/set points (reservoir flows / levels) To reach the targets as fast as possible To ensure the smoothest possible operation of valves/pumps To control the slow transients For real time operation monitored by SCADA Particularly useful for complex pipe networks 21

22 Introduction to different controllers PID/PD/PI controllers - Proportional Integral (PI) controller, Proportional Derivative (PD) controller and Proportional Integral Derivative controller (PID)-most commonly used controllers. -Have been in use in different forms since long time. -Works well for linear systems Dynamic inversion based controllers: - Nonlinear control design - Technique of feedback linearisation - Output tracking problems - May be implemented as PD, PI or PID 22

23 Contd. PD Controller: u K p e K d de dt PID Controller: Where K p Proportional Gain K d Derivative Gain K I Integral Gain u K p e K d de dt K i edt Dynamic Inversion based controller: u. 1. g ( X ) X f ( X ) des X f( X) g( X) u

24 Clean Water for Healthy Living Conditions To provide secured and safe water Secured adequate amount of water Safe suitable quality is maintained of water To improve environmental sanitation Increase sanitation coverage To increase hygiene and health care Improve quality of water supply sources and storage facilities 24

25 Management of Treated Water during Distribution and Storage Regulation for maintaining water quality standards in distribution systems Maintain minimum residence time Regular monitoring at storage and other junctions Flushing and maintenance of storage facilities 25

26 Management Concepts Modeling of GIS based WDS Equitable supply of water among consumers Pressure regulation in the network Minimization of UFW 26

27 Modeling of sensor network to get the real time operation of the system Modeling of Reliability, resilience and vulnerability of the network Asset management plan Management Concepts

28 Model Application Test Problem 3 Used for Conservative and Reactive Constituent Tank details Diameter Initial height Minimum height Maximum height m m m m First order chlorine reaction constants used Bulk reaction constant 0.55 /d Wall reaction constant 0.15 m/d 28

29 Test Problem (Conservative Constituent) 29

30 Test Problem (Reactive Constituent) 30

31 Model Application to a Network Problem 203 First order chlorine reaction constants used TOC 3.55 mg/l (Lake) 0.56 mg/l (River) Wall reaction constant Zone m/d Zone m/d Zone m/d Zone m/d Chlorine Conc. At Lake: 0.49 mg/l River: Varies between 1.00 and 1.50 mg/l 31

32 Case (i) Chlorine concentrations 32

33 Case (i) Substrate concentrations 33

34 Case (ii) Chlorine and Biomass concentrations 34

35 Case (ii) Substrate concentrations 35

36 Studies on Application of Control Systems for Urban Water Networks

37 Schematic diagram of the Gaziantep (Turkey) water supply system - Test Problem 37

38 Data for Gaziantep water supply system l p1 = m h s1 = 113.4m D=1.4 m l p2 = m h s2 = 210.4m A 0 = l p3 = m h s3 = 283.4m B 0 = l p4 = m h s4 = 279.7m C 0 = 3.98 A pi = m 2 A t = 475 m 2 n = 1 Pump Rated Discharge Pump Rated Speed 2830 lit/sec 985 rpm Initial Reservoir levels 3.20 m,2.15 m,4.20 m Targeted Reservoir levels 4.0 m,2.50 m,3.91 m 38

39 Target outflow rate (Qo * ): 2.4 m 3 s -1 Target reservoir levels (h t1 *, h t2 *, h t3* ): 4.0 m, 2.5 m and 3.91 m 1 st Initial condition: X(0) = = (2.83, 3.20, 2.83, 2.15, 2.83, 4.20, 2.83) T 2 nd Initial condition: X(0) = = (2.20, 3.50, 2.20, 2.70, 2.20, 3.80, 2.20) T Case 1: Constant set point over the time period T a t b t c t o Q h Q h Q h Q T a t b t c t o Q h Q h Q h Q 39

40 Error plots and Variation in pump speeds 40

41 Bangalore city water supply system Test problem Salient features Inflow 673 Mld Cauvery Stages I (132), II(131), III(294) and ARK(116) 48 reservoirs spread over 2190 sq.km Several reservoirs on one complex 26 pumps Diameter 1750 mm to 150 mm Type of pipe and age MS, CI, DI etc, new to 50 year old 41

42 Schematic diagram of the Bangalore water supply system - Test problem 42

43 Targeted Inflows to the Ground Level Reservoirs S.No Reservoir Targeted Inflow Mld 1 KGR 40 2 KUM 10 3 BSK 35 4 BTM 10 5 BTR 75 6 MNK 7 7 BYR 50 8 MR 6 9 AER HGR 50 43

44 S.No Reservoir Targeted Inflow Mld 11 LLR WCR BCR KMH CJF KGT I MBR CLR 20 Total

45 Error (1-9) plots for flows - Test problem 45

46 Error (10-18) plots for flows - Test problem. 46

47 Variation in valve loss coefficients (1-9) - Test problem 47

48 Variation in valve loss coefficients (10-18) - Test problem 48

49 Thank You 49