[{"data":1,"prerenderedAt":866},["ShallowReactive",2],{"layer:tides:investigate":3},{"layer":4,"contentHash":842,"dependencyHashes":843,"approval":859,"releaseId":865},{"schemaVersion":5,"conceptId":6,"locale":7,"depth":8,"revision":5,"title":9,"subtitle":10,"summary":11,"objectives":12,"estimatedMinutes":18,"plate":19,"blocks":40,"sourceIds":837,"reviewStatus":838,"authoring":839},1,"tides","en","investigate","Investigate: predicting, classifying and staying safe","Test the ideas from Understand against a real tide table, real coasts and real disasters","Predict and check a day of tide heights, learn to tell semidiurnal, diurnal and mixed tides apart, meet the Hooghly bore and storm surges, see how tidal power and INCOIS's predictions work, and test the funnelling and resonance ideas with real numbers.",[13,14,15,16,17],"Predict, then check, the height of the tide at a given hour using a tide table or graph.","Classify a coast as semidiurnal, diurnal or mixed from a description of its daily tide.","Explain how a tidal bore forms and why a storm surge is most dangerous at high tide.","Describe how a tidal barrage generates electricity and why few have been built.","Explain, with a worked calculation, how INCOIS predicts tides years in advance and test the funnelling and resonance explanations for tidal range against real numbers.",45,{"title":20,"rows":21},"Lesson plate",[22,25,28,31,34,37],{"label":23,"value":24},"Depth","Investigate",{"label":26,"value":27},"Reading time","≈ 45 minutes",{"label":29,"value":30},"Prior knowledge","Understand: bulges, lunar day, spring–neap, rule of twelfths",{"label":32,"value":33},"Chapters","9",{"label":35,"value":36},"Labs","Data lab, tide lab, sort, match",{"label":38,"value":39},"Maths used","Averages, square roots, ratios, reading tables and graphs",[41,45,51,57,60,78,142,147,197,211,225,230,233,238,280,300,305,310,313,317,320,334,339,344,347,351,370,375,378,383,386,407,411,415,419,424,427,430,486,513,519,524,527,531,535,540,562,567,570,585,601,623,628,631,660,663,666,694,810,823],{"id":42,"type":43,"markdown":44},"i-intro","prose","Discover gave you the words. Understand gave you the mechanism. This layer hands you the tools of a real tide-watcher: a tide table to test yourself against, a way to tell one kind of tide from another, and a look at what happens when the ordinary tide turns dangerous.\n\nThe rule for this whole layer is simple: **predict before you look**. Every time you meet a table, a graph or a lab, decide what you think will happen first. Being wrong and finding out why is how tide-watchers — and scientists of every kind — actually learn.",{"id":46,"type":47,"variant":48,"title":49,"markdown":50},"i-how-to","callout","observation","How to use this lesson","Chapter 1 is the heart of the layer: a real predict-then-check exercise with a tide table. Do it properly before moving on. Later chapters can be read in any order, but the case study in the final chapter pulls several of them together.",{"id":52,"type":53,"title":54,"eyebrow":55,"navLabel":56},"i-ch1","chapter","Predict, then check: a day of tide heights","Chapter 01","1 Predict & check",{"id":58,"type":43,"markdown":59},"i-predict-setup","Here is the port from the rule-of-twelfths lesson in Understand: low water **0.6 m**, high water **5.0 m**, a range of **4.4 m**, with high and low water about **12 h 25 min** apart. Below is the water height at the start of every hour, beginning at a low tide at midnight.\n\nBefore you read the table, predict: at roughly what hour will the water be highest? At roughly what hour will it be back at its lowest? Will the water rise at a steady rate all morning, or unevenly?",{"id":61,"type":62,"prompt":63,"options":64,"explanation":77},"i-predict-hour","prediction","Low water is at 00:00. Using what you know about the tidal day, at roughly what hour will the **next** high water be?",[65,68,71,74],{"id":66,"label":67},"a","About 03:00",{"id":69,"label":70},"b","About 06:00",{"id":72,"label":73},"c","About 09:00",{"id":75,"label":76},"d","About 12:00","**About 06:00.** High water follows low water by a quarter of a lunar day, which you worked out in Understand as about **6 h 13 min** — close enough to six hours that “about six hours after low water” is the right habit of mind, even though the exact figure is a few minutes over.",{"id":79,"type":80,"caption":81,"columns":82,"rows":85},"i-table-ptc","table","One day of hourly heights at a Mumbai-like port, low water at 00:00",[83,84,83,84,83,84],"Hour","Height (m)",[86,93,100,107,114,121,128,135],[87,88,89,90,91,92],"00","0.60","08","4.16","16","3.32",[94,95,96,97,98,99],"01","0.88","09","3.15","17","4.29",[101,102,103,104,105,106],"02","1.63","10","2.05","18","4.89",[108,109,110,111,112,113],"03","2.68","11","1.14","19","4.96",[115,116,117,118,119,120],"04","3.76","12","0.65","20","4.49",[122,123,124,125,126,127],"05","4.60","13","0.69","21","3.60",[129,130,131,132,133,134],"06","4.99","14","1.27","22","2.51",[136,137,138,139,140,141],"07","4.83","15","2.22","23","1.49",{"id":143,"type":47,"variant":144,"title":145,"markdown":146},"i-model-limit-cosine","model_limit","This table is a model, not a measurement","These heights were not measured; they were **calculated** from a smooth wave with the right mean height, the right range and the right timing, so you can check your own predictions exactly. Real tide curves are close to this shape but not identical: they tend to change a little more slowly right at the top and bottom (which is exactly what the rule of twelfths in Understand captures, with its 1, 2, 3, 3, 2, 1 pattern) and a little faster through the middle. A real port's official tide table comes from years of actual measurement, analysed by INCOIS or the Survey of India, not from a formula.",{"id":148,"type":149,"component":150,"componentVersion":5,"config":151,"objective":195,"textAlternative":196},"i-lab-data","interactive","data-lab",{"datasets":152,"valueRange":182,"step":185,"challenges":186},[153],{"label":154,"unit":155,"values":156},"Water height","m",[157,158,159,160,161,162,163,164,165,166,167,168,169,170,171,172,173,174,175,176,177,178,179,180,181],0.6,0.88,1.63,2.68,3.76,4.6,4.99,4.83,4.16,3.15,2.05,1.14,0.65,0.69,1.27,2.22,3.32,4.29,4.89,4.96,4.49,3.6,2.51,1.49,0.8,{"min":183,"max":184},0,5.5,0.1,[187,191],{"measure":188,"target":189,"prompt":190},"range",4.4,"Read off the highest and lowest points and find the tidal range.",{"measure":192,"target":193,"prompt":194},"mean",2.8,"What is the mean (average) water height over the whole day?","Explore the same day of heights as a dot plot, and check the range and mean you can read from it.","This lab shows the 24 hourly heights from the table above as a dot plot, rising from 0.6 m at hour 0 to 5.0 m around hour 6, back down to about 0.6 m around hour 12, up again to about 5.0 m around hour 19, and back towards 0.6 m by hour 24 — one and a half full tidal cycles.