Groundwater abstraction terminology: An Abyssinian tube well is a special type of which well construction?

Introduction / Context:
Abyssinian tube wells are small-diameter, shallow wells used widely for rural and emergency water supply. Understanding how they differ from other well types (cavity, slotted, dug-cum-bore, artesian) is important for source selection, screen design, and maintenance planning.

Given Data / Assumptions:

• Driving depth is limited to shallow aquifers with adequate yield.
• Well consists of a small-diameter pipe with a screened (strainer) section at the bottom.
• Often installed by driving or jetting with a hand pump attached.

Concept / Approach:
An Abyssinian well employs a strainer (screen) to admit water while excluding sand. The assembly is driven into a permeable formation. The screen aperture and slot size are selected relative to the aquifer grain-size curve to minimize sand pumping. This is characteristic of strainer type wells, not cavity type wells (which rely on a developed cavity in coarse strata) or slotted terminology used differently in large-diameter tubewells.

Step-by-Step Solution:

Verification / Alternative check:
Field practice confirms that maintenance involves screen cleaning and ensuring the foot-valve and hand pump remain airtight to maintain suction.

Why Other Options Are Wrong:

• Slotted type well: generic phrasing, but Abyssinian specifically denotes strainer use with small-diameter driven pipes.
• Cavity type well: depends on developing a cavity in coarse formations; not the Abyssinian method.
• Dug-cum-bore well and artesian well: different construction and hydraulic behavior.

Common Pitfalls:
Using too fine a screen (excessive headloss) or too coarse (sand carryover); trying to install in tight clays with negligible yield.

Final Answer:
Strainer type well