Watershed Greening and Soil Characteristics

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Questions and Answers

What is the main effect of sand soil on runoff water?

It has no significant impact on runoff dynamics.

It retains water, leading to flooding.

It causes increased erosion and faster runoff.

It absorbs a larger amount of runoff water, reducing flow. (correct)

How do geological conditions influence a watershed?

They determine the size, shape, and drainage characteristics of the watershed. (correct)

They only impact the quality of surface water available.

They do not have any significant influence on watershed characteristics.

They only affect the vegetation types in the watershed.

What happens to evaporation and percolation when rainfall lasts for a longer period but is of low intensity?

Percolation rates drop drastically.

Both evaporation and percolation remain unchanged.

Evaporation increases, while runoff decreases. (correct)

Runoff increases significantly.

What is critical to understand for the implementation of effective watershed management regarding groundwater?

The nature, thickness, and characteristics of aquifers should be understood. Signup and view all the answers

What factors should be considered in the socio-economic survey of watershed inhabitants?

Economic conditions, health, and participation in management. Signup and view all the answers

What are the main classifications of watersheds based on stability?

Fragile, Instable, Stable, Moderately stable Signup and view all the answers

Which indicator is NOT considered when classifying watershed stability?

Fishing capacity Signup and view all the answers

What is the size classification criterion for large watersheds?

More than 2500 km² Signup and view all the answers

Which type of watershed is characterized by a dominant overland flow and is highly sensitive to high-intensity rainfalls?

Small Watersheds Signup and view all the answers

How does the size of a watershed influence its hydrological processes?

Spatial variability of watershed characteristics increases with size. Signup and view all the answers

Which of the following factors does NOT influence watershed classification based on land use?

Intensity of rainfall Signup and view all the answers

What is considered a characteristic of medium-sized watersheds?

They offer easy workability due to accessible approach. Signup and view all the answers

What is characteristic of an agricultural watershed?

High ability to store depression storage Signup and view all the answers

How do urban watersheds primarily affect rainfall runoff?

They modify the natural water flow pattern Signup and view all the answers

In terms of watershed characteristics, how does the channel phase develop with watershed size?

It is well-developed in large watersheds. Signup and view all the answers

What factor contributes to higher surface runoff in mountainous watersheds?

Steep gradients and less porous soils Signup and view all the answers

In forest watersheds, which hydrological process is most dominant?

Evapotranspiration Signup and view all the answers

What is the primary result of tillage operations in agricultural watersheds?

Enhanced soil compactness and reduced infiltration Signup and view all the answers

Why are mountainous watersheds vulnerable to flooding?

Significant meltwater and snow runoff during warmer months Signup and view all the answers

What watershed classification combines two or more types?

Mixed Watershed Signup and view all the answers

What effect do urban watersheds have on soil erosion?

Increase due to impervious surfaces Signup and view all the answers

How does a dry climatic condition prior to rainfall affect runoff?

It increases loss due to infiltration and evapotranspiration. Signup and view all the answers

Which of the following is NOT considered a climatic characteristic affecting runoff?

Basin shape Signup and view all the answers

What is the relationship between rainfall intensity and peak flow disposal?

Higher rainfall intensity increases peak flow disposal. Signup and view all the answers

Which hydrological structures require accurate peak flow assessment?

Dams Signup and view all the answers

What does the basin area primarily reflect in hydrologic analysis?

The volume of water generated from rainfall. Signup and view all the answers

Which component of watershed area contributes directly to streams of order higher than 1?

Inter-basin areas Signup and view all the answers

What does basin geomorphology include?

Basin area, slope, and shape Signup and view all the answers

What is the significance of measuring the drainage area for first-order streams?

It delineates the stream area for hydrologic analysis. Signup and view all the answers

What impact does drainage density have on peak runoff?

Higher drainage density leads to increased peak runoff. Signup and view all the answers

Which land type is primarily beneficial for forestry according to physiographic characteristics?

Hilly tracts Signup and view all the answers

What four factors influence the hydrographic network of a watershed?

