| Author | Pathmarajah, Selvarajah |
| Call Number | AIT Diss. no.WM-95-01 |
| Subject(s) | Irrigation farming--Environmental aspects
|
| Note | A dissertation submitted in partial fulfillment of the requirement for the degree of Doctor of Technical Science, School of Civil Engineering |
| Publisher | Asian Institute of Technology |
| Series Statement | Dissertation ; no. WM-95-01 |
| Abstract | Rice is the main food crop in most of the Asian countries wherein large areas are under
rice cultivation. The use of pesticides in rice production activities in these areas has been
increasing recently to sustain the yields.
In this study, theoretical and experimental studies were carried out to evaluate the nature
of contribution by ricefields to surface water contamination with pesticide residues. A
mathematical model was developed to simulate the effect of managerial and environmental factors
on the movement of the pesticides that were applied to a lowland ricefield. The model was based
on the mathematical functions which govern the surface water movement and pesticide
degradation and adsorption processes.
Experimental approach included two components where field plot experiments were
carried out in the Asian Institute of Technology (AIT) experimental field and actual field
investigations were carried out in the Tha Maka sub-project of the Mae Klong irrigation project,
Thailand. The field plot experiments were conducted to determine the model parameters and
obtain the data required to calibrate the model.
Water quality monitoring at Mae Klong included EC, pH, N03 , K, P and three relatively
hazardous and commonly used pesticides namely methyl parathion, monocrotophos, and
carbofuran. Intensive studies at AIT experimental field were carried out with methyl parathion
and monocrotophos.
The inorganic parameters that were monitored indicated that the levels present in
irrigation and drainage waters are acceptable for eutrophication and irrigation reuse. However,
it may vary due to the site specific characteristics of the point of monitoring. Present information
indicates that pesticides under certain conditions could pose environmental contamination
problems. However, the adverse effects could be reduced considerably by proper water
management and proper application of pesticides in relevant to irrigation and drainage in
ricefields.
The model calibration and verification experiments indicated a good agreement between
observed and simulated values for evapotranspiration, ponding water depth, and pesticide
concentration in ponding water. The model was applied to hypothetical field situations formulated
using different areas in combination with various management and environmental factors. It was ยท
demonstrated that the model can be a valuable tool in evaluating the effect of unforseen rainfall,
improper management of irrigation water, and inappropriate rate and timing of pesticide
application on the movement of applied pesticides under lowland ricefield conditions. |
| Year | 1995 |
| Corresponding Series Added Entry | Asian Institute of Technology. Dissertation ; no. WM-95-01 |
| Type | Dissertation |
| School | School of Engineering and Technology |
| Department | Department of Civil and Infrastucture Engineering (DCIE) |
| Academic Program/FoS | Water Engineering and Management (WM) |
| Chairperson(s) | Murty, V.V.N.
; |
| Examination Committee(s) | Ammentorp, C. H.;Visvanathan, C.; |
| Scholarship Donor(s) | German Academic Exchange Program (DAAD) ; |
| Degree | Thesis (Ph.D.) - Asian Institute of Technology, 1995 |