\n\nTwo challenges ask you to read off the tidal range (the highest dot minus the lowest) and the mean height (the average of all 24 dots), and compare your reading with the numbers from the table.",{"id":198,"type":199,"title":200,"problem":201,"steps":202,"help":206},"i-we-check","worked_example","Checking a prediction against the formula","Using the pattern in the table, roughly how high is the water at **10:30**, halfway between the 10:00 and 11:00 readings?",[203,204,205],"From the table, height at 10:00 is **2.05 m** and at 11:00 is **1.14 m**.","The water is falling fast through the middle hours of the ebb, so a straight-line average is a reasonable estimate for **half an hour**: (2.05 + 1.14) ÷ 2 = **1.59 m**.","Check the idea, not just the number: is the water still falling at 10:30? Yes — the table shows it keeps falling all the way to hour 12, so an in-between estimate is sensible here, unlike near the very top or bottom of the tide where the curve flattens out and a straight-line guess would be less accurate.",{"simplerExplanation":207,"hints":208},"Between two nearby readings, especially in the middle of the flood or ebb, the average of the two is a fair estimate.",[209,210],"Add the two surrounding readings and divide by 2.","Check whether the water is rising, falling, or near a turning point — the estimate is least reliable near a turning point.",{"id":212,"type":213,"itemId":214,"prompt":215,"check":216,"hints":219,"feedback":222},"i-pr-range","practice","tides.investigate-range","Using the table, what is the tidal range shown for this day, in metres?",{"kind":217,"answer":189,"tolerance":218,"unit":155},"number",0.05,[220,221],"Find the highest and lowest values in the table.","Subtract low from high.",{"correct":223,"incorrect":224},"Right: the highest value is 5.0 m and the lowest is 0.6 m, so the range is **4.4 m**.","Scan the whole table for the biggest and smallest numbers, then subtract.",{"id":226,"type":53,"title":227,"eyebrow":228,"navLabel":229},"i-ch2","One a day, two a day, or two unequal ones","Chapter 02","2 Three tide types",{"id":231,"type":43,"markdown":232},"i-three-types","The two-bulge picture predicts two equal high tides and two equal low tides every lunar day, everywhere. Go and measure real coasts and you find **three** different patterns, because continents, currents and the shapes of ocean basins bend the simple picture.\n\n- A **semidiurnal** tide has two high waters and two low waters each lunar day, of similar height. This is the pattern at most of India's ports, including Mumbai and Kochi, and along most of the world's Atlantic coasts.\n- A **diurnal** tide has only **one** high water and **one** low water each lunar day. The Gulf of Mexico (at ports such as Pensacola) and the Gulf of Tonkin, off Vietnam, are classic examples.\n- A **mixed** tide has two highs and two lows, like a semidiurnal tide, but the two highs (or the two lows) are noticeably **unequal** in height. Much of the west coast of the United States, including San Francisco, works this way, and parts of India's east coast show a milder version of the same unevenness.",{"id":234,"type":47,"variant":235,"title":236,"markdown":237},"i-nuance-why-three","nuance","Why isn't every coast the same?","The simple two-bulge model has one Moon, one plane and one steady rhythm — it should give the same clean semidiurnal tide everywhere. Real oceans do not cooperate: each ocean basin has its own shape and its own natural sloshing rhythm (you met this idea, **resonance**, in Understand), and the Moon does not always sit over the equator, so its pull on the northern and southern bulges is not always equal.\n\nWhere a basin's natural rhythm favours the twice-daily beat, you get a strong semidiurnal tide. Where it favours the once-daily beat instead, or where the Moon's northward or southward swing matters a lot at that latitude, you get a diurnal or mixed tide. The type is a fingerprint of the ocean basin, not of the Moon.",{"id":239,"type":149,"component":240,"componentVersion":5,"config":241,"objective":278,"textAlternative":279},"i-lab-sort-types","sort-game",{"prompt":242,"bins":243,"items":253,"seconds":183},"Semidiurnal, diurnal, or mixed? Sort each coast by the pattern it shows.",[244,247,250],{"id":245,"label":246},"semi","Semidiurnal",{"id":248,"label":249},"diurnal","Diurnal",{"id":251,"label":252},"mixed","Mixed",[254,258,262,266,270,274],{"id":255,"label":256,"bin":245,"why":257},"t1","Mumbai: two similar high tides and two similar low tides every lunar day","Two highs, two lows, similar heights: the textbook semidiurnal pattern.",{"id":259,"label":260,"bin":245,"why":261},"t2","Kochi: two nearly equal high tides a day","Again two similar highs and lows — semidiurnal, just with a much smaller range than Mumbai.",{"id":263,"label":264,"bin":245,"why":265},"t3","Bay of Fundy: an enormous range, but still two similar highs and two similar lows a day","Size of range and type of tide are different questions. Fundy's tide is semidiurnal; it is just semidiurnal on a huge scale.",{"id":267,"label":268,"bin":248,"why":269},"t4","Pensacola, on the Gulf of Mexico: usually just one high tide and one low tide a day","One high, one low: the Gulf of Mexico is one of the world's classic diurnal coasts.",{"id":271,"label":272,"bin":248,"why":273},"t5","The Gulf of Tonkin, off Vietnam: one high water and one low water most days","Another classic diurnal coast, shaped by the basin of the South China Sea.",{"id":275,"label":276,"bin":251,"why":277},"t6","San Francisco Bay: two highs and two lows a day, but one high is clearly bigger than the other","Two of each, but unequal: the definition of a mixed tide.","Sort six real coasts into semidiurnal, diurnal or mixed by the pattern of their daily tide.","A sorting game with three bins and six coast cards.\n\nSemidiurnal: Mumbai and Kochi (two similar highs and lows), and the Bay of Fundy (also two similar highs and lows, just on a huge scale — range and type are separate ideas).\n\nDiurnal: Pensacola on the Gulf of Mexico, and the Gulf of Tonkin off Vietnam, both with just one high and one low most days.