Quantification of Water Savings Using Intelligent Irrigation Systems: Application of CROPWAT Model in a Semi-arid Watershed

Abstract:

Agricultural water consumption is a major part of the global water withdrawals. Since the resource demand is expected to increase because of the rapid population growth, it is necessary to optimize the agricultural processes. Intelligent irrigation provides a sustainable solution for this problem. The aim of this study is to evaluate water savings using intelligent irrigation systems in a semi-arid watershed, Ankara creek basin, Turkey. Ankara Creek basin is divided into 6 sub-basins and irrigated area in each sub-basin is determined using ArcGIS. Crop pattern consists of major crops in the area which are small vegetables, green beans, small grains, table grapes, maize, sugar beet, sunflower, and tomato. The climatic data is retrieved from CLIMWAT for CROPWAT database and soil characteristics are determined from literature survey. After collection of the data, water consumption is examined under two scenarios: conventional and intelligent irrigation using CROPWAT model. For conventional irrigation, irrigation schedules for each crop is calculated with respect to irrigation water requirement (IWR) and for intelligent irrigation, irrigation schedule is selected according to the literature research. The results of two scenarios are showed that considering all the crops in each sub-basin, median of water savings is between 30-40% and the total of 39% water savings is achieved in Ankara creek basin. The amount of rainwater used by crop is also increased. In conventional irrigation, crop is irrigated independent from soil moisture, and water retention of soil exceeds field capacity. Since intelligent irrigation system gathers information about the readily available soil moisture and irrigate accordingly, rainwater used by crop is increased according to the rainfall data. Since the results are affected by climatic condition of the area, the amount of water savings may vary accordingly. Therefore, the cost-benefit analysis should be conducted before implementation since water savings may not outweigh the cost of intelligent irrigation system for specific area.

We would like to acknowledge the Scientific and Technological Research Council of Turkey (TÜBİTAK) for providing funding for the project entitled ‘Evaluation of Water, Energy and Food Nexus in Sakarya Watershed’ with project number 116Y166.