Προγραμματισμός των αρδεύσεων με εφαρμογή μαθηματικών μοντέλων και συστημάτων γεωγραφικών πληροφοριών

Abstract

Irrigation can double or triple agricultural production. Irrigation provides the farmers security to face the highly uneven distribution of rainfall in amount, time and space. It also stabilizes the quantities and quality of agricultural products. Because of these advantages, irrigation water was treated irrationally without taking into account the high environmental cost of excess irrigation. In Greece irrigation consumes almost 85% of total available water resources of good quality. Rational irrigation scheduling can save large quantities of water. The sustainability of both surface and sub-surface water resources can be secured by the proper management of irrigation water. A software that provides to the irrigation network managers the ability to predict the crops’ irrigation needs is presented in this Thesis. Its core is the mathematical model SWBACROS which solves the well known Richards equation for the prediction of soil water distribution in the soil profile. Soil hydraulic parameters’ spatial variability are considered using the scaling theory. Finally the mathematical model is integrated in ESRI ArcMap 9.x using VB6 and VBA parts of code. This integration enables the analysis of soil hydraulic parameters data and also offers to the user the ability to monitor the changes of both soil water and irrigation needs through a user friendly environment. This software follows a three step procedure: first the irrigation network region is divided in a number of texture and crop homogeneous subregions. Afterwards the subregion’s mean hydraulic properties are calculated. Finally the mathematical model is executed for each subregion. The results show that this software can serve as an environmental tool that can assist irrigation network managers to (a) distribute the network’s water more efficiently and (b) provide clear irrigation advice to farmers on when and how much to irrigate.