Hydraulics and Hydrology Lec

48362 – HYDRAULICS and HYDROLOGY James E Ball – Hydrology Component SUBJECT DETAILS 1 CONTACTS ? Assoc Prof James Ball ? ? ? james. [email  protected] edu. au ph – 9514 2623 Office Hours ? ? Monday 2:00 – 4:00pm Contact by email for appointment SUBJECT CONCEPT The objective of this component of the subject is: ? Introduce engineering hydrology; ? Introduce hydrological processes; ? Introduce flood estimation; and ? Introduce engineering hydrology applications in water resources management. 2 SUBJECT CONCEPT This introduction is aimed at: ? Providing an ability to apply commonly used methods in hydrology; and ?Provide an understanding of the theory behind these methods. REFERENCES Three references that may be useful are ? Applied Hydrology – Chow, Maidment & Mays, McGraw-Hill Book Co. ? Hydrology An Australian Introduction – Ladson, Oxford University Press ? Australian Rainfall & Runoff – A Guide to Flood Estimation – Engineers Australia No published Course Notes are available for this subject. 3 SUBJECT DOCUMENTS UTS-Online will be used for distribution of ? Copies of lecture slides; ? Reading material; and ? Tutorial problems. Students should note that additional reference books may be noted in the lecture slides.LECTURE STRUCTURE Each Hydrology lecture period will comprise: ? 2 hour lecture; and ? 1 hour tutorial. It is expected that students will have accessed the lecture slides, reading material and tutorials prior to the lecture period. 4 SUBJECT TIMETABLE Date Topic 27 February Hydrology and Water Resources 5 March Meteorology 12 March Hydrologic Data 19 March Surface Water 27 March Storm Runoff 2 April Hydrologic Design 9 April Design Rainfall 1 May Peak Flow Estimation 7 May Hydrograph Estimation – Part 1 13 May Hydrograph Estimation – Part 2 14 May Environmental Flows 21 May Water Sensitive Urban Design 4 JuneCourse Review HYDROLOGIC CYCLE Lecture 1 5 CONTENT ? Introduction to Hydr ology ? Development of Hydrology ? Hydrologic Cycle ? Australian Hydrology INTRODUCTION 6 DEFINITION OF HYDROLOGY Greek word: Hydor => water & ology => study of Hydraulics comes from Greek word hydraulikos which in turn comes from hydor (Greek for water) and aulos (meaning pipe). DEFINITION OF HYDROLOGY UNESCO (1979)1 defines hydrology as â€Å"the physical science which treats the waters of the Earth, their Occurrence, Circulation and Distribution, their Chemical and Physical Properties, and their Reaction with the Environment†. UNESCO, (1979), Impact of urbanisation and industrialisation on water resources planning and management, Studies and Reports in Hydrology, UNESCO, UNESCO, Paris. 7 WATER Water is essential for maintenance of life. Early civilisations were concentrated on rivers ? ? establishment of settlements near rivers analogous to looking for signs of water on Mars Management of water is multi-disciplinary; many professions are involved. WATER Variety of problems encountered include ? Flood mitigation ? Sanitary sewer systems ? Land drainage ? Water Supply ? Culvert and bridge design ? Environmental Flows ? Erosion ?Mine tailings ? Drought ? Adaptation to climate change ? Irrigation systems ? Hydro-electric and power generation ? Stormwater systems 8 RURAL FLOODING URBAN FLOODS 9 STORMWATER STRUCTURES STORMWATER DRAINS 10 WATER SUPPLY HYDRO-ELECTRIC POWER 11 IRRIGATION SCHEMES DROUGHT 12 DEVELOPMENT OF HYDROLOGY Ancient civilisations were integrated with their river valleys. Examples are ? ? ? ? ? Egyptian Civilisations and the Nile