DRRR - MODULE 1 - 3

• Landslide - a ground movement on a sloping terrain
• Landslide - Does not happen on flat ground
• Landslide - It is aggravated by rain because water is a natural agent for erosion.
• Without plants and trees whose roots can absorb water and hold the soil together, subsequent rainwater can continue to loosen up the soil that anchors the buildings.
• A heavy downpour of rain can quickly destroy these buildings and communities, giving way to landslides, mudslides, or mudflows.
• Areas that are highly vulnerable to landslides: ● structures built on steep-slope mountains
• Areas that are highly susceptible to rainfallinduced landslide hazards: ● steep slope ● dense population ● denuded terrain
• Soil Creep Landslide -very slow downslope movement of particles that occurs in every slope covered with loose, weathered material
• Debris flow landslide - happens when the slope becomes saturated with water, this then triggers a landslide of water-soaked mass of rock and soil that slides down the slope.
• Rock fall landslides - sudden slides caused by heavy rain the rock on the slope loosens and then slides down the slope.
• Sinkhole - a topographic depression created when groundwater dissolves the underlying limestone bedrock.
• Sinkhole - Occur in areas where the soil foundation is made of soft minerals and rocks such as limestone, salt beds, or any acidic rocks.
• Sinkhole -The depth of sinkholes ranges from a couple of meters to several miles deep.
• Water from the rainfall seeps underneath the soil through the cracks and fissures. ➔ As water passes through these cracks and fissures, it erodes the soil and forms a conduit system, these underground water systems increase in size as the soil is carried by the water through internal erosion. ➔ This can either form a void filled with air with an underground drainage. ➔ If the void is clogged with clay, then it forms a depression which then accumulates water and forms a pond. ➔ Otherwise it forms a hole once the cover collapses into the void which can be either filled with air or water
• Cover collapse sinkhole - It develops suddenly (over an hour period) thus, causing catastrophic damage.
• Cover sudsidence sinkhole - It gradually grows where the sediment covers are permeable and contain sand.
• Dissolution sink hole -occurs in areas where calcareous is exposed on the ground or where thin layers of soil and permeable sand are also covere
• Limestone or dolomite dissolution - most intense when the water first reaches the rock surface
• Artificial sinkhole - Such types of sinks may be caused by various human activities, including groundwater pumping and building.
• Signs of impending landslides and sinkholes are observed on man-made infrastructures, bodies of water, and vegetation.
• The Philippines is located in an archipelago characterized by having mountainous terrains and is often visited by typhoons which bring heavy rain.
• Signs of impending landslides and sinkholes are observed on man-made infrastructures, bodies of water, and vegetation.
• Warning signs of an Impending Landslide - 1. Earlier landslide as indicator 2. Tension cracks 3. Things moving 4. Water doing something different
• The most common of these is that trees are bending up in a J-curve as a sign that the ground slips out from underneath them.
• Indicators of slow landslides are categorized by movement of floor tiles, deformation of door frames which causes difficulty in closing and opening the door, and broken electric posts, gas, water and sewage pipes.
• A debris flow is a very wet, very mobile landslide, where water is loaded with trees, mud, rock, and everything else caught in the current.
• A debris flow is a very wet, very mobile landslide, where water is loaded with trees, mud, rock, and everything else caught in the current.
• Hydrometeorological - A process or phenomenon of atmospheric, hydrological or oceanographic nature that may cause loss of life, injury or other health impacts, property damage, loss of livelihoods and services, social and economic disruption, or environmental damage.
• Hydrometeorological hazards - typhoon, thunderstorm, flood, ,flashflood, storm surge, el nino, la nina
• Tropical cyclone - intense circular storm that originates over warm tropical oceans and is characterized by low atmospheric pressure, high winds, and heavy rain
• WEATHER FORECAST is a scientific estimate of future weather condition, wherein a weather condition is a state of the atmosphere at a given time expressed in terms of the most significant variables.
• two forms of the basic weather map: surface map and upper-air map: 1. surface map and 2. upper-air maps
• Weather radars - used to track the position of the atmosphere within radar range.
• UPPER AIR CHARTS - data plotted on this weather map are analyzed using streamline analysis
• NUMERICAL WEATHER PREDICTION MODEL OUTPUT, the computer-plotted weather maps are analyzed manually so that weather systems like cyclones and anticyclones are located
• plotted crosssection data, rainfall charts and 24 hour pressure change charts are analyzed to determine wind wave movement, rainfall distribution and atmospheric pressure behavior.
• Thunderstorm - A powerful, short-lived weather disturbance, almost always associated with lightning, thunder, dense clouds, heavy rain or hail, and fast, roaring winds.
• Thunderstorms- occur when layers of dry, moist air rise to cooler regions of the atmosphere in a broad, rapid updraft
• Cumulus Stage - the sun heats the Earth's surface during the day and warms the air around it
• Mature Stage - A cumulus cloud becomes very large, where the water therein becomes large and heavy, and raindrops begin to fall through the cloud when the rising air can no longer hold them up