基于模糊综合优化模型的湛江市地下水灌溉适宜性评价

Suitability Evaluation of Groundwater Irrigation in Zhanjiang City Based on Optimization of Fuzzy Synthetic Evaluation

为分析湛江市地下水灌溉适宜性,选取2016年枯水期(3月)与丰水期(9月)共55个地下水样品数据,基于地下水水化学特征分析,运用模糊综合优化模型对灌溉适宜性进行评价,并利用Wilcox、USSL图解法以及参数MHR等单项指标的评价结果进行验证分析。结果表明,湛江市地下水偏酸性,岩石与水的相互作用是控制该区地下水化学的主要机制,Cl·SO4-Ca·Na、HCO3-Na、HCO3-Ca为地下水主要水化学类型。湛江市93%的浅层地下水和41%的中深层地下水适宜灌溉,丰水期地下水整体的灌溉适宜性优于枯水期。USSL图中93%、Wilcox图中94.5%的地下水样品适宜灌溉,但中深层地下水样中59%的MHR、31%的KR、77%的PI偏高,不适宜长期灌溉。农业水资源利用应以浅井开采为主,部分区域不适宜采用本地地下水进行灌溉。

A total of 55 groundwater samples from the 2016 dry season(March) and wet season(September) were collected in the urban area of Zhanjiang City. Based on the analysis of groundwater chemical characteristics and water chemistry type, the optimization of fuzzy synthetic evaluation was used to evaluate the irrigation suitability, with results verified by analysis of Wilcox, USSL graphic method and parameter MHR, PI, KR single index evaluation. The results show that the groundwater is acidic, and the interaction between rock and water is the main mechanism to control the groundwater chemistry in the area. Cl·SO4-Ca·Na、HCO3-Na and HCO3-Ca are the main water chemistry types of groundwater. 93% of shallow groundwater and 41% of medium and deep groundwater in Zhanjiang are suitable for irrigation. The overall irrigation suitability of groundwater in the wet season is better than that in dry season. 93% of groundwater samples in USSL map and 94.5% in Wilcox map are suitable for irrigation, but 59% of groundwater samples’ MHR, 31% of groundwater samples’ KR, and 77% of groundwater samples’ PI in the middle and deep layers are high, which easily destroys the fertility and permeability of the soil, and are not suitable for long-term irrigation. Shallow well mining should be the main way to utilize agricultural water resources, and some areas are not suitable for local groundwater for irrigation.