Valley Mesopotamian Civilisations and the TigrisEuphrates Indian Civilisations and the Indus Valley Ancient China and the Yellow River Andean Civilisations and Coastal Peru DEVELOPMENT OF HYDROLOGYMany of structures from early civilisations are still in operation. Large scale irrigation and drainage works were associated with these civilisations. Earliest recorded dam is about 2900BC (the Sadd Al-Kafara at Wadi Al-Garawi, 25km south of Cairo) Used for both flood protection and irrigation. Also site of earliest known dam failure. 13 DEVELOPMENT OF HYDROLOGY Oldest surviving dam in the world is the Grand Anicut Dam on the Kaveri River in Southern India. This structue dates back to 2nd Century AD. DEVELOPMENT OF HYDROLOGY Water supply to Ancient Rome has been estimated as being approx 500L/c/d.Current water supply requirements are ? ? ? Australian cities, design – approx. 430L/c/d Australian cities, actual – approx. 230L/c/d US cities, design – approx 600L/c/d Drainage structures (such as the Cloaca Maxima) from Ancient Rome are still being used today. 14 ANCIENT ROMANS Cloaca maxima Bath, UK AQUEDUCTS Pont du Gard, France c19 BC Hampi, India 1st century AD 15 DEVELOPMENT OF HYDROLOGY Flood protection has been practiced for thousands of years along the Yellow and Yangtze Rivers. It remains an issue of concern in these areas to the current day. DEVELOPMENT OF HYDROLOGY Wat er has been of interest for many years.Ancient Greek and Roman philosophers speculated on a hydrologic cycle – Homer, Plato, Aristotle, Lucretius, Seneca, Pliny. This cycle was developed from their observations of water in their environment. Use of observations remains a fundamental component of current hydrologic applications and research. 16 DEVELOPMENT OF HYDROLOGY Chinese recorded observations of rain ? ? ? An-yang oracle bones as early as 1200BC; Used rain gauges around 1000BC; and Established systematic records about 200BC. Indian records date back to 400BC. DEVELOPMENT OF HYDROLOGY Scientific development of hydrology occurred uring the Renaissance period. Examples are ? ? ? Leonardo da Vinci – velocity distributions in streams. Bernard Palissy – springs originated from rainfall. Pierre Perrault – runoff is a fraction of rainfall. 17 DEVELOPMENT OF HYDROLOGY Other contributions during this period were made by ? ? ? ? ? Galileo Newton Bernoulli Euler Lagrange DEVELOPMENT OF HYDROLOGY Significant scientific development occurred in the 19th Century when ? ? ? ? ? Dalton proposed the principle of evaporation. Hagen-Poiseuille described capillary flow. Mulvaney developed the Rational method. Darcy described mathematically porous media low. Rippl developed methods for determining storage requirements. 18 DEVELOPMENT OF HYDROLOGY 20th Century saw rapid development of quantitative hydrology. Biggest influence during this period was the development of the digital computer and the development of catchment modelling systems. Limitation now is data availability rather than calculation capacity. HYDROLOGIC CYCLE 19 HYDROLOGICAL CYCLE One of the fundamental cycles of nature. Basis for the science of hydrology. Important points ? ? ? ? Cycle has no start and no end. Cycle is continuous. Flow of water in the cycle is not continuous.Water moves erratically through the cycle. HYDROLOGICAL CYCLE 20 HYDROLOGICAL CYCLE HYDROLOGICAL CYCLE 21 HYDROL OGICAL CYCLE HYDROLOGICAL CYCLE General components of the cycle are ? Atmospheric Water ? Surface Water ? Ground Water In analysis of water resource problems, these components are treated with a systems approach. 