\n\nMixed: San Francisco Bay, with two highs and two lows a day but one high clearly bigger than the other.",{"id":281,"type":80,"caption":282,"columns":283,"rows":288},"i-table-types","The three tide types at a glance",[284,285,286,287],"Type","Highs and lows per lunar day","Are the two highs equal?","Example",[289,293,297],[246,290,291,292],"2 highs, 2 lows","Yes, similar heights","Mumbai; Kochi; the Bay of Fundy",[249,294,295,296],"1 high, 1 low","There is only one to compare","Gulf of Mexico; Gulf of Tonkin",[252,290,298,299],"No — one is clearly bigger","San Francisco Bay",{"id":301,"type":47,"variant":302,"title":303,"markdown":304},"i-example-count","example","How to tell, from a tide table alone","You do not need to visit a coast to classify its tide: count the entries in a week of its tide table. Two clearly separate high-water times most days means semidiurnal or mixed; only one means diurnal. If the two highs are close in height, call it semidiurnal; if one is consistently bigger, call it mixed.",{"id":306,"type":53,"title":307,"eyebrow":308,"navLabel":309},"i-ch3","The Hooghly bore: when a tide becomes a wave","Chapter 03","3 The Hooghly bore",{"id":311,"type":43,"markdown":312},"i-bore-intro","Almost everywhere, the tide arrives quietly: the water simply gets a little higher, hour by hour. In a few special places, the incoming tide arrives instead as a single steep wall of water, called a **tidal bore**, that runs up a river against the current like a wave with nowhere else to go.\n\nIndia has one, on the **Hooghly**, the river that flows past Kolkata to the sea. It begins near Hooghly Point, where the river first narrows, and can be felt as far as **35 km** upstream, near Naihati. Wikipedia's account of the river describes the bore as often exceeding about **2.1 m** in height, with the most extreme bores — in March and September — reaching **2.4 to 6.1 m**. It needs two things at once: a bigger-than-average spring tide, and extra river flow pushing back against it. Small boats caught by surprise have been capsized by it.",{"id":314,"type":47,"variant":302,"title":315,"markdown":316},"i-example-qiantang","The world's biggest: the Qiantang, China","The Hooghly's bore is real but modest next to the world's largest, on the **Qiantang River** in China. There, the funnel shape of Hangzhou Bay meets one of the world's largest tidal ranges, and the bore can reach about **9 m** high, travelling at up to about **40 km\u002Fh** — faster than a bicycle can outrun it. Crowds gather safely on raised banks every year to watch it arrive; every year, a few people who ignore the safety barriers are swept away.",{"id":318,"type":43,"markdown":319},"i-why-bore-forms","Why does a bore form in some rivers and not others? Three things have to line up.\n\n**A large tidal range.** There has to be a lot of water trying to get in.\n\n**A funnel-shaped, shallowing mouth.** As you saw with the Gulf of Khambhat, a narrowing, shallowing channel squeezes the same water into less room, forcing the level up fast.\n\n**Water moves faster where it is deeper.** A wave in deep water outruns the same wave in shallow water. As the front of the incoming tide reaches into the shallowing river mouth, the water just behind it is still in slightly deeper water and catches up. Given enough of a head start and enough distance, the gently sloping front of the tide steepens into an abrupt, breaking wall — the bore.",{"id":321,"type":199,"title":322,"problem":323,"steps":324,"help":329},"i-we-bore-speed","Why a shallowing river makes a bore steepen (an illustration)","A simple rule for how fast a long, shallow wave travels is speed = √(g × depth), with g ≈ 9.8 m\u002Fs². Suppose (just as an illustration, not a survey of the Hooghly) one part of a river mouth is 1 m deep and, a little downstream where the falling tide has not yet drained away, another part is still 4 m deep. How much faster does the wave move in the deeper water?",[325,326,327,328],"Speed in the 1 m water: √(9.8 × 1) = √9.8 ≈ **3.13 m\u002Fs**.","Speed in the 4 m water: √(9.8 × 4) = √39.2 ≈ **6.27 m\u002Fs**.","Difference: 6.27 − 3.13 ≈ **3.14 m\u002Fs**, which is about **11.3 km\u002Fh** faster.","That is the whole mechanism in one sum: the deeper water behind keeps gaining on the shallower water ahead, piling up into a steeper and steeper front until, given enough distance, it breaks into a bore.",{"simplerExplanation":330,"hints":331},"Deeper water lets a wave travel faster. Where a river shallows quickly, the deeper water behind catches up with the shallower water ahead, and the tide's leading edge steepens into a wall.",[332,333],"√9.8 is a little more than 3.","√39.2 is a little more than 6.",{"id":335,"type":47,"variant":336,"title":337,"markdown":338},"i-careful-bore","careful","Never treat a bore, or the river it runs on, casually","A tidal bore arrives fast, without the slow warning of an ordinary tide, and it can capsize small boats and sweep away anyone standing too close to the water's edge. Watch one only from a safe, raised bank with a knowledgeable adult, and never in the river itself.",{"id":340,"type":53,"title":341,"eyebrow":342,"navLabel":343},"i-ch4","Storm surge: the tide's dangerous cousin","Chapter 04","4 Storm surge",{"id":345,"type":43,"markdown":346},"i-surge-intro","A cyclone crossing the Bay of Bengal does two things to the sea at once, and the combination is what makes coastal flooding from a cyclone so severe.\n\n**Low pressure lifts the sea.** Right under the eye of a cyclone, air pressure drops sharply, and with less air weighing down on it, the sea surface rises — a small effect on its own, typically tens of centimetres.\n\n**Wind piles water onshore.** Far more important, ferocious onshore winds physically shove water ahead of the storm and pile it against the coast, sometimes for tens of kilometres in front of the landfall point. Together these two effects are called a **storm surge**, and it can raise the sea by several metres above its normal level, for hours.\n\nHere is the crucial link to this whole lesson: **a storm surge rides on top of whatever the ordinary tide is doing.** A surge that arrives at low tide adds to a low starting level; the very same surge arriving at high tide adds to a high one. A cyclone's landfall time relative to the tide can be the difference between a bad flood and a catastrophic one.",{"id":348,"type":47,"variant":302,"title":349,"markdown":350},"i-example-1999","The 1999 Odisha Super Cyclone","On 29 October 1999, a super cyclone with winds of about **260 km\u002Fh** made landfall near Paradip, on the Odisha coast — a coast you have already met for its comparatively modest everyday tidal range of about 2.3 m. Accounts of the disaster describe a storm surge of about **6 to 7 metres**, which drove seawater far inland across the flat delta country near Ersama, destroying embankments, homes and standing crops and contributing to a death toll of several thousand people. It remains one of the starkest reminders, anywhere in the world, of how much more dangerous the sea becomes when a storm adds itself to a tide.",{"id":352,"type":80,"caption":353,"columns":354,"rows":359},"i-table-surges","Two storm surges that show what 'arriving at high tide' can do",[355,356,357,358],"Event","Storm