Geology, climate, relief, and environment Signup and view all the answers

How is the order of a watercourse determined when two watercourses of the same order confluence?

It obtains the higher order of the two confluencing watercourses. Signup and view all the answers

What role does vegetation cover play in a watershed?

Retards flow and enhances infiltration and interception Signup and view all the answers

Which of the following activities is NOT considered a land use in a watershed?

High-rise building construction Signup and view all the answers

What is the first order of a watercourse defined as?

All watercourses without tributaries Signup and view all the answers

How does land use affect runoff rates in a watershed?

Vegetated areas generally reduce runoff rates. Signup and view all the answers

Study Notes

Vegetation and Watershed Management

Detailed vegetation information is essential for selecting appropriate methods for greening watersheds.

Physiographic Characteristics

Soil

Sandy soils absorb more runoff water, resulting in reduced flow rates.
Clay soils have lower absorption capacities, leading to increased runoff.
Soil properties such as depth, type, moisture, and fertility influence crop growth.

Geology

Rock structure dictates watershed formation, affecting size, shape, drainage, and groundwater conditions.
Geological features, like cracks in rocks, can facilitate rapid underground water flow.
Lakes, swamps, and storage systems help manage excess rainfall.

Hydrology

Availability and quality of surface water are crucial for successful greenery growth in watersheds.
Hydrological factors, including rainfall intensity and duration, define water quantity in a watershed.
Prolonged low-intensity rainfall leads to increased evaporation and percolation, minimizing runoff.

Hydrogeology

Groundwater is vital for irrigation, drinking, and industrial needs due to its purity.
Understanding aquifer characteristics (nature, thickness) aids in watershed planning.

Socio-Economic Characteristics

Surveys of local populations should assess their needs, economic conditions, health, livestock, farming practices, and management participation.
Watersheds classified by land use include:
- Agricultural
- Urban
- Mountainous
- Forest
- Desert
- Coastal
- Mixed (combinations of the above)

Types of Watersheds

Agricultural Watershed

Dominated by agricultural activities and experiences significant land-use changes.
Increased runoff and erosion can result from compaction during barren periods.

Urban Watershed

Characterized by buildings and infrastructure, reducing natural infiltration and increasing runoff.
Vulnerable to flooding due to altered natural drainage patterns.

Mountainous Watershed

Higher altitudes result in substantial snowfall and high surface runoff.
Downstream areas are prone to flooding from snowmelt in warmer seasons.

Forest Watershed

Natural forest cover provides significant interception and moisture retention.
Stability classifications: fragile, unstable, moderately stable, stable, based on various biophysical and socio-economic indicators.

Watershed Classification

Classification based on size, shape, location, groundwater exploitation, and land use.
Two watersheds of similar size may behave differently if land use or channel types vary.

Size Classification

Small Watersheds: < 250 km²; overland flow is dominant.
Medium Watersheds: 250 to 2500 km²; accessible and well-balanced.
Large Watersheds: > 2500 km²; channel phase is prominent with lower sensitivity to short-duration rainfall.

Land Use Characteristics

Land use affects hydrological processes and runoff rates.
Variability in climate and physiographic conditions influences land exploitation patterns.

Climatic Characteristics

Dry conditions before rainfall increase infiltration and evapotranspiration losses.
Intensity and duration of rainfall directly impact peak flow rates.
Accurate peak flow assessments are critical for hydraulic structure design (e.g., dams, weirs).

Hydrographic and Drainage Characteristics

The hydrographic network includes all watercourses influencing runoff.
Key factors affecting the hydrographic network: geology, climate, relief, and environment.
The classification of rivers based on stream order aids in understanding watershed dynamics.

Vegetation Cover

Vegetative cover reduces peak flow by retarding flow and enhancing infiltration.
Essential for protecting soil from erosion and managing runoff effectively.

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Description

This quiz focuses on the significance of vegetation in selecting appropriate methods for greening watersheds. It covers the impact of soil types, moisture, and geological features on water absorption and crop selection. Understand how these factors contribute to effective watershed management.