Drainage of Agricultural Lands - Practices of Irrigation and On-farm Water Management - page 373

where h v is the head in the piezometer in the vicinity of the drain pipe (usually 40 cm
away from the drain center). The approach flow resistance ( W ap )is

W ap = h ap / qL

where q is the specific discharge (m 3 /d/m) and L is the drain spacing (m).
Measured data can be expressed in equation similar to Hooghoudt equation.
Rimidis and Dierickx ( 2003 ) expressed their experimental evaluation data in the
form:

Ah t q = + Bh t

The above equation is similar to the well-known equation of Hooghoudt ( 1940 ) :

4 Kh t
L 2

8 Kdh t
L 2

q = +

where

L 2 , and B 8 Kd / L 2

A = 4 K / =

9.12 Challenges and Needs in Drainage Design and Management

To meet the challenge of a sustainable irrigated agriculture, minimum impact on the
environment should be ensured. Controlled drainage, a comparatively new approach
of drainage management, is suffering from lack of design criteria for both humid and
arid regions. Ayars et al. ( 2006 ) urged for development of new design criteria and
management methods for controlled drainage system that should have minimum
impact on environment.
Drain installation and maintenance still require a huge investment and skill oper-
ators. Low-cost drainage material with robustness should be sought in order to bring
the technology to common farmers, who need it.

Relevant Journals

- Trans. ASAE
- Journal of Irrigation & Drainage Engg., ASCE
- ASAE Papers
- Land Management and Reclamation
- Irrigation and Drainage System
- Applied Engineering in Agriculture
- Irrigation Science