Go Phutlhama ga Dikago Tse di Tlogetsweng kgotsa Tsela e e Kafa Tlase ga Borogo, Morwalela o o Tlang ka Tshoganyetso mo Dithaneleng tsa Metsi a Setsuatsue, le go Falola ga Metsi a a Kwa Godimo¶

Go batla tshireletso mo maemong a bosa a a maswe thata, serame, kgotsa go gogolwa ga mebila mo teng ga thanele ya konkoreite e e kafa tlase ga lefatshe ya go ntsha metsi a setsuatsue (flood-control box culvert, e e jaaka mesele e e kafa tlase ga lefatshe e e kafa tlase ga Las Vegas, Phoenix, Los Angeles, San Antonio, Madrid, kgotsa Tokyo), tsela e e fetang ka fa tlase ga borogo jwa noka e e nang le diphatlha tse di kwa tlase (concrete abutment shelf), kgotsa kago e e tlogetsweng e e sentsweng ke molelo kgotsa e e bodileng ke metsi (vacant factory, unreinforced masonry warehouse, or condemned house squat) e tsenya batho ba ba se nang matlo, batlhotlhomisi ba ditoropo, le badiri ba phalotso mo dikotsing tse pedi tse di bolayang tse di tsamayang ka bonako thata mo tikologong e e agilweng: (1) Morwalela wa Tlhagiso wa Lefela wa Ka fa Tlase ga Lefatshe (where a thunderstorm 25 kilometers / 15 miles away in the mountains sends a 2-meter / 6.5-foot wall of water racing through a bone-dry underground tunnel at 25 to 40 km/h / 15 to 25 mph under a clear blue sky).

Fa o le mo teng ga mosele wa setsuatsue o o kafa tlase ga lefatshe, mosele wa lebokoso, kgotsa mo nokeng e e omileng ya sekontiri gone jaanong mme o utlwa terena ya dithoto e e kgakala e rora, o utlwa monko wa tshoganyetso wa ozone/lefatshe le le metsi, kgotsa o bona metsi a a elelang fa fatshe a fetoga seretse mme a tlhatloga le eleng ka disentimetara di le 2 (3/4 inch), latlhela dithoto tsotlhe tse di bokete mme o tswe kwa godimo kgotsa o palame lere e e gaufi e e emeng ya manhole mo metsotswaneng e le 60. Leletsa nomoro ya tshoganyetso ya selegae sa gago (911 kwa United States le kwa Canada, . 112 go kgabaganya Yunione ya Yuropa, 999 kwa Bogosi jo bo Kopaneng, 000 kwa Australia) ka dinomoro tsa tshoganyetso, mme o botse merwalela, go tshela kwantle ga ntlo le go tlhaola maemo a bosa a a feteletseng, go feela dikampa, go tseelwa dithoto, le ditshwanelo tsa bonno, le go tlhoka magae ka tshoganyetso: diura tsa ntlha di le 48 le bonno jwa tshoganyetso.