surge","Coast","What made it so severe",[360,365],[361,362,363,364],"1999 Odisha Super Cyclone","about 6–7 m","Paradip \u002F Ersama, Odisha","Winds of about 260 km\u002Fh drove the surge across a flat, low-lying delta coast.",[366,367,368,369],"1970 Bhola cyclone","about 10.5 m","East Pakistan (now Bangladesh) and West Bengal","The deadliest tropical cyclone on record, with at least 300,000 deaths, most from the surge itself.",{"id":371,"type":47,"variant":372,"title":373,"markdown":374},"i-misc-surge-tide","misconception","“A storm surge is just a really big wave”","It is not a wave in the everyday sense at all. A wind-driven wave rocks the surface up and down for a few seconds and moves on. A storm surge is the **whole sea level** staying elevated for hours, the way a tide is — except caused by wind and pressure instead of the Moon, and arriving with far less warning than a tide ever does. On top of the surge, ordinary wind waves still crash in, which is why the worst damage happens where a raised sea level lets storm waves reach buildings and land that would normally be safely above the water.",{"id":376,"type":43,"markdown":377},"i-surge-safety","This is why India's cyclone warnings, issued by the India Meteorological Department, always give the expected storm surge height **alongside** the tide forecast for the landfall time, and why coastal evacuation orders are timed around high tide, not just around the storm's arrival. It is also why the Sundarbans and the low-lying deltas of Odisha and Andhra Pradesh have built networks of raised cyclone shelters: buildings tall and strong enough to keep people above a surge that an ordinary house cannot survive.",{"id":379,"type":53,"title":380,"eyebrow":381,"navLabel":382},"i-ch5","Tidal power: catching the rise and fall","Chapter 05","5 Tidal power",{"id":384,"type":43,"markdown":385},"i-tidal-power","If a tide can float a ship or empty a harbour, it can also turn a turbine. A **tidal barrage** is a dam built across a bay or estuary with gates and turbines built into it. Water is let through as the tide rises, and again as it falls, and each time some of that moving water spins turbines connected to generators — the same idea you met for hydroelectric dams in Electricity, but powered by the Moon instead of a river.",{"id":387,"type":388,"title":389,"items":390},"i-steps-barrage","steps","How a simple tidal barrage works, one tide at a time",[391,395,399,403],{"title":392,"tag":393,"text":394},"Tide rises","Gates open","As the sea rises outside the barrage, gates let water flow in through the turbines, generating electricity as it goes.",{"title":396,"tag":397,"text":398},"High water","Gates shut","At the peak, the gates close, trapping a basin full of water at the high-tide level, ready to be released under control.",{"title":400,"tag":401,"text":402},"Tide falls outside","Water is held","Outside the barrage the sea keeps falling, but the trapped water stays at the high level, building up a difference in height across the barrage.",{"title":404,"tag":405,"text":406},"Release through turbines","Generating again","Once the difference in height is large enough, gates open and the trapped water rushes out through the turbines, generating electricity a second time on the same tide.",{"id":408,"type":47,"variant":302,"title":409,"markdown":410},"i-example-rance","Real tidal barrages, and why there are so few","The world's first big tidal barrage, the **Rance** in France, has generated electricity since **1966** with a capacity of about **240 MW**. The **Sihwa Lake** station in South Korea, completed in **2011**, is bigger still, at about **254 MW** — currently the world's largest.\n\nBoth were only worth building because of an unusually **large tidal range** at that exact spot — you now know that means a funnel shape, or resonance, or both. That is precisely why the Gulf of Khambhat and the Gulf of Kutch, with India's biggest tidal ranges, have been studied for tidal power for decades, while no large barrage has yet been built on either: the cost of a barrage across a wide gulf, and its effect on shipping, fishing and the mudflats that herons and horseshoe crabs depend on, are not small problems to solve.",{"id":412,"type":47,"variant":235,"title":413,"markdown":414},"i-nuance-tradeoffs","Clean electricity is not automatically a free choice","A tidal barrage produces no smoke and no carbon dioxide while it runs, which is genuinely valuable. But changing the tide inside a gulf changes everything downstream of it: less water reaching the mudflats can starve the shellfish and worms that shorebirds and fish depend on, and blocking a channel can affect the fishing boats and ferries that already use it.\n\nThis is not a reason to say no automatically — hydroelectric dams and solar farms have trade-offs too. It is a reason to insist on the same kind of careful, honest weighing-up you have used throughout this layer: name the benefit, name the cost, and ask who bears each one.",{"id":416,"type":417,"prompt":418},"i-reflect-barrage","reflection","A tidal barrage across a gulf changes the water level, the currents and the mudflats for every fisher, bird and mangrove tree in it, as well as generating clean electricity. Write two questions you would want answered before deciding whether to build one across the Gulf of Kutch.",{"id":420,"type":53,"title":421,"eyebrow":422,"navLabel":423},"i-ch6","Living and working by the tide, in detail","Chapter 06","6 Living by the tide",{"id":425,"type":43,"markdown":426},"i-sundarbans","Nowhere in India runs more completely on the tide than the **Sundarbans**, the tangle of tidal rivers, mudflats and mangrove forest where the Ganga and Brahmaputra meet the Bay of Bengal, shared between India and Bangladesh. Every one of its hundreds of channels rises and falls twice a day, and everything about life there is arranged around that fact.\n\nVillages are protected from the daily tide by earthen **embankments**; a breach at high tide, especially a spring tide pushed higher still by a storm surge, can flood fields with salt water for a growing season or more. Ferries and country boats time every crossing to the tide, because a boat that leaves too early or too late can be stranded on a mudbank for six hours. Honey collectors who go into the forest to gather wild honey from giant honeybee combs must also watch the tide as carefully as they watch for tigers, since the same channels they cross by boat can become impassable, or dangerously fast, as the tide turns.",{"id":428,"type":43,"markdown":429},"i-salt-detail","You met salt pans briefly in Discover. Here is the sum behind them. A salt maker lets a spring high tide flood a shallow pan through a sluice gate, then closes the gate and lets nine or ten weeks of sun and wind evaporate the water away, leaving a crust of salt to be raked up and stacked. Missing a good spring tide can mean waiting a whole fortnight for the next chance to refill the pans — one more reason coastal calendars are built around the Moon, not just the Sun.