22 SYSTEMS CONCEPT A systems concept is applied when considering the hydrological cycle or some component thereof. This is consistent with the reductionist concept used in many engineering problems. SYSTEMS CONCEPT The reductionist philosophy is based on reducing the system to a number of smaller omponents. The response of the system then is determined from summation of the responses of the individual components. 23 SYSTEMS CONCEPT WATER BALANCE 24 WATER BALANCE Amount of water does not change. Where it may be found does change. Water maybe found in the seas and oceans, in the atmosphere, on the surface, below the surface, and in biological systems. WATER BALANCE ITEM Oceans Polar Ice Groundwater Lakes Soil Moisture Atmospheric Water Rivers Biological Water ?Water VOLUME (k m3) % TOTAL WATER 1. 338 x 109 96. 5 24. 0 x 106 1. 7 23. 4 x 106 1. 69 187. 9 x 103 0. 0138 16. 5 x 103 0. 0012 12. 9 x 103 . 001 2. 1 x 103 0. 0002 1. 1 x 103 0. 0001 1. 386 x 109 100. 0 UNESCO, 1978 – ref 11, ladson ch1 25 WATER BALANCE Not all water is freshwater. Only approx 2. 5% of the water is fresh water – water in the oceans and some lake water and ground water is saline. Considering only fresh water, the values in the previous table are modified to WATER BALANCE UNESCO, 1978 ITEM VOLUME (km3) % TOTAL WATER Polar Ice 24. 0 x 106 68. 6 Groundwater 23. 4 x 106 30. 1 103 0. 26 Soil Moisture 16. 5 x 103 0. 05 Atmospheric Water 103 0. 04 Rivers 2. 1 x 103 0. 006 Biological Water 1. 1 x 103 0. 003 Fresh Water 35. 0 x 106 00. 0 Lakes 187. 9 x 12. 9 x 26 WATER BALANCE Basis of any volume based problem is a water balance. This is a usage of the concept of continuity. In general, application of continuity gives in volume terms Inflow – Outflow = Change in Stora ge (? S) And in flux terms Qi – Qo = ? S / ? t WATER BALANCE Components of inflow for a water body such as a lake or reservoir are ? Precipitation (P) ? Inflow from rivers or groundwater (I) 27 WATER BALANCE Components of outflow for a water body such as a lake or reservoir are ? Evapo-transpiration (ET); ? Outflows – Extractions, Downstream flows, (O); and ? Seepage (G)WATER BALANCE Hence the water balance for a water body is P + I – O – ET – G = ? S 28 WATER FLOWS While the volume of water in a source is important, the flux of water through a component is important also. An indication of the flux can be obtained from the diagram of the hydrological cycle. WATER FLOWS The Global Annual Water Balance is shown on in units relative to the annual volume of precipitation on land masses. Note that this is a flow rate (km3/yr). 29 WATER FLOWS ? Precipitation ? ? ? ? Land – 119,000 km3/yr (800mm/yr) Ocean – 458,000 km3/yr (1270mm/yr) Total à ¢â‚¬â€œ 577,000 km3/yr Evaporation ? ? ?Land – 72,000 km3/yr (484mm/yr) Ocean – 505,000 km3/yr (1400mm/yr) Total – 577,000 km3/yr WATER FLOWS ? Runoff to Oceans ? ? ? Rivers – 44,700 km3/yr Groundwater – 2,200 km3/yr Total Runoff – 47,000 km3/yr (316mm/yr) 30 WATER FLOWS Considering the volume and flux gives the mean residence times in a particular source. The mean residence time for atmospheric water is obtained by dividing the volume (S) of water in the atmosphere by the flux (Q), ie TR ? S 12,900 ? ? 0. 022 yr ? 8. 2days Q 577,000 WATER FLOWS ITEM Oceans Polar Ice & Glaciers Groundwater Lakes Soil Moisture Rivers Atmosphere Biological WaterTR 2600 years 1100 years 700 years 13 years 155 days 13 days 8. 2 days 3. 