Dira se jaanong¶

1. **FA O LE MO TENG GA THUNNELE YA GO TSHOLA METSI A SEFEFO KGOTSA O TLHATSWA GA KONKOREITI MME O UTLWE MODUMO O O TLHAGSE, O UTLWE MOWA O O TSIDILENG KA TSHOGANYETSO, KGOTSA O BONE FOAM/MATLAKALA A A BOROTLHO A TLHAGANA: Tlogela Didirisiwa Tsotlhe tsa Vertical Manholest ka bonako le go Sprint.
2. O se ka wa ema go phutha kgetsi ya go robala, tante, mokotla, kgotsa baesekele mo teng ga mosele wa setsuatsue o o nang le morwalela. Dithanele tsa konkoreite tse di laolang morwalela di dirilwe gore e nne ditšhute tsa haeteroliki tse di senang kgotlhego: fa metsi a a tsamayang ka bonako a fitlha go 15 centimeters (6 inches) boteng mo bodilong jwa konkoreiti jo bo borethe, jo bo apesitsweng algae kwa 3 to 5 meters per second (10 to 16 feet per second), maatla a kgogedi a metsi (half of water density multiplied by velocity squared and area) e kgwa dinao tsa motho yo mogolo go tswa ka fa tlase ga tsone ka ponyo ya leitlho mme e bo e di tshwara ka fa tlase ga metsi mo dikereiti tsa matlakala tse di kwa tlase (bar screens).
3. Fa o sa kgone go feta metsi ka boleele go ya kwa molomong wa thanele, tlhatlogela kwa godimo ka bonako: batla ditepisi tsa lere tsa tshipi e e magogodi kgotsa tsa tshipi tse di latlhetsweng mo dišafoteng tsa chimney tsa manhole tsa konkoreiti tse di emeng tse di katoganeng ka sekgala sa dimitara dingwe le dingwe di le 90 go ya go di le 150 (300 to 500 feet) go bapa le siling ya thanele, palamela kwa godimo ga serwalatlhogo sa peipi e kgolo, mme o bo o tsenya dibutse tsa gago mo šafoteng e e emeng (or push the street manhole cover up with your legs/shoulders, not your hands).
4. FA O TSHWARELE MO LETJENG YA TSELA YA BOROGO (ABUTMENT SHELF) FA NOKA E TLHOTLHOMELA FA TLASE GA GAGO: Tlhatlogela kwa Lefelong la Tsela e Kgolo Pele ga Metsi a Fitlha mo Dikhuting tsa Gago (Never Wait Until Water Touches the Bridge Girders).
5. Fa noka e tlala ka fa tlase ga tsela e kgolo kgotsa borogo jwa seporo, ditlhare tse di kokobetseng le dithotobolo di thulana le dipilara tsa borogo mme di dira letamo la go sefa, go dira gore selekanyo sa metsi ka fa tlase ga borogo se tlhatlogele kwa godimo dimitara di le 1.5 (5 feet) mo metsotsong e le 5 fa e ntse e dira sediko se se bolayang se se yang kwa tlase (hydraulic boil) go dikologa dipilara tsa konkoreite.
6. Tlhatloga mokgokolosa wa go gagoga ga konkoreiti (at the 45-degree corner wing-walls of the bridge) go ya kwa legetleng le le kwa godimo la tsela e kgolo ka bonako, tsoka lebone le le phatsimang kgotsa letsela le le bonalang sentle fa pharakano e feta, mme o letsetse ** .911 / 112 / 999** ya Setlhopha sa Phalotso ya Thapo ya Swiftwater / ya Angle e e Kwa Godimo.
7. FA O LE MO GARENG GA KAGO E E TLOGELWENG MME O UTLWA MEDUMO E E BOGALE YA GO PHATLHA/GO THHUNYA, BONA LEROLE LA POLASETERA LE WELA MO DIJOISTENG TSA SILING, KGOTSA O UTLWA FA FATSHE LE SAG: Tswa ka Perimeter Masonry Stairwell (Never the Center of the Floor).
8. Ditlhomeso tsa fa fatshe tsa logong tse di bodileng le ditlhomeso tsa marulelo a tshipi e e rusitseng di palelwa mo bogareng jwa sepan pele, di latlhela bogare jwa fa fatshe ka tlhamalalo mo kamoreng e e kwa tlase (while the outer edges bolted into the thick exterior brick walls often remain hanging as triangular "Lean-To V-Voids").
9. Atlarela lebota la setena le le rwalang morwalo la kwa ntle kgotsa la konkoreite (or an enclosed corner masonry stairwell) fa o tswa; fa matlakala a simolola go wa pele ga o ka fitlha kwa kgorong, thuma fa thoko ga kholomo e e tiileng e e emeng e e rwalang morwalo, lebota la sekontiri la ditepisi, kgotsa metšhini e e bokete ya madirelo (which creates a survivable void space) mme o ikgoge go nna bolo e e gagametseng e e sireletsang tlhogo le sehuba sa gago (never lie flat on your stomach where collapsing beams crush your ribcage preventing chest expansion).
10. FA O KA GOGOELWA MO METSI A MORELA A A TSAMAYANG KA BOFEFO MO TENG GA MOSELE KGOTSA NOKA: Akanya gore "Defensive Swiftwater Swimming Position" (On Your Back, Feet First Downstream, Toes Up, Sculling With Hands).
11. O se ka wa leka go ema mo metsing a morwalela a a tsamayang a a fitlhang mo mangoleng kgotsa mo lethekeng: fa setlhako sa gago se tsena mo teng ga kolotsana ya mabenkele e e nweletseng, mo lelokololong la konkoreite, kgotsa mo setlhopheng sa dithapo ("Foot Entrapment"), maatla a moela ono a mena mmele wa gago ka bonako o lebile fa fatshe ka fa tlase ga metsi mme a go tshwara foo.
12. Phaphamala ka mokwatla wa gago o supile maoto kwa tlase (in front of you), mangole a obegile go sekae, le menwana ya dinao kwa godimo ga boalogodimo ka jalo ditlhako tsa gago tsa ditlhako di boa mo matlapeng a konkoreite le mabota jaaka di-shock absorber, mme o dire angle ya mmele wa gago ka 45-degree ferry angle go ya kwa bankeng e e gaufi ya konkoreite kgotsa lere ya pholoso.