\n\nGujarat alone produces most of India's salt this way, much of it around the Gulf of Kutch and the Rann, where some of the country's largest tidal ranges make it easy to flood pans high above the working floor.",{"id":431,"type":432,"title":433,"prompt":434,"options":435},"i-explorer-livelihoods","explorer","Four coasts, four ways of working with the tide","Pick a coast to see how its own tidal range shapes the work people do there.",[436,449,462,474],{"id":437,"label":438,"chain":439,"badge":445,"note":448},"kochi-fish","Kochi: small-range fishing",[440,441,442,443,444],"Range about 1 m","Boats float almost all the time","Nets set by daylight, not the tide","Backwaters usable any hour","Tide barely rules the working day",{"text":446,"tone":447},"Tide is a minor factor","no","With only about a metre of range, Kochi's backwater boats are rarely stranded and rarely swamped. Fishing there is timed mostly by daylight, weather and fish behaviour, with the tide as a background rhythm rather than the deciding factor — the opposite of almost every other coast in this layer.",{"id":450,"label":451,"chain":452,"badge":458,"note":461},"khambhat-salt","Khambhat: big-range salt pans",[453,454,455,456,457],"Range about 10 m","A spring tide floods the pans","Gate shut at the very top of the tide","Weeks of evaporation follow","Miss it, wait a fortnight",{"text":459,"tone":460},"Tide sets the calendar","yes","A ten-metre range means a single spring high tide can flood a pan far above the working floor, giving weeks of salt water to evaporate from one filling. Time it wrong — miss the best spring tide of the fortnight — and the whole batch is delayed until the next one.",{"id":463,"label":464,"chain":465,"badge":471,"note":473},"sundarbans-ferry","Sundarbans: ferries and honey",[466,467,468,469,470],"Land very flat; range moderate","Channels are the only roads","Ferries timed to avoid mudbanks","Honey collectors watch tide too","Embankments hold back the tide",{"text":472,"tone":460},"Tide rules daily movement","In a maze of tidal creeks with almost no roads, the tide decides which channels are passable and when. An embankment breach at a spring high tide, worsened by a storm surge, can turn a field salty for a whole growing season.",{"id":475,"label":476,"chain":477,"badge":483,"note":485},"hooghly-port","Hooghly: piloting past a bore",[478,479,480,481,482],"Range large enough for a bore","Ships time arrival to the flood","Pilots know the bore's likely days","Kolkata's docks have gates for water","A missed tide can cost a day's delay",{"text":484,"tone":460},"Tide sets the shipping schedule","Getting a loaded ship up the Hooghly to Kolkata means timing the voyage to the flood tide, respecting the shallow bar at the river mouth, and knowing which spring tides are likely to bring a bore. River pilots plan around all three, the way an airline plans around weather.",{"id":487,"type":149,"component":488,"componentVersion":5,"config":489,"objective":511,"textAlternative":512},"i-lab-match-people","match-pairs",{"prompt":490,"mode":491,"pairs":492},"Match each coastal activity to the tide fact it depends on.","connect",[493,496,499,502,505,508],{"a":494,"b":495},"Salt pan","Flooded on a spring high tide, then sealed and evaporated",{"a":497,"b":498},"Sundarbans ferry","Timed so the boat is never stranded on a mudbank",{"a":500,"b":501},"Tidal barrage","Needs an unusually large tidal range to be worth building",{"a":503,"b":504},"Storm surge shelter","Built tall enough to stay above a surge added to a high tide",{"a":506,"b":507},"Tidal bore","Forms where a big spring tide meets a shallowing, funnel-shaped river",{"a":509,"b":510},"Embankment","Protects fields from the twice-daily tide and from storm flooding","Match six coastal activities or structures to the tide fact each one depends on.","A matching game with six pairs. Salt pan goes with 'flooded on a spring high tide, then sealed and evaporated'. Sundarbans ferry goes with 'timed so the boat is never stranded on a mudbank'. Tidal barrage goes with 'needs an unusually large tidal range to be worth building'. Storm surge shelter goes with 'built tall enough to stay above a surge added to a high tide'. Tidal bore goes with 'forms where a big spring tide meets a shallowing, funnel-shaped river'. Embankment goes with 'protects fields from the twice-daily tide and from storm flooding'.",{"id":514,"type":515,"conceptId":516,"relation":517,"explanation":518},"i-conn-exploration","connection","exploration","applied_in","Long before engines, sailing ships timed their departure and arrival to the tide and to the monsoon winds together; whole trading seasons across the Indian Ocean were built around both clocks at once.",{"id":520,"type":53,"title":521,"eyebrow":522,"navLabel":523},"i-ch7","How INCOIS predicts a tide years ahead","Chapter 07","7 Predicting tides",{"id":525,"type":43,"markdown":526},"i-incois","You already know tide prediction is possible because the Moon and Sun move predictably. Here is roughly how it is actually done.\n\nA tide gauge at a port records the sea level, often every few minutes, for months or years. That record is not a single clean wave — it is a messy squiggle, because the Moon's tide, the Sun's tide, the shape of the local coast and the weather are all mixed into it together. **Harmonic analysis** is the mathematics that untangles the mix: it treats the messy squiggle as the sum of many simple, steady waves (called **constituents**), each with its own period, height and timing, and works out what those waves must be. INCOIS, the Indian National Centre for Ocean Information Services in Hyderabad, describes the real curve at a port as built from as many as about **115** such constituents, though a handful of the largest ones — the Moon's main semidiurnal wave, the Sun's, and two daily ones — usually do almost all of the work.