Surface Water and Groundwater

• Surface water and groundwater are valuable water resources, but they can also pose hazards.
• It will be able to explain the factors and processes related to surface and underground water, water usage, and the impacts of floods and other related hazards.

Surface Water and Groundwater

• Surface water is the water that collects on the Earth's surface including seas, oceans, streams, lakes, canals, and swamps.
• Seas and oceans are salt water due to their high salt content.
• Streams, lakes, and canals are fresh water, vital for sustaining life on land.
• When rain or snow falls, some water falls directly in the sea and the rest falls on land.
• Some water is absorbed by plants, some evaporates, and some seeps into the soil.
• Runoff is the excess water not absorbed by the surrounding area, which flows into nearby water bodies.
• Groundwater is water beneath the surface in the zone of saturation, where soil particles are saturated with water.
• Above it is the zone of aeration, where soil particles contain both air and water.
• The water table marks the boundary between the zones of saturation and aeration.
• The water table level fluctuates due to changes in the water cycle, precipitation, stream flow, geological events, and human activities.
• Groundwater comes from rain and snow, seeping into the soil until it reaches an impermeable layer where it is stored.
• The soil filters and cleans the water, making groundwater often clean.
• Groundwater and surface water can interchange, as groundwater moves into lakes or streams, and surface water seeps into the ground to become groundwater.
• In dry periods, more groundwater is extracted, while abundant rainfall replenishes it.
• Groundwater can be contaminated by leaky underground tanks, landfills, or excessive fertilizers and pesticides.
• Streams that are steep and fast-flowing are usually narrow and shallow, whereas slow-flowing streams are wider and deeper.

Water Usage and Management:

• Freshwater and groundwater are essential for the survival of living organisms.
• Water is used for irrigation, washing, cleaning, generating electricity, and cooling machinery.
• Conserving both surface water and groundwater reduces water bills, environmental impact, and water treatment costs.
• Ways to conserve water includes washing vegetables in basins, washing full loads of clothes, taking showers instead of baths, fixing dripping taps, collecting rainwater, and using a bucket to wash cars.
• Rainwater can be collected in large-scale reservoirs and catchment areas to help prevent flooding.
• Wastewater can be treated for industrial use.
• Desalination plants can remove salt from seawater to address water insecurity, but this process is expensive
• A spring is a location where groundwater naturally emerges from the Earth's surface, discharging into riverbeds or the sea

Hazards of Surface Water and Groundwater:

• Hazards include surface water flooding, soil erosion, landslides, sinkholes, and land subsidence.

Surface Water Flooding:

• Surface water flooding occurs when runoff cannot be absorbed or drained, resulting in puddles, flowing water, or stagnant water on paved surfaces.
• Heavy rainfall, prolonged wet weather, and saturated soil mainly cause it.
• Urban areas are more prone to flooding due to paved surfaces that restrict water infiltration.
• Factors influencing flood likelihood include rainfall intensity, vegetation cover, steepness, soil type, and drainage system effectiveness.
• Floods negatively affect the economy, environment, and people by destroying infrastructure, displacing people, and disrupting normal life.
• Sediments and minerals deposited by floods can increase soil fertility and replenish water supplies.

Soil Erosion:

• Moving water, like rainwater and streams, is the primary cause of soil erosion.
• Raindrops can break up and displace soil particles of bare soil.
• Runoff removes topsoil, which contains essential nutrients and organic matter.
• Soil loss often goes unnoticed until channels deepen.
• Soil erosion can be reduced by planting vegetation, which stabilizes the soil.
• The roots stabilize and hold the soil firmly, and the leaves reduce the effects of splashing by raindrops.
• Reducing soil surface disturbance, such as tilling, can help, as can building contour drains; this breaks slope length can also breaks slope length.

Landslides:

• Landslides involve the movement of rock and soil down a slope, often triggered by excessive water during monsoons; this weakens the bonding of the soil.and adds extra weight to the slope.
• Contributing factors include erosion, earthquakes, volcanic eruptions, erosion and human activities which can cause property damage, injury, and death.

Sinkholes:

• A sinkhole is a hole formed when the soil collapses into underground cavities.
• This occurs when water dissolves soluble rocks like limestone and rock salt.
• Human activities, like groundwater extraction, mining, construction, broken pipes, improperly compacted soil after excavation work, and heavy traffic, can also create sinkholes.

Land Subsidence:

• Land subsidence is the gradual sinking of land, mainly due to groundwater, oil and natural mineral removal.
• The main reason for subsidence is excessive groundwater extraction.
• Extraction exceeds natural replenishment which reduces water table levels which affects the ability to hold the weight of the soil.
• Land subsidence causes changes in elevation, damage to structures, and increased flood risk.