Setlhare sa tshwetso: Porothokholo ya go falola ka bonako mo merwaleleng ya dithanele, go tlhatloga ga ditsela tse di fetang ka fa tlase ga lefatshe, le go phutlhama ga di-squat¶

flowchart TD
    A["Maemo a Tshoganyetso a a Potlakileng a Kago kgotsa a Morwalela mo Moseleng wa Sefefo, mo Tseleng e e Fetang ka fa Tlase ga Borogo, kgotsa mo Lefelong le le Tlogetsweng"] --> B{"O Mo Tikologong Efe Ga Jaana?"}
    B -->|"1. Thanele e e ka fa Tlase ga Lefatshe ya Mosele wa Sefefo, Mosele wa Lebokoso, kgotsa Go Tlhatswa Konkoreite"| C{"A Metsi a Tlhatloga Kgotsa A O Utlwa Go Rora Kgakala / O Utlwa Phefo e e Fokang?"}
    C -->|"Ee: Metsi a a Tlhatloga / Go Utlwa Go Rora"| D["LATLHELA DIKERI TSOTLHE KA BONAKO: O SE KE wa Paka Tente kgotsa Dikgetsi (O na le < Metsotswana e le 60 go ya go e le 120 Pele ga Knockdown Flow)"]
    D --> E{"A Kgoro ya Thanele e e Buletsweng / Lebota le le Mokgokolosa le mo Bogareng jwa 100m Kwa Godimo/Ka fa thoko?"}
    E -->|"Ee"| F["Taboga go tswa mo Molomong wa Thanele kgotsa Palama Lebota la Motšhine o o Mokgokolosa wa Trapezoidal o Dirisa Terata ya Kgokagano ya Ketane / Ditokololo tsa Katoloso"]
    E -->|"Nnyaa (Mo teng ga Lebokoso la Ka fa Tlase ga Lefatshe)"| G["PALAMA LERE YA CHIMNEY YA MANHOLE E E TSEMENG KA BONAKO: Tlhatlogela kwa Godimo ga Serwalatlhogo sa Peipi, Itshegetse Morago Kgatlhanong le Shafote, Ponta mo Sekhurumelong sa Manhole sa Mmila ka Selo sa Tshipi le Leletsa 911/112"]
    B -->|"2. Leje la Tsela e e ka fa Tlase ga Borogo / Kampa ya Lebopo la Noka"| H["Go Tshaba ka go Tshwaraganya ka Motheo wa Riprap wa Lebota la Diphuka la Didikirii di le 45 go ya kwa Legetleng la Tsela e Kgolo e e kwa Godimo Pele ga Metsi a Fitlha kwa Dikhuting; Leletsa Phalotso ya Swiftwater"]
    B -->|"3. Kago e e Tlogetsweng / Bobolokelo jo bo senang Ope"| I{"A Bodilo bo a Kgona, Mabota a a Obama Kgotsa Marulelo a a Phatloga?"}
    I -->|"Matshwao a Tlhagiso Pele ga go Phutlhama"| J["Tswa ka Bofefo: Tsamaya mo Diphemithareng tsa Lebota le le Rwang Morwalo la Kwa Ntle (O se ka wa Kgabaganya Sephara sa Bodilo jo bo Fa Gare)"]
    I -->|"Go Tshwarwa mo Teng Go Phutlhama go go Matlhagatlhaga / Go Tshwarwa ke Matlakala"| K["Dive Go Bapa le Lebota la Sekhutlo le le Rwang Morwalo kgotsa Kholomo e e Bokete ya Popego ('Khutlotharo / Lean-To Void'); Khurumetsa Molomo ka Hempe Kgatlhanong le Lerole la Silica/Asbestos; Konya Peipi Makgetlo a le 3 Metsotswana mengwe le mengwe e le 60"]

Boemo 1: Merwalela ya tshoganyetso mo dithanele tse di ka fa tlase ga lefatshe tsa mesele ya ditsuatsue le mesele ya morwalela ya konkoreite¶