\n\nOnce you know each constituent, predicting the future is just arithmetic: run each simple wave forward by however many years you like, using the *known, predictable* motion of the Moon and Sun, and add them all back together. That is why a tide table can be printed with confidence years in advance, even though the ocean itself is turbulent and hard to model in every other way.",{"id":528,"type":515,"conceptId":529,"relation":517,"explanation":530},"i-conn-data","data-handling","Harmonic analysis is data handling at scale: years of measurements are broken into patterns (the constituents), and those patterns, not guesswork, are what gets projected forward into next year's tide table.",{"id":532,"type":47,"variant":235,"title":533,"markdown":534},"i-nuance-weather","What a tide table cannot predict","A tide table predicts the **astronomical** tide: the part driven by the Moon and Sun, which repeats forever on schedule. It cannot predict the extra rise or fall caused by weather — a storm surge, a strong onshore wind, or a spell of unusually high or low air pressure. On a normal day the weather's effect is a few centimetres and barely noticed. During a cyclone it can be metres, which is exactly why storm-surge warnings are issued **on top of**, not instead of, the ordinary tide table.",{"id":536,"type":47,"variant":537,"title":538,"markdown":539},"i-tryit-real-table","try_it","Find a real tide table for your own coast","INCOIS publishes tide predictions for Indian ports online, and so does the Survey of India. With an adult, search for a current tide table for the Indian port nearest to you (or the one you have visited).\n\n1. How many high tides and how many low tides does it show today? Is the coast semidiurnal, diurnal or mixed?\n2. What is today's tidal range? Compare it with the typical figures in this layer for the nearest large port you recognise.\n3. Find the next spring tide in the table. How many days away is it, and does that match the roughly two-week rhythm you learned in Understand?\n\nReal tide tables use local clock time and a chart datum specific to that port, so do not be surprised if the numbers look a little different from the made-up examples in this layer.",{"id":541,"type":213,"itemId":542,"prompt":543,"check":544,"hints":556,"feedback":559},"i-pr-incois","tides.investigate-incois","Why can a tide table be printed years in advance and still be accurate to within a few minutes?",{"kind":545,"options":546,"correct":555},"choice",[547,549,551,553],{"id":66,"label":548},"Tides never change from year to year",{"id":69,"label":550},"The Moon and Sun's motions are extremely predictable, and harmonic analysis turns measured tides into a formula that can be run forward",{"id":72,"label":552},"Computers guess the pattern from last week's weather",{"id":75,"label":554},"INCOIS re-measures the sea every single day and reprints the table",[69],[557,558],"Think about what actually drives a tide, and how predictable that thing is.","The 'why' is astronomy plus mathematics, not daily re-measurement.",{"correct":560,"incorrect":561},"Right: harmonic analysis breaks a port's tide into simple, steady waves tied to the Moon and Sun, whose future positions can be calculated exactly. Add those waves back together for any future date and you have a prediction.","It is not guesswork or daily remeasurement: the constituents, once known from past data, can be projected forward using the predictable motion of the Moon and the Sun.",{"id":563,"type":53,"title":564,"eyebrow":565,"navLabel":566},"i-ch8","Testing the funnel and resonance ideas","Chapter 08","8 Testing range ideas",{"id":568,"type":43,"markdown":569},"i-test-range-ideas","Understand offered three explanations for why tidal range varies so much by place: funnelling, shallowing and resonance. A good scientist does not just accept an explanation — they look for a test that could show it wrong.\n\n**Test for funnelling and shallowing:** if these matter, tidal range should generally **grow** as you travel further into a narrowing, shallowing gulf. Along the Gulf of Khambhat, ranges do exactly that: about 4–5 m near the open mouth, growing to about 10 m up near Bhavnagar. That is consistent with the explanation — though consistent is not the same as proven; a sceptic could still ask whether something else also changes along that same stretch of coast.\n\n**Test for resonance:** resonance predicts that basins whose natural sloshing period happens to be close to the tidal period should have unusually **large** ranges even without an extreme funnel shape, while similarly shaped basins with a very different natural period should not. The Bay of Fundy fits this well: you calculated in the worked example below that a bay of about its real depth naturally resonates at close to the tidal period, which is exactly where its enormous range comes from.",{"id":571,"type":199,"title":572,"problem":573,"steps":574,"help":580},"i-we-fundy-check","Estimating the length a resonant bay 'should' have","A basin resonates strongly with the tide when it is close to a **quarter of a tidal wavelength** long. Using the shallow-water wave speed rule v = √(g × depth) and the Bay of Fundy's average depth of about 75 m, estimate that quarter wavelength, and compare it with the description of the Gulf of Maine–Bay of Fundy system as being close to it.",[575,576,577,578,579],"Wave speed: v = √(9.8 × 75) ≈ **27.1 m\u002Fs**.","The main lunar tide's period is 12 h 25 min, which in seconds is about 12 × 3,600 ÷ 24 ≈ 44,540 s (using 12.4206 hours precisely).","A quarter wavelength: L = v × T ÷ 4 = 27.1 × 44,712 ÷ 4 ≈ **303 km**.","That is close to the length of the combined Gulf of Maine–Bay of Fundy system, which is why the whole system, not the narrow inner bay alone (about 151 km), is what actually resonates with the tide.","This is exactly the kind of check a scientist wants: the resonance idea makes a testable **number**, and that number lands close to the real geography, not just close to a vague description.",{"simplerExplanation":581,"hints":582},"Work out how fast a long wave moves in water that deep, then how far it could travel in a quarter of a tidal cycle. That distance should match the size of a basin that resonates strongly.",[583,584],"√(9.8 × 75) is a little over 27.","Multiply the speed by the full period in seconds, then divide by 4.",{"id":586,"type":587,"items":588},"i-formulas-testing","formulas",[589,592,595,598],{"expression":590,"caption":591},"v = √(g × depth)","Shallow-water wave speed. Deeper water lets a long wave travel faster.",{"expression":593,"caption":594},"quarter wavelength = v × T ÷ 4","The basin length that resonates strongly with a tide of period T.",{"expression":596,"caption":597},"75 m depth → v ≈ 27.1 m\u002Fs","Bay of Fundy's average depth, used in the worked example below.",{"expression":599,"caption":600},"→ resonant length ≈ 303 km","Close to the real Gulf of Maine–Bay of Fundy system's size.",{"id":602,"type":149,"component":603,"componentVersion":5,"config":604,"objective":621,"textAlternative":622},"i-lab-tide-clock-test","tide-lab",{"modes":605,"places":608,"challenges":620},[606,607],"tide-clock","spring-neap",[609,612,616],{"id":610,"label":611,"rangeM":5},"kochi","Kochi (about 1 m)",{"id":613,"label":614,"rangeM":615},"bhavnagar","Bhavnagar (about 10 m)",10,{"id":617,"label":618,"rangeM":619},"fundy","Bay of Fundy (about 16 m)",16,4,"Compare a small, an open, and a resonant coast side by side, and re-check the spring–neap pattern on top of each one's own range.","This lab reruns the tide clock for three very different coasts — Kochi's open, unremarkable one metre; Bhavnagar's funnelled ten metres; the Bay of Fundy's resonant sixteen metres — and adds the spring–neap mode on top, so you can see the fortnightly rhythm riding on top of each place's very different baseline range.