Dynamics models to Surface irrigation design

Dynamics models to Surface irrigation design

SUMMARY

Of total of the irrigated surface in Mexico, approximately the 90 per cent correspond it at surface irrigated systems (Furrows, Basins and Borders mainly) being this that report the lowest efficiencies in the water use. For this reason, it is necessary search alternatives to increase this efficiency. The pressurized irrigation systems allow diminish the loss of water, however, the initial investments required limit their use. This panorama show that the surface irrigation is, and it will continue being the principal form of apply the water to corps, therefore, an viable alternative to increase the efficiency of this method, is carry out an appropriate design and handling of the variables that intervene in the irrigation event (flow, irrigation time, watering sheet and geometry of the basin, border or furrows). With the purpose of supporting at the persons interested in the surface irrigation, in this work, is presented the development of a computational program that designing surface irrigation systems making use of the method of balance of volume applied to two points of the advance trajectory, by means of the focus of the numeric solution proposed by Walker (1989), implemented in a friendly environment.

SURFACE IRRIGATION PHASES

1) Advance: Water runs along all the field making wet the ground

2) Storage: Field surface is covered by water and infiltration is carried out.

3) Consumption: Phase from the water supply is stoped till the water over the field desapears

4)Recession: Starts when the wated at the application point desappears and finsh when in the final of the land, water desappers.

Fig. 1. Surface irrigation phases

THE HYDRODYNAMIC MODEL VOLUME VALANCE

Fig. 2. The dynamic surface irrigation model

energy balance:

V= water volume at the begining and end of the irrigation event

Q = total of applied water to the field in the irrigation event

A= Water area

Solution

necesary data

1) Lr = required wet area in the ground (required wet area)

2) Q = water amount that does not erosion field

3) field inclination

4) field length

5) rugosity manning coeficient

6) geometric parameter of irrigation system

7) experimental parameteres water advance test

8) infiltration land specific parameters (Kostiakov-lewis form)