Mo ditoropong go kgabaganya Borwabophirima jwa Amerika (Las Vegas's 1,000 kilometers / 600 miles of underground flood tunnels managed by the Clark County Regional Flood Control District; Phoenix; Albuquerque; Los Angeles's concrete river channels; San Antonio; Austin; Dallas), Yuropa, le Asia, diketekete tsa batho ba ba se nang matlo ba iphitlha mo teng ga dimitara di le 3 ka dimitara di le 4 (10-by-13-foot) di-culvert tsa mabokoso a konkoreiti e e nonotshitsweng ka gonne di nna di tsidifetse mo mogoteng wa selemo wa 45°C le go oma malatsi a le 340 ka ngwaga.

====================================================================================
     ANATOMY OF AN UNDERGROUND STORM-DRAIN FLASH FLOOD ("SURCHARGE PIPE FLOW")
====================================================================================

   [Street Level] ======[Cast-Iron Manhole Cover (50-110 kg)]======
                                    |     |  <-- VERTICAL MANHOLE CHIMNEY SHAFT
                                    |  H  |      - Steel ladder rungs on wall
                                    |  H  |      - SURVIVAL REFUGE: Climb up into
                                    |  H  |        this vertical chimney ABOVE the
   [Tunnel Ceiling] ----------------+  H  +----------------  tunnel ceiling before
      AIR SPACE VANISHES IN 3 MINS  |  H  |                  water fills the pipe.
   ........................................................  <-- Rising Flood Crest
         ---> 25 to 40 km/h (15-25 mph) Debris Wall --->          (Zero Air Pocket
   ========================================================       Once "Surcharged")
   [Slick Algae Concrete Floor: 15 cm (6 in) Fast Water Knocks an Adult Down]
====================================================================================

Matshwao a le 4 a a tlhagisang go sa le gale a morwalela o o atamelang wa thanele (Even Under a Sunny Sky)¶

Ka gonne mesele ya metsi a pula e phutha metsi a a tswang mo mebileng e e tsentsweng ditsela le mo dithabeng dikhilometara di le 10 go ya go di le 30 (6 to 20 miles) kwa godimo ga noka, gangwe le gape ga o kitla o bona lerothodi le le lengwe la pula kgotsa o utlwa maru** kwa kgorong ya thanele pele ga lekhubu la morwalela le le bolayang le goroga. Tshwara ditlhagiso tseno tse nnè tsa dikutlo ka tlhogo:

1. Phefo ya Piston le Monkgo wa Lefatshe le le Metsi (3 to 8 Minutes Before the Water Wall):
2. Fa lebota la metsi a morwalela le tlatsa karolo e e kgabaganyang ya thanele e e kwa godimo, le dira jaaka plunger e kgolo ya sering e e kgoromeletsang kholomo ya mowa o o sutang kwa pele ga yone go ya kwa tlase mo peiping. Fa ka tshoganetso o utlwa phefo e e tswelelang, e e tsidifetseng, e e metsi e foka mo thaneleng e e tlwaelegileng e e sa tshikhinyeng e patilwe ke monko wa sekontiri se se metsi, gase ya kgeleloleswe, le ozone, lekhubu la morwalela le setse le le mo teng ga peipi e e kwa godimo ga gago.
3. Modumo wa "Tsela e e tsamayang ka fa tlase ga lefatshe / Terena ya Dithoto" (1 to 4 Minutes Before Impact):
4. Di-culvert tsa mabokoso a konkoreiti di dira jaaka dikaedi tsa makhubu tsa modumo: go tlhotlhora ga metsi go thula matlapa, dikolotsana tsa mabenkele, le dikota mo bodilong jwa konkoreite go dira go rora go go tseneletseng, go go tlhatlogang ga makhubu a a kwa tlase go go boelelang mo thaneleng metsotso pele ga metsi a tlhagelela.
5. "Dirty Trickle" & Go Tlhatloga ka Tshoganyetso ga Diboko/Dipeba mo Maboteng (30 to 90 Seconds Before the Crest):
6. Lebelela mosele o monnye o o mo gare o o elelang kwa tlase (invert channel) mo bodilong jwa thanele: ka bonako fela fa metsi a a phepa a fetoga go nna borokwa jwa tšhokolete, go nna le bubble, kgotsa go rwala marago le matlhare a sekerete a a phaphametseng, KGOTSA o bona **makgolokgolo a dipeba, digokgo, le dipeba di phaphasela ka tshoganyetso di phaphasela ka tsepamo mo maboteng a matlhakore a konkoreite, hins is the second.
7. Kafa o ka Tshwarang ka gone ka Chimney ya Manhole e e Tsepameng fa Thanele e Tlala:
8. Leba kwa godimo kwa siling fa o tsena mo moseleng ope wa setsuatsue mme bala dikgato tsa gago go ya kwa lere e e gaufi ya šafote ya manhole e e emeng.
9. Fa e le gore o tshwaregile ka fa tlase ga lefatshe ke metsi a a tlhatlogang, palama dikgato tsa lere ya tshipi go ya kwa godimo go tsena mo chimini e tshesane e e sediko e e emeng ka fa tlase ga mmila.
10. Tlhokomediso mo Dithapong tsa Lere tse di Rusitseng: Ka metlha tlhokomela dintlha tse tharo tsa kgolagano mme o beye diatla le dinao tsa gago di tlhatswa mo dintlheng tse di kwa ntle tsa dithapo tsa tshipi gone fa e tsenang mo leboteng la konkoreite (never in the middle of a corroded rung, where bending stress is highest and rusted steel snaps).
11. Kafa o ka Bulang Dikilogeramo di le 70 (150-Pound) Sekhurumelo sa Manhole sa Mmila sa Tshipi e e Latlhetsweng Go tswa kwa Tlase: Le ka motlha o se ke wa leka go kgoromeletsa sekhurumetso sa manhole kwa godimo o otlolotse matsogo mo tlhogong ya gago. Tlhatlogela kwa godimo mo e leng gore magetla a gago kgotsa ditlhako tsa ditlhako tsa gago (fa o ntse o tshegetsa mokwatla wa gago ka go rapama kgatlhanong le lebota le le lebaganeng la konkoreite la šafote) o ka kgweetsa go ya kwa godimo ka maatla a leoto/mokwatla, KGOTSA go jamela peipi/crowbar ya tshipi mo di 2.5-centimeter (1-inch) tlhopha dikhutsi mo sekhurumelong sa tshipi e e tshetsweng mme o tsoketse letsela le le phatsimang kgotsa lesedi la lebone mo mmileng gore bakgweetsi le batsamaya ka dinao ba go bone mme ba letsetse 911.

Boemo 2 : Dikotsi tsa go phutlhama ga dikago mo teng ga dikago tse di tlogetsweng (Squats), matlo a bobolokelo, le dikago tse di fisitsweng¶

Mo bathong ba ba senang matlo ba ba sireletsegileng mo teng ga matlo a a senang ope, ditshilo tsa madirelo tse di tlogetsweng, kgotsa dikago tse di sentsweng ke molelo, go phutlhama ga dikago mo e ka nnang ka metlha go bakwa ke go tsenelela ga metsi ka marulelo a a dutlang (which silently rots wooden floor joists over months) kgotsa merwalo ya kapoko/pula ya mariga go oketsa masomesome a ditone tsa meteriki tsa bokete mo ditlhomesong tse di sa siamang.

Tsela ya go falola le go bolelela baphalotsi fa ba tshwaregile ka fa tlase ga matlakala a kago (USAR Void-Space Survival)¶