\n\nFour challenges ask you to identify which place is being shown from its range alone, predict how much bigger a spring tide is than a neap tide at each place (roughly the same **ratio** everywhere, even though the actual metres are wildly different), and explain in one sentence why the ratio stays similar while the range does not.",{"id":624,"type":53,"title":625,"eyebrow":626,"navLabel":627},"i-ch9","Case study: one tide, one whole coastal day","Chapter 09","9 Case study",{"id":629,"type":43,"markdown":630},"i-case-study","Put the whole layer to work on one imagined but realistic day at a fishing and ferry town on a tidal creek near the Gulf of Khambhat, where the spring range is about 10 m.",{"id":632,"type":80,"caption":633,"columns":634,"rows":639},"i-table-case","One spring-tide day, worked from the facts in this layer",[635,636,637,638],"Time","Tide state","What is happening","What people are doing",[640,645,650,655],[641,642,643,644],"04:30","Low water","Mudflats and boat hulls exposed; slack, still water","Nets and hulls checked; nobody crosses the main channel on foot",[646,647,648,649],"~10:40","High water (≈ 6 h 13 min after low)","Creek full to the top of its banks; a salt pan's sluice gate is opened","Ferries run; the salt pan is flooded, then the gate is shut",[651,652,653,654],"~17:05","Low water again","Mudflats reappear; boats settle onto the mud","Fishing boats that left on the morning ebb return and wait for the next flood",[656,657,658,659],"Any time","Cyclone warning issued","IMD forecasts a storm surge for this evening's high tide","Evacuation to a raised shelter begins well before the surge and high tide coincide",{"id":661,"type":43,"markdown":662},"i-case-lessons","Notice how many separate ideas from this layer show up in that single table. The **quarter of a lunar day** between low and high water is the same arithmetic from Understand's rule of twelfths. The salt pan's sluice gate depends on catching a **spring** tide, the fortnightly rhythm from Discover. The ferries and boats are running a **semidiurnal** routine, twice a day, every day. And the cyclone warning is a reminder that the one thing a tide table cannot predict — the weather — can turn an ordinary high tide into the most dangerous moment of the year.",{"id":664,"type":417,"prompt":665},"i-reflect-case","Using the table above and the whole of this layer, explain in three or four sentences why the very last row is the most dangerous one in the table, even though nothing about the ordinary tide changed that day.",{"id":667,"type":668,"title":669,"terms":670},"i-glossary","glossary","New words from Investigate",[671,674,677,680,682,685,687,690],{"term":672,"meaning":673},"Semidiurnal tide","Two similar high waters and two similar low waters each lunar day: most of India's coast.",{"term":675,"meaning":676},"Diurnal tide","Just one high water and one low water each lunar day, as on the Gulf of Mexico.",{"term":678,"meaning":679},"Mixed tide","Two highs and two lows each day, like a semidiurnal tide, but noticeably unequal in height.",{"term":506,"meaning":681},"A steep, breaking wave of the incoming tide running up a river, seen on the Hooghly and, far bigger, on China's Qiantang.",{"term":356,"meaning":683,"example":684},"A rise in sea level caused by a cyclone's low pressure and onshore wind, added on top of whatever the ordinary tide is doing.","The 1999 Odisha Super Cyclone's surge was about 6–7 m.",{"term":500,"meaning":686},"A dam across a bay or estuary with turbines, generating electricity from the rise and fall of the tide.",{"term":688,"meaning":689},"Harmonic analysis","The mathematics that splits a measured tide into simple, steady waves (constituents) tied to the Moon and Sun, which can then be projected forward to predict future tides.",{"term":691,"meaning":692,"example":693},"Resonance","The build-up in range that happens when a bay's natural sloshing period is close to the tidal period, as in the Bay of Fundy.","Quarter-wavelength test: a resonant basin's length should be close to speed × period ÷ 4.",{"id":695,"type":696,"title":697,"questions":698},"i-quiz","quiz","Check yourself: predicting, classifying and staying safe",[699,712,722,732,745,758,771,784,797],{"itemId":700,"prompt":701,"options":702,"correct":69,"why":711},"tides.investigate-q-predict","A tide table can be printed years ahead because…",[703,705,707,709],{"id":66,"label":704},"The sea never changes",{"id":69,"label":706},"Harmonic analysis turns measured tides into steady waves tied to the predictable Moon and Sun",{"id":72,"label":708},"Weather is included in the prediction",{"id":75,"label":710},"It is re-measured every day and simply copied forward","The Moon's and Sun's future positions are known precisely, so the constituents found by harmonic analysis can be run forward to any future date.",{"itemId":713,"prompt":714,"options":715,"correct":69,"why":721},"tides.investigate-q-diurnal","A coast with just one high tide and one low tide a day has a…",[716,717,718,719],{"id":66,"label":672},{"id":69,"label":675},{"id":72,"label":678},{"id":75,"label":720},"Neap tide","One high, one low, each lunar day: that is the definition of a diurnal tide, as on the Gulf of Mexico.",{"itemId":723,"prompt":724,"options":725,"correct":72,"why":731},"tides.investigate-q-mixed","San Francisco Bay has two high tides a day, but one is clearly bigger than the other. What kind of tide is this?",[726,727,728,729],{"id":66,"label":249},{"id":69,"label":246},{"id":72,"label":252},{"id":75,"label":730},"No tide at all","Two highs and two lows, but unequal: a mixed tide.",{"itemId":733,"prompt":734,"options":735,"correct":69,"why":744},"tides.investigate-q-bore","What two things does a tidal bore need?",[736,738,740,742],{"id":66,"label":737},"Cold water and a full moon",{"id":69,"label":739},"A large tidal range and a shallowing, funnel-shaped river mouth",{"id":72,"label":741},"An earthquake under the river",{"id":75,"label":743},"A very deep, wide river with no narrowing at all","A big enough tide, forced into a shallowing, narrowing channel, lets the deeper water behind catch up with the shallower water ahead until the front steepens into a bore.",{"itemId":746,"prompt":747,"options":748,"correct":69,"why":757},"tides.investigate-q-surge","Why is a storm surge especially dangerous if it arrives