Optimal Irrigation Scheduling For Crops:Based On GIS And CROPWAT Application In Hetao District Of Inner Mongolia Autonomous Region, China

Irrigation plays an important role on agricultural development when taking the food supplies into account. Hetao Irrigation District has uneven distributed climatic and an irregular rainfall during the agricultural year. Hetao Irrigation District is plagued by a serious shortage of water resources due to the low and irregular rainfall, representing nearly the global area of the irrigation district. Yellow River is the second largest River in China which is the main sources of water supplies water for nine provinces in the Northwest and North China. The Yellow River basin suffered from severe shortage of water resources, with less than 500 m3 per capita per year. Accounting for 81% of the total water use, the head stream of the Yellow river basin becomes drier due to climate change. In addition increased water supplies for industrial, domestic and hydropower uses exacerbate water scarcity in the basin. Due to this water scarcity conditions the middle and low reaches of the river dried up during 1972-2008, with 226 days of no flow in 1997. This scheduling show the result as follow: Corn: application at 40 mm after 40 mm depletion, sunflower: application at 40 mm evrery 10 days wheat: irrigat at fixed interval per stage (interval days:int 10, dev 10, mid 10, late 10) after fixed application depth at 45 mm, tomato application at critical depletion after refill soil at field capacity. It increase crop yield and achieve water use efficiency of 70% using GIS and CROPWAT software.The main crops of Hetao Districtare corn, sunflower, wheat and tomato. The crop water requirements were determinedby using climatic data (2001-2008) with CROPWAT version 8.0.The planting date for crop were 21/04 2008 for corn,18/04 2008 for sunflower,15/05 2008 for wheat and 22/04 2008 for tomato respectively. The results showed that, the water deficit varied between 247.4 mm/year to 677.5 mm/year from 2001 to 2008; the crop coefficients were determined. The evapotranspiration (ET。) was determined by using the FAO Penman-Monteith method and the effective rainfall was calculated using USDA S.C. Method. The study in the area showed that the evapotranspiration (ET。) varied from 0.47 mm/day to 0.92 mm/day in January-April and 5.73 mm/day to 5.80mm/day during May to July and the effective rainfall variedbetween 75mm to 133.8 mm, with peak rainfall during June in 2008 and between 34.2 mm/year (2001) to 185.8 mm/year (2004)during the study period. The crop water requirements were 312.5 mm/year for corn, 347 mm/year for sunflower,525.1 mm/year for wheat,527.4 mm/year for tomato in 2008 and between 245.6 mm/year and 518.3 mm/year during the study period.