Fa marulelo a kago e e tlogetsweng kgotsa bodilo bo ka phutlhama pele ga o ka tswa: 1. Sireletsa Tsela ya Gago ya Mowa Kgatlhanong le Silica, Polasetere, le Lerole la Asbestos (Seconds 1 to 30): - Go phutlhama ga dikago go tlatsa mowa ka lerole le le foufatsang, le le hupetsang silica ya kristale, sekontiri sa kalaka se se thugilweng, fiberglass, le lerole la asebesetose. Ka bonako fela goga kholara ya sekipa kgotsa baki ya gago kwa godimo ga nko le molomo wa gago (breathe through 2 to 4 layers of cloth) mme o nne o tswetse matlho go fitlhela leru la lerole le tlhomama. 2. O se ka wa Tshuba Lesedi, Motšhini, kgotsa Sethuthafatsi sa Propane ka Tlase ga Matlakala: - Dikago tse di phutlhameng gantsi di na le dipeipi tsa gase ya tlholego tse di kgaotsweng (or decaying organic/sewer pockets). Go itaya kgabo go dira gore go thunye mo lefelong le le pitlaganeng mme go je kgetsi ya gago e e lekanyeditsweng ya okosejene. Dirisa sekerini sa smartphone kgotsa lebone la LED ka kelotlhoko. 3. Dirisa Boditšhabatšhaba "3-Tap Acoustic Pipe Signal" (Do NOT Scream Continuously): - Go goa mo matlakaleng a a lerole go lapisa okosejene ya gago, go fedisa metsi mo kgokgotsong ya gago, mme go tsenelela ka bonya mo konkoreiting ya metara e le 1. - Go na le moo, tsaya tshipi, peipi, kgotsa letlapa mme o thute dipompo di le 3 tse di farologaneng, tse di nang le moribo (TAP - TAP - TAP ... pause ... TAP - TAP - TAP) kgatlhanong le peipi ya metsi ya tshipi, peipi ya radiator, I-beam ya tshipi, kgotsa kholomo ya konkoreite metsotswana mengwe le mengwe e le 60. Dithoromo tsa modumo di tsamaya dimitara di le 50 go bapa le dipeipi tsa tshipi tse di tswelelang ka tlhamalalo go ya kwa FEMA / Lefapha la Molelo la Patlo le Phalotso ya Toropo (USAR) Disensara tsa go reetsa tsa Delsar seismic/acoustic, mme fa o utlwa dintša tsa pholoso kgotsa mantswe a a fa godimo, emisa go kokota ga gago gore o kgone go utlwa pitso ya tsone le go kokota gape fa o laela.

Boemo 3: Go thuthafatsa go go babalesegileng ga mariga/ditsuatsue le melao ya khabonemonokosaete mo dikhuting le mo ditseleng tse di fetang ka fa tlase ga lefatshe¶

Batho ba le bantsi ba ba sireletsang mo dikagong tse di tlogetsweng, mo diforomong tsa mabokoso, le mo ditseleng tse di fetang ka fa tlase ga maborogo ba swa mariga mangwe le mangwe ka ntlha ya Carbon Monoxide (CO) poisoning and mattress fires than from structural collapse: - Never burn a charcoal grill, wood pallet fire, gas generator, or camp stove inside an unvented room, basement, or concrete culvert: Burning charcoal or damp pallet wood indoors produces 3,000 to 10,000 ppm of odorless Carbon Monoxide (CO), causing fatal coma during sleep within 20 to 45 minutes. - Keep Two Independent Physical Exit Paths Clear (The Squat Fire Rule): Vacant buildings filled with cardboard, mattresses, and tarps burn from a single candle tip to total flashover (600°C / 1,100°F) in under 180 seconds. Never sleep in a room where the windows are welded shut with steel security bars or boarded over from the outside with plywood unless you have pried open a second ground-floor window/door escape path before lying down.

Scenario 4: Bridge underpass hydraulic hazards, riprap climbing, and low-head dam ("drowning machine") escape¶

Rough sleepers and flood evacuees frequently camp on the flat concrete bridge abutment shelf (bridge seat) directly beneath highway overpasses or alongside urban river walk channels. While a highway bridge blocks vertical rainfall, the underpass itself sits inside the engineered floodway constriction of the river or drainage channel:

1. Why Rivers Rise Twice as Fast Underneath a Bridge (Venturi Constriction & Debris Strainer Dams):
2. Engineers narrow the riverbank with concrete wing-walls to shorten the bridge span. When storm runoff surges down the channel, that narrowing forces the water to accelerate and pile up vertically (backwater rise) right against the bridge piers.
3. Worse, as soon as the first uprooted tree, floating dumpster, or wooden pallet catches sideways across the concrete bridge piers, every piece of downstream debris slams into that tree, building a solid Debris Dam in minutes that backs floodwater right up onto the upper underpass ledge where tents are pitched.
4. How to Escape Up Steep Concrete Channel Walls (Trapezoidal Flood Channels):
5. If you are caught inside a sloped, 45-degree concrete flood channel (such as the Los Angeles River, Las Vegas Wash, or San Antonio River flood tunnels) where algae and silt make the wet concrete as slick as greased glass:
   • Do not try to walk straight up smooth wet concrete in wet rubber shoe soles: crawl on all fours along the vertical concrete expansion-joint grooves (spaced every 6 to 9 meters / 20 to 30 feet), which provide finger- and boot-edge purchase, OR grab the bottom tension cable of the perimeter chain-link fence at the top lip of the channel.
   • The "Backpack Throw-Bag" Rescue From the Bank: If a companion is swept down a concrete channel and you are standing safe on the bank above them, never jump in after them (both of you will be swept away). Instead, empty half the heavy clothes out of a backpack, clip a 15-meter (50-foot) nylon paracord or tarp rope to the backpack grab-handle (leaving one sealed empty plastic 2-liter water bottle or closed sleeping pad inside the pack for buoyancy), hold the tail end of the rope wrapped around a fence post (never tied around your own wrist or waist), and throw the floating backpack upstream of your companion so they can hug the pack to their chest and pendulum-swing into the bank.
6. Escaping a Low-Head Dam or Box-Culvert Drop-Off (The "Recirculating Hydraulic Boil"):
7. Where an underground storm-drain culvert empties out into a concrete dissipation basin (or where an urban river drops 1 to 3 meters over a concrete weir / low-head dam), the falling sheet of water plunges to the bottom and curls backward upstream, creating a submerged recirculating washing-machine vortex (hydraulic jump / keeper hydraulic) that pulls floating victims back into the falling curtain of water over and over.
8. If caught in a recirculating hydraulic at a culvert mouth: Do not waste your breath trying to swim forward on the surface against the backward-flowing boil. Instead, (a) try to work your body sideways (laterally) along the face of the weir toward the angled concrete wing-wall where the hydraulic breaks, OR (b) tuck into a ball, sink to the bottom concrete floor directly beneath the falling curtain where the green bottom current shoots downstream, and push off the floor downstream past the white foamy boil line before surfacing.

Protecting your critical ID documents, EBT card, and phone inside a flood-prone encampment¶

When evacuating a flooding storm drain or collapsing squat in the dark, losing your driver's license, birth certificate, Social Security card, SNAP/EBT card, and Lifeline phone inside a flooded tent sets your housing recovery back by months. Sleep every night with your ID cards, EBT card, medication bottles, and phone sealed inside a waterproof roll-top dry bag (or double-zipped quart freezer Ziploc bags) clipped directly to your belt loop or worn inside a cross-body chest pouch under your jacket, never left loose on the tent floor.

First aid note for floodwater immersion, hypothermia, and crush injuries¶

Urban storm-drain floodwater is a toxic soup of raw sanitary sewer overflow (CSO), rat urine (Leptospira), motor oil, hypodermic needles, and freezing runoff. Anyone pulled from a flooded tunnel or river channel must: (1) strip off wet clothing immediately and wrap in dry blankets/Mylar to prevent conductive hypothermia (which strikes even in 20°C / 68°F water), (2) flush all cuts and scrapes with clean bottled water + soap + antiseptic (povidone-iodine) to prevent leptospirosis, tetanus, and Vibrio / Aeromonas soft-tissue infections, and (3) visit an emergency department or street-medicine clinic if any floodwater was swallowed or aspirated ("secondary pulmonary injury"). Taking a hands-on First Aid and CPR course from the Red Cross or St John Ambulance prepares you to manage drowning and trauma before EMS arrives.

Regional emergency, swiftwater rescue, and severe-weather shelter contacts¶

• United States & Canada:
• Immediate Tunnel Flood, Swiftwater Rescue, or Building Collapse: Call 911 and state clearly: "SWIFTWATER RESCUE NEEDED IN [STORM DRAIN / CHANNEL LOCATION]" kgotsa "STRUCTURAL BUILDING COLLAPSE WITH PERSON TRAPPED AT [ADDRESS]" (so dispatch sends Technical Rescue / USAR and Swiftwater boats rather than a single patrol car).
• 24/7 Emergency Severe-Weather Shelter & Outreach Van Dispatch: Dial 211 (or 311 in NYC, Chicago, LA, SF, Toronto). During Flash Flood Watches, Freeze Warnings, or Code Blue/Code Red alerts, municipal outreach teams (such as HELP of Southern Nevada's tunnel outreach team in Las Vegas, LAHSA ERT in Los Angeles, or DHS Outreach in NYC) provide emergency transport to dry shelters with no ID barriers.
• United Kingdom & European Union:
• Emergency Fire & Technical Rescue: Dial 999 (UK) or 112 (EU).
• Rough Sleeper Emergency Shelter Referral: In the UK, contact StreetLink (thestreetlink.org.uk) or local council SWEP (Severe Weather Emergency Protocol) ditafole tsa matlo; kwa Fora, daela 115 (SAMU Social Mola wa tshireletso wa tshoganyetso wa mahala wa 24/7).
• Australia:
• Morwalela wa Tshoganyetso / Mapodisi / Phalotso ya Molelo: Letsa 000; Tirelo ya Maemo a Tshoganyetso ya Puso (SES Phalotso ya Morwalela le Setsuatsue): Letsa 132 500.
• For emergency numbers in over 190 countries, consult dinomoro tsa tshoganyetso.

Dipotso tse di bodiwang kgapetsakgapetsa¶

How can an underground storm-drain tunnel flood with a 6-foot wall of water when it isn't even raining outside?¶

Concrete storm drains and flood-control channels act as giant funnels collecting rainwater from paved streets and mountains 15 to 30 kilometers (10 to 20 miles) away. A heavy thunderstorm over distant foothills sends millions of liters of runoff racing down frictionless concrete pipes at 25 to 40 km/h (15 to 25 mph), arriving under a sunny sky with zero local rain. If you are in a tunnel and feel a sudden cool breeze, smell wet dirt, hear a low freight-train rumble, or see the floor trickle turn muddy, drop all belongings and exit or climb a vertical manhole ladder within 60 seconds.

Why should I never try to stand up or walk if I get knocked down in knee-deep moving floodwater?¶

Moving water at just 15 centimeters (6 inches) deep can knock an adult off their feet, and trying to put your feet down in knee-deep or waist-deep fast water creates a deadly "Foot Entrapment" hazard. If your boot or ankle catches inside a submerged grate, rebar stub, concrete expansion joint, or shopping cart, the immense force of the current immediately pushes your chest and head face-down under the water and pins you there. Always float on your back with your feet pointed downstream in front of you and your toes up near the surface to bounce off obstacles while angling 45 degrees toward the bank.

Where is the safest place to move if an abandoned building starts cracking or collapsing while I am inside?¶

In older brick and timber buildings, rotting or overloaded floor joists always give way in the center of the room first, dropping the middle of the floor straight down into the basement while the outer edges bolted into the thick perimeter walls often remain attached as angled "Lean-To V-Voids." Immediately move off the center floor span and hug the exterior load-bearing wall, an arched masonry doorway, or an enclosed corner stairwell. If rubble begins falling before you can exit, dive beside a solid load-bearing corner or heavy structural column, curl into a tight ball to protect your ribcage, and pull your shirt over your nose and mouth against dust.

Why is it dangerous to lift a heavy collapsed beam off someone's legs if they have been pinned for more than two hours?¶

When a heavy concrete slab or timber beam crushes and pins a person's legs or pelvis for more than 1 to 2 hours, the oxygen-starved muscle cells break down and trap deadly levels of potassium, myoglobin, and acid inside the legs. If rescuers suddenly jack the beam off the legs without paramedics present, that trapped potassium rushes straight to the heart and causes fatal cardiac arrest within 60 seconds, a medical emergency known as "Crush Syndrome" or reperfusion arrest. Unless fire or rising floodwater forces immediate movement, call 911 and keep the beam stabilized until paramedics arrive to administer IV fluids and heart-protecting medications before lifting.

Metswedi e tlhotlhomisitswe¶

• Federal Emergency Management Agency (FEMA, United States): Urban Search and Rescue (USAR) Field Operations Guide, Structural Collapse Void Types, Marking Systems, and Shoring.
• National Fire Protection Association (NFPA, United States): NFPA 1006 and 1670 Standards for Technical Rescuer Professional Qualifications, Swiftwater Rescue, Low-Head Dam Mechanics, and Confined Space Hazards.
• National Oceanic and Atmospheric Administration (NOAA) & National Weather Service (NWS, United States): Flash Flood Mechanics in Urban Drainage Systems and Engineered Channels.
• United States Fire Administration (USFA, United States): Emergency First Care for Crush Syndrome and Prolonged Entrapment.
• Environment Agency (United Kingdom): Flood Warning Systems, Culvert Hazards, and Urban Waterway Safety.
• Australasian Fire and Emergency Service Authorities Council (AFAC, Australia): Urban Search and Rescue and Flood Rescue Operations Manual.

Dikaedi tse di tsamaelanang¶

• Unhoused survival and extreme weather triage
• Sudden homelessness: first 48 hours and emergency shelter
• Encampment sweeps, property confiscation, and shelter rights
• Merwalela ya tshoganetso
• Tshenyo ya dikago le go phutlhama