at high tide?",[749,751,753,755],{"id":66,"label":750},"High tide always causes storms",{"id":69,"label":752},"The surge adds on top of an already-high sea level, making the total far higher",{"id":72,"label":754},"Storms only happen at high tide",{"id":75,"label":756},"It doesn't matter; the surge is the same size either way","A storm surge rides on top of whatever the ordinary tide is doing, so the same surge arriving at high tide reaches a much higher total level than at low tide.",{"itemId":759,"prompt":760,"options":761,"correct":69,"why":770},"tides.investigate-q-barrage","What does a tidal barrage need to be worth building?",[762,764,766,768],{"id":66,"label":763},"A river with no tide at all",{"id":69,"label":765},"An unusually large tidal range",{"id":72,"label":767},"Constant sunshine",{"id":75,"label":769},"A very deep, tide-free harbour","Both real examples in this layer, the Rance and Sihwa Lake, sit where the tidal range is unusually large — exactly the condition India's Gulf of Khambhat and Gulf of Kutch meet.",{"itemId":772,"prompt":773,"options":774,"correct":69,"why":783},"tides.investigate-q-incois-limit","What can a tide table NOT predict?",[775,777,779,781],{"id":66,"label":776},"The time of the next high tide",{"id":69,"label":778},"The extra rise caused by a storm surge",{"id":72,"label":780},"The height of an ordinary spring tide",{"id":75,"label":782},"The date of the next neap tide","A tide table predicts the astronomical tide only. Storm surges come from weather, which is why surge warnings are issued separately, on top of the tide table.",{"itemId":785,"prompt":786,"options":787,"correct":69,"why":796},"tides.investigate-q-sundarbans","Why do Sundarbans ferries and honey collectors watch the tide so carefully?",[788,790,792,794],{"id":66,"label":789},"The tide affects mobile phone signal",{"id":69,"label":791},"A boat or a person crossing a channel at the wrong time can be stranded or caught by a fast current",{"id":72,"label":793},"Tigers only appear at high tide",{"id":75,"label":795},"The tide changes the taste of the honey","Channels that are easily crossed at one state of the tide can be impassable mudbanks or dangerously fast currents a few hours later.",{"itemId":798,"prompt":799,"options":800,"correct":72,"why":809},"tides.investigate-q-bhola","The 1970 Bhola cyclone, one of the deadliest disasters ever recorded, struck with a storm surge of roughly…",[801,803,805,807],{"id":66,"label":802},"0.5 m",{"id":69,"label":804},"2 m",{"id":72,"label":806},"10 m",{"id":75,"label":808},"50 m","About 10.5 m — enough to drown huge areas of the flat delta coast of East Pakistan (now Bangladesh) and West Bengal, contributing to at least 300,000 deaths.",{"id":811,"type":812,"title":813,"points":814},"i-cheat-sheet","summary","Cheat sheet: investigating real tides",[815,816,817,818,819,820,821,822],"A real tide table is a **measured, predicted** record, not a smooth formula — the smooth cosine model in this layer is a teaching approximation, close but not exact.","**Semidiurnal** = two similar highs and lows a day (most of India). **Diurnal** = one high, one low (Gulf of Mexico). **Mixed** = two of each, clearly unequal (San Francisco).","A **tidal bore** needs a large tidal range squeezed into a shallowing, narrowing river mouth, so the deeper water behind outruns the shallower water ahead. India's Hooghly has one; China's Qiantang, at about 9 m, has the world's biggest.","A **storm surge** is sea level raised by a cyclone's low pressure and onshore wind. It rides on top of the ordinary tide, so a surge at high tide is far worse than the same surge at low tide — as the 1999 Odisha Super Cyclone showed.","A **tidal barrage** turns the tide's rise and fall into electricity, but is only worth building where the range is unusually large, as at the Rance (240 MW) or Sihwa Lake (254 MW).","Coastal life — the Sundarbans, salt pans, ferries, fishing — is organised around the tide in fine detail, not just roughly.","**INCOIS** and the **Survey of India** predict tides using harmonic analysis: splitting a measured tide into steady waves tied to the Moon and Sun, then running them forward. This cannot predict weather-driven storm surges, which are forecast separately.","Funnelling, shallowing and resonance are testable ideas, not just stories: range really does grow up a funnel, and a resonant basin's calculated size lands close to the real geography.",{"id":824,"type":825,"sourceIds":826},"i-sources","sources",[827,828,829,830,831,832,833,834,835,836],"tides-noaa-tides-tutorial","tides-incois-tide-forecasting","tides-survey-of-india-tidal","tides-wikipedia-tidal-bore","tides-wikipedia-hooghly","tides-wikipedia-qiantang","tides-wikipedia-odisha-cyclone","tides-wikipedia-bhola-cyclone","tides-wikipedia-tidal-power","tides-wikipedia-tidal-resonance",[827,828,829,830,831,832,833,834,835,836],"needs_review",{"generatedBy":840,"notes":841},"claude-code","Draft generated locally; pending owner review.","1b8dd445137dc1f7db8d147090e3e182e0c80149c0cb2691d53938d90ca2130a",{"component:data-lab@1":844,"logic:practice":845,"component:sort-game@1":846,"component:match-pairs@1":847,"component:tide-lab@1":848,"source:tides-incois-tide-forecasting":849,"source:tides-noaa-tides-tutorial":850,"source:tides-survey-of-india-tidal":851,"source:tides-wikipedia-bhola-cyclone":852,"source:tides-wikipedia-hooghly":853,"source:tides-wikipedia-odisha-cyclone":854,"source:tides-wikipedia-qiantang":855,"source:tides-wikipedia-tidal-bore":856,"source:tides-wikipedia-tidal-power":857,"source:tides-wikipedia-tidal-resonance":858},"466896cc37735f48db03875fe9c9ce42fc8bcb7e5f937c9779d70513703b91bd","3d6b0fe1b15255975a32b0fcd94e8019bc959ad45cbf12e136e86149549c6878","b164f45a2c8ca08f26c450768ff0231e113e9fe45381eddb34dc6d0548596c38","2a8ee4ac87460b4e1175a4bb13c96b03d577db06dde95670eb7fcfe4ad787899","5fef8b331bba35d6df96a31b84dd1f98200bcd0242eeed843d22914391057b6c","c8bcfd0dc5b9671b4b89f5c1abc1f9dbf9e3f3caf1325102661e5d41a455803f","82683db912324c1f40c9e2f4d4cc0312c637b4af2490f13ca404549ec5e414a0","2e99068442e3818ea49964d49796e478ce8718d4e7d9cb9138f2efc27ba39702","aebec1a98571f18e35aced24ca8dd00162763eaf059debee6b4f94dc994390b4","3e3f0aff2cf32dda4ee61951556d2f088789f06d1a2e919ed0ee769153c62f43","bd4f06a296f5bd340255d59b68c176e06a3de54a83b0eabdb678365a9972df3f","9962bf41f63ccaaec7b71807b8c1de8a0f6f80967328373a3a3cabf46a091b20","222194db3ca5354e6223f949e0d1a5ce0ac74beeaa0bf6454f037b9941deb145","1a7cb919ac647db8b0abf9bb573b1c1bd1473fe1367b38c58e6cf5748617f370","7f84f7fc92ea0f8bd091c0a1e41d05af8277c84577f2ad7f3eeadb32d479dc99",{"state":860,"reviewer":861,"selfReview":862,"reviewedAt":863,"method":864},"approved","The library owner",true,"2026-09-20T10:18:37.581Z","owner_bulk","preview-7e1cbbcc4f",1789899598979]