UNIT 6

Question 1

Land surfaces are repshaped as necessary to eliminate ponding and establishbslopes sufficient tominduce gravitstional flow overland through channels toman outlet.

Answer 1

Surface drainage

Question 2

Ditches and buried drains are installed within the soil profile to collect and convey excess groundwater to a gravity or pumped outlet.

Answer 2

Subsurface drainage

Question 3

These drains are used to prevent entry upon the land when the groundwater moves laterally.

Answer 3

Interceptor Drains

Question 4

These drains are used when land surfaces are flat, low flow velocities, or ineffective groundwater interception.

Answer 4

Relief Drains

Question 5

This design criteria is based on experience and assessments of various factors.

Answer 5

Empirical Criteria

Question 6

A design criteria wherein proven principles to problems with known limiting conditions, allowing the rational design of new systems.

Answer 6

Theoretical Analysis

Question 7

Removing excess water in soil requires expensive installation and regular maintenance to ensure effective water removal.

Answer 7

Subsurface-drainage problems

Question 8

The water table in valley bottoms and wide bench lands is a slow-moving body of groundwater.

Answer 8

Basin-type free-water table

Question 9

Confined in aquifers with higher pressure surfsces, causing upward flow and seepage.

Answer 9

Water table over an artisan aquifer

Question 10

In stratified soil, a subsurface drainage problem occurs when excess water in the root zone is held up by a layer of low permeability, disconnecting it from groundwater.

Answer 10

Perched Water Table

Question 11

Subsurface drainage issues thsat involve horizontal groundwater percolation within crop root zones.

Answer 11

Lateral groundwater flow problems