Abstract
To analyze the water-resource limitations for crops in irrigation districts along the lower reach of the Yellow River, we used the single-crop coefficient method provided by FAO-56 to analyze crop water demand (CWD) and irrigation water requirement (IWR) for the main crops (winter wheat, summer maize, and cotton) from 1971 to 2015. The impact of climate threats on IWR was then quantified based on the standardized precipitation evapotranspiration index (SPEI), following which the conflicts between water demand and water supply were analyzed. The results show that about 75.4% of the total annual IWR volume is concentrated from March to June. Winter wheat is the largest water consumer; it used an average of 67.9% of the total IWR volume. The study area faced severe water scarcity, and severe water deficits occurred mainly between March and June, which is consistent with the occurrence of drought. With the runoff from the Yellow River Basin further decreasing in the future, the water supply is expected to become more limited. IWR is negatively correlated with the SPEI. Based on the relationship between SPEI and IWR, the water allocation for irrigation can be planned at different timescales to meet the CWD of different crops.
Highlights
Irrigation districts along the lower reach of the Yellow River is an important grain and cotton base of China
Runoff in the Yellow River Basin will be further reduced under the impact of climate change in the future [1], which will inevitably worsen the conflict between water demand and water supply and will constitute a strong threat to the safety of crop production in the study area
Based on the cropping area in 2000, the average annual total irrigation water requirement (IWR) volume was 131.7 × 108 m3, and precipitation was negatively correlated to total IWR volume
Summary
Irrigation-water sources in this study area include local surface water, groundwater, and water from the Yellow River. Local surface water and groundwater are in short supply and are difficult to use, so water from the Yellow River is the most important irrigation-water source for crop production. The proportion of the water withdrawn from the Yellow River for agriculture has declined since 2001 (Figure 1), which has worsened the water shortage for crop growth in the study area. Runoff in the Yellow River Basin will be further reduced under the impact of climate change in the future [1], which will inevitably worsen the conflict between water demand and water supply and will constitute a strong threat to the safety of crop production in the study area.
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