Evaluation of Border Irrigation System Efficiencies in Some Fields of Kohgiloyeh and Boyer-Ahmad Province

This study aims to evaluate the present management of border irrigation systems applied to wheat, alfalfa and sugar-beet farms in Boyer-Ahmad and Gachsaran cities in Kohgiloyeh and Boyer-Ahmad Province. Experimental farms included 8 alfalfa farms, 5 wheat farms and 5 sugar-beet farms. The experiments were conducted at different growth stages of plants and customary borders with prevalent dimensions, slopes, and management practices. The relationship between management allowable deficit, moisture deficit before irrigation, and infiltrated depth indicated that in most cases either “deficit irrigation” or “stress irrigation” had been applied. This type of irrigation has positive effects on water use but negative effects on supply of required soil moisture for plants. In the first to third irrigations, measured application efficiencies ranged from 40.8% to 100%, 52.2% to 100%, and 61.1% to 100%, respectively. Graphs of advance, recession, and ideal recession showed the effects of border slope and length on inflow cut time and uniformity of water distribution. Water infiltration curves showed the amount of deficit irrigation. The results showed that weak irrigation management is the result of three parameters: lack of knowledge on the part of farmers about soil moisture conditions and correct time for irrigation, weak irrigation scheduling, as well as an imbalance between available water supply and irrigation requirements which leads to wasting water and reduced irrigation efficiency.