4 days 31 AUSTRALIAN CLIMATE AUSTRALIAN CLIMATE â€Å"†¦of droughts and flooding rains† 32 RIVER RUNOFF Australia has low runoff per unit area (average depth of surface runoff). Also, Australian runoff has greater vari ability due to lack of snow melt period. RAINFALL COMPARISON Variability of Annual rainfall 20 18 Coefficient (%) 16 14 12 10 8 6 4 2 0 A ustralia S. A frica Germany France NZ India UK Canada China USA Russia Country 33 AUSTRALIAN CLIMATE CLIMATE CLASSIFICATIONS Marked wet summer and dry winter of northern Australia.Wet summer and low winter rainfall of southeast QLD and northeast NSW. Uniform rainfall in southeast Australia. Wet winter and dry summer of southwest WA and parts of the southeast. Arid area comprising about half of the continent More on BoM website 34 AUSTRALIAN RAINFALL Pluviometer Network Daily Read Network PRECIPITATION 35 AUSTRALIAN RAINFALL City Average Annual Rainfall (mm) Average Number of Rain Days Darwin 1714 111 Sydney 1217 138 Brisbane 1149 122 Perth 786 114 Melbourne 653 147 Canberra 623 105 Hobart 569 135 Adelaide 530 121 Alice Springs 279 31 After Ladson, 2008 AUSTRALIAN CONDITIONSAustralian rainfall is influenced by general circulation patterns. Most of Australia is around 30o latitude which tend to be areas of descending air. Note – that the solar equator moves during the year. 36 AUST. CLIMATE VARIABILITY Known major causes Approximate time scale Effect Synoptic weather patterns Day / week â€Å"Weather† Southern Annular Mode Weeks +ve phase => winter rainfall deficiencies in southern Australia; summer increases in MDB El Nino / La Nina (Southern Oscillation Index) Inter-annual El nino => lower rainfalls La nina => higher rainfalls Indian Ocean Dipole Inter-annual ve phase => increased rainfall +ve phase => decreased rainfall Inter-decadal Pacific Oscillation Inter-decadal Flip flops between drier and wetter periods e. g. 1st half of 20th century wetter than 2nd half The Australian climate – influences http://www. bom. gov. au/watl/about-weather-and-climate/australian-climate-influences. html 37 The Australian climate – influences The Australian climate – topography 38 Seasonal rainfall variatio n across the country Seasonal rainfall variation across the country Mean rainfall – Katherine mm Mean rainfall – Dubbo mm 240 220 200 180 160 140 120 100 80 60 40 0 0 240 220 200 180 160 140 120 100 80 60 40 20 0 J F M A M J J A S O N J D F Mean rainfall – Alice Springs mm M A M J A S O N D Mean rainfall – Sydney mm 240 220 200 180 160 140 120 100 80 60 40 20 0 J 240 220 200 180 160 140 120 100 80 60 40 20 0 J F M A M J J A S O N D J F M A M J J A S O S O N N D Mean rainfall – Perth mm Mean rainfall – Strahan mm 240 220 200 180 160 140 120 100 80 60 40 20 0 J F M A M J J A S O N D 240 220 200 180 160 140 120 100 80 60 40 20 0 Perth wind rose February J F M A M J J A D Rainfall variability – a comparison Annual rainfall – Birdsville mm 600 400 200 2000 1980 1960Annual rainfall – Bourke mm Annual rainfall – Perth 1940 1920 1900 0 mm 1000 1400 1200 800 1000 600 800 600 400 400 200 200 1980 1960 1940 1920 1900 1980 19 60 1940 1920 1900 1880 1880 0 0 39 NSW annual rainfall time-series New South Wales Annual Rainfall 1000 900 Dry Period: 1900 – 1946 Average Rainfall: 477. 7mm *Dry conditions commenced 1890 Standard Deviation: 90. 4 Wet Period: 1947 – 2000 Average Rainfall: 573. 9mm 20. 1% increase Standard Deviation: 127. 0 800 New Dry 2001/06 439. 5mm 23. 4% decline Rainfall (mm) 700 600 500 400 300 200 100 0 1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000 Year 40