Evaluation of the Effect of Sewage Irrigation on Groundwater
2020
Xiuli Li and Xiaoyu Li
In areas with water resources shortage, sewage irrigation can alleviate the contradiction between supply and demand for water. However, long-term use of sewage irrigation will affect soil, crops and groundwater. In this paper, irrigation water and groundwater in different irrigation source areas were sampled and analysed respectively to study the effect of sewage irrigation on groundwater. The irrigation water was evaluated for Cl-, Cd, Pb, Cr6+, As, Cu, F-, TP, Hg and Zn as standards for irrigation water quality which along with Nemerow index method were used for comprehensive evaluation. The result of the evaluation is that the water quality of the reclaimed water, domestic sewage and mixed sewage meet the requirements of the agricultural irrigation, and the industrial sewage pollution index is relatively high and less suitable for agricultural irrigation. The fuzzy comprehensive evaluation method was adopted to evaluate groundwater quality, using Quality Standard for Ground Water (GBT14848- 2017) as evaluation factor standard and ammonia nitrogen (NH3-N), chloride (Cl-), nitrate (NO3-N) and nitrite (NO2-N) as evaluation indicators. The results of the evaluation showed that the water quality of 2 monitor wells among the 11 monitor wells was within Category II, 6 within Category III, and 3 within Category IV. With regards to the influence of different irrigation sources on groundwater, the comprehensive evaluation results are reasonable as well. According to the comprehensive membership grades, it can be concluded that the influence of different water sources on groundwater quality, in turn, is reclaimed water < domestic sewage < mixed sewage < industrial sewage. The evaluation results are in line with the